Hello my name is Jayden these are my facts about River Ecosystem


  • Flowing water that is mostly unidirectional
  • A state of continuous physical change
  • Many different and changing ) micro habitats
  • variability in the flow rates of water
  • plants and Animals that have adopted to live with water flow conditions.




ecosytem- an ecosyten includes all of the living things

(plants animals and oranisms.




community- community is a group of people living or working

together in the same things they also help.




population- is the whole number of people living in a cuntry city

or are a group of people animals.



Niche- a job activity etc that is very suitable for someone.




biome- a large naturally occurring community of flora and

fauna occupying





habitat- the place or type of place where a plant or animal naturally or

normally lives or grows




adaptation-something that is adpted especially a movie book play etc.















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Hello my name is Rainell Tejeda from class 5-777 here are some facts about River Ecosystem


1. The ecology of the river refers to the relationships that living organisms have with each organisms have with each other and with there environment the ecosystem an ecosystem is the sum of in between plant animal and microorganisms and between them and non living physical and chemical component in a particular natural environment.

2. Flow is unidirectional there is high degree of spatial and temporal variability between systems is quite high the biome is specialized to live with flow conditions heterogeneity at all scales cohabitants.

3. Over 70 percent of the world is covered with water – that’s a lot of beaches for you beach lovers. Until the year 2000, there were only four oceans – the Pacific, the Atlantic, the Indian and the Arctic Oceans.

4. In 2000, scientists labeled a new ocean, the Southern Ocean, which is near Antarctica. The truth is, there’s only one ocean, because all the oceans run into each other, but scientists have labeled the various areas of the ocean by different names.

5. Not only do oceans provide a home for thousands of plants and animals, they also help regulate the earth’s weather and temperature. The oceans keep the earth warmer in the winter and cooler in the summer.




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river ecosystem food chain




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river ecosystem food web

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river ecosystem food pyramid



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Hello my name is Jose Luis Ventura from class 5-999

Today I will provide you some facts about Rivers
rivers and streams are of ten called lotic ecosystems this means that they have flowing waters unlike the still waters of ponds and lakes this biome can vary in size rivers normally contain freshwater the word upriver or upstream) refers to the direction of the rivers water source while downriver or down stream refers to the direction in which the water flows i.e. towards the end of the rlver rivers have many uses which include fishing bathing transport.
Here are some definitions that you should know:
what is an ecosystem?A biological community of interacting organisms and their physical environment.
what is a population?all the inhabitants of a particular town area or country.
what is a community? a group of people living in the same place or having a particular characteristic in common.
what is a niche? a shallow recess especially one in a wall to display a statue or other ornament.
what is a biome? a large naturally occurring community of flora and fauna occupying a major habitat e.g. forest or tundra.

HERE ARE SOME PICTURES ABOUT RIVER ECOSYSTEM


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THIS IS THE FOOD CHAIN IN THE RIVER ECOSYSTEM


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This is the River Ecosystem Pyramid

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Facts about Rivers by: Kayla Jones

  • Small rivers often have different names which include Creek,Stream,and Brook.
  • Most of the worlds major cities are located near banks or rivers
  • The Ganges,Yangtze and Indus rivers are the most polluted rivers on earth
  • Rivers normally contain fresh water
  • The second largest river in the world is the Amazon river, it reaches around 6,400 Kilometers (4,000) in length.

hi my name is Fernando and i am working on the river ecosystem and my partners are Tristan and Alex

The text that I got online are fine because do to the river
facts that it rains often. The river is a large amount of water
that many fish and in some places there can even be dolphins. The animals
can be dangerous but the animals also can be trained.Some animals in the amazon river
are nice and do not hurt any boy when they get hurt. The river is a nice place filled with water
but this is the point of the following passage to under stand whats in the river ecosystem.






Diagrams

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Flow Diagram

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Ecosystem:A system formed by the interaction of a community of organisms with their enviroments.

Population:The number or body of inhabitants of a particular race or class in a place.

Community:A social group of any size whose members reside in a specific locality.

Niche:The position or function of an organisms in a community of plants and animals.







Hi my name is Aleksander Yrrizarry.
I will be working on the river ecosystem.
My partners are Tristan Wong and Fernando Paulino.

By:Tristan Wong

Information from National Geographic, The Ducksters, Others
Rivers are all aquatic ecosystems. Critical elements of Earth's dynamic processes and essential to human economies and health. They serve as important transportation, recreation, and wildlife hubs.Learning more about the ecosystem within your watershed, like all the water in your region drains to the same point.
This can help you better understand how everything is connected.Like what is at stake with freshwater pollution and drought.


By: Aleksander Yrrizarry Summary

A river is a natural watercourse. A river simply flows into the ground or dries up completely at the end of it's course. Small rivers may be called stream, creak, brook, rivulet or rill. Rivers are part of the hydrological cycle.A river ecosystem includes such elements as the flowing water; the river bed and shoreline; the air above them; and various forms of life. Animals are important members of an ecosystem. They benefit from it and contribute to its well- being.The Nile River reaches around 6650 in length.





THIS IS A PICTURE OF THE NILE RIVER



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Info

The longest river in the USA is the Missouri river.Stretching 2340 miles in length.You can protect rivers by not throwing garbage in them.Some of the animals that live in rivers may eat the garbage.When they eat it they die.One of those animals may be the Water rat.

Picture of Water rat









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Detail Summary




A river ecosystem provides a home for such animals as freshwater fish, frogs, salamanders, turtles and even an occasional dolphin. Various insects live in rivers, such as the water strider and the mayfly larva. A healthy river ecosystem has a food chain that provides food for all, with such plankton as diatoms and heliozoans on the bottom and ducks and otters farther up. Such animals as the mink occasionally come to fish, and deer come to drink.Animals promote the health of river ecosystems. Beaver dams provide a haven for plants and animals that prefer quiet waters rather than a rushing stream. Manatees sometimes clean up a river that is clogged with aquatic weed. Over 1,000 years people have been putting dams to damage the ecosystem of the river by not letting fish and other kind of animals past through the dam for more fish to be born sometimes they do have a hole for fishes to go trough but some times they might die with bad water preasher.





by:fernando paulino


A river is a natural watercourse,[1] usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely at the end of its course, and does not reach another body of water. Small rivers may be called by several other names, includingstream, creek, brook, rivulet, and rill. There are no official definitions for generic terms, such as river, as applied to geographic features,[2] although in some countries or communities a stream may be defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in the United States, "burn" in Scotland and northeast England, and "beck" in northern England. Sometimes a river is defined as being larger than a creek,[3] but not always: the language is vague.[4]

Rivers are part of the hydrological cycle. Water generally collects in a river from precipitation through a drainage basin from surface runoff and other sources such as groundwater recharge, springs, and the release of stored water in natural ice and snowpacks (e.g. from glaciers). Potamology is the scientific study of rivers while limnology is the study of inland waters in general.

No extraterrestrial rivers are currently known, though large flows of hydrocarbons described as rivers have recently been found on Titan.[5][6] Channels may indicate past rivers on other planets, specifically outflow channels on Mars[7] and are theorised to exist on planets and moons in habitable zones of stars.

A river begins at a source (or more often several sources) and ends at a mouth, following a path called a course. The water in a river is usually confined to a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Floodplains may be very wide in relation to the size of the river channel. This distinction between river channel and floodplain can be blurred, especially in urban areas where the floodplain of a river channel can become greatly developed by housing and industry.





Rivers can flow down mountains, through valleys (depressions) or along plains, and can create canyons or gorges.

The term upriver (or upstream) refers to the direction towards the source of the river, i.e. against the direction of flow. Likewise, the term downriver (or downstream) describes the direction towards the mouth of the river, in which the current flows.

The river channel typically contains a single stream of water, but some rivers flow as several interconnecting streams of water, producing a braided river. Extensive braided rivers are now found in only a few regions worldwide, such as the South Island of New Zealand. They also occur on peneplains and some of the larger river deltas. Anastamosing rivers are similar to braided rivers and are also quite rare. They have multiple sinuous channels carrying large volumes of sediment. There are only two cases in the world[citation needed] of rivers dividing and the resultant flows ending in different seas: one of these is the Bifurcation of Nerodime river in Kosovo.

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The River Cam from the Green Dragon Bridge, Cambridge UK

A river flowing in its channel is a source of energy which acts on the river channel to change its shape and form. In 1757, the German hydrologist Albert Brahmsempirically observed that the submerged weight of objects that may be carried away by a river is proportional to the sixth power of the river flow speed.[8] This formulation is also sometimes called Airy's law.[9] Thus, if the speed of flow is doubled, the flow would dislodge objects with 64 times as much submerged weight. In mountainous torrential zones this can be seen as erosion channels through hard rocks and the creation of sands and gravels from the destruction of larger rocks. In U-shaped glaciated valleys, the subsequent[clarification needed] river valley can often easily be identified by the V-shaped channel that it has carved. In the middle reaches where a river flows over flatter land, meanders may form through erosion of the river banks and deposition on the inside of bends. Sometimes the river will cut off a loop, shortening the channel and forming an oxbow lake or billabong. Rivers that carry large amounts of sediment may develop conspicuous deltas at their mouths. Rivers whose mouths are in saline tidal waters may form estuaries.

Throughout the course of the river, the total volume of water transported downstream will often be a combination of the free water flow together with a substantial volume flowing through sub-surface rocks and gravels that underlie the river and its floodplain (called the hyporheic zone). For many rivers in large valleys, this unseen component of flow may greatly exceed the visible flow.

Subsurface streams


Most but not all rivers flow on the surface. Subterranean rivers flow underground in caves or caverns. Such rivers are frequently found in regions with limestonegeologic formations. Subglacial streams are the braided rivers that flow at the beds of glaciers and ice sheets, permitting meltwater to be discharged at the front of the glacier. Because of the gradient in pressure due to the overlying weight of the glacier, such streams can even flow uphill.

Permanence of flow


An intermittent river (or ephemeral river) only flows occasionally and can be dry for several years at a time. These rivers are found in regions with limited or highly variable rainfall, or can occur because of geologic conditions such as a highly permeable river bed. Some ephemeral rivers flow during the summer months but not in the winter. Such rivers are typically fed from chalk aquifers which recharge from winter rainfall. In England these rivers are called bournes and give their name to places such as Bournemouth and Eastbourne.

Classification


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Nile River delta, as seen from Earth orbit. The Nile is an example of a wave-dominated delta that has the classic Greek letter delta (Δ) shape after which river deltas were named.



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A radar image of a 400-km river of methane and ethane near the north pole of Saturn's moon Titan.

Rivers have been classified by


Rivers throughout Massachusetts are running at record low levels this spring, the result of one of the warmest and driest winters on record. If these drought conditions continue into the summer, many environmental advocates and state officials worry that river levels will be too low for resident fish to survive and for migratory fish to spawn.

Meanwhile, the public comment period just closed for the state's Sustainable Water Management Initiative (SWMI). Recently, ORI delivered a letter with many comments signed by over 1,000 members. We also collaborated with 24 signatory organizations on the letter from the Massachusetts Rivers Alliance. While SWMI is the result of much collaborative work and represents a big step towards ecosystem-based management, it also encourages municipalities to draw more ground water than we think watersheds can sustain in an average rainfall year. And, the regulators do not account for water taken by private and corporate wells!

It seems wrong for the state to encourage taking more water with a liberal water usage permitting process when we have made progress in conserving water in Massachusetts. Over the last two decades water usage in the MWRA service area has gone down over 100 million gallons per day. Withdrawals of more groundwater can more greatly overwhelm sewage treatment operations. In March 2010, extraordinarily high rainfall caused approximately 15 million gallons of sewage to spill from the Deer Island wastewater treatment plant into Boston Harbor. We certainly do not need more of that! Conservation and responsible water use is good for both ends of the pipeline
  • he longest river in the world is the Nile River, it reaches around 6650 kilometers in length (4132 miles). More Nile River facts.
  • The second longest river in the world is the Amazon River, it reaches around 6400 kilometres in length (4000 miles). More Amazon River facts.
  • The longest river in the USA is the Missouri River, stretching around 2,340 miles (3,770 km) in length (slightly longer than the Mississippi River). The two combine to form the longest river system in North America, reaching around 3902 miles in length (6275 km). More Mississippi River facts.
  • Small rivers often have different names which include creek, stream and brook.
  • Rivers normally contain freshwater.
  • The word upriver (or upstream) refers to the direction of the river’s water source, while downriver (or downstream) refers to the direction in which the water flows, i.e. towards the end of the river.
  • Rivers have many uses which include fishing, bathing, transport, rafting and swimming among others.
  • Most of the world’s major cities are located near the banks of rivers.
  • The Ganges, Yangtze and Indus rivers are three of the most polluted on Earth.
  • The University Boat Race is held every year on the Thames River in London between the Oxford University Boat Club and the Cambridge University Boat Club. The crews feature eight members who battle it out on the 6,779 m (4 miles and 374 yards) course.
  • The Colorado River travels through the south western United States and north western Mexico, it is home to the famous Hoover Dam.
  • On January 15 2009, a US Airways plane successfully made an emergency landing in the Hudson River that runs through New York. After being hit by birds, the pilot of flight 1549 managed to land the plane in the river with the loss of no lives.

Mississippi River Overview

The Mississippi River is one of the world’s major river systems in size, habitat diversity and biological productivity. It is the third longest river in North America, flowing 2,350 miles from its source at Lake Itasca through the center of the continental United States to the Gulf of Mexico.
When compared to other world rivers, the Mississippi-Missouri River combination ranks fourth in length (3,710 miles/5,970km) following the Nile (4,160 miles/6,693km), the Amazon (4,000 miles/6,436km), and the Yangtze Rivers (3,964 miles/6,378km). The reported length of a river may increase or decrease as deposition or erosion occurs at its delta, or as meanders are created or cutoff. As a result, different lengths may be reported depending upon the year or measurement method.

Length

For reasons mentioned above there are competing claims as to the Mississippi's length. The staff of Itasca State Park at the Mississippi's headwaters say the river is 2,552 miles long. The US Geologic Survey has published a number of 2,300 miles, the EPA says it is 2,320 miles long, and the Mississippi National River and Recreation Area suggests the river's length is 2,350 miles.

Width

At Lake Itasca, the river is between 20 and 30 feet wide, the narrowest stretch for its entire length. The widest part of the Mississippi can be found at Lake Winnibigoshish near Bena, MN, where it is wider than 11 miles. The widest navigable part of the Mississippi is Lake Pepin, where it is approximately 2 miles wide.
Speed

At the headwaters of the Mississippi, the average surface speed of the water is near 1.2 miles per hour - roughly one-third as fast as people walk. At New Orleans the river flows 3 miles per hour on average.
Mississippi River Watershed

Mississippi River Watershed

The Mississippi River watershed is the fourth largest in the world, extending from the Allegheny Mountains in the east to the Rocky Mountains in the west. The watershed includes all or parts of 31 states and 2 Canadian Provinces. The watershed measures approximately 1.2 million square miles, covering about 40% of the lower 48 states.
Water Supply

Communities up and down the river use the Mississippi to obtain freshwater and to discharge their industrial and municipal waste. We don't have good figures on water use for the whole Mississippi River Basin, but we have some clues. A January 2000 study published by the Upper Mississippi River Conservation Committee states that close to 15 million people rely on the Mississippi River or its tributaries in just the upper half of the basin (from Cairo, IL to Minneapolis, MN). A frequently cited figure of 18 million people using the Mississippi River Watershed for water supply comes from a 1982 study by the Upper Mississippi River Basin Committee. The Environmental Protection Agency simply says that more than 50 cities rely on the Mississippi for daily water supply.
Commerce

Agriculture has been the dominant land use for nearly 200 years in the Mississippi basin, and has altered the hydrologic cycle and energy budget of the region. The agricultural products and the huge agribusiness industry that has developed in the basin produce 92% of the nation's agricultural exports, 78% of the world's exports in feed grains and soybeans, and most of the livestock and hogs produced nationally. Sixty percent of all grain exported from the US is shipped on the Mississippi River through the Port of New Orleans and the Port of South Louisiana.
In measure of tonnage, the largest port district in the world is located along the Mississippi River delta in Louisiana. The Port of South Louisiana is one of the largest volume ports in the United States. Representing 500 million tons of shipped goods per year (according to the Port of New Orleans), the Mississippi River barge port system is significant to national trade.
Shipping at the lower end of the Mississippi is focused on petroleum and petroleum products, iron and steel, grain, rubber, paper, wood, coffee, coal, chemicals, and edible oils.
Feature Icon Background Information

To move goods up and down the Mississippi, the U.S. Army Corps of Engineers maintains a 9-foot shipping channel from Baton Rouge, LA to Minneapolis, MN. From Baton Rouge past New Orleans to Head of Passes, a 45 foot channel is maintained to allow ocean-going vessels access to ports between New Orleans and Baton Rouge.
Volume

At Lake Itasca, the average flow rate is 6 cubic feet per second. At Upper St. Anthony Falls, the northern most Lock and Dam, the average flow rate is 12,000 cubic feet per second or 89,869 gallons per second. At New Orleans, the average flow rate is 600,000 cubic feet per second.

Feature Icon Background Information

There are 7.489 gallons of water in a cubic foot. One cubic foot of water weighs 62.4 pounds. A 48 foot semi-truck trailer is a 3,600 cubic foot container.
At Lake Itasca, it would take 10 minutes for one semi-trailer of water to flow out of the lake into the Mississippi.

At St. Anthony Falls, the equivalent of 3 semi-trailers full of water go over the falls every second.

At New Orleans, the equivalent of 166 semi-trailers of water flow past Algiers Point each second.

Wildlife

The Mississippi River and its floodplain are home to a diverse population of living things:
At least 260 species of fish, 25% of all fish species in North America;

Forty percent of the nation's migratory waterfowl use the river corridor during their Spring and Fall migration;

Sixty percent of all North American birds (326 species) use the Mississippi River Basin as their migratory flyway;

From Cairo, IL upstream to Lake Itasca there are 38 documented species of mussel. On the Lower Mississippi, there may be as many as 60 separate species of mussel;

The Upper Mississippi is host to more than 50 mammal species;

At least 145 species of amphibians and reptiles inhabit the Upper Mississippi River environs.
What is a river?

A river is a flowing, moving stream of water. Usually a river feeds water into an ocean, lake, pond, or even another river. Rivers can vary in size and there is no hard definition or rule on how big a flow of water must be to be categorized as a river. Water from a river can come from rain, melting snow, lakes, ponds, or even glaciers. Rivers flow downhill from their source. They are considered part of thefreshwater biome.

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Nile River going through Cairo, Egypt

The 10 longest rivers in the world are:

1. Nile - The Nile River is 4,135 miles long. It is located in the continent of Africa, mostly in the countries of Egypt and Sudan. It flows north into the Mediterranean Sea.

2. Amazon - The Amazon River is 3,980 miles long. It is located in the continent of South America and flows through several countries including Brazil, Venezuela, Bolivia, and Ecuador. It ends at the Atlantic Ocean.

3. Yangtze - Located in China, the Yangtze River is 3,917 miles long and flows into the East China Sea.

4. Mississippi, Missouri - The river system of the Mississippi River and the Missouri Rivers is the longest river system in North America at 3,902 miles. It flows south into the Gulf of Mexico.

5. Yenisei - The Yenisei River starts in Mongolia and flows through Russia to the Kara Sea in the Arctic Ocean. It is 3,445 miles long.

6. Yellow - At 3,398 miles long, the Yellow river is the 6th longest river in the world, but only the 2nd longest in China. It ends at the Bohai Sea.

7. Ob, Irtysh - The river system of the Ob River and the Irtysh River is 3,364 miles long. It flows through Russia, China, and Mongolia on its way to the Gulf of Ob.

8. Congo - The Congo River flows 2,922 miles through several countries in Africa before reaching the Atlantic Ocean.

9. Amur - The Amur River is 2,763 miles long. It flows through Russia, China, and Mongolia and ends at the Sea of Okhotsk.

10. Lena - The Lena River flows through Russia on its way to the Laptev Sea in the Arctic Ocean. It is 2,736 miles long.

Mississippi River
Mississippi River

Mississippi River
Fun Facts About World Rivers
  • There are 76 rivers in the world over 1000 miles long.
  • A lot of people think that rivers always flow south, but 4 of the 10 longest rivers in the world flow north.
  • The United States alone has around 3.5 million miles of rivers.
  • Four of the top 10 longest rivers flow through Russia at some point.
  • Four of the top 10 longest rivers flow through China at some point as well.
  • World Rivers have been a great source of trade and transport throughout human history.

Ohio River Facts

The River and Its Watershed

    • The Ohio River is 981 miles long, starting at the confluence of the Allegheny and the Monongahela Rivers in Pittsburgh, Pennsylvania, and ending in Cairo, Illinois, where it flows into the Mississippi River.
    • The Ohio River flows through or borders six states: Illinois, Indiana, Kentucky, Ohio, Pennsylvania, and West Virginia. In addition, water from parts of New York, Virginia, North Carolina, Tennessee and Alabama drain into tributaries that empty into the Ohio.
    • The Ohio River is the source of drinking water for more than three million people.
    • Over 25 million people, almost 10% of the US population, live in the Ohio River Basin.
    • There are 20 dams on the Ohio River, managed by the Army Corps of Engineers. The dams have greatly changed the flow of the river, creating a series of very slow moving pools rather than a free flowing river. This makes the river muddier, which is harmful to benthic (bottom-dwelling) organisms. In addition, the Corps regularly dredges the river, disrupting wildlife and increasing turbidity.

What is Happening to the Ohio River

    • During rainstorms, raw sewage is discharged directly into the river at over 1,350 points along the river. A result is that stretches of the Ohio River near many major cities are closed to swimming.
    • Non-point source pollution from urban runoff and agricultural activities contributes significant amounts of contaminants to the river.
    • Acid mine drainage (AMD) is a major source of water quality problems for the upper Ohio River and its tributaries. (As water runs through old mines, it becomes contaminated with sulfur and high concentrations of metals.)
    • Many sections of the Ohio River do not meet water quality standards for bacteria and pathogens, PCBs, lead, mercury, metals, organics and other pollutants.
    • Approximately 164 species of fish have been found in the Ohio River. However, the dams have drastically altered the habitat for river organisms, as they prevent fish and other organisms from moving up and down the river in their natural cycles.
    • 80 species of mussels once lived in the Ohio River. Currently only 50 species occur and 5 of those are in danger of extinction.
    • There are fish consumption advisories in place for the entire length of the river. Carp and catfish should not be eaten at all, and limited consumption advisories are in place for other types of fish including smallmouth buffalo (1 meal/month) white bass, drum, sauger, black bass (1 meal/week)The foodweb below, therefore, should be viewed as just one blurry look at a foodweb. It describes a small river in the Pacific Northwest of the United States. Although you can see that is quite complex, still a number of animals have been left out of it.

      PNW foodweb
      PNW foodweb
      In foodwebs like this one, an arrow is drawn from "dinner" to the "diner." That is, whoever the arrow is pointing at is eating the animal or plant that is pointing the arrow. So you can see, plants, fungus, and bacteria are on the bottom of the web, and the "top predators," whom no one else eats, are at the top (like bears and bald eagles).
      Here is another very simplified foodweb, this one of a medium-sized Southwestern U.S. river.

      SW foodweb
      SW foodweb
      The term aufwuchs (pronounce: OWF-vooks) that you see in the above diagram is used to describe the fuzzy, sort of furry-looking, slimy green coating that you see on objects like plant stems below water. It consists not only of algae like Chlorophyta, but also diatoms, protozoans, bacteria, and fungi. An animal may be so tiny it can only graze on aufwuchs--but it contains plenty of protein and other nutrients.
      Even here, we leave out an important consumer: the scavenger! When a bear dies, it may be picked apart by vultures. When the vulture dies, it is eaten by insects, fungus, and bacteria, and eventually the ultra-processed "nutrients" may be washed back into the stream, for other life-forms to use. Some stream residents are scavengers as well, including catfish and crayfish. Other important parts of the foodweb are feces--the waste products of other animals--as well asscales that have been shed by fish, and the body parts, exuviae (outer shell, or exoskeleton, that is shed by an insect nymph during metamorphosis), and pupa cases of insects. Finally, parasites infiltrate the foodweb at every level.


      There is so much diversity in eating habits within the orders of immature insects, like mayflies, caddisflies, stoneflies, and true flies, that it makes more sense to lump them into guilds. One particular group of insects, with representatives from several different orders--or maybe all of them!--will be called Scrapers, for example. These insects all have mouthparts that allow them to scrape algae and diatoms off of rocks and wood, and whether they are mayflies or true flies, we'll still call them Scrapers. In the foodweb above, you'll see that some of the words are in boldface type, with asterisks: Scrapers, Predators, Collectors, Shredders, and Filterers. These are some of the guilds to which we might assign insect larvae and nymphs.
      A lot of the food that is eaten grows right in the stream, like algae, diatoms, nymphs and larvae, and fish. This food that originates from within the stream is called autochthonous (ah-TAHK-the-nuss). Most food in a stream, however, comes from outside the stream. Leaves fall from bushes and trees. Worms drown in floods and get washed in. Leafhoppers and caterpillars fall from trees. Adult mayflies and other insects mate above the stream, lay their eggs in it, and then die in it. All of this food from outside the stream is called allochthonous (al-AHK-the-nuss).
      Insects that have fallen in are ready-to-eat, and may join exuviae, copepods, dead and dying animals, rotifers, bacteria, and dislodged algae and immature insects in their float downstream to a waiting hungry mouth. This swarm of edible foodstuffs that travels downstream is an important source of food to trout and juvenile salmon, and is called (reasonably enough) drift.
      Leaves that fall in are not ready to eat. They must be processed. A host of microorganisms takes over, covering each leaf with a slimy coating, and these begin the process of decay. The tiny organisms include bacteria, fungi (especiallyHyphomycetes), and protozoa. They essentially cause the leaf to break down, to decay into smaller and more easily digested fragments. A crayfish comes along, and eats the leaves: it is not looking for plant material, but rather the organisms that coat the leaves. It digests its food, excretes it, and the leaf floats on downstream in the form of smaller particles. A big stonefly may get the next particle and shred it (we would call this stonefly a Shredder). It gets what it wants and sends even smaller particles downstream, to a waiting mayfly, who collects it (we call the mayfly a Collector), and sends even tinier fragments downstream. These tiny fragments may be filtered out of the water by a true fly larva, and we'll call that larva a Filterer
      Did you Know? List of Interesting Facts about Rivers

      Facts are statements which are held to be true and often contrasted with opinions and beliefs. Our unusual andinteresting facts about Rivers, trivia and information, including some useful statistics will fascinate everyone from kids and children to adults. Interesting Facts about Rivers are as follows:
      • Fact 1 - Definition: A river is a natural course of water, usually freshwater, flowing toward an ocean, a lake, a sea or another river. Rivers drains surplus water from a drainage basin.
      • Fact 2 - All rivers start at the highest point in an area called the source. As it flows downstream, it gains more water from other streams, rivers, springs, rainfall, and other water sources.
      • Fact 3 - Rivers have been a source of food since pre-history
      • Fact 4 - The riverbed is the ground at the bottom of rivers - often made up of sand and stones
      • Fact 5 - The gravel and sand, generated and moved by rivers are extensively used in construction
      • Fact 6 - A Confluence is where two rivers meet
      • Fact 7 - Downstream is the direction that rivers flow - towards the mouth of rivers
      • Fact 8 - A Drainage Basin is the area of land that is drained by a river and its tributaries. The boundary of a river basin is called the watershed.
      • Fact 9 - An Estuary occurs near or at the mouth of rivers, where the tide meets the current and the fresh and salt waters mix.
      • Fact 10 - Flooding occurs when rivers are filled with too much water. The water breaks through the riverbanks and spreads over the surrounding land.
      • Fact 11 - The flood plain is the flat land of the river valley close to the river banks. The floodplain is usually found in the lower course of a river. It is a fertile area of land, used for agriculture and growing crops.
      • Fact 12 - The Mouth is the end of the river
      • Fact 13 - Rapids are fast-flowing stretches of water formed where the river surface breaks up into waves because rocks are near to the surface.
      • Fact 14 - Sediment is the material that has been carried by rivers or the sea and then deposited. Sediment may be called alluvium if it deposited on the bed or a river.
      • Fact 15 - Rivers are divided into three primary zones: the crenon, rhithron and potamon
        • The crenon is the uppermost zone at the source of rivers
        • The rhithron is the upstream portion of rivers
        • The potamon is the downstream stretch of rivers

      • Fact 16 - A watershed is the term given to the land that drains water into a particular stream, lake, or river.
      • Fact 17 - A waterfall is a sudden drop in a river as it flows over a rock cliff.
      • Fact 18 - The River Nile is the longest river in the world. It measures 6,695 kilometres from its source in Burundi to its delta on the Mediterranean Sea.
      • Fact 19 - The Amazon River is the second longest river in the World approximately 6400 kilometres (4000 miles)
      • Fact 20 - The world's shortest river is the Roe River which is 200 feet (61 meters) long and flows between Giant Springs and the Missouri River near Great Falls, Montana.
      • Fact 21 - The longest river of Europe is the River Volga which flows through Russia into the Caspian Sea. The second longest is the Danube, flows west to east before entering the Black Sea.
      • Fact 22 - The Chang Jiang is the longest river in China and in Asia and flows east for a distance of 6300 km before it drains into the Yellow Sea.
      • Fact 23 - The 8 largest rivers in the U.S., based on volume, are (in descending order) the Mississippi, St. Lawrence, Ohio, Columbia, Yukon, Missouri, Tennessee and the Mobile.
      • Fact 24 - A dam is a barrier built for holding back water or diverting the flow of water. 600,000 miles of our rivers lie behind an estimated 60,000 to 80,000 dams
      • Fact 25 - 1.2 Billion people world-wide who do not have access to clean water
    • Facts about Rivers

    • We have included a selection of trivia and interesting facts about Rivers which we hope will be of help with homework. Most of these interesting facts about Rivers are quite amazing and some are little known pieces of trivia! Many of these interesting and random pieces of information and fun facts about Rivers and info will help you increase your knowledge on the subject of Rivers.
    • The Black Warrior River drains portions of seventeen counties in Alabama. The area the river drains, known as its watershed, covers 6,276 square miles in Alabama and measures roughly 300 miles from top to bottom. The Black Warrior River watershed is home to over one million residents and contains 16,145.89 miles of mapped streams.
    • The Black Warrior River's headwaters consist of the beautiful Sipsey, Mulberry, and Locust Forks. Once these rivers merge west of Birmingham, the Black Warrior River proper forms the border of Jefferson and Walker counties. Near Tuscaloosa, the
    • river flows out of the rocky Cumberland Plateau and through the Fall Line Hills before entering the sandy East Gulf Coastal Plain, forming the border of Greene and Hale counties in the Black Belt. This lower section of the river below Tuscaloosa still operates as a floodplain, covered with expanses of river bottom hardwoods and bald cypress and tupelo gum wetlands. Between Eutaw and Demopolis white and gray limestone and chalk bluffs crop up along the river's banks. At Demopolis the Black Warrior flows into the Tombigbee River towards
    • Mobile Bay.



    • The Black Warrior River and its tributaries are a major source of
    • drinking water for many cities including Birmingham, Tuscaloosa, Bessemer, Cullman, Oneonta, and Jasper.


    • The Sipsey Fork, one of the Black Warrior’s three major tributaries (aka “Forks”) and the headwater of
    • Smith Lake, is Alabama's only federally designated Wild & Scenic River. Learn more at: http://www.rivers.gov/wsr-black-warrior.html. Its headwaters originate in the 24,922-acre Sipsey Wilderness within Bankhead National Forest. The Sipsey Wilderness was the first
    • wilderness area created east of the
    • Mississippi River, thus starting the eastern wilderness movement. It remains the largest wilderness area east of the Mississippi.

    • The Mulberry Fork is the most impacted of the three headwater forks of the Black Warrior River. Because of agricultural, municipal, and industrial pollution the Mulberry has a more simplified aquatic environment than the other Black Warrior forks.
    • The Locust Fork is the only headwater fork of the Black Warrior River that rises in a region other than the Cumberland Plateau, in a physiographic province known as Sand Mountain. According to Alabama geologist Jim Lacefield, the Locust flows through an ancient riverbed that is 300 million years old. Older than the Appalachian Mountains, this ancient riverbed actually cuts through the mountain a number of times through features known as "water gaps."

    • According to Eastern Fly
    • Fishing Magazine, the
    • National Park Service rated the Black Warrior's three forks in the top 2% of U.S. streams for "outstandingly remarkable values."

    • Boating magazine called the Black Warrior River one of America's best kept secrets for recreational boating.


    • Alabama, "the River State," contains more miles of navigable waterways than any other state. Over 200 miles of the river are navigable by barge - from Demopolis to North of Birmingham up the Mulberry and Locust forks. This is made possible due to 4 large lock and dam structures on the main stem of the river.

    • The Black Warrior River watershed is home to 127 freshwater fish species (4 of which are federally listed as endangered), 36 species of mussels (5 of which are federally listed as endangered), 15 turtle species (1 of which is federally listed as threatened), an endangered snail, and numerous other aquatic animals.
    • According to the Alabama Office of Water Resources, Alabama has more species of freshwater turtles than the rest of North America combined. (52% of the continent's species) According to the Alabama Department of Natural Resources, Alabama is home to 83 species of crayfish, more than any other state.

    • Most of Alabama's coal reserves are found in the Warrior Coal Field. The proposed Shepherd Bend Mine on the Black Warrior River's Mulberry Fork has landed the Black Warrior on the annual list of America’s Most Endangered Rivers™ – a report issued by the conservation group American Rivers: http://blackwarriorriver.org/news/black-warrior-joins-2013-most-endangered-rivers.html











    • The Black Warrior River is named after Chief Tushkalusa, also the namesake of Tuscaloosa, Alabama. In Choctaw,tushka means "warrior" and lusa means "black."
    • The Black Warrior River was a major base of Mississippian culture, a.k.a. Moundbuilders, particularly at Moundville, where Moundville Archaeological Park is now located on the border of Hale and Tuscaloosa Counties. Eight hundred years ago, Moundville was the largest population center in North America. Learn more at http://moundville.ua.edu/













    • When Black Warrior Riverkeeper was founded the protect the Black Warrior River in 2001, we were the 72nd autonomous chapter of Waterkeeper Alliance. Now there are over 200 Waterkeeper groups on 6 continents working to protect their sources of clean water.
    • .One of the world's longest snakes, the anaconda spends much of its life in sluggish fresh water but also climbs small trees and bushes with the aid of its slightly prehensile tail. It does not pursue its prey but lurks in murky water, waiting for birds and animals to come to the edge to drink. It seizes its victim and then kills it by constriction. It can only remain submerged for about 10 minutes and usually glides along with the top of its head showing above the water. In the breeding season, males court their mates by making loud booming sounds. Females produce litters of as many as 40 live young, each of which is about 66 cm (26 in) long at birth.
    • The largest of the side-necks, the arrau turtle may weigh over 45 kg (100 lb). Females have wide, flattened shells and are larger and more numerous than males. Adults feed entirely on plant matter. The nesting habits of these turtles are similar to those of sea turtles in that they gather in large numbers to travel to certain suitable nesting areas. They lay their eggs on sandbanks which are exposed only in the dry season, and there are relatively few such sites. The females come out onto the sandbanks at night, and each lays as many as 90 or 100 softshelled eggs. They then return to their feeding grounds. The hatchlings, which are about 5 cm (2 in) long, emerge to the attentions of many predators; even without man's activities, only about 5 percent reach adult feeding grounds. Uncontrolled hunting of adults and excessive collecting of eggs have seriously reduced the population of this turtle. It is now an endangered species and is protected in most areas
    • A slender, long-bodied fish, the barbel has a characteristic high dorsal fin and two pairs of sensory barbels around its fleshy lips. It is a bottom-living fish, most active at night and at dusk, and feeds on insect larvae, mollusks and crustaceans. It is a member of the family Cyprinidae. Barbels breed in late spring, often migrating upstream before spawning. They shed their eggs in shallow, gravel-bottomed water, where they lodge among the stones until they hatch from 10 to 15 days later.
    • The boutu has a strong beak studded with short bristles and a mobile, flexible head and neck. Most boutus have a total of 100 or more teeth. Their eyes, although small, seem to be more functional than those of other river dolphins. Boutus feed mainly on small fish and some crustaceans, using echolocation clicks to find their prey. Boutus live in pairs and seem to produce young between July and September.

    • Typically, the central stoneroller lives in small streams in riffle areas (shallow water where the flow is broken by the stones and gravel on the streambed). It feeds at the bottom on tiny plants, insect larvae and mollusks. In spring, the dorsal and anal fins of breeding males turn bright orange and black, and tubercles develop on the upper half of the body. The male makes a shallow nest in the gravel of the streambed, in which the female lays her eggs.
    • One of the few freshwater puffers, the common pufferfish has a rotund body, attractively colored with green and patches of yellow. When threatened, it inflates its body with water until it is virtually globular, but it does not have skin spines. With its plump, rather rigid, body the puffer moves slowly, using undulations of its small dorsal and anal fins, but it compensates for this lack of speed by its defensive techniques. It feeds on bottom-dwelling invertebrates and on fish. Common puffers are very popular aquarium fishes and have been bred in captivity. The female sheds her eggs on the bottom, where they are guarded by the male, who lies over them until they hatch. Many members of the puffer family are considered good food fish, despite the fact that their internal organs -- and occasionally even the flesh -- are extremely toxic and can cause fatal poisoning. In Japan, chefs are specially trained in the cooking of puffers, known as fugu, but there are still a number of cases of poisoning.
    • A wren-shaped bird, the dipper has a compact body, long, stout legs and a short, square-tipped tail. Its bill is hooked and is notched at the tip. Like all dippers, it frequents mountain streams and walks or dives into the water, swims underwater and even walks on the bottom, to obtain insect and invertebrate prey, especially caddis fly larvae. A bulky, domed nest, made of moss and grass, is built by the female on a rock in a stream or beside a stream among tree roots or rocks; it has a side entrance. The female lays 3 to 6 eggs, which she incubates for 15 to 17 days.
    • Although agile on land, otters have become well adapted for an aquatic life. The Eurasian otter has the slim mustelid body, but its tail is thick, fleshy and muscular for propulsion in water. All four feet are webbed, and the nostrils and ears can be closed when the otter is in water. Its fur is short and dense and keeps the skin dry by trapping a layer of air around the body. An excellent swimmer and diver, the otter moves in water by strong undulations of its body and tail and strokes of its hind feet. It feeds on fish, frogs, water birds, voles and other aquatic creatures. Otters are solitary, elusive creatures, now rare in much of their range. They den in a riverbank in a burrow called a holt and are most active at night. Even adult otters are playful animals and enjoy sliding down a muddy bank. A litter of 2 or 3 young is born in the spring -- or at any time of year in the south of the otter's range. There are 8 species of Lutra, all with more or less similar habits and adaptations.


    • The Indian gavial has an extremely long narrow snout, studded with about 100 small teeth -- ideal equipment for seizing fish and frogs underwater. Like all crocodilians, the gavial has been hunted for its skin, and it is now one of the rarest in Asia. Its hind limbs are paddle-like, and the gavial seems rarely to leave the water except to nest. The female lays her eggs at night in a pit dug in the riverbank.


Despite the implications of its common name, this giant salamander is a harmless creature which feeds on crayfish, snails and worms. It has the flattened head characteristic of its family and loose flaps of skin along the lower sides of its body. A nocturnal salamander, the hellbender hides under rocks in the water during the day. It depends on its senses of smell and touch, rather than on sight, to find its prey, since its eyes are set so far down the sides of its head that it cannot focus on an object with both eyes at once. Hellbenders breed in autumn: the male makes a hollow beneath a rock or log on the stream bed, and the female lays strings of 200 to 500 eggs. As she lays the eggs, the male fertilizes them and then guards the nest until the eggs hatch 2 or 3 months later.
Range of Hellbender
Range of Hellbender






external image forecast_graph_cotulla2.gif




external image images?q=tbn:ANd9GcTZ1ZaqrmXXRoSPZl8QZHHgsmd_Jv1XrQbYs76PVKRE3R0s1qiF





The Mississippi Delta
The Mississippi Delta





Potholes

Potholes are cylindrical holes drilled into the bed of a river that vary in depth & diameter from a few centimetres to several metres. They’re found in the upper course of a river where it has enough potential energy to erode vertically and its flow is turbulent. In the upper course of a river, its load is large and mainly transported by traction along the river bed. When flowing water encounters bedload, it is forced over it and downcuts behind the bedload in swirling eddie currents. These currents erode the river’s bed and create small depressions in it.
external image pothole-eddie-currents.svg
The creation of eddie currents as a result of bedload in a river.
As these depressions deepen, pebbles can become trapped in them. As a result of the eddie currents, the pebbles drill into the depressions making them more circular, wider & deeper. Pebbles will only be able to erode a river’s bed though if the rock the pebble’s made of is stronger than the rock the river bed is made of.
external image river-clyde-pothole-jim-ness.jpg
A pothole that has formed along the River Clyde.
Copyright Jim Ness. Licensed under the Creative Commons 2.0 license.

V-Shaped Valleys

V-Shaped valleys are found in the upper course of the river and are a result of both erosion by the river and weathering. V-Shaped valleys are deep river valleys with steep sides that look like a letter V when a cross section of them is taken, hence the name. They’re found in the upper course because this is where the river has the greatest gravitational potential energy and so the greatest potential to erode vertically. It does so during periods of high discharge. When the river’s discharge is high, it is able to transport its large bedload by traction eroding the river’s bed and valley by corrasion, deepening it. Not much lateral erosion takes place so the channel and valley remains relatively narrow.
As the channel and valley deepens the sides of the valley are exposed and become susceptible to weathering. The valley’s sides also undergo mass movements resulting in large volumes of material falling into the river’s channel, adding to its erosive power and causing the valley sides to take up a V shape. The steepness of the valley sides and whether the valley actually looks like a V is dependent on the climate, vegetation and rock structure among things. In cold, wet climates, freeze thaw weathering is abundant and rainwater can act as a lubricant, aiding mass movements. Vegetation can impede mass movements because it will help bind the soil. If the valley is composed of hard rock the valley sides will be very steep because they won’t be weathered easily.

Waterfalls (Geological)

Waterfalls develop when a change of lithology (rock type) takes place along the river’s course resulting in differential erosion. When the rock type of the river’s channel changes from a resistant rock to a less resistant one (e.g. granite to limestone), the river erodes the less resistant rock faster producing a sudden drop in the gradient of the river with the resistant rock being higher up than the less resistant rock. As the river flows over the resistant rock, it falls onto the less resistant rock, eroding it and creating a greater height difference between the two rock types, producing the waterfall.
When water flows over the waterfall it creates a plunge pool at its base and the splashback from the falling water undercuts the resistant rock. The unsupported rock is known as the cap rock and it eventually collapses into the plunge pool causing the waterfall to retreat upstream. Over thousands of years, the repeated collapse of the cap rock and retreat of the waterfall produces a gorge of recession.
external image waterfall-diagram.svg

Rapids

Rapids are sections of a river where the gradient of the river bed is relatively steep resulting in an increase in the river’s turbulence and velocity. They form where the gradient of the river is steep and the bed is composed mainly of hard rocks.

Meanders

Meanders are bends in a river that form as a river’s sinuosity increases. The sinuosity of a river is a measurement of how much a river varies from a straight line. It’s a ratio between the channel length and displacement (straight line distance) between two points in the river’s course:


A sinuosity of 1 means that the channel is perfectly straight. A sinuosity greater than 1 means that the river meanders.
Meanders develop when alternating riffles & pools form along a river channel. A riffle is a a shallow section of a channel while a pool is a deep section. These riffles and pools develop at equal points along the river channel with each pool being about 5× the length of the channel.
In a pool, the channel is more efficient while at a riffle, the channel is less efficient. This causes the flow of the river to become irregular and the maximum flow is concentrated on one side of the river. This increases erosion on one side of the river and increases deposition on the other causing the river’s channel to appear to bend. Erosion is greatest on the outside bend and deposition is greatest on the inside bend.

Characteristics

A cross section of a meander would show that on the outside bend, the channel is very deep and concave. This is because the outside bend is where the river flows fastest and is most energetic, so lots of erosion by hydraulic action and corrasion takes place. River cliffs form on the outside bend as the river erodes laterally. The inside bend is shallower with a gentle slip-off slope made of sand or shingle that is brought across from the outside bend by the helicoidal flow of the river. The river flows much slower on the inside bend so some deposition takes place, contribution to the slip-off slope.
external image meander-cross-section.svg
A picture of a river cliff
A picture of a river cliff
A river cliff on a meander that has had rocks placed near it to slow down erosion.
A picture of a slip-off slope
A picture of a slip-off slope
A slip-off slope on a river's meander.

Oxbow Lakes

Oxbow lakes are an evolution of meanders that undergo extensive deposition and erosion. As we’ve just seen, strong erosion takes place on the outside bend of a meander while deposition takes place on the inisde bend. As a result, the neck of a meander narrows. During extremely high discharge (e.g., a flood), it’s more efficient for a river to flow accross the neck of a meander rather than around it. When discharge returns to normal levels, the river continues follow this new course. The meander is left connected to the channel as a cutoff. Deposition eventually separates the cutoff from the main channel leaving behind an oxbow lake. With its main source of water disconnected, the lake eventually dries up leaving behind a meander scar.
external image tagliamento-braided-channel-diego-cruciat.jpg

Floodplains

Floodplains are large, flat expanses of land that form on either side of a river. The floodplain is the area that a river floods onto when it’s experiencing high discharge. When a river floods, its efficiency decreases rapidly because of an increase in friction, reducing the river’s velocity and forcing it to deposit its load. The load is deposited across the floodplain as alluvium. The alluvium is very fertile so floodplains are often used as farmland.
The width of a floodplain is determined by the sinuosity of the river and how much meander migration takes place. If there’s a lot of meander migration, the area that the river floods on will change and the floodplain will become wider.

Levees

Levees are natural embankments produced, ironically, when a river floods. When a river floods, it deposits its load over the flood plain due to a dramatic drop in the river’s velocity as friction increases greatly. The largest & heaviest load is deposited first and closest to the river bank, often on the very edge, forming raised mounds. The finer material is deposited further away from the banks causing the mounds to appear to taper off. Repeated floods cause the mounds to build up and form levees.
Levees aren’t permanent structures. Once the river’s discharge exceeds its bankfull discharge1, the levees can be burst by the high pressure of the water. Levees increase the height of the river’s channel though, so the bankfull discharge is increased and it becomes more difficult for the river to flood.
external image levee-diagram.svg

Deltas

Deltas are depositional landforms found at the mouth of a river where the river meets a body of water with a lower velocity than the river (e.g. a lake or the sea). For a delta to develop, the body of water needs to be relatively quiet with a low tidal range so that deposited sediment isn’t washed away and has time to accumulate.
When a river meets a stationary body of water, its velocity falls causing any material being transported by the river to be deposited. Deltas are made up of three sediment beds that have been sorted by the size of the sediment. The bottom most bed, the bottomset bed, is composed primarily of clay and some other fine grained sediments. Clay is the main constituent because when clay meets salt water a process called flocculation takes place where clay & salt particles clump together (flocculate) due to an electrostatic charge developing between the particles. This makes the clay particles sink due to their increased weight producing the bottomset bed. The bottomset bed stretches a fair distance from the mouth of the river as the fine sediments can be transported a reasonable distance from the river’s mouth.
The foreset bed lies on top of the bottomset bed. The foreset bed is composed of coarser sediments that are deposited due to a fall in the river’s velocity and aren’t transported very far into the stationary body of water that the river flows into. The foreset bed makes up the majority of the delta and is dipped towards deep water in the direction that the river is flowing in.
The topset bed is, as the name suggests, the topmost bed of the delta. It too is composed of coarse sediment but, unlike the foreset bed, the topset bed doesn’t dip, it’s horizontally bedded.
external image delta-bedding-layers.svg
Deltas can take on many different shapes. The three primary shapes of delta are cuspate, arcuate and bird’s foot.
Arcuate deltas (e.g. The Nile Delta, Egypt) are shaped like a triangle (which is where the term delta comes from, the Greek letter delta Δ) and form when a river meets a sea with alternating current directions that shape the delta so that it looks like a triangle.

The Ebro Delta
The Ebro Delta


Current data typically are recorded at 15- to 60-minute intervals, stored onsite, and then transmitted to USGS offices every 1 to 4 hours, depending on the data relay technique used. Recording and transmission times may be more frequent during critical events. Data from current sites are relayed to USGS offices via satellite, telephone, and/or radio telemetry and are available for viewing within minutes of arrival.
Wetlands, rivers, lakes, and coastal estuaries are all aquatic ecosystems—critical elements of Earth’s dynamic processes and essential to human economies and health.
Wetlands connect land and water, serving as natural filters, reducing pollution, controlling floods, and acting as nurseries for many aquatic species. Rivers, lakes, and estuaries serve as important transportation, recreation, and wildlife hubs.
Learning more about the ecosystems within your watershed—all the water in your region that drains to the same point—can help you better understand how everything is connected and what is at stake with freshwater overuse, pollution, and drought.


Fast Facts

  • Global extinction rates for freshwater species are four to six times higher than those for terrestrial or marine species.
  • Forty percent of all fish species in North America are at risk of extinction.
  • In the U.S., 69 percent of freshwater mussel species, which help to filter water, are at risk of extinction.


Ecological Communities of the East River

By Kate Dlugosz
The East River is not usually thought of as a rich, life-sustaining ecosystem. Because of the pollution that has plagued the river in recent years, the East River has developed a reputation as an ecological wasteland. Many people assume the East River is incapable of supporting a large and diverse wildlife population. This is entirely untrue. Throughout history, the East River has served as the home to many species of plants and animals and at one time contained one of the most wide-ranging populations in the world. Though pollution has had a large effect on the ecological health of the East River in the past few centuries, many of the native species still remain. This essay will describe the various ecosystems that have existed in and along the East River, past and present, with a focus on the various organisms that inhabited them. Pollution’s effect on the various habitats of the East River will be mentioned only briefly; greater attention will be paid to the description of these habitats and the detailing of the relationships between the organisms inhabiting them.

The East River as an Estuary

The East River itself is part of the New York-New Jersey Harbor Estuary, a larger region “encompassing the waters of New York Harbor and the tidally influenced rivers and streams flowing into it”.1 An estuary is a region of transition between fresh and saltwater, between land and sea.2Estuaries are great sources of biodiversity because they link together ecologically distinct areas. Estuarine waters carry nutrients from both fresh and salt water, enabling them to support a very rich community of species.3 The wetlands typically found along the shores of estuaries are also supportive of many forms of life. It is therefore no surprise that the East River, part of an estuary, is an area that harbors great biodiversity.
external image photo1.jpg


A map showing the location of the NY-NJ Harbor Estuary

(NY-NJ Harbor Estuary Program)

Ecological Communities

Many different ecological communities are present in the East River. An ecological community can be likened to a city neighborhood; each is defined by the combination of plants and animals (or people) who reside there.4 Manhattan Island once contained fifty-five distinct ecological neighborhoods. This figure is greater than that of coral reefs and rainforests of similar sizes, meaning that Manhattan was once one of the most biologically diverse areas in the world.5 Many of Manhattan’s ecological neighborhoods can be or were once found in and along the East River. The East River itself is a tidal river community and the home to a great number of fish species, among them the striped bass, bluefish, weakfish, and spotted sea trout.6 Native Americans and early settlers once completely depended on the East River’s rich fish stocks for food. Fish are not the only species one sees swimming in the East River. Harbor porpoises and seals can, even today, occasionally be found in the river or sunning themselves on its banks.7
external image photo2.jpg


The striped bass is one of the most commonly found fish in the East River.

(http://mythousandmileyear.com/wp-content/uploads/2010/09/stripedbass.gif)

Oysters

At one time, the East River was filled with extensive oyster reefs. These oysters were a valuable food source to European settlers. Oysters are often viewed as “ecosystem engineers” because their presence promotes biodiversity. Oyster reefs often serve as nursery and feeding grounds to small fish, crabs, and shrimp.9 The presence of these organisms attracts many larger species, such as birds and game fish.10 Oyster reefs also help the stability of wetland habitats. This stabilization helped sustain the very biodiverse marshes and mudflats that once existed along the East River. Unfortunately, pollution and overharvesting within the last two centuries has led to the degradation of the East River’s oyster population.
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This image shows a typical oyster reef (not a photo of the East River).

(http://aquaviews.net/wp-content/uploads/2009/08/Oyster-Reef.jpg)
Among the various ecosystems once found along the East River’s shores are mudflats, salt marshes, and marine eelgrass meadows. Each of these ecosystems are distinct; their physical characteristics and the wildlife that they support are each very different.

Mudflats and Eel Grass Meadows

Mudflats, “wet, silky, smooth flats of mud descending from the land to the sea”, were located along much of Manhattan’s east coast.11 In these mudflats lived many different types of shellfish, including oysters, soft-shell clams, and mud-snails.12 Marine eel grass meadows were located in many of the bays and coves along the East River. These areas, named for the large amounts of eel grass that flourished in the waters just off shore, provided habitats for algae, ducks, and small species of fish.13Sea turtles were also present in these meadows.14 Turtle Bay on Manhattan’s east side was so named because of the sea turtle population residing in its eel grass meadows. In the 1930s, an outbreak of disease destroyed what remained of the eel grass in the East River, essentially destroying the entire marine eel grass meadow ecological community.15
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An image of an eelgrass meadow.

(http://www.somas.stonybrook.edu/research/highlights/Peterson/Eelgrass_meadow_2.jpg)

Salt Marshes

Salt marshes, some of the most productive ecosystems on earth, made up the majority of the East River’s shore. Salt marshes are made up of masses of vegetation as large as several acres. The grasses typically seen in the salt marshes of the East River were short, yellow-green cord grasses of the genus spartina.16 In salt marshes during high tide, saltwater washes over and flows through the grass.17 When the tide recedes, organic matter is left behind and eventually begins to decompose. This decomposition attracts many microorganisms and bottom-dwelling scavengers who consume the detritus left behind by the tides such as worms, fish, shrimps, and crabs. Salt marshes are sheltered from the waves of the sea and from larger predators; many small species and newly hatched fish inhabit these marshes due to their protected nature. Salt marshes are often referred to as the “nurseries of the sea” for this very reason; more than three-fourths of all seafood raised on the East Coast spent its early life in a salt marsh.18
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This image compares the 1664 coastline of Manhattan to the 1983 coastline.

Notice the location of the wetlands and streams that once lined the shore.

(http://academic.brooklyn.cuny.edu/)

Water Birds of the East River’s Islands

The islands of the East River are home to a wide variety of wading birds. Because the majority of these islands are undeveloped and uninhabited, these bird communities are very well-preserved and continue to thrive. North Brother Island, South Brother Island, and Mill Rock Island are all largely avian habitats. South Brother Island, a small outcropping in the upper East River, is currently the location of the largest wading bird colony in the entire New York-New Jersey Harbor, with 592 nests.19 Five prominent species of wading birds found on the East River’s islands are the black-crowned night heron, the glossy ibis, and the great, snowy, and cattle egrets.20 The trees and shrubs found on the islands provide viable nesting locations for these species. The box elder, mulberry species, and the black cherry are among the trees and bushes that the herons and ibises call home.21 Egrets typically prefer trees covered in vines of Asiatic Bittersweet.22 Another water bird found on these islands is the double-crested cormorant; 350 active breeding pairs were discovered on North and South Brother Islands in 2004.23
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Egrets on South Brother Island in the East River.

(http://graphics8.nytimes.com/images/2006/06/02/nyregion/02islands.600.jpg)

A Diverse River

The East River has served as the home to a very wide array of plants and animals throughout history; a variety of species have inhabited its waters, islands, and shores over the years. As part of an estuary, the East River is by its very nature a productive and biodiverse environment. The different ecological communities that have existed within and along the East River are as distinct and diverse as New York City’s different neighborhoods; the East River is biologically diverse as New York City is culturally diverse. Though the influence of humans has certainly had a diminishing effect on the ecology of the river in the last few centuries, the East River still contains many thriving species and life-supporting habitats. Many of these species and habitats have even seen a revival within the last several decades due to efforts to restore the East River to its former glory.

The Amazon River (US /ˈæməzɒn/ or UK /ˈæməzən/; Spanish and Portuguese: Amazonas) in South America is generally regarded as the second longest river in the world and is by far the largest by waterflow with an average discharge of about 209,000 cubic meters per second (7,381,000 cu ft/s), greater than the next seven largest rivers combined (not including Madeira and Rio Negro, which are tributaries of the Amazon). The Amazon, which has the largest drainage basin in the world, about 7,050,000 square kilometres (2,720,000 sq mi), accounts for approximately one-fifth of the world's total river flow. The river would have the biggest drainage basin in the world even just counting Brazil, which it enters with only one-fifth of the volume that will finally be discharged into the Atlantic.[3][4]
In its upper stretches, above the confluence of the Rio Negro, the Amazon is called Solimões in Brazil; however, in Peru, Colombia and Ecuador, as well as the rest of the Spanish-speaking world, the river is generally called the Amazon downstream from the confluence of the Marañón andUcayali rivers in Peru. The Ucayali-Apurímac river system is considered the main source of the Amazon, with its main headstream being theCarhuasanta glacial stream flowing off the Nevado Mismi mountain.
The width of the Amazon is between 1.6 and 10 kilometres (1.0 and 6.2 mi) at low stage but expands during the wet season to 48 kilometres (30 mi) or more. The river enters the Atlantic Ocean in a broad estuary about 240 kilometres (150 mi) wide. The mouth of the main stem is 80 kilometres (50 mi).[5] Because of its vast dimensions, it is sometimes called The River Sea. The first bridge in the Amazon river system (over the Rio Negro) opened on 10 October 2010 near Manaus, Brazil.
The total volume of water of the Amazon river in a year is about 6,591 cubic kilometers (to compare, the water volume of Lake Baikal is 23,615 cubic km).

Drainage area[edit]

Main article: Amazon Basin

The Amazon Basin, the largest in the world, covers about 40% of South America, an area of approximately 7,050,000 square kilometres (2,720,000 sq mi). It drains from west to east, from Iquitos in Peru, across Brazil to the Atlantic. It gathers its waters from 5 degrees north latitude to 20 degrees south latitude. Its most remote sources are found on the inter-Andean plateau, just a short distance from thePacific Ocean. The locals often refer to it as "El Jefe Negro", referring to an ancient god of fertility.
The Amazon River and its tributaries are characterized by extensive forested areas that become flooded every rainy season. Every year the river rises more than 9 metres (30 ft), flooding the surrounding forests, known as várzea ("flooded forests"). The Amazon's flooded forests are the most extensive example of this habitat type in the world.[6] In an average dry season, 110,000 square kilometres (42,000 sq mi) of land are water-covered, while in the wet season, the flooded area of the Amazon Basin rises to 350,000 square kilometres (140,000 sq mi).[7]
The quantity of water released by the Amazon to the Atlantic Ocean is enormous: up to 300,000 cubic metres per second (11,000,000 cu ft/s) in the rainy season, with an average of 209,000 cubic metres per second (7,400,000 cu ft/s) from 1973 to 1990.[8] The Amazon is responsible for about 20% of the Earth's fresh water entering the ocean.[6] The river pushes a vast plume of fresh water into the ocean. The plume is about 400 kilometres (250 mi) long and between 100 and 200 kilometres (62 and 120 mi) wide. The fresh water, being lighter, flows on top of the seawater, diluting the salinity and altering the color of the ocean surface over an area up to 1,000,000 square miles (2,600,000 km2) in extent. For centuries ships have reported fresh water near the Amazon's mouth yet well out of sight of land in what otherwise seemed to be the open ocean.[4]
The Atlantic has sufficient wave and tidal energy to carry most of the Amazon's sediments out to sea, thus the Amazon does not form a true delta. The great deltas of the world are all in relatively protected bodies of water, while the Amazon empties directly into the turbulent Atlantic.[9]
There is a natural water union between the Amazon and the Orinoco basins, the so-called Casiquiare canal. The Casiquiare is a river distributary of the upper Orinoco, which flows southward into the Rio Negro, which in turn flows into the Amazon. The Casiquiare is the largest river on earth that links two major river systems, a so-called bifurcation.

Origins[edit]

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The Amazon originates from the Apacheta cliff in Arequipa at the Nevado Mismi, marked only by a wooden cross.external image 250px-The_Source_of_the_Amazon_River.jpg
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Source of the Amazon

The Amazon river has a series of major river systems in Colombia, Ecuador and Peru, some of which flow into theMarañón and Ucayali, others directly into the Amazon proper. Among others, these include the following rivers:Putumayo, Caquetá, Vaupés, Guainía, Morona, Pastaza, Nucuray, Urituyacu, Chambira, Tigre, Nanay, Napo, andHuallaga.
The most distant source of the Amazon was established in 1996,[10] 2001,[11] 2007,[12] and 2008,[13] as a glacial stream on a snowcapped 5,597 m (18,363 ft) peak called Nevado Mismi in the Peruvian Andes, roughly 160 km (99 mi) west of Lake Titicaca and 700 km (430 mi) southeast of Lima. The waters from Nevado Mismi flow into the Quebradas Carhuasanta and Apacheta, which flow into the Río Apurímac which is a tributary of the Ucayali which later joins the Marañón to form the Amazon proper. While the Ucayali–Marañón confluence is the point at which most geographers place the beginning of the Amazon proper, in Brazil the river is known at this point as theSolimões das Águas. Further downriver from that confluence the darkly colored waters of the Rio Negro meet the sandy colored Rio Solimões, and for over 6 km (4 mi) these waters run side by side without mixing.
After the confluence of Apurímac and Ucayali, the river leaves Andean terrain and is surrounded by floodplain. From this point to the Marañón, some 1,600 km (990 mi), the forested banks are just out of water and are inundated long before the river attains its maximum flood stage. The low river banks are interrupted by only a few hills, and the river enters the enormous Amazon Rainforest.
The river systems and flood plains in Brazil, Peru, Ecuador, Colombia and Venezuela, whose waters drain into theSolimões and its tributaries, are called the "Upper Amazon". The Amazon River proper runs mostly through Brazil and Peru. It is part of the border between Colombia and Perú, and it has tributaries reaching into Venezuela, Colombia, Ecuador, and Bolivia.

Flooding[edit]

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A NASA satellite image of a flooded portion of the river

Not all of the Amazon's tributaries flood at the same time of the year. Many branches begin flooding in November and may continue to rise until June. The rise of the Rio Negro starts in February or March and begins to recede in June. The Madeira River rises and falls two months earlier than most of the rest of the Amazon.
The average depth of the Amazon between Manacapuru and Óbidos has been calculated as between 20 to 26 metres (66 to 85 ft). At Manacapuru the Amazon's water level is only about 24 metres (79 ft) above mean sea level. More than half of the water in the Amazon downstream of Manacapuru is below sea level.[14] In its lowermost section the Amazon's depth averages 20 to 50 metres (66 to 160 ft), in some places as much as 100 metres (330 ft).[15]
The main river is navigable for large ocean steamers to Manaus, 1,500 kilometres (930 mi) upriver from the mouth. Smaller ocean vessels of 3,000 tons or 9,000 tons[5] and 5.5 metres (18 ft) draft can reach as far as Iquitos, Peru, 3,600 kilometres (2,200 mi) from the sea. Smaller riverboats can reach 780 kilometres (480 mi) higher as far as Achual Point. Beyond that, small boats frequently ascend to the Pongo de Manseriche, just above Achual Point.
Annual flooding is caused by tidal waves called "pororoca." The waves occur in late winter at high tide, when the Atlantic Ocean overlaps into the river. The resulting waves can be up to 4 meters high and travel 13 kilometers inland.[16]

Geography

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Meeting of Waters is the confluence of the Rio Negro (black) and the Rio Amazonas (sandy) near Manaus, Brazil.

At some points the river divides into anabranches, or multiple channels, often very long, with inland and lateral channels, all connected by a complicated system of natural canals, cutting the low, flat igapó lands, which are never more than 5 metres (16 ft) above low river, into many islands.
From the town of Canaria at the great bend of the Amazon to the Negro, vast areas of land are submerged at high water, above which only the upper part of the trees of the sombre forests appear. Near the mouth of the Rio Negro to Serpa, nearly opposite the river Madeira, the banks of the Amazon are low, until approaching Manaus, they rise to become rolling hills. At Óbidos, a bluff 17 m (56 ft) above the river is backed by low hills. The lower Amazon seems to have once been a gulf of the Atlantic Ocean, the waters of which washed the cliffs near Óbidos.
Only about ten percent of the Amazon's water enters downstream of Óbidos, very little of which is from the northern slope of the valley. The drainage area of the Amazon Basin above Óbidos city is about 5,000,000 square kilometres (1,900,000 sq mi), and, below, only about 1,000,000 square kilometres (390,000 sq mi) (around 20%), exclusive of the 1,400,000 square kilometres (540,000 sq mi) of the Tocantins basin. The Tocantins River enters the Amazon very close to its mouth.
In the lower reaches of the river, the north bank consists of a series of steep, table-topped hills extending for about 240 kilometres (150 mi) from opposite the mouth of the Xingu as far as Monte Alegre. These hills are cut down to a kind of terrace which lies between them and the river.
On the south bank, above the Xingu, a line of low bluffs bordering the floodplain extends nearly to Santarém in a series of gentle curves before they bend to the southwest, and, abutting upon the lower Tapajós, merge into the bluffs which form the terrace margin of the Tapajós river valley.

Mouth[edit]

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A satellite image of the mouth of the Amazon River, looking south

The definition of where exactly the mouth of the Amazon is located, and how wide it is, is a matter of dispute, because of the area's peculiar geography. The Pará and the Amazon are connected by a series of river channels called furos near the town of Breves; between them lies Marajó, the world's largest combined river/sea island.
If the Pará river and the Marajó island ocean frontage are included, the Amazon estuary is some 325 kilometres (202 mi) wide.[7] In this case, the width of the mouth of the river is usually measured from Cabo Norte, the cape located straight east of Pracuúba in the Brazilian state of Amapá, to Ponta da Tijoca near the town ofCuruçá, in the state of Pará.
A more conservative measurement excluding the Pará river estuary, from the mouth of the Araguari River to Ponta do Navio on the northern coast of Marajó, would still give the mouth of the Amazon a width of over 180 kilometres (110 mi). If only the river's main channel is considered, between the islands of Curuá (state of Amapá) and Jurupari (state of Pará), the width falls to about 15 kilometres (9.3 mi).

Fauna[edit]

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Amazon rainforest
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Characins, such as the piranha species, are prey for the giant otter, but these aggressive fish may also pose a danger to humans.

More than one-third of all known species in the world live in the Amazon Rainforest,[17] a giant tropical forest and river basin with an area that stretches more than 5,400,000 square kilometres (2,100,000 sq mi). It is the richest tropical forest in the world in terms of biodiversity. There are over 2,100 species of fish currently recognized in the Amazon Basin, with more being discovered every year.[18]

Mammals[edit]

Along with the Orinoco, the Amazon is one of the main habitats of the boto, also known as the Amazon river dolphin (Inia geoffrensis). It is the largest species ofriver dolphin, and it can grow to lengths of up to 2.6 metres (8 ft 6 in). The color of its skin changes with age. It varies from gray when it is young, to pink and white as it matures. The dolphins use echolocation to navigate and hunt in the river's tricky depths.[19] The boto is the subject of a legend in Brazil about a dolphin that turns into a man and seduces maidens by the riverside. The tucuxi (Sotalia fluviatilis), also a dolphin species, is found both in the rivers of the Amazon Basin and in the coastal waters of South America. The Amazonian manatee (Trichechus inunguis) also known as "seacow" is found in the northern Amazon River Basin and its tributaries. It is a mammal and an herbivore. Its population is limited to fresh water habitats and unlike other manatees, it does not venture into salt water. It is classified as vulnerable by the International Union for Conservation of Nature.
The Amazon and its tributaries are the main habitat of the giant otter (Pteronura brasiliensis). It is a member of the weasel family and is the largest of its kind. Because of habitat destruction and hunting its population has dramatically decreased.

Reptiles

The anaconda is found in shallow waters in the Amazon Basin. One of the world's largest species of snake, the anaconda spends most of its time in the water, with just its nostrils above the surface. In addition to the thousands of species of fish, the river supports crabs, algae, and turtles. The caiman, which is related to alligators and other crocodilians, also inhabits the Amazon.

Fish[edit]

The Amazonian fish fauna is the center of diversity for Neotropical fishes, of which more than 5,600 species are currently known[20] The bull shark (Carcharhinus leucas) has been reported 4,000 kilometres (2,500 mi) up the Amazon River at Iquitos in Peru. The arapaima, known in Brazil as the pirarucu (Arapaima gigas), is a South American tropical freshwater fish. It is one of the largest freshwater fish in the world, reportedly with a maximum length of 3 metres (9.8 ft) and weight up to 200 kilograms (440 lb).[21] Another Amazonian freshwater fish is the arowana (or aruanã in Portuguese), such as the silver arowana (Osteoglossum bicirrhosum), which is also a predator and very similar to the arapaima but only reaches a length of 120 centimetres (47 in). Also present in large numbers is the notorious piranha, an omnivorous fish which congregates in large schools and may attack livestock and even humans. There are approximately 30 to 60 species of piranha. However, only a few of its species are known to attack humans, most notably Pygocentrus nattereri, the red-bellied piranha. The candirú are a number of general parasitic,[22] fresh water catfish in the family Trichomycteridae; all are native to the Amazon River.[23] The electric eel (Electrophorus electricus) and more than 100 species of weakly electric fishes Gymnotiformes also inhabit the Amazon Basin. River stingrays (Potamotrygonidae) are also known.

Microbiota[edit]

Freshwater microbes are generally not very well known, even less so for a pristine ecosystem like the Amazon. Recently, metagenomics has provided answers to what kind of microbes inhabit the river.[24]The most important microbes in the Amazon River are Actinobacteria, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Crenarchaeota.

History[edit]

Exploration[edit]

See also: Timeline of Amazon history

During what many archaeologists call the formative period, Amazonian societies were deeply involved in the emergence of South America's highland agrarian systems, and possibly contributed directly to the social and religious fabric constitutive of the Andean civilizational orders.


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Shrunken head of a Spanish or mestizo man by Jivaro indigenous people. In 1599, the Jivaro destroyed Spanish settlements in eastern Ecuador and killed all the men.

In 1500, Vicente Yáñez Pinzón was the first European to sail into the river.[25] Pinzón called the river flow Río Santa María del Mar Dulce, later shortened to Mar Dulce(literally, sweet sea, because of its fresh water pushing out into the ocean). For 350 years after the first European encounter of the Amazon by Pinzón, the Portuguese portion of the basin remained an untended former food gathering and planned agricultural landscape occupied by the indigenous peoples who survived the arrival of European diseases. There is ample evidence for complex large-scale, pre-Columbian social formations, including chiefdoms, in many areas of Amazonia (particularly the inter-fluvial regions) and even large towns and cities.[26] For instance the pre-Columbian culture on the island of Marajó may have developed social stratification and supported a population of 100,000 people.[27] The Native Americans of the Amazon rain forest may have used Terra preta to make the land suitable for the large-scale agriculture needed to support large populations and complex social formations such as chiefdoms.[27]
Gonzalo Pizarro, set off in 1541 to explore east of Quito into the South American interior in search of El Dorado and the "Country of Cinnamon".[28] After 170 km, the Coca River joined the Napo River (at a point now known as Puerto Francisco de Orellana); the party stopped for a few weeks to build a boat just upriver from this confluence. They continued downriver through an uninhabited area, where they could not find food. Orellana offered and was ordered to follow the Napo River, then known as Río de la Canela("Cinnamon River") and return with food for the party. Based on intelligence received from a captive native chief named Delicola, they expected to find food within a few days downriver by ascending another river to the north. Orellana took about 57 men, the boat, and some canoes and left Pizarro's party on December 26, 1541. However, Orellana apparently missed the confluence (probably with the Aguarico) where he was to look for food. By the time he and his men reached another village many of them were sick from hunger and eating "noxious plants," and near death. Seven men died at that village. His men threatened to mutiny if he followed his orders and the expedition turned back to join Pizarro's larger party. He accepted to change the purpose of the expedition to discover new lands in the name of the King of Spain, and the men built a larger boat in which to navigate downstream. After a journey of 600 km down the Napo River they reached a further major confluence, at a point near modernIquitos, and then followed what is now known as the Amazon River for a further 1,200 km to its confluence with the Rio Negro (near modern Manaus), which they reached on 3 June 1542. Downriver from Manaus Orellana's party had a fierce battle with warriors who, they reported, were led by fierce female warriors who beat the men to death with clubs if they tried to retreat.[citation needed] Orellana's men began referring to the women as Amazons, a reference to the women of Greek Mythology. The river was initially known as the Maranon (the name by which part of the river is still known today) or Rio de Orellana. It later became known as the Amazonas, the name by which it is still known in both Spanish and Portuguese. Regarding the initial mission of finding cinnamon, Pizarro reported to the King that they had found cinnamon trees, but that they could not be profitably harvested. In fact, true cinnamon (Cinnamomum verum) is not native to South America. Other related cinnamon-containing plants (of the family Lauraceae) are fairly common in that part of the Amazon and Pizarro probably saw some of these. The expedition reached the mouth of the Amazon, on 24 August 1542, demonstrating the practical navigability of the Great River.
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Mundurukú Indians. Painted by Hercules Florence

In 1560, another Spanish conquistador, Lope de Aguirre, may have made the second descent of the Amazon. Historians are uncertain whether the river he descended was the Amazon or the Orinoco River, which runs more or less parallel to the Amazon further north.
Between 1637 and 1647, the Portuguese explorer Pedro Teixeira was the first European to ascend the river from Belém, near the mouth, to Quito, part of the Spanish Viceroyalty of Peru, and then to return the same way. Teixeira's expedition was massive—some 2,000 people in 37 large canoes. From 1648 to 1652,António Raposo Tavares lead one of the longest known expeditions from São Paulo to the mouth of the Amazon, investigating many of its tributaries, including the Rio Negro, and covering a distance of more than 10,000 km (6,214 mi).
In what is currently Brazil, Ecuador, Bolivia, Colombia, Peru, and Venezuela, a number of colonial and religious settlements were established along the banks of primary rivers and tributaries for the purpose of trade, slaving and evangelization among the indigenous peoples of the vast rain forest, such as the Urarina. Father Fritz, apostle of the Omaguas, established some forty mission villages. Charles Marie de La Condamine accomplished the first scientific exploration of the Amazon River.
Many indigenous tribes engaged in constant warfare. James Stuart Olson wrote: "The Munduruku expansion dislocated and displaced the Kawahib, breaking the tribe down into much smaller groups... [Munduruku] first came to the attention of Europeans in 1770 when they began a series of widespread attacks on Brazilian settlements along the Amazon River."[29]

Post-colonial exploration and history[edit]

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Henry Walter Bates was most famous for his expedition to the Amazon (1848–1859).

The Cabanagem, one of the bloodiest regional wars ever in Brazil, which was chiefly directed against the white ruling class, reduced the population of Pará from about 100,000 to 60,000.[30]
The total population of the Brazilian portion of the Amazon Basin in 1850 was perhaps 300,000, of whom about two-thirds comprised by Europeans and slaves, the slaves amounting to about 25,000. The Brazilian Amazon's principal commercial city, Pará (now Belém), had from 10,000 to 12,000 inhabitants, including slaves. The town of Manáos, now Manaus, at the mouth of the Rio Negro, had a population between 1,000 to 1,500. All the remaining villages, as far up as Tabatinga, on the Brazilian frontier of Peru, were relatively small.
On 6 September 1850 Emperor Pedro II of Brazil sanctioned a law authorizing steam navigation on the Amazon and gave the Viscount of Mauá (Irineu Evangelista de Sousa) the task of putting it into effect. He organized the "Companhia de Navegação e Comércio do Amazonas" in Rio de Janeiro in 1852; in the following year it commenced operations with three small steamers, the Monarch, the Marajó and Rio Negro.
At first, navigation was principally confined to the main river; and even in 1857 a modification of the government contract only obliged the company to a monthly service between Pará and Manaus, with steamers of 200 tons cargo capacity, a second line to make six round voyages a year between Manaus and Tabatinga, and a third, two trips a month between Pará and Cametá. This was the first step in opening up the vast interior.
The success of the venture called attention to the opportunities for economic exploitation of the Amazon, and a second company soon opened commerce on the Madeira, Purús and Negro; a third established a line between Pará and Manaus; and a fourth found it profitable to navigate some of the smaller streams. In that same period, the Amazonas Company was increasing its fleet. Meanwhile, private individuals were building and running small steam craft of their own on the main river as well as on many of its tributaries.
On 31 July 1867 the government of Brazil, constantly pressed by the maritime powers and by the countries encircling the upper Amazon basin, especially Peru, decreed the opening of the Amazon to all countries, but they limited this to certain defined points: Tabatinga – on the Amazon; Cametá – on the Tocantins; Santarém – on the Tapajós; Borba – on the Madeira, and Manaus – on the Rio Negro. The Brazilian decree took effect on 7 September 1867.
Thanks in part to the mercantile development associated with steamboat navigation coupled with the internationally driven demand for natural rubber, the Peruvian city of Iquitos became a thriving, cosmopolitan center of commerce. Foreign companies settled in Iquitos, from whence they controlled the extraction of rubber. In 1851 Iquitos had a population of 200, and by 1900 its population reached 20,000. In the 1860s, approximately 3,000 tons of rubber was being exported annually, and by 1911 annual exports had grown to 44,000 tons, representing 9.3% of Peru's exports.[31] During the rubber boom it is estimated that diseases brought by immigrants such as typhus or malaria killed 40,000 native Amazonians.[32]
The first direct foreign trade with Manaus was commenced around 1874. Local trade along the river was carried on by the English successors to the Amazonas Company—the Amazon Steam Navigation Company—as well as numerous small steamboats, belonging to companies and firms engaged in the rubber trade, navigating the Negro, Madeira, Purús and many other tributaries, such as the Marañón to ports as distant as Nauta, Peru.
By the turn of the 20th century, the exports of the Amazon Basin were India-rubber, cacao beans, Brazil nuts and a few other products of minor importance, such as pelts and exotic forest produce (resins, barks, woven hammocks, prized bird feathers, live animals) and extracted goods such as lumber and gold.
In August 2010 Ed Stafford became the first man in history to walk the entire length of the Amazon River. His expedition is documented in the book Walking the Amazon.

20th- and 21st-century concerns[edit]

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Manaus, the largest city in Amazonas, as seen from a NASA satellite image, surrounded by the dark Rio Negro and the muddy Amazon River

Four centuries after the European discovery of the Amazon river, the total cultivated area in its basin was probably less than 65 square kilometres (25 sq mi), excluding the limited and crudely cultivated areas among the mountains at its extreme headwaters. This situation changed dramatically during the 20th century.
Wary of foreign exploitation of the nation's resources, Brazilian governments in the 1940s set out to develop the interior, away from the seaboard where foreigners owned large tracts of land. The original architect of this expansion was President Getúlio Vargas, with the demand for rubber from the Allied forces in World War II providing funding for the drive.
In 1960, the construction of the new capital city of Brasília in the interior also contributed to the opening up of the Amazon Basin. A large-scale colonization program saw families from northeastern Brazil relocated to the forests, encouraged by promises of cheap land. Many settlements grew along the road from Brasília to Belém, but rainforest soil proved difficult to cultivate.
Still, long-term development plans continued. Roads were cut through the forests, and in 1970, the work on the Trans-Amazonian highway (Transamazônica) network began. The network's three pioneering highways were completed within ten years but never fulfilled their promise. Large portions of the Trans-Amazonian and its accessory roads, such as BR-319 (Manaus-Porto Velho), are derelict and impassable in the rainy season. Small towns and villages are scattered across the forest, and because its vegetation is so dense, some remote areas are still unexplored.
With a current population of 1.8 million people, Manaus is the Amazon's largest city. Manaus alone represents approximately 50% of the population of the Brazilian state of Amazonas, which is the largest state. The racial makeup of the city is 64% Pardo (Mulatto and mestizo) and 32% White.[33]

Dispute regarding length

While debate as to whether the Amazon or the Nile is the world's longest river has gone on for many years, the historic consensus of geographic authorities has been to regard the Amazon as the second longest river in the world, with the Nile being the longest. However, the Amazon has been measured by different geographers as being anywhere between 6,259 and 6,800 kilometres (3,889 and 4,200 mi) long. It is often said to be "at least" 6,400 kilometres (4,000 mi) long.[34] The Nile is reported to be anywhere from 5,499 to 6,690 kilometres (3,417 to 4,160 mi). Often it is said to be "about" 6,650 kilometres (4,130 mi) long.[35] There are many factors that can affect these measurements.
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River taxi in Peru

A study by Brazilian scientists concluded that the Amazon is actually longer than the Nile. Using Nevado Mismi, which in 2001 was labeled by the National Geographic Society as the Amazon's source, these scientists made new calculations of the Amazon's length. They calculated the Amazon's length as 6,992 kilometres (4,345 mi). Using the same techniques they calculated the length of the Nile as 6,853 kilometres (4,258 mi), which is longer than previous estimates but still shorter than the Amazon. They made it possible by measuring the Amazon downstream to the beginning of the tidal estuary of Canal do Sul and then, after a sharp turn back, following tidal canals surrounding the isle of Marajó and finally including the marine Waters of the Río Pará bay in its entire length.[13][36] Guido Gelli, director of science at the Brazilian Institute of Geography and Statistics (IBGE), told the Brazilian TV network Globo in June 2007 that it could be considered as a fact that the Amazon was the longest river in the world. However, other geographers have had access to the same data since 2001, and a consensus has yet to emerge to support the claims of these Brazilian scientists. The length of both the Amazon and the Nile remains open to interpretation and continued debate.[34]

Underground "river"[edit]

Scientists have discovered the longest underground "river" (actually a salt aquifer) in the world, in Brazil, running for a length of 6,000 kilometres (3,700 mi) at a depth of nearly 4,000 metres (13,000 ft) It flows from the Andean foothills to the Atlantic coast in a nearly west-to-east direction like the Amazon River. The discovery was made public in August 2011[37] meeting of the Brazilian Geophysical Society in Rio de Janeiro. The "river", named Hamza after the discoverer, an Indian-born scientist Valiya Hamza who is working with the National Observatory at Rio, makes it the first and geologically unusual instance of a twin-river system flowing at different levels of the earth's crust in Brazil. If the slowing down of certain seismic waves caused by the damp spot helped uncover the underground ocean, the unusual temperature variation with depth measured in 241 inactive oil wells helped locate the subterranean river. Except for the flow direction, the Amazon and the Hamza have very different characteristics. The most obvious ones are their width and flow speed. While the Amazon is 1 kilometre (0.62 mi) to 100 kilometres (62 mi) wide, the Hamza is 200 kilometres (120 mi) to 400 kilometres (250 mi) in width. But the flow speed is 5 metres per second (16 ft/s) in the Amazon and less than 1 millimetre per second (0.039 in/s) speed in the Hamza.[37]
Several geological factors have played a vital role in the formation and existence of these subterranean water bodies. The underground ocean, discovered in 2007, has been formed when the plate carrying the Pacific Ocean bottom gets dragged and ends up under the continental plate. Water at such depths would normally escape upwards but the unusual conditions that exist along the eastern Pacific Rim allow the moisture to remain intact. In the case of the Hamza, the porous and permeable sedimentary rocks behave as conduits for the water to sink to greater depths. East-west trending faults and the karst topography present along the northern border of the Amazon basin may have some role in supplying water to the "river". If the impermeable rocks stop the vertical flow, the west to east gradient of the topography directs it to flow towards the Atlantic Ocean. Unlike the Hamza, the 153 km-long underground river in Mexico's Yucatán Peninsula and the 8.2 km-long Cabayugan River in the Puerto Princesa Subterranean River National Park in the Philippines have come into being thanks to the karst topography. Water in these places drills its way downward by dissolving the carbonate rock to form an extensive underground river system.
The Nile (Arabic: النيل, an-Nīl; Ancient Egyptian: Iteru & Ḥ'pī; Coptic Egyptian: ⲫⲓⲁⲣⲱ, P(h)iaro; Amharic: ዓባይ?, ʿAbbai) is a major north-flowing river in northeastern Africa, generally
Above Khartoum the Nile is also known as the White Nile, a term also used in a limited sense to describe the section betweenLake No and Khartoum. At Khartoum the river is joined by the Blue Nile. The White Nile starts in equatorial East Africa, and the Blue Nile begins in Ethiopia. Both branches are on the western flanks of the East African Rift.
The drainage basin of the Nile covers 3,254,555 square kilometres (1,256,591 sq mi), about 10% of the area of Africa.[10] The Nile basin is complex, and because of this, the discharge at any given point along the mainstem depends on many factors including weather, diversions, evaporation and evapotranspiration, and groundwater flow.

Sources

The source of the Nile is sometimes considered to be Lake Victoria, but the lake has feeder rivers of considerable size. TheKagera River, which flows into Lake Victoria near the Tanzanian town of Bukoba, is the longest feeder, although sources do not agree on which is the longest tributary of the Kagera and hence the most distant source of the Nile itself.[11] It is either theRuvyironza, which emerges in Bururi Province, Burundi,[12] or the Nyabarongo, which flows from Nyungwe Forest in Rwanda.[13]The two feeder rivers meet near Rusumo Falls on the Rwanda-Tanzania border.
In 2010, an exploration party[14] went to a place described as the source of the Rukarara tributary,[15] and by hacking a path up steep jungle-choked mountain slopes in the Nyungwe forest found (in the dry season) an appreciable incoming surface flow for many miles upstream, and found a new source, giving the Nile a length of 4199 miles (6758 kilometers)
Gish Abay is reportedly the place where the "holy water" of the first drops of the Nile develop.[16]

Lost headwaters

Further information: List of rivers by length

Formerly Lake Tanganyika drained northwards along the African Rift Valley into the White Nile, making the Nile about 1,400 kilometres (870 mi) longer, until it was blocked in Miocene times by the bulk of the Virunga Volcanoes.

In Uganda

The Nile leaves Lake Victoria at Ripon Falls near Jinja, Uganda, as the Victoria Nile. It flows for approximately 500 kilometres (300 mi) farther, through Lake Kyoga, until it reaches Lake Albert. After leaving Lake Albert, the river is known as the Albert Nile.

In South Sudan

It then flows into South Sudan, where it is known as the Bahr al Jabal ("Sea of the Mountain", possibly from Nahr al Jabal, "River of the Mountain"). The Bahr al Ghazal, itself 716 kilometres (445 mi) long, joins the Bahr al Jabal at a small lagoon called Lake No, after which the Nile becomes known as the Bahr al Abyad, or the White Nile, from the whitish clay suspended in its waters. When the Nile floods it leaves a rich silty deposit which fertilizes the soil. The Nile no longer floods in Egypt since the completion of the Aswan Dam in 1970. An anabranch river, the Bahr el Zeraf, flows out of the Nile's Bahr al Jabal section and rejoins the White Nile.
The flow rate of the Bahr al Jabal at Mongalla, South Sudan is almost constant throughout the year and averages 1,048 m3/s (37,000 cu ft/s). After Mongalla, the Bahr Al Jabal enters the enormous swamps of the Sudd region of South Sudan. More than half of the Nile's water is lost in this swamp to evaporation and transpiration. The average flow rate of the White Nile at the tails of the swamps is about 510 m3/s (18,000 cu ft/s). From here it soon meets with the Sobat River at Malakal. On an annual basis, the White Nile upstream of Malakal contributes about fifteen percent of the total outflow of the Nile River.[17]
The average flow of the White Nile at Malakal, just below the Sobat River, is 924 m3/s (32,600 cu ft/s); the peak flow is approximately 1,218 m3/s (43,000 cu ft/s) in October and minimum flow is about 609 m3/s (21,500 cu ft/s) in April. This fluctuation is due the substantial variation in the flow of the Sobat, which has a minimum flow of about 99 m3/s (3,500 cu ft/s) in March and a peak flow of over 680 m3/s (24,000 cu ft/s) in October.[18] During the dry season (January to June) the White Nile contributes between 70 percent and 90 percent of the total discharge from the Nile.

In Sudan

Below Renk the White Nile enters Sudan, it flows north to Khartoum and meets the Blue Nile.
The course of the Nile in Sudan is distinctive. It flows over six groups of cataracts, from the first at Aswan to the sixth at Sabaloka(just north of Khartoum) and then turns to flow southward before again returning to flow north. This is called the Great Bend of the Nile.
In the north of Sudan the river enters Lake Nasser (known in Sudan as Lake Nubia), the larger part of which is in Egypt.

In Egypt

Below the Aswan High Dam, at the northern limit of Lake Nasser, the Nile resumes its historic course.
North of Cairo, the Nile splits into two branches (or distributaries) that feed the Mediterranean: the Rosetta Branch to the west and the Damietta to the east, forming the Nile Delta.
regarded as the longest river in the world.[2] It is 6,853 km (4,258 miles) long. The Nile is an "international" river as its water resources are shared by eleven countries, namely, Tanzania, Uganda, Rwanda, Burundi, Democratic Republic of the Congo, Kenya, Ethiopia, Eritrea,South Sudan, Sudan and Egypt.[3] In particular, the Nile is the primary water resource and life artery for Egypt and Sudan.[4]
The Nile has two major tributaries, the White Nile and Blue Nile. The White Nile is longer and rises in the Great Lakes region of central Africa, with the most distant source still undetermined but located in either Rwanda or Burundi. It flows north through Tanzania, Lake Victoria, Uganda and South Sudan. The Blue Nile is the source of most of the water and fertile soil. It begins at Lake Tana in Ethiopia at 12°02′09″N 037°15′53″E and flows into Sudan from the southeast. The two rivers meet near the Sudanese capital of Khartoum.
The northern section of the river flows almost entirely through desert, from Sudan into Egypt, a country whose civilization has depended on the river since ancient times. Most of the population and cities of Egypt lie along those parts of the Nile valley north of Aswan, and nearly all the cultural and historical sites of Ancient Egypt are found along riverbanks. The Nile ends in a large delta that empties into the Mediterranean Sea

Atbara River

Below the confluence with the Blue Nile the only major tributary is the Atbara River, roughly halfway to the sea, which originates in Ethiopia north of Lake Tana, and is around 800 kilometres (500 mi) long. The Atbara flows only while there is rain in Ethiopia and dries very rapidly. During the dry period of January to June, it typically dries up. It joins the Nile approximately 300 kilometres (200 mi) north of Khartoum.

Blue Nile

Main article: Blue Nileexternal image 220px-Blue_Nile_Falls_Ethiopia.jpg
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The Blue Nile Falls fed by Lake Tananear the city of Bahir Dar, Ethiopia.external image 220px-Nile_River_and_delta_from_orbit.jpg
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Nile Delta from space

The Blue Nile (Ge'ez ጥቁር ዓባይ Ṭiqūr ʿĀbbāy (Black Abay) to Ethiopians; Arabic: النيل الأزرق‎; transliterated: an-Nīl al-Azraq) springs from Lake Tana in the Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile[19] originates in Ethiopia, with fifty-nine percent of the water from the Blue Nile (the rest being from the Tekezé, Atbarah, Sobat, and small tributaries). The erosion and transportation of silt only occurs during the Ethiopian rainy season in the summer, however, when rainfall is especially high on the Ethiopian Plateau; the rest of the year, the great rivers draining Ethiopia into the Nile (Sobat, Blue Nile, Tekezé, and Atbarah) have a weaker flow.
The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During the dry season the natural discharge of the Blue Nile can be as low as 113 m3/s (4,000 cu ft/s), although upstream dams regulate the flow of the river. During the wet season the peak flow of the Blue Nile often exceeds 5,663 m3/s (200,000 cu ft/s) in late August (a difference of a factor of 50).
Before the placement of dams on the river the yearly discharge varied by a factor of 15 at Aswan. Peak flows of over 8,212 m3/s (290,000 cu ft/s) occurred during late August and early September, and minimum flows of about 552 m3/s (19,500 cu ft/s) occurred during late April and early May.

Bahr el Ghazal and Sobat River

The Bahr al Ghazal and the Sobat River are the two most important tributaries of the White Nile in terms of discharge.
The Bahr al Ghazal's drainage basin is the largest of any of the Nile's sub-basins, measuring 520,000 square kilometres (200,000 sq mi) in size, but it contributes a relatively small amount of water, about 2 m3/s (71 cu ft/s) annually, due to tremendous volumes of water being lost in the Sudd wetlands.
The Sobat River, which joins the Nile a short distance below Lake No, drains about half as much land, 225,000 km2 (86,900 sq mi), but contributes 412 cubic metres per second (14,500 cu ft/s) annually to the Nile.[20] When in flood the Sobat carries a large amount of sediment, adding greatly to the White Nile's color.[21]

Yellow Nile

The Yellow Nile is a former tributary that connected the Ouaddaï Highlands of eastern Chad to the Nile River Valley c. 8000 to c. 1000 BC.[22] Its remains are known as the Wadi Howar. The wadi passes through Gharb Darfur near the northern border with Chad and meets up with the Nile near the southern point of the Great Bend.

History

Further information: Climate history of the Saharaexternal image 220px-Herodotus_world_map-en.svg.png
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Reconstruction of the Oikoumene(inhabited world), an ancient map based onHerodotus' description of the world, circa 450 BC.external image 170px-River_Nile_and_Bulaq_by_Piri_Reis.jpg
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Historic map of the River Nile by Piri Reis

The Nile (iteru in Ancient Egyptian) has been the lifeline of civilization in Egypt since the Stone Age, with most of the population and all of the cities of Egypt resting along those parts of the Nile valley lying north of Aswan. Climate change at the end of the most recent ice age led to the formation of the Sahara desert, possibly as long ago as 3400 BC.




The Eonile

The present Nile is at least the fifth river that has flowed north from the Ethiopian Highlands. Satellite imagery was used to identify dry watercourses in the desert to the west of the Nile. An Eonile canyon, now filled by surface drift, represents an ancestral Nile called the Eonile that flowed during the later Miocene (23–5.3 million years before present). The Eonile transported clastic sediments to the Mediterranean; several natural gas fields have been discovered within these sediments.
During the late-Miocene Messinian salinity crisis, when the Mediterranean Sea was a closed basin and evaporated to the point of being empty or nearly so, the Nile cut its course down to the new base level until it was several hundred feet below world ocean level at Aswan and 8,000 feet (2,400 m) below Cairo.[23] This created a very long and deep canyon which was filled with sediment when the Mediterranean was recreated. At some point the sediments raised the riverbed sufficiently for the river to overflow westward into a depression to create Lake Moeris.
Lake Tanganyika drained northwards into the Nile until the Virunga Volcanoes blocked its course in Rwanda. The Nile was much longer at that time, with its furthest headwaters in northern Zambia.

The integrated Nile

There are two theories about the age of the integrated Nile. One is that the integrated drainage of the Nile is of young age, and that the Nile basin was formerly broken into series of separate basins, only the most northerly of which fed a river following the present course of the Nile in Egypt and Sudan. Said postulated that Egypt itself supplied most of the waters of the Nile during the early part of its history.[24]
The other theory is that the drainage from Ethiopia via rivers equivalent to the Blue Nile and the Atbara and Takazze flowed to the Mediterranean via the Egyptian Nile since well back into Tertiary times.[25]
Salama suggested that during the Paleogene and Neogene Periods (66 million to 2.588 million years ago) a series of separate closed continental basins each occupied one of the major parts of the Sudanese Rift System: Mellut rift, White Nile rift, Blue Nile rift, Atbara rift and Sag El Naam rift.[26] The Mellut Rift Basin is nearly 12 kilometres (7.5 mi) deep at its central part. This rift is possibly still active, with reported tectonic activity in its northern and southern boundaries. The Sudd swamps which form the central part of the basin may still be subsiding. The White Nile Rift System, although shallower than the Bahr el Arab rift, is about 9 kilometres (5.6 mi) deep. Geophysical exploration of the Blue Nile Rift System estimated the depth of the sediments to be 5–9 kilometres (3.1–5.6 mi). These basins were not interconnected until their subsidence ceased, and the rate of sediment deposition was enough to fill and connect them. The Egyptian Nile connected to the Sudanese Nile, which captures the Ethiopian and Equatorial headwaters during the current stages of tectonic activity in the Eastern, Central and Sudanese Rift Systems.[27] The connection of the different Niles occurred during cyclic wet periods. The River Atbara overflowed its closed basin during the wet periods that occurred about 100,000 to 120,000 years ago. The Blue Nile connected to the main Nile during the 70,000–80,000 years B.P. wet period. The White Nile system in Bahr El Arab and White Nile Rifts remained a closed lake until the connection of the Victoria Nile to the main system some 12,500 years ago.

Role in the founding of Egyptian civilization

The Greek historian Herodotus wrote that "Egypt was the gift of the Nile". An unending source of sustenance, it provided a crucial role in the development of Egyptian civilization. Silt deposits from the Nile made the surrounding land fertile because the river overflowed its banks annually. The Ancient Egyptians cultivated and traded wheat, flax, papyrus and other crops around the Nile. Wheat was a crucial crop in the famine-plagued Middle East. This trading system secured Egypt's diplomatic relationships with other countries, and contributed to economic stability. Far-reaching trade has been carried on along the Nile since ancient times. The Ishango bone is probably an early tally stick. It has been suggested that this shows prime numbers and multiplication, but this is disputed. In the book How Mathematics Happened: The First 50,000 Years, Peter Rudman argues that the development of the concept of prime numbers could only have come about after the concept of division, which he dates to after 10,000 BC, with prime numbers probably not being understood until about 500 BC. He also writes that "no attempt has been made to explain why a tally of something should exhibit multiples of two, prime numbers between 10 and 20, and some numbers that are almost multiples of 10."[28] It was discovered along the headwaters of the Nile (near Lake Edward, in northeastern Congo) and was carbon-dated to 20,000 BC.
Water buffalo were introduced from Asia, and Assyrians introduced camels in the 7th century BC. These animals were killed for meat, and were domesticated and used for ploughing—or in the camels' case, carriage. Water was vital to both people and livestock. The Nile was also a convenient and efficient means of transportation for people and goods. The Nile was an important part of ancient Egyptian spiritual life. Hapy was the god of the annual floods, and both he and the pharaoh were thought to control the flooding. The Nile was considered to be a causeway from life to death and the afterlife. The east was thought of as a place of birth and growth, and the west was considered the place of death, as the god Ra, the Sun, underwent birth, death, and resurrection each day as he crossed the sky. Thus, all tombs were west of the Nile, because the Egyptians believed that in order to enter the afterlife, they had to be buried on the side that symbolized death.
As the Nile was such an important factor in Egyptian life, the ancient calendar was even based on the 3 cycles of the Nile. These seasons, each consisting of four months of thirty days each, were calledAkhet, Peret, and Shemu. Akhet, which means inundation, was the time of the year when the Nile flooded, leaving several layers of fertile soil behind, aiding in agricultural growth.[29]
Peret was the growing season, and Shemu, the last season, was the harvest season when there were no rains.[29]

The search for the source of the Nile

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Pliny the Elder speculated on the source of the Nileexternal image 170px-ST-Burton.jpg
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Richard Francis Burton, Victorian explorerexternal image 170px-Henry_Morton_Stanley_1.jpg
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Henry Morton Stanleyconfirmed the source of the Nile in 1875

Despite the failed attempts of the Greeks and Romans to penetrate the Sudd wetlands in South Sudan, the upper reaches of the Nile remained largely unknown to them. Various expeditions failed to determine the river's source. Agatharcides records that in the time of Ptolemy II Philadelphus, a military expedition had penetrated far enough along the course of the Blue Nile to determine that the summer floods were caused by heavy seasonal rainstorms in the Ethiopian Highlands, but no European of antiquity is known to have reached Lake Tana.
The Tabula Rogeriana depicted the source as three lakes in 1154.
Europeans began to learn about the origins of the Nile in the 15th and 16th centuries, when travelers to Ethiopia visited Lake Tana and the source of the Blue Nile in the mountains south of the lake. Although James Bruce claimed to be the first European to have visited the headwaters,[30] modern writers give the credit to the Jesuit Pedro Páez. Páez's account of the source of the Nile[31] is a long and vivid account of Ethiopia. It was published in full only in the early 20th century, although it was featured in works of Páez's contemporaries, including Baltazar Téllez,[32] Athanasius Kircher[33] and by Johann Michael Vansleb.[34]
Europeans had been resident in Ethiopia since the late 15th century, and one of them may have visited the headwaters even earlier without leaving a written trace. The Portuguese João Bermudes published the first description of the Tis Issat Falls in his 1565 memoirs, compared them to the Nile Falls alluded to in Cicero's De Republica.[35]Jerónimo Lobo describes the source of the Blue Nile, visiting shortly after Pedro Páez. Telles also used his account.
The White Nile was even less understood. The ancients mistakenly believed that the Niger River represented the upper reaches of the White Nile. For example, Pliny the Elder wrote that the Nile had its origins "in a mountain of lower Mauretania", flowed above ground for "many days" distance, then went underground, reappeared as a large lake in the territories of the Masaesyli, then sank again below the desert to flow underground "for a distance of 20 days' journey till it reaches the nearest Ethiopians."[36] A merchant named Diogenes reported that the Nile's water attracted game such as water buffalo.
Lake Victoria was first sighted by Europeans in 1858 when the British explorer John Hanning Speke reached its southern shore while traveling with Richard Francis Burton to explore central Africa and locate the great lakes. Believing he had found the source of the Nile on seeing this "vast expanse of open water" for the first time, Speke named the lake after the then Queen of the United Kingdom. Burton, recovering from illness and resting further south on the shores of Lake Tanganyika, was outraged that Speke claimed to have proved his discovery to be the true source of the Nile when Burton regarded this as still unsettled. A very public quarrel ensued, which sparked a great deal of intense debate within the scientific community and interest by other explorers keen to either confirm or refute Speke's discovery. British explorer and missionary David Livingstone pushed too far west and entered the Congo River system instead. It was ultimately Welsh-American explorer Henry Morton Stanley who confirmed Speke's discovery, circumnavigating Lake Victoria and reporting the great outflow at Ripon Falls on the Lake's northern shore.
European involvement in Egypt goes back to the time of Napoleon. Laird Shipyard of Liverpool sent an iron steamer to the Nile in the 1830s. With the completion of the Suez Canal and the British takeover of Egypt in the 1870s, more British river steamers followed.
The Nile is the area's natural navigation channel, giving access to Khartoum and Sudan by steamer. The Siege of Khartoum was broken with purpose-built sternwheelersshipped from England and steamed up the river to retake the city. After this came regular steam navigation of the river. With British Forces in Egypt in the First World War and the inter-war years, river steamers provided both security and sightseeing to the Pyramids and Thebes. Steam navigation remained integral to the two countries as late as 1962. Sudan steamer traffic was a lifeline as few railways or roads were built in that country. Most paddle steamers have been retired to shorefront service, but modern diesel tourist boats remain on the river.


The modern era

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The confluence of the Kagera andRuvubu rivers near Rusumo Falls, part of the Nile's upper reaches.external image 220px-Nile03%28js%29.jpg
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Dhows on the Nileexternal image 220px-View_from_Cairo_Tower_31march2007.jpg
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The Nile passes through Cairo, Egypt's capital city

The Nile has long been used to transport goods along its length. Winter winds blow south, up river, so ships could sail up river, and down river using the flow of the river. While most Egyptians still live in the Nile valley, the 1970 completion of the Aswan High Dam ended the summer floods and their renewal of the fertile soil, fundamentally changing farming practices. The Nile supports much of the population living along its banks, enabling Egyptians to live in otherwise inhospitable regions of the Sahara. The rivers's flow is disturbed at several points by the Cataracts of the Nile, which are sections of faster-flowing water with many small islands, shallow water, and rocks, which form an obstacle to navigation by boats. The Sudd wetlands in Sudan also forms a formidable navigation obstacle and impede water flow, to the extent that Sudan had once attempted to canalize (the Jonglei Canal) to bypass the swamps.[37][38]
Nile cities include Khartoum, Aswan, Luxor (Thebes), and the GizaCairo conurbation. The first cataract, the closest to the mouth of the river, is at Aswan, north of the Aswan Dam. This part of the river is a regular tourist route, with cruise ships and traditional wooden sailing boats known as feluccas. Many cruise ships ply the route between Luxor and Aswan, stopping at Edfu and Kom Ombo along the way. Security concerns have limited cruising on the northernmost portion for many years.
A computer simulation study to plan the economic development of the Nile was directed by H.A.W. Morrice and W.N. Allan, for the Ministry of Hydro-power of the Republic of the Sudan, during 1955–1957[39][40][41] Morrice was their Hydrological Adviser, and Allan his predecessor. M.P. Barnett directed the software development and computer operations. The calculations were enabled by accurate monthly inflow data collected for 50 years. The underlying principle was the use of over-year storage, to conserve water from rainy years for use in dry years. Irrigation, navigation and other needs were considered. Each computer run postulated a set of reservoirs and operating equations for the release of water as a function of the month and the levels upstream. The behaviour that would have resulted given the inflow data was modeled. Over 600 models were run. Recommendations were made to the Sudanese authorities. The calculations were run on an IBM 650 computer. Simulation studies to design water resources are discussed further in the article on Hydrology transport models, that have been used since the 1980s to analyze water quality.
Despite the development of many reservoirs, drought during the 1980s led to widespread starvation in Ethiopia and Sudan, but Egypt was nourished by water impounded in Lake Nasser. Drought has proven to be a major cause of fatality in the Nile River basin. According to a report by the Strategic Foresight Group around 170 million people have been affected by droughts in the last century with half a million lives lost.[42] From the 70 incidents of drought which took place between 1900 and 2012, 55 incidents took place in Ethiopia, Sudan, South Sudan, Kenya and Tanzania.[42]

Water sharing dispute

The Nile's water has affected the politics of East Africa and the Horn of Africa for many decades. Countries including Uganda, Sudan, Ethiopia and Kenya have complained about Egyptian domination of its water resources. The Nile Basin Initiative promotes a peaceful cooperation among those states.[43][44]
Several attempts have been made to establish agreements between the countries sharing the Nile waters. It is very difficult to have all these countries agree with each other given the self-interest of each country and their political, strategic, and social differences. On 14 May 2010 at Entebbe, Uganda, Ethiopia, Rwanda,Tanzania and Uganda signed a new agreement on sharing the Nile water even though this agreement raised strong opposition from Egypt and Sudan. Ideally, such international agreements should promote equitable and efficient usage of the Nile basin's water resources. Without a better understanding about the availability of the future water resources of the Nile River, we could expect more conflicts between these countries relying on the Nile for their water supply, economic and social developments.[4]


Modern achievements and exploration

The White Nile Expedition, led by South African national Hendrik Coetzee, became the first to navigate the Nile's entire length. The expedition began at the source of the Nile in Uganda on January 17, 2004 and arrived safely at the Mediterranean in Rosetta, four and a half months later.[45]
On April 28, 2004, geologist Pasquale Scaturro and his partner, kayaker and documentary filmmaker Gordon Brown became the first people to navigate the Blue Nile, from Lake Tana in Ethiopia to the beaches of Alexandria on the Mediterranean. Though their expedition included others, Brown and Scaturro were the only ones to complete the entire journey.[46] The team used outboard motors for most of their journey. On January 29, 2005 Canadian Les Jickling and New Zealander Mark Tanner completed the first human powered transit.
A team led by South Africans Peter Meredith and Hendrik Coetzee on April 30, 2005, became the first to navigate the major remote source of the Nile, the Akagera river, which starts as the Ruvyironza in Bururi Province, Burundi.
The Hudson River is a 315-mile (507 km) watercourse that flows from north to south through eastern New York State in the United States. The river begins at Henderson Lake in Newcomb, New York. The river flows southward past the state capital at Albany and then eventually forms the boundary between New York City and the U.S. state of New Jersey at its mouth before emptying into Upper New York Bay. Its lower half is atidal estuary,[4] which occupies the Hudson Fjord. This formed during the most recent North American glaciation over the latter part of the Wisconsin Stage of the Last Glacial Maximum, 26,000 to 13,300 years ago.[5] Tidal waters influence the Hudson's flow as far north as Troy, New York.
The river is named after Henry Hudson, an Englishman sailing for the Dutch East India Company, who explored it in 1609. It had previously been observed by Italian explorer Giovanni da Verrazano sailing for King Francis I of France in 1524, as he became the first European known to have entered the Upper Bay, but he considered the river to be an estuary. The Dutch called the river the "North River" – with the Delaware River called the "South River" – and it formed the spine of the Dutch colony of New Netherland. Settlement of the colony clustered around the Hudson, and its strategic importance as the gateway to the American interior led to years of competition between the English and the Dutch over control of the river and colony.
During the eighteenth century, the river valley and its inhabitants were the subject and inspiration of Washington Irving, the first internationally acclaimed American author. In the nineteenth century, the area inspired the Hudson River School of landscape painting, an American pastoral style, as well as the concepts of environmental conservation and wilderness
The river was called Muh-he-kun-ne-tuk, the Great Mohegan, by the Iroquois,[6][7][8] and it was known as Muhheakantuck ("river that flows two ways") by the Lenape tribe who inhabited both banks of the lower portion of the river - all of present day New Jersey and the island of Manhattan.
An early name for the Hudson used by the Dutch was "Rio de Montaigne". Later, they generally termed it the "North River", the Delaware Riverbeing known as the "South River." The name "North River" was used in the New York City area up until the early 1900s, with limited use continuing until modern times.[9] The term persists in radio communication among commercial shipping traffic, especially below Tappan Zee.[10]
The river was included on the 1529 map of Estêvão Gomes and Diego Gutiérrez. On their map it was named Río de San Antonio (St Anthony River), in the context of the Spanish Ajacán Mission of the sixteenth century.[11]
The official source of the Hudson River is Lake Tear of the Clouds in the Adirondack Mountains.[12] However, the waterway from the lake is known as Feldspar Brook and the Opalescent River, feeding into the Hudson at Tahawus. The actual Hudson River begins several miles north of Tahawus at Henderson Lake in Newcomb, New York. The Hudson is joined at Waterford (north of Albany) by the Mohawk River, its major tributary, just south of which the Federal Dam separates the Upper Hudson River Valley from the Lower Hudson River Valley or simply theHudson River Valley. The Hudson river then flows south, passing between the Catskill Mountains and the Taconic Mountains, widening significantly at the Tappan Zee, finally flowing between Manhattan Island and the New Jersey Palisades and into the Atlantic Ocean at New York Bay, an arm of the ocean, where it forms New York Harbor.
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View of the Hudson during the 1880s showing Jersey City.

The lower Hudson is actually a tidal estuary, with tidal influence extending as far as the Federal Dam at Troy.[4] Strong tides make parts of New York Harbor difficult and dangerous to navigate. During the winter, ice floes drift south or north, depending upon the tides. The Mahican name of the river represents its partially estuarine nature: muh-he-kun-ne-tuk means "the river that flows both ways."[13] The Hudson is often mistaken for one of the largest rivers in the United States, but it is an estuary throughout most of its length below Troy and thus only a small fraction of fresh water, about 15,000 cubic feet (425 m³) per second, is present. The mean fresh water discharge at the river's mouth in New York is approximately 21,400 cubic feet (606 m³) per second. The Hudson and its tributaries, notably theMohawk River, drain a large area. Parts of the Hudson River form coves, such as Weehawken Cove in Hoboken andWeehawken.
The Hudson is sometimes called, in geological terms, a drowned river. The rising sea levels after the retreat of theWisconsin glaciation, the most recent ice age, have resulted in a marine incursion that drowned the coastal plain and brought salt water well above the mouth of the river. The deeply eroded old riverbed beyond the current shoreline,Hudson Canyon, is a rich fishing area. The former riverbed is clearly delineated beneath the waters of the Atlantic Ocean, extending to the edge of the continental shelf.
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Looking downriver from Battery Park Cityin Manhattan.
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Hudson from Midtown Manhattan with Javits Convention Center in foreground. TheNew Jersey Palisades is visible across the river.

The Delaware and Hudson Canal ended at the Hudson at Kingston, running southwest to the coal fields of northeastern Pennsylvania.
Notable landmarks on the Hudson include West Point, Home of Franklin D. Roosevelt National Historic Site, Bard College, the Culinary Institute of America, Marist College, the Thayer Hotel at West Point, Bannerman's Castle,Metro-North Railroad's Hudson Line (formerly part of the New York Central Railroad system), the Tappan Zee, theNew Jersey Palisades, Hudson River Islands State Park, Hudson Highlands State Park, Walkway over the Hudson,Sing Sing Correctional Facility, New York Military Academy, Fort Tryon Park with The Cloisters, Liberty State Park, and Stevens Institute of Technology. Cities and towns on the New Jersey side include Alpine, Tenafly, Englewood Cliffs, Fort Lee, Edgewater, North Bergen, Guttenberg, West New York, Weehawken, Hoboken, and Jersey City. Cities in New York State include Troy, Albany, Hudson, Kingston, Poughkeepsie, Glens Falls, Yonkers, NewburghBeacon and New York City.
The natural beauty of the Hudson Valley earned the Hudson River the nickname "America's Rhine", being compared to that of the famous 40 mile (65 km) stretch of Germany's Rhine River valley between the cities of Bingen andKoblenz. A similar 30-mile (48 km) stretch on the east bank of the Hudson has been designated the Hudson River Historic District, a National Historic Landmark. The Hudson was designated as one of the American Heritage Rivers in 1997.

he Narrows[edit]

The Narrows, a tidal stream between the New York City boroughs of Staten Island and Brooklyn, connects the upper and lower sections of New York Bay. It has long been considered the maritime "gateway" to New York City and historically has been the most important entrance into the harbor.
The Narrows were most likely formed about 6,000 years ago at the end of the last ice age. Previously, Staten Island and Long Island were connected, preventing the Hudson River from terminating via The Narrows. At that time, the Hudson River emptied into the Atlantic Ocean through a more westerly course through parts of present day northern New Jersey, along the eastern side of the Watchung Mountains to Bound Brook, New Jersey and then on into the Atlantic Ocean via Raritan Bay. A build up of water in the Upper Bay eventually allowed the Hudson River to break through previous land mass that was connecting Staten Island and Brooklyn to form The Narrows as it exists today. This allowed the Hudson River to find a shorter route to the Atlantic Ocean via its present course between New Jersey and New York City (Waldman, 2000).

North River[edit]

Main article: North River (Hudson River)
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Lower Hudson River as seen fromRiverside Park in Manhattan's Upper West Side.

North River is an alternate name for the southernmost portion of the Hudson, usually referring to all or part of the waterway located between Manhattan and Hudson County.[14][15][16][17][18] The colonial name given by the Dutch to the entire river in the early seventeenth century, the term fell out of popular use for most of it some time in the early 1900s,[9] but continues in use locally by mariners and others[19][20][21] as well as on some nautical charts[22] and maps. The term also lives on in the names of a variety of facilities such as the North River piers, North River Tunnels, and the North River Wastewater Treatment Plant, and has strong historical ties with New York Harbor.


Haverstraw Bay[edit]

Haverstraw Bay, just north of the Tappan Zee (the widest part of the river), is located between Croton Point in the Southeast and the town of Haverstraw in the Northwest. Haverstraw Bay is a popular destination for recreational boaters and is home to many yacht clubs and marinas, including Croton Yacht Club, Croton Sailing School, Half Moon Bay Marina (Croton), Pennybridge Marina, Minisceongo Yacht Club, Stony Point Bay Marina, and Haverstraw Marina, and is traversed byNY Waterway's Haverstraw–Ossining Ferry.

Transportation[edit]

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The George Washington Bridge, connecting Fort Lee, New Jersey across the Hudson River to New York City, is the world's busiest motor vehicle bridge.[23]external image 250px-PokRRBridge.JPG
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The Poughkeepsie Bridge was the world's longest bridge when it opened for rail traffic in 1889.[24] In 2009, it became the world's longest pedestrian bridge and a New York State Historic Park, Walkway Over The Hudson.[25]external image 220px-TappanZeeBridgeFromBelow.JPG
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The Tappan Zee Bridge connectsTarrytown, Westchester County, and South Nyack, Rockland County, in the Lower Hudson Valley of New York State.external image 250px-Hudson_River.jpg
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Looking downriver from the Circle Line Sightseeing Cruises boat. George Washington Bridge can be seen in the background.

The Hudson River is navigable for a great distance above mile 0 (at 40°42.1'N., 74°01.5'W.) off The Battery. The original Erie Canal, opened in 1825 to connect the Hudson with Lake Erie, emptied into the Hudson at the Albany Basin, just three miles (5 km) south of the Federal Dam in Troy (at mile 134). The canal enabled shipping between cities on the Great Lakes and Europe via the Atlantic Ocean. The New York State Canal System, the successor to the Erie Canal, runs into the Hudson River north of Troy and uses the Federal Dam as the Lock 1 and natural waterways whenever possible. The first railroad in New York, the Mohawk and Hudson Railroad, opened in 1831 between Albany and Schenectady on the Mohawk River, enabling passengers to bypass the slowest part of the Erie Canal.
In northern Troy, the Champlain Canal split from the Erie Canal and continued north along the west side of the Hudson to Thomson, where it crossed to the east side. At Fort Edward the canal left the Hudson, heading northeast to Lake Champlain. A barge canal now splits from the Hudson at that point, taking roughly the same route (also parallel to the Delaware and Hudson Railway's Saratoga and Whitehall Railroad) to Lake Champlain at Whitehall. From Lake Champlain, boats can continue north into Canada to the Saint Lawrence Seaway.
The Hudson Valley also proved attractive for railroads, once technology progressed to the point where it was feasible to construct the required bridges over tributaries. The Troy and Greenbush Railroad was chartered in 1845 and opened that same year, running a short distance on the east side between Troy and Greenbush[disambiguation needed](east of Albany). The Hudson River Railroad was chartered the next year as a continuation of the Troy and Greenbush south to New York City, and was completed in 1851. In 1866 the Hudson River Bridge opened over the river between Greenbush and Albany, enabling through traffic between the Hudson River Railroad and the New York Central Railroad west to Buffalo. When the Poughkeepsie Rail Bridge opened in 1889, it became the longest single span bridge in the world. On October 3, 2009, it re-opened as a pedestrian walkway over the Hudson, as part of the Hudson River Quadricentennial Celebrations and connects over 25 miles of existing pedestrian trails.[26][27]
The New York, West Shore and Buffalo Railway began at Weehawken Terminal and ran up the west shore of the Hudson as a competitor to the merged New York Central and Hudson River Railroad. Construction was slow, and was finally completed in 1884; the New York Central purchased the line the next year.
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A sailboat on the Hudson River, withLower Manhattan in the background.

The Hudson is crossed at numerous points by bridges, tunnels, and ferries. The width of the Lower Hudson River required major feats of engineering to cross, the results today visible in the Verrazano-Narrows Bridge, the George Washington Bridge, and the Tappan Zee Bridge, as well as the Lincoln and Holland Tunnels and the PATH andPennsylvania Railroad tubes. The George Washington Bridge (signed as I-95/US 1-9/US 46), connecting Fort Lee, New Jersey to the Washington Heights neighborhood of Upper Manhattan in New York City, is the world's busiest motor vehicle bridge.[28] The Troy–Waterford Bridge at Waterford was the first bridge over the Hudson, opened in 1809. The Rensselaer and Saratoga Railroad was chartered in 1832 and opened in 1835, including the Green Island Bridge, the first bridge over the Hudson south of the Federal Dam.[29]
The Upper Hudson River Valley was also useful for railroads. Sections of the Rensselaer and Saratoga Railroad, Troy and Boston Railroad and Albany Northern Railroad ran next to the Hudson between Troy and Mechanicville. North of Mechanicville the shore was bare until Glens Falls, where the short Glens Falls Railroad ran along the east shore. At Glens Falls the Hudson turns west to Corinth before continuing north; at Corinth the Adirondack Railway begins to run along the Hudson's west bank. The original Adirondack Railway opened by 1871, ending at North Creek along the river. In World War II an extension opened to Tahawus, the site of valuable iron and titaniummines. The extension continued along the Hudson River into Hamilton County, and then continued north where the Hudson makes a turn to the west, crossing the Hudson and running along the west shore of the Boreas River. South of Tahawus the route returned to the east shore of the Hudson the rest of the way to its terminus.


PCB contamination[edit]

PCBs were widely used as dielectric and coolant fluids, for example in transformers, capacitors, and electric motors.[37] General Electric manufacturing facilities atHudson Falls and Fort Edward discharged between 209,000–1,300,000 lb (95–590 metric tons) of polychlorinated biphenyl (PCBs) into the river from 1947 to 1977. The PCBs caused extensive contamination of fish in the river and apparently triggered a rapid evolutionary change in the Atlantic tomcod, which after about 50 years of exposure evolved a two amino acid change in its AHR2 receptor gene, causing the receptor to bind more weakly with PCBs than normal.[38] The mutation does not prevent the tomcods from accumulating PCBs in their bodies and passing them on to striped bass and whatever else eats them.[38] This system of passing contamination on to larger organisms is also known as biomagnification. The toxic chemicals also accumulated in sediments that settled to the river bottom.[39] The highest concentration of PCBs comes from the Thompson Island Pool.[40]
In 1966, Pete Seeger and Toshi Seeger founded Hudson River Sloop Clearwater, an environmental education organization and an actual boat (a sloop), that promotes awareness of the river and its history. Clearwater has gained national recognition for its activism starting in the 1970s to force a clean-up of PCB contamination of the Hudson caused by GE and other companies.[41]
There are many economic effects caused by the PCB Contamination. The water cannot be used for agriculture use, money is lost from the fishing industry because of the ban on recreational fishing, medical expenses for people who have side-effects from the water, and the cost of clean-up efforts.
In 1976 the New York State Department of Environmental Conservation banned all fishing in the Upper Hudson due to health concerns with PCBs.[42][43] PCBs are thought to be responsible for health issues that include neurological disorders, lower IQ and poor short-term memory (active memory), hormonal disruption, suppressed immune system, cancer, skin Irritations, Parkinson’s disease, ADHD, heart disease, and diabetes. PCB contamination in humans may come from drinking the contaminated water, absorption through the skin, eating contaminated aquatic life, and/or inhaling volatilized PCBs. PCB contamination is especially dangerous for pregnant and nursing women. The contamination can reach the fetus and potentially cause birth defects. Contamination through breast milk can also have harmful effects on the child indirectly.
In 1977, PCBs were banned in the United States.[44] In 1983, the United States Environmental Protection Agency (EPA) declared a 200-mile (322-km) stretch of the river, from Hudson Falls to New York City, to be a Superfund site requiring cleanup.This superfund site is considered to be one of the largest in the nation. In 2001, after a ten year study of PCB contamination in the Hudson River, the EPA proposed a plan to clean up the river by dredging more than 100,000 pounds of PCBs. The worst PCB hotspots are targeted for remediation by removing and disposing of more than 2.6 million cubic yards of contaminated sediment.[45] The dredging project is the most aggressive environmental effort ever proposed to clean up a river, and will cost GE about $460,000,000. GE began sediment dredging operations to clean up the PCBs on May 15, 2009.[46] This stage (Phase One) of the cleanup was completed in October 2009, and was responsible for the removal of approximately 300,000 cubic yards of contaminated sediment, which was more than the targeted amount. Over 620 barges filled with sediment were transported to the processing facility on the Champlain Canal, and over 80 rail cars transported the dredged sediment to a waste facility in Andrews, Texas.[47] The true scope of Phase One was about 100,000 cubic yards more than planned, and Phase Two will be expanded as a consequence. Before Phase two of the cleanup, GE was given the opportunity to opt out of the clean up efforts, but they chose to complete the project. Phase two of the cleanup project, led by GE and monitored by the EPA, began in June 2011. This phase targets approximately 2.4 million cubic yards of PCB-contaminated sediment from a forty mile section of the Upper Hudson River. Phase Two of the clean up will take approximately 5 to 7 years to complete.[48]

Other pollutants[edit]

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Bird's-eye view of the Hudson from theWalkway Over the Hudson.

Other ongoing pollution issues affecting the river include: accidental sewage discharges, urban runoff, heavy metals, furans, dioxin, pesticides, and polycyclic aromatic hydrocarbons (PAHs).[49]
A study reported in the August 2008 issue of the journal Environmental Toxicology and Chemistry suggests that mercury in common Hudson River fish, includingstriped bass, yellow perch, largemouth bass, smallmouth bass and carp, has declined strongly over the past three decades. The conclusions were extracted from a large database of mercury analyses of fish fillets accumulated by NYSDEC and collected over much of the length of the Hudson from New York City waters to the Adirondack watershed. The research indicates that the trends are in line with the recovery that the Hudson River has experienced over the past few decades, now that activist groups, government officials and industry are beginning to cooperate to help clean up the river system.[50]
NYSDEC has listed various portions of the Hudson as having impaired water quality due to PCBs, cadmium, and other toxic compounds. Hudson River tributaries with impaired water quality (not necessarily the same pollutants as the Hudson main stem) are Mohawk River, Dwaas Kill, Schuyler Creek, Saw Mill River, Esopus Creek, Hoosic River, Quaker Creek, and Batten Kill. Many lakes in the Hudson drainage basin are also listed.[51]

Other environmental impacts[edit]

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Sunset on the Hudson at Riverside Park, with New Jersey in the background

Proposed hydroelectric facility[edit]

In 1980, Consolidated Edison (Con Ed) agreed to drop its 17-year fight to build a pumped-storage hydroelectricity facility on Storm King Mountain, after a legal challenge by the non-profit environmental organization Scenic Hudson.[52] The actions of local citizen organizations that led to the Con Ed decision spurred the creation ofRiverkeeper, a non-profit environmental organization that grew into a global umbrella organization, the Waterkeeper Alliance.[53]

Cooling water withdrawals[edit]

In 2010 NYSDEC charged that the Indian Point Energy Center, a nuclear power plant in Buchanan, is violating the Clean Water Act due to its large withdrawals of water from the Hudson, which kills millions of fish and other aquatic organisms each year. The state is demanding that Entergy, the plant operator, construct cooling towers to mitigate the environmental impacts.[54]
The Hudson River estuary system is part of The National Estuarine Research Reserve System.[55]



The Mississippi River is the chief river of the largest drainage system in North America.[3][4] Flowing entirely in the United States (though its drainage basin reaches into Canada), it rises in northern Minnesota and meanders slowly southwards for 2,530 miles (4,070 km)[5] to the Mississippi River Deltaat the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 31 US states and 2 Canadian provinces between theRocky and Appalachian Mountains. The Mississippi ranks as the fourth longest and tenth largest river in the world. The river either borders or cuts through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
Native Americans long lived along the Mississippi and its tributaries. Most were hunter-gatherers or herders, but some, such as the Mound builders, formed prolific agricultural societies. The arrival of Europeans in the 1500s changed the native way of life as first explorers, then settlers, ventured into the basin in increasing numbers. The river served first as a barrier – forming borders for New Spain, New France, and the early United States – then as a vital transportation artery and communications link. In the 19th century, during the height of Manifest Destiny, the Mississippi and several western tributaries, most notably the Missouri, formed pathways for the western expansion of the United States.
Formed from thick layers of this river's silt deposits, the Mississippi River Valley is one of the most fertile agricultural regions of the country, which resulted in the river's storied steamboat era. During the American Civil War, the Mississippi's capture by Union forces marked a turning point towards victory because of the river's importance as a route of trade and travel, not least to the Confederacy. Because of substantial growth of cities and the larger ships and barges that supplanted riverboats, the decades following the 1900s saw the construction of massive engineering works such as levees,locks and dams, often built in combination.
Since modern development of the basin began, the Mississippi has also seen its share of pollution and environmental problems – most notably large volumes of agricultural runoff, which has led to the Gulf of Mexico dead zone off the Delta. In recent years, the river has shown a steady shift towards the Atchafalaya River channel in the Delta; a course change would prove disastrous to seaports such as New Orleans. While a system of dikes and gates has held the Mississippi in its current channel to date, the shift becomes more likely each year due to fluvial processes.

The word itself comes from Messipi, the French rendering of the Anishinaabe (Ojibwe or Algonquin) name for the river, Misi-ziibi (Great River). See below in History section for additional information.
In addition to historical traditions shown by names, there are at least two other measures of a river's identity, one being the largest branch (by water volume), and the other being the longest branch. Using the largest-branch criterion, the Ohio (not the Middle and Upper Mississippi) would be the main branch of the Lower Mississippi. Using the longest-branch criterion, the Middle Mississippi-Missouri-Jefferson-Beaverhead-Red Rock-Hellroaring Creek River would be the main branch. According to either school of thought, the Upper Mississippi from Lake Itasca, Minnesota to St. Louis, despite its name, would only be a secondary tributary of the final river flowing from Cairo to the Gulf of Mexico.
While the Missouri River, flowing from the confluence of the Jefferson, Madison and Gallatin Rivers to the Mississippi, is the longest continuously named river in the United States,[4] the serially named river known sequentially as Hellroaring Creek, Red Rock, Beaverhead, Jefferson, Missouri, Middle Mississippi, and Lower Mississippi, as one continuous waterway, is the longest river in North America and the third or fourth longest river in the world. Its length of at least 3,745 mi (6,027 km)[citation needed] is exceeded only by the Nile, the Amazon,[6] and perhaps the Yangtze River[7] among the longest rivers in the world. The source of this waterway is at Brower's Spring, 8,800 feet (2,700 m) above sea level in southwestern Montana, along the Continental Divide outside Yellowstone National Park.
The Mississippi River is widely considered a convenient if approximate dividing line between the Eastern, Southern, and Midwestern United States and the Western U.S., as exemplified by the Gateway Archin St. Louis and the phrase "Trans-Mississippi", used for example in the name of the 1898 Trans-Mississippi Exposition held in Omaha, Nebraska.

The geographical setting of the Mississippi River includes considerations of the course of the river itself, its watershed, its outflow, its prehistoric and historic course changes, and possibilities of future course changes. The New Madrid Seismic Zone along the river is also noteworthy. These various basic geographical aspects of the river in turn underlie its human history and present uses of the waterway and its adjacent lands.

Divisions[edit]

The Mississippi River is divided into the Upper Mississippi, the Middle Mississippi, and the Lower Mississippi, with the Upper Mississippi upriver of its confluence with the Missouri River, the Middle Mississippi from there downriver to the Ohio River, and the Lower Mississippi from there downriver to the Gulf of Mexico.

Upper Mississippi[edit]

The Upper Mississippi runs from its headwaters to its confluence with the Missouri River at St. Louis, Missouri. The Upper Mississippi is divided into two sections:
  1. The headwaters, 493 miles (793 km), from the source to Saint Anthony Falls in Minneapolis, Minnesota; and
  2. A navigable channel, formed by a series of man-made lakes between Minneapolis and St. Louis, Missouri, some 664 miles (1,069 km).
The source of the Upper Mississippi branch is traditionally accepted as Lake Itasca, 1,475 feet (450 m) above sea level in Itasca State Park in Clearwater County, Minnesota. The name "Itasca" is a combination of the last four letters of the Latin word for truth (veritas) and the first two letters of the Latin word for head (caput).[8] However, the lake is in turn fed by a number of smaller streams.
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The beginning of the Mississippi River atLake Itasca (2004)
Coon Rapids Dam
Coon Rapids Dam

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Mississippi Head of Navigation: Coon Rapids Dam

From its origin at Lake Itasca to St. Louis, Missouri, the waterway's flow is moderated by 43 dams. Fourteen of these dams are located above Minneapolis in theheadwaters region and serve multiple purposes, including power generation and recreation. The remaining 29 dams, beginning in downtown Minneapolis, all contain locks and were constructed to improve commercial navigation of the upper river. Taken as a whole these 43 dams significantly shape the geography and influence the ecology of the upper river. Beginning just below Saint Paul, Minnesota, and continuing throughout the upper and lower river, the Mississippi is further controlled by thousands of wing dikes that moderate the river's flow in order to maintain an open navigation channel and prevent the river from eroding its banks.
The head of navigation on the Mississippi is the Coon Rapids Dam in Coon Rapids, Minnesota. Before its construction in 1913, steamboats could occasionally go upstream as far as Saint Cloud, Minnesota, depending on river conditions.
The uppermost lock and dam on the Upper Mississippi River is the Upper St. Anthony Falls Lock and Dam in Minneapolis. Above the dam, the river's elevation is 799 feet (244 m). Below the dam, the river's elevation is 750 feet (230 m). This 49-foot (15 m) drop is the largest of all the Mississippi River locks and dams. The origin of the dramatic drop is a waterfall preserved adjacent to the lock under an apron of concrete. Saint Anthony Falls is the only true waterfall on the entire Mississippi River. The water elevation continues to drop steeply as it passes through the gorge carved by the waterfall.
The Upper Mississippi features various natural and artificial lakes, with its widest point being Lake Winnibigoshish, near Grand Rapids, Minnesota, over 7 miles (11 km) across. Also of note is Lake Onalaska (created by Lock and Dam No. 7), near La Crosse, Wisconsin, over 4 miles (6.4 km) wide. On the other hand, Lake Pepin is natural, formed due to the delta formed by the Chippewa River of Wisconsin as it enters the Upper Mississippi; it is more than 2 miles (3.2 km) wide.[9]
By the time the Upper Mississippi reaches Saint Paul, Minnesota, below Lock and Dam No. 1, it has dropped more than half its original elevation and is 687 feet (209 m) above sea level. From St. Paul to St. Louis, Missouri, the river elevation falls much more slowly, and is controlled and managed as a series of pools created by 26 locks and dams.[10]
The Upper Mississippi River is joined by the Minnesota River at Fort Snelling in the Twin Cities; the St. Croix River near Prescott, Wisconsin; the Cannon River nearRed Wing, Minnesota; the Zumbro River at Wabasha, Minnesota; the Black, La Crosse, and Root rivers in La Crosse, Wisconsin; the Wisconsin River at Prairie du Chien, Wisconsin; the Rock River at the Quad Cities; the Iowa River near Wapello, Iowa; the Skunk River south of Burlington, Iowa; and the Des Moines River at Keokuk, Iowa. Other major tributaries of the Upper Mississippi include the Crow River in Minnesota, the Chippewa River in Wisconsin, the Maquoketa River and theWapsipinicon River in Iowa, and the Big Muddy River and Illinois River.
The Upper Mississippi is largely a multi-thread stream with many bars and islands. From its confluence with the St. Croix River downstream to Dubuque, Iowa, the river is entrenched, with high bedrock bluffs lying on either side. The height of these bluffs decreases to the south of Dubuque, though they are still significant through Savanna, Illinois. This topography contrasts strongly with the Lower Mississippi, which is a meandering river in a broad, flat area, only rarely flowing alongside a bluff (as at Vicksburg, Mississippi).


Middle Mississippi[edit]

The Mississippi River is known as the Middle Mississippi from the Upper Mississippi River's confluence with the Missouri River at St. Louis, Missouri, for 190 miles (310 km) to its confluence with the Ohio River at Cairo, Illinois.[11][12]
The Middle Mississippi is a relatively free-flowing river. From St. Louis to the Ohio River confluence, the Middle Mississippi falls a total of 220 feet (67 m) over a distance of 180 miles (290 km) for an average rate of 1.2 feet per mile (23 cm/km). At its confluence with the Ohio River, the Middle Mississippi is 315 feet (96 m) above sea level. Apart from the Missouri and Meramec rivers of Missouri and the Kaskaskia River of Illinois, no major tributaries enter the Middle Mississippi River.

Lower Mississippi[edit]

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Lower Mississippi River near the city New Orleans

The Mississippi River is called the Lower Mississippi River from its confluence with the Ohio River to its mouth at the Gulf of Mexico. Measured by water volume, the Lower Mississippi's primary branch is the Ohio River. At the confluence of the Ohio and the Middle Mississippi, the Ohio is the bigger river, with its long-term mean discharge at Cairo, Illinois being 281,500 cu ft/s (7,970 m3/s),[13] while the long-term mean discharge of the Mississippi at Thebes, Illinois (just upriver from Cairo) is 208,200 cu ft/s (5,900 m3/s).[14] Thus, by volume, the main branch of the Mississippi River system at Cairo can be considered to be the Ohio River (and the Allegheny River further upstream), rather than the Middle Mississippi.
In addition to the Ohio River, the major tributaries of the Lower Mississippi River are the White River, flowing in at the White River National Wildlife Refuge in east central Arkansas; the Arkansas River, joining the Mississippi at Arkansas Post; the Big Black River in Mississippi; the Yazoo River, meeting the Mississippi atVicksburg, Mississippi; and the Red River in Louisiana. The widest point of the Mississippi River is in the Lower Mississippi portion where it exceeds 1 mile (1.6 km) in width in several places.
Deliberate water diversion at the Old River Control Structure in Louisiana allows the Atchafalaya River in Louisiana to be a major distributary of the Mississippi River, with 30% of the Mississippi flowing to the Gulf of Mexico by this route, rather than continuing down the Mississippi's current channel past Baton Rouge and New Orleans on a longer route to the Gulf.[15][16][17]

Watershed[edit]

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Mississippi watershed (2005)See also: List of drainage basins by area

The Mississippi River has the world's fourth largest drainage basin ("watershed" or "catchment"). The basin covers more than 1,245,000 sq mi (3,220,000 km2), including all or parts of 32 U.S. states and two Canadian provinces. The drainage basin empties into the Gulf of Mexico, part of the Atlantic Ocean. The total catchment of the Mississippi River covers nearly 40% of the landmass of the continental United States.
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Sequence of NASA MODIS images showing the outflow of fresh water from the Mississippi (arrows) into the Gulf of Mexico (2004)

In the United States, the Mississippi River drains the majority of the area between crest of the Rocky Mountains and the crest of the Appalachian Mountains, except for various regions drained to Hudson Bay by the Red River of the North; to the Atlantic Ocean by the Great Lakes and the Saint Lawrence River; and to the Gulf of Mexico by the Rio Grande, the Alabama and Tombigbee rivers, the Chattahoochee and Appalachicola rivers, and various smaller coastal waterways along the Gulf.
The Mississippi River empties into the Gulf of Mexico about 100 miles (160 km) downstream from New Orleans. Measurements of the length of the Mississippi from Lake Itasca to the Gulf of Mexico vary somewhat, but the United States Geological Survey's number is 2,340 miles (3,770 km). The retention time from Lake Itasca to the Gulf is typically about 90 days.[18]

Outflow[edit]

The Mississippi River discharges at an annual average rate of between 200 and 700 thousand cubic feet per second (7,000–20,000 m3/s).[19] Although it is the 5th largest river in the world by volume, this flow is a mere fraction of the output of the Amazon, which moves nearly 7 million cubic feet per second (200,000 m3/s) during wet seasons. On average, the Mississippi has only 8% the flow of the Amazon River.[20]
Fresh river water flowing from the Mississippi into the Gulf of Mexico does not mix into the salt water immediately. The images from NASA's MODIS (to the right) show a large plume of fresh water, which appears as a dark ribbon against the lighter-blue surrounding waters. These images demonstrate that the plume did not mix with the surrounding sea water immediately. Instead, it stayed intact as it flowed through the Gulf of Mexico, into the Straits of Florida, and entered the Gulf Stream. The Mississippi River water rounded the tip of Florida and traveled up the southeast coast to the latitude of Georgia before finally mixing in so thoroughly with the ocean that it could no longer be detected by MODIS.
Prior to 1900, the Mississippi River transported an estimated 400 million metric tons of sediment per year from the interior of the United States to coastal Louisiana and the Gulf of Mexico. During the last two decades, this number was only 145 million metric tons per year. The reduction in sediment transported down the Mississippi River is the result of engineering modification of the Mississippi, Missouri, and Ohio rivers and their tributaries by dams, meander cutoffs, river-training structures, and bank revetments and soil erosion control programs in the areas drained by them.[21]

Course changes[edit]

Over geologic time, the Mississippi River has experienced numerous large and small changes to its main course, as well as additions, deletions, and other changes among its numerous tributaries, and the lower Mississippi River has used different pathways as its main channel to the Gulf of Mexico across the delta region.
Through a natural process known as avulsion or delta switching, the lower Mississippi River has shifted its final course to the mouth of the Gulf of Mexico every thousand years or so. This occurs because the deposits of silt and sediment begin to clog its channel, raising the river's level and causing it to eventually find a steeper, more direct route to the Gulf of Mexico. The abandoned distributaries diminish in volume and form what are known as bayous. This process has, over the past 5,000 years, caused the coastline of south Louisiana to advance toward the Gulf from 15 to 50 miles (25–80 km). The currently active delta lobe is called the Birdfoot Delta, after its shape, or the Balize Delta, after La Balize, Louisiana, the first French settlement at the mouth of the Mississippi.

Prehistoric courses[edit]

The current form of the Mississippi River basin was largely shaped by the Laurentide Ice Sheet of the most recent Ice Age. The southernmost extent of this enormous glaciation extended well into the present-day United States and Mississippi basin. When the ice sheet began to recede, hundreds of feet of rich sediment were deposited, creating the flat and fertile landscape of the Mississippi Valley. During the melt, giant glacial rivers found drainage paths into the Mississippi watershed, creating such features as the Minnesota River, James River, and Milk River valleys. When the ice sheet completely retreated, many of these "temporary" rivers found paths to Hudson Bay or the Arctic Ocean, leaving the Mississippi Basin with many features "oversized" for the existing rivers to have carved in the same time period.
Ice sheets during the Illinoian Stage about 300,000 to 132,000 years before present, blocked the Mississippi near Rock Island, Illinois, diverting it to its present channel farther to the west, the current western border of Illinois. The Hennepin Canal roughly follows the ancient channel of the Mississippi downstream from Rock Island to Hennepin, Illinois. South of Hennepin, to Alton, Illinois, the current Illinois Riverfollows the ancient channel used by the Mississippi River before the Illinoian Stage.[22][23]
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View along the former riverbed at theTennessee/Arkansas state line nearReverie, Tennessee (2007)

Historic course changes[edit]

In March 1876, the Mississippi suddenly changed course near the settlement of Reverie, Tennessee, leaving a small part of Tipton County, Tennessee, attached toArkansas and separated from the rest of Tennessee by the new river channel. Since this event was an avulsion, rather than the effect of incremental erosion and deposition, the state line remains located in the old channel.[24]

New Madrid Seismic Zone[edit]

The New Madrid Seismic Zone, along the Mississippi River near New Madrid, Missouri, between Memphis and St. Louis, is related to an aulacogen (failed rift) that formed at the same time as the Gulf of Mexico. This area is still quite active seismically. Four great earthquakes in 1811 and 1812, estimated at approximately 8 on the Richter magnitude scale, had tremendous local effects in the then sparsely settled area, and were felt in many other places in the midwestern and eastern U.S. These earthquakes created Reelfoot Lake in Tennessee from the altered landscape near the river, and temporarily reversed the direction of flow of the Mississippi itself.


State boundaries[edit]

The Mississippi River runs through or along 10 states, from Minnesota to Louisiana, and was used to define portions of these states' borders, with Wisconsin, Illinois, Kentucky, Tennessee, and Mississippialong the east side of the river, and Iowa, Missouri, and Arkansas along its west side. Substantial parts of both Minnesota and Louisiana are on either side of the river, although the Mississippi defines part of the boundary of each of these states.
In all of these cases, the middle of the riverbed at the time the borders were established was used as the line to define the borders between adjacent states.[25][26] In various areas, the river has since shifted, but the state borders have not changed, still following the former bed of the Mississippi River as of their establishment, leaving several small isolated areas of one state across the new river channel, contiguous with the adjacent state. Also, due to a meander in the river, a small part of western Kentucky is contiguous with Tennessee, but isolated from the rest of its state.

Communities along the river[edit]

Metro Area
Population
Minneapolis-Saint Paul
3,615,902
St. Louis
2,900,605
Memphis
1,316,100
New Orleans
1,214,932
Baton Rouge
802,484
Quad Cities, IA-IL
382,630
St. Cloud, MN
189,148
La Crosse, WI
133,365
Cape Girardeau–Jackson MO-IL
96,275
Dubuque, IA
93,653
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In Minnesota, the Mississippi River runs through the Twin Cities (2007)external image 220px-WinonaMNboathouses2006-05-09.JPG
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Community of boathouses on the Mississippi River in Winona, MN (2006)external image 220px-Miss_R_dam_27.jpg
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The Mississippi River at the Chain of Rocks just north of St. Louis (2005)

Many of the communities along the Mississippi River are listed below; most have either historic significance or cultural lore connecting them to the river. They are sequenced from the source of the river to its end.



Bridge crossings[edit]

See also: List of crossings of the Upper Mississippi River and List of crossings of the Lower Mississippi Riverexternal image 220px-Mississippi_River_from_the_Guthrie_Theater.jpg
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The Stone Arch Bridge, the Third Avenue Bridge and the Hennepin Avenue Bridge in Minneapolis (2004)

The first bridge across the Mississippi River was built in 1855. It spanned the river in Minneapolis, Minnesota where the current Hennepin Avenue Bridge is located.[27] No highway or railroad tunnels cross under the Mississippi River.
The first railroad bridge across the Mississippi was built in 1856. It spanned the river between the Rock Island Arsenal in Illinois and Davenport, Iowa. Steamboat captains of the day, fearful of competition from the railroads, considered the new bridge a hazard to navigation. Two weeks after the bridge opened, the steamboatEffie Afton rammed part of the bridge, catching it on fire. Legal proceedings ensued, with Abraham Lincoln defending the railroad. The lawsuit went to the Supreme Court of the United States and was eventually ruled in favor of the railroad.
Below is a general overview of selected Mississippi bridges which have notable engineering or landmark significance, with their cities or locations. They are sequenced from the Upper Mississippi's source to the Lower Mississippi's mouth.
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The Dubuque-Wisconsin Bridge (2004)

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Norbert F. Beckey bridge at Muscatine, Iowa, with LED lighting
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The Chain of Rocks Bridge at St.Louis, Missouri


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The Hernando de Soto Bridge inMemphis, Tennessee (2009)


Navigation and flood control[edit]

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Towboat and barges at Memphis, Tennessee


A clear channel is needed for the barges and other vessels that make the main stem Mississippi one of the great commercial waterways of the world. The task of maintaining a navigation channel is the responsibility of the United States Army Corps of Engineers, which was established in 1802.[28] Earlier projects began as early as 1829 to remove snags, close off secondary channels and excavate rocks and sandbars.
Steamboats entered trade in the 1820s, so the period 1830 – 1850 became the golden age of steamboats. As there were few roads or rails in the lands of the Louisiana Purchase, river traffic was an ideal solution. Cotton, timber and food came down the river, as did Appalachian coal. The port of New Orleans boomed as it was the trans-shipment point to deep sea ocean vessels. As a result, the image of the twin stacked, wedding cake Mississippi steamer entered into American mythology. Steamers worked the entire route from the trickles of Montana, to the Ohio river; down the Missouri and Tennessee, to the main channel of the Mississippi. Only with the arrival of the railroads in the 1880s did steamboat traffic diminish. Steamboats remained a feature until the 1920s. Most have been superseded by pusher tugs. A few survive as icons—the Delta Queen and the River Queen for instance.
A series of 29 locks and dams on the upper Mississippi, most of which were built in the 1930s, is designed primarily to maintain a 9 feet (2.7 m) deep channel for commercial barge traffic.[29][30] The lakes formed are also used for recreational boating and fishing. The dams make the river deeper and wider but do not stop it. No flood control is intended. During periods of high flow, the gates, some of which are submersible, are completely opened and the dams simply cease to function. Below St. Louis, the Mississippi is relatively free-flowing, although it is constrained by numerous levees and directed by numerouswing dams.

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Barges on the Mississippi River near Ste. Genevieve, Missouri.

19th century[edit]

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Lock and Dam No. 11, north of Dubuque, Iowa (2007)

In 1829, there were surveys of the two major obstacles on the upper Mississippi, the Des Moines Rapids and the Rock Island Rapids, where the river was shallow and the riverbed was rock. The Des Moines Rapids were about 11 mi (18 km) long and just above the mouth of the Des Moines River at Keokuk, Iowa. The Rock Island Rapids were between Rock Island and Moline, Illinois. Both rapids were considered virtually impassable.
In 1848, the Illinois and Michigan Canal was built to connect the Mississippi River to Lake Michigan via the Illinois River near Peru, Illinois. The canal allowed shipping between these important waterways. In 1900, the canal was replaced by the Chicago Sanitary and Ship Canal. The second canal, in addition to shipping, also allowed Chicago to address specific health issues (typhoid fever, cholera and other waterborne diseases) by sending its waste down the Illinois and Mississippi river systems rather than polluting its water source of Lake Michigan.
The Corps of Engineers recommended the excavation of a 5 ft (1.5 m) deep channel at the Des Moines Rapids, but work did not begin until after Lieutenant Robert E. Lee endorsed the project in 1837. The Corps later also began excavating the Rock Island Rapids. By 1866, it had become evident that excavation was impractical, and it was decided to build a canal around the Des Moines Rapids. The canal opened in 1877, but the Rock Island Rapids remained an obstacle. In 1878, Congress authorized the Corps to establish a 4.5-foot (1.4 m) deep channel to be obtained by building wing dams which direct the river to a narrow channel causing it to cut a deeper channel, by closing secondary channels and by dredging. The channel project was complete when the Moline Lock, which bypassed the Rock Island Rapids, opened in 1907.
To improve navigation between St. Paul, Minnesota, and Prairie du Chien, Wisconsin, the Corps constructed several dams on lakes in the headwaters area, including Lake Winnibigoshish and Lake Pokegama. The dams, which were built beginning in the 1880s, stored spring run-off which was released during low water to help maintain channel depth.
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Lock and Dam No. 2, near Hastings, Minnesota (2007)external image 220px-Mississippi_River_Lock_and_Dam_number_15.jpg
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Lock and Dam No. 15, is the largest roller dam in the world Davenport, Iowa; Rock Island, Illinois. (1990)

20th century[edit]

In 1907, Congress authorized a 6-foot (1.8 m) deep channel project on the Mississippi, which was not complete when it was abandoned in the late 1920s in favor of the 9 feet (2.7 m) deep channel project.
In 1913, construction was complete on a dam at Keokuk, Iowa, the first dam below St. Anthony Falls. Built by a private power company (Union Electric Company of St. Louis) to generate electricity (originally for Streetcars in St. Louis), the Keokuk dam was one of the largest hydro-electric plants in the world at the time. The dam also eliminated the Des Moines Rapids. Lock and Dam No. 1 was completed in Minneapolis, Minnesota in 1917. Lock and Dam No. 2, near Hastings, Minnesotawas completed in 1930.
Prior to the Great Mississippi Flood of 1927, the Corps' primary strategy was to close off as many side channels as possible to increase the flow in the main river. It was thought that the river's velocity would scour off bottom sediments, deepening the river and decreasing the possibility of flooding. The 1927 flood proved this to be so wrong that communities threatened by the flood began to create their own levee breaks to relieve the force of the rising river.
The Rivers and Harbors Act of 1930 authorized the 9 feet (2.7 m) channel project, which called for a navigation channel 9 ft (2.7 m) deep and 400 ft (120 m) wide to accommodate multiple-barge tows.[31][32] This was achieved by a series of locks and dams, and by dredging. Twenty-three new locks and dams were built on the upper Mississippi in the 1930s in addition to the three already in existence.
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Project design flood flow capacity for the Mississippi river in thousands of cubic feet per second.[33]
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Formation of the Atchafalaya River and construction of the Old River Control Structure.

Until the 1950s, there was no dam below Lock and Dam 26 at Alton, Illinois. Chain of Rocks Lock (Lock and Dam No. 27), which consists of a low-water dam and an 8.4 mi (13.5 km) long canal, was added in 1953, just below the confluence with the Missouri River, primarily to bypass a series of rock ledges at St. Louis. It also serves to protect the St. Louis city water intakes during times of low water.
U.S. government scientists determined in the 1950s that the Mississippi River was starting to switch to the Atchafalaya River channel because of its much steeper path to the Gulf of Mexico. Eventually the Atchafalaya River would capture the Mississippi River and become its main channel to the Gulf of Mexico, leaving New Orleans on a side channel. As a result, the U.S. Congress authorized a project called the Old River Control Structure, which has prevented the Mississippi River from leaving its current channel that drains into the Gulf via New Orleans.[34]
Because the large scale of high-energy water flow threatened to damage the structure, an auxiliary flow control station was built adjacent to the standing control station. This US$ 300 million project was completed in 1986 by the U.S. Army Corps Of Engineers. Beginning in the 1970s, the Corps applied hydrological transport models to analyze flood flow and water quality of the Mississippi. Dam 26 at Alton, Illinois, which had structural problems, was replaced by the Mel Price Lock and Dam in 1990. The original Lock and Dam 26 was demolished.


21st century[edit]

The Corps now actively creates and maintains spillways and floodways to divert periodic water surges into backwater channels and lakes, as well as route part of the Mississippi's flow into the Atchafalaya Basin and from there to the Gulf of Mexico, bypassing Baton Rouge and New Orleans. The main structures are the Birds Point-New Madrid Floodway in Missouri; the Old River Control Structure and the Morganza Spillway in Louisiana, which direct excess water down the west and east sides (respectively) of the Atchafalaya River; and the Bonnet Carré Spillway, also in Louisiana, which directs floodwaters to Lake Pontchartrain (see diagram).
Some of the pre-1927 strategy is still in use today, with the Corps actively cutting the necks of horseshoe bends, allowing the water to move faster and reducing flood heights. [35]

History[edit]

Native Americans[edit]

Main articles: Woodland period, Hopewell tradition, and Mississippian culture
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Monks Mound, a platform mound at the site of the Mississippian city of Cahokia.external image 220px-Eastman_Johnson_-_Ojibwe_Wigwam_at_Grand_Portage_-_ebj_-_fig_22_pg_41.jpg
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Ojibwe Wigwam at Grand Portageoil on canvas by Eastman Johnson (1857)

The area of the Mississippi River basin was first settled by hunting and gathering Native American peoples and is considered one the few independent centers of plant domestication in human history.[36] Evidence of early cultivation of sunflower, a goosefoot, amarsh elder and an indigenous squash dates to the 4th millennium BCE. The lifestyle gradually became more settled after around 1000 BCE during what is now called the Woodland period, with increasing evidence of shelter construction, pottery, weaving and other practices. A network of trade routes referred to as theHopewell interaction sphere was active along the waterways between about 200 and 500 CE, spreading common cultural practices over the entire area between the Gulf of Mexico and the Great Lakes. A period of more isolated communities followed, and agriculture introduced from Mesoamerica based on the Three Sisters(maize, beans and squash) gradually came to dominate. After around 800 CE there arose an advanced agricultural society today referred to as the Mississippian culture, with evidence of highly stratified complex chiefdoms and large population centers. The most prominent of these, now called Cahokia, was occupied between about 600 and 1400 CE[37] and at its peak numbered between 8,000 and 40,000 inhabitants, larger than London, England of that time. At the time of first contact with Europeans, Cahokia and many other Mississippian cities had dispersed, and archaeological finds attest to increased social stress.[38][39][40]
Modern American Indian nations inhabiting the Mississippi basin include Cheyenne, Sioux, Ojibwe, Potawatomi, Ho-Chunk, Fox, Kickapoo, Tamaroa, Moingwena,Quapaw and Chickasaw.
The word Mississippi itself comes from Messipi, the French rendering of the Anishinaabe (Ojibwe or Algonquin) name for the river, Misi-ziibi (Great River).[41][42] TheOjibwe called Lake Itasca Omashkoozo-zaaga'igan (Elk Lake) and the river flowing out of it Omashkoozo-ziibi (Elk River). After flowing into Lake Bemidji, the Ojibwe called the river Bemijigamaag-ziibi (River from the Traversing Lake). After flowing into Cass Lake, the name of the river changes to Gaa-miskwaawaakokaag-ziibi(Red Cedar River) and then out of Lake Winnibigoshish as Wiinibiigoonzhish-ziibi (Miserable Wretched Dirty Water River), Gichi-ziibi (Big River) after the confluence with the Leech Lake River, then finally as Misi-ziibi (Great River) after the confluence with the Crow Wing River.[43] After the expeditions by Giacomo Beltrami andHenry Schoolcraft, the longest stream above the juncture of the Crow Wing River and Gichi-ziibi was named "Mississippi River". The Mississippi River Band of Chippewa Indians, known as the Gichi-ziibiwininiwag, are named after the stretch of the Mississippi River known as the Gichi-ziibi. The Cheyenne, one of the earliest inhabitants of the upper Mississippi River, called it the Máʼxe-éʼometaaʼe (Big Greasy River) in the Cheyenne language. The Arapaho name for the river is Beesniicíe.[44] The Pawnee name is Kickaátit.[45]
The River Thames (
Listen
Listen
i
/tɛmz/ //**temz**//) flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom, after the River Severn. While it is best known for flowing through London, the river also flows alongside other towns and cities, includingOxford, Reading, Henley-on-Thames, and Windsor.

The river gives its name to three informal areas: the Thames Valley, a region of England around the river between Oxford and west London; theThames Gateway; and the greatly overlapping Thames Estuary around the tidal Thames to the east of London and including the waterway itself.Thames Valley Police is a formal body that takes its name from the river, covering three counties.
In an alternative name, derived from its long tidal reach up to Teddington Lock in south west London, the lower reaches of the river are called theTideway.
The administrative powers of the Thames Conservancy have been taken on with modifications by the Environment Agency and, in respect of the Tideway part of the river, such powers are split between the agency and the Port of London Authority.
In non-administrative use, stemming directly from the river and its name are Thames Valley University, Thames Water, Thames Televisionproductions, Thames & Hudson publishing, Thameslink (north-south railways passing through central London), and South Thames College. Historic entities include the Thames Ironworks and Shipbuilding Company.
Two canals link the river to other river basins: the Kennet and Avon Canal and the Grand Union Canal, westward and northward respectively. Two further cross-basin canals are disused but are under reconstruction: the Thames and Severn Canal (via Stroud), which operated until 1927 (to the west coast of England), and the Wey and Arun Canal to Littlehampton, which operated until 1871 (to the south coast).
Rowing and sailing clubs are common along the Thames, which is navigable to such vessels. Kayaking and canoeing also take place. Safe headwaters and reaches are a summer venue for organised swimming, which is prohibited on safety grounds in a stretch centred on Central London. Non-Olympic watersports with a lesser presence include skiffing and punting.

Summary[edit]

With a total length of 215 miles (346 km), the Thames is the longest river entirely in England and the second longest in the United Kingdom. It rises at Thames Head in Gloucestershire, and flows into theNorth Sea via the Thames Estuary. On its way, it passes through London, the country's capital, where the river is deep and navigable to ships; the Thames drains the whole of Greater London.[1] Its tidal section, reaching up to Teddington Lock, includes most of its London stretch and has a rise and fall of 7 metres (23 ft).
Along its course are 45 navigation locks with accompanying weirs. Its catchment area covers a large part of South Eastern and a small part of Western England and the river is fed by 38 named tributaries[citation needed]. The river contains over 80 islands. With its waters varying from freshwater to almost seawater, the Thames supports a variety of wildlife and has a number of adjoining Sites of Special Scientific Interest, with the largest being in the remaining parts of the North Kent Marshes and covering 5,449 hectares (13,460 acres).[2]
The marks of human activity, in some cases dating back to Pre-Roman Britain, are visible at various points along the river. These include a variety of structures connected with use of the river, such as navigations, bridges, and watermills, as well as prehistoric burial mounds. A major maritime route is formed for much of its length for shipping and supplies: through the Port of London for international trade, internally along its length and by its connection to the British canal system. The river's position has put it at the centre of many events in British history, leading to it being described by John Burns as "liquid history".

Etymology[edit]

external image 250px-Father_Thames%2C_St_John%27s_Lock%2C_Lechlade.jpg
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A statue of Old Father Thames by Raffaelle Monti at St John's Lock, Lechlade.

The Thames, from Middle English Temese, is derived from the Celtic name for the river, Tamesas (from *tamēssa),[3] recorded in Latin as Tamesis and yielding modern Welsh Tafwys "Thames". The name probably meant "dark" and can be compared to other cognates such as Russian темно (Proto-Slavic *tьmьnъ),Sanskrit tamas, Irish teimheal and Welsh tywyll "darkness" (Proto-Celtic *temeslos) and Middle Irish teimen "dark grey",[3] though Richard Coates[4] mentions other theories: Kenneth Jackson's[5] that it is non Indo-European (and of unknown meaning), and Peter Kitson's[6] that it is Indo-European but pre-Celtic and has a name indicating "muddiness" from a root *tā-, 'melt'.
Note also other river names such as Teme, Tavy, Teviot, Teifi (cf Tafwys).
The river's name has always been pronounced with a simple t /t/; the Middle English spelling was typically Temese and Celtic Tamesis. A similar spelling from this era (1210 AD), "Tamisiam", is found in the Magna Carta.[7] The th spelling lends an air of Greek to the name and was added during theRenaissance[citation needed], possibly to reflect or support a claim that the name was derived from River Thyamis in the Epirus region of Greece, whence earlyCeltic tribes were wrongly thought to have migrated to Britain[citation needed].
Indirect evidence for the antiquity of the name 'Thames' is provided by a Roman potsherd found at Oxford, bearing the inscription Tamesubugus fecit(Tamesubugus made this). It is believed that Tamesubugus' name was derived from that of the river.[8]
The Thames through Oxford is sometimes given the name the River Isis. Historically, and especially in Victorian times, gazetteers and cartographers insisted that the entire river was correctly named the River Isis from its source down to Dorchester-on-Thames, and that only from this point, where the river meets the River Thame and becomes the "Thame-isis" (supposedly subsequently abbreviated to Thames) should it be so called. Ordnance Survey maps still label the Thames as "River Thames or Isis" down to Dorchester. However, since the early 20th century this distinction has been lost in common usage even in Oxford, and some historians suggest the name Isis is nothing more than a truncation of Tamesis, the Latin name for the Thames.
Richard Coates suggests that while the river was as a whole called the Thames, part of it, where it was too wide to ford, was called *(p)lowonida. This gave the name to a settlement on its banks, which became known as Londinium, from the Indo-European roots *pleu- "flow" and *-nedi "river" meaning something like the flowing river or the wide flowing unfordable river.[4]
Tamese was referred to as a place, not a river in the Ravenna Cosmography.
For merchant seamen, the Thames has long been just 'the London River'. Londoners often refer to it simply as 'the river', in expressions such as 'south of the river'.[9]


Physical and natural aspects[edit]

Course of the river[edit]

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The marker stone at the official source of the River Thames near Kemble.
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The River Thames Flood Barrier.
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The Thames passes by some of the sights of London, including the Houses of Parliament and theLondon Eye.

The usually quoted source of the Thames is at Thames Head (at grid reference ST980994). This is about 1200 m (three-quarters of a mile)[10] north of Kembleparish church in southern Gloucestershire, near the town of Cirencester, in the Cotswolds.[11] Seven Springs near Cheltenham, where the river Churn rises, is also sometimes quoted as the Thames' source,[12] as this location is furthest from the mouth, and adds some 14 miles (23 km) to the length.
The springs at Seven Springs also flow throughout the year, while those at Thames Head are only seasonal (a winterbourne). The Thames is the longest river entirely in England, but the River Severn, which is partly in Wales, is the longest river in the United Kingdom. As the Churn, sourced at Seven Springs is 14 miles (23 km) longer than the Thames (from its traditional source at Thames head), its length 229 miles (369 km) is greater than the Severn's length 220 miles (350 km). Thus, the Churn/Thames river may be regarded as the longest natural river flow in the United Kingdom.
The Thames flows through or alongside Ashton Keynes, Cricklade, Lechlade, Oxford, Abingdon, Wallingford, Goring-on-Thames and Streatley, Reading,Wargrave, Henley-on-Thames, Marlow, Maidenhead, Windsor and Eton, Staines-upon-Thames and Egham, Chertsey, Shepperton, Weybridge, Sunbury-on-Thames, Walton-on-Thames, Molesey and Thames Ditton. Minor redefining and widening of the main channel around Oxford, Abingdon and Marlow took place before 1850 since which specific cuts to ease navigation have assisted in cutting journey distances.
Molesey faces Hampton, London, and in Greater London the Thames passes Hampton Court, Surbiton, Kingston upon Thames, Teddington, Twickenham,Richmond (with a famous view of the Thames from Richmond Hill), Syon House, Kew, Brentford, Chiswick, Barnes, Hammersmith, Fulham, Putney,Wandsworth, Battersea and Chelsea. In central London, the river passes Pimlico and Vauxhall, and then forms one of the principal axes of the city, from thePalace of Westminster to the Tower of London. At this point, it historically formed the southern boundary of the medieval city, with Southwark, on the opposite bank, then being part of Surrey.
Beyond central London, the river passes Bermondsey, Wapping, Shadwell, Limehouse, Rotherhithe, Millwall, Deptford, Greenwich, Cubitt Town, Blackwall, New Charlton and Silvertown, before flowing through the Thames Barrier, which protects central London from flooding by storm surges. Below the barrier, the river passes Woolwich, Thamesmead, Dagenham, Erith, Purfleet, Dartford, West Thurrock, Northfleet, Tilbury and Gravesend before entering the Thames Estuarynear Southend-on-Sea.

Catchment area and discharge[edit]

Main article: Tributaries of the River Thames

The Thames River Basin District, including the Medway catchment, covers an area of 16,133 square kilometres (6,229 sq mi).[13] The river basin includes both rural and heavily urbanised areas in the east and northern parts while the western parts of the catchment are predominantly rural. The area is among the driest in the United Kingdom. Water resources consist of ground-water from aquifers and water taken from the Thames and its tributaries, much of it stored in largebank-side reservoirs.[13]
The Thames itself provides two-thirds of London's drinking water while groundwater supplies about 40 per cent of public water supplies in the total catchment area. Groundwater is an important water source, especially in the drier months, so maintaining its quality and quantity is extremely important. Groundwater is vulnerable to surface pollution, especially in highly urbanised areas.[13]

The non-tidal section[edit]

Main article: Locks and weirs on the River Thames
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The Jubilee River at Slough Weir.

Brooks, canals and rivers, within an area of 9,950 square kilometres (3,842 sq mi),[14] combine to form 38 main tributaries feeding the Thames between its source and Teddington Lock. This is the usual tidal limit; however, high spring tides can raise the head water level in the reach above Teddington and can occasionally reverse the river flow for a short time. In these circumstances, tidal effects can be observed upstream to the next lock beside Molesey weir,[15]which is visible from the towpath and bridge beside Hampton Court Palace.
Before Teddington Lock was built in 1810–12, the river was tidal at peak spring tides as far as Staines upon Thames, which has been prevented through timing discharges and dredging the lower river, particularly beside its banks. This has decreased flash flood risk throughout the river and allowed for private moorings of small and medium-sized motor vessels along almost all of this course below Oxford.
In descending order, non-related tributaries of the non-tidal Thames, with river status, are the Churn, Leach, Cole, Ray, Coln, Windrush, Evenlode, Cherwell,Ock, Thame, Pang, Kennet, Loddon, Colne, Wey and Mole. In addition, there are occasional backwaters and artificial cuts that form islands, distributaries(most numerous in the case of the Colne), and man-made distributaries such as the Longford River. Three canals intersect this stretch: the Oxford Canal,Kennet and Avon Canal, and Wey Navigation.
Its longest artificial secondary channel (cut), the Jubilee River, was built between Maidenhead and Windsor for flood relief and completed in 2002.[16][17]
The non-tidal section of the river is owned and managed by the Environment Agency, which is responsible for managing the flow of water to help prevent and mitigate flooding, and providing for navigation: the volume and speed of water downstream is managed by adjusting the sluices at each of the weirs and, at peak high water, levels are generally dissipated over preferred flood plains adjacent to the river. Occasionally, flooding of inhabited areas is unavoidable and the agency issues flood warnings. Due to stiff penalties applicable on the non-tidal river, which is a drinking water source before treatment, sanitary sewer overflow from the many sewage works covering the upper Thames basin is rare in the non-tidal Thames, which ensures clearer water compared to the river's tideway.[18]

The tidal section[edit]

Main article: Tideway
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London Stone at Staines, built in 1285 marked the customs limit of the Thames and the City of London's jurisdiction.


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A map of the lower course of the Thames in 1840.

Below Teddington Lock (about 55 miles or 89 kilometres upstream of the Thames Estuary), the river is subject to tidal activity from the North Sea. Before the lock was installed, the river was tidal as far as Staines, about 16 miles (26 km) upstream.[19] London, capital of Roman Britain, was established on two hills, now known asCornhill and Ludgate Hill. These provided a firm base for a trading centre at the lowest possible point on the Thames.[20]
A river crossing was built at the site of London Bridge. London Bridge is now used as the basis for published tide tables giving the times of high tide. High tide reaches Putney about 30 minutes later than London Bridge, and Teddington about an hour later. The tidal stretch of the river is known as "the Tideway". Tide tables are published by the Port of London Authority and are available online. Times of high and low tides are also posted on Twitter.
The principal tributaries of the River Thames on the Tideway include the rivers Brent, Wandle, Effra, Westbourne, Fleet, Ravensbourne (the final part of which is calledDeptford Creek), Lea, Roding, Darent and Ingrebourne. At London, the water is slightly brackish with sea salt, being a mix of sea and fresh water.
This part of the river is managed by the Port of London Authority. The flood threat here comes from high tides and strong winds from the North Sea, and the Thames Barrier was built in the 1980s to protect London from this risk.

Islands[edit]

Main article: Islands in the River Thames

The River Thames contains over 80 islands ranging from the large estuarial marshlands of the Isle of Sheppey and Canvey Island to small tree-covered islets like Rose Isle in Oxfordshire and Headpile Eyot in Berkshire. They are found all the way from the Isle of Sheppey in Kent to Fiddler's Island in Oxfordshire. Some of the largest inland islands, for example Formosa Island near Cookham and Andersey Island at Abingdon, were created naturally when the course of the river divided into separate streams.
In the Oxford area the river splits into several streams across the floodplain (Seacourt Stream, Castle Mill Stream, Bulstake Stream and others), creating several islands (Fiddler's Island, Osney and others). Desborough Island, Ham Island at Old Windsor, and Penton Hook Islandwere artificially created by lock cuts and navigation channels. Chiswick Eyot is a familiar landmark on the Boat Race course, while Glover's Island forms the centrepiece of the spectacular view from Richmond Hill.
Islands of historical interest include Magna Carta Island at Runnymede, Fry's Island at Reading, and Pharaoh's Island near Shepperton. In more recent times Platts Eyot at Hampton was the place where MTBs were built, Tagg's Island near Molesey was associated with the impresario Fred Karno, and Eel Pie Island at Twickenham was the birthplace of the South East's R&B music scene.
Westminster Abbey and the Palace of Westminster (commonly known today as the Houses of Parliament) were built on Thorney Island, which used to be an eyot.

Geological and topographic history[edit]

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European LGM refuges, 20,000 years ago. The Thames was a minor river that joined the Rhine, in the southern North Sea basin at this time.

Solutrean and Proto Solutrean Cultures

Epi Gravettian Culture
.

The River Thames can first be identified as a discrete drainage line as early as 58 million years ago, in the Thanetian stage of the latePalaeocene epoch.[21] Until around 500,000 years ago, the Thames flowed on its existing course through what is now Oxfordshire, before turning to the north east through Hertfordshire and East Anglia and reaching the North Sea near Ipswich.
At this time the river system headwaters lay in the English West Midlands and may, at times, have received drainage from the Berwyn Mountains in North Wales. Streams and rivers like the River Brent, Colne Brook, and Bollo Brook either flowed into the then river Thames or went out to sea on the course of the present-day river Thames.
About 450,000 years ago, in the most extreme Ice Age of the Pleistocene, the Anglian, the furthest southern extent of the ice sheet was atHornchurch in east London.[22] It dammed the river in Hertfordshire, resulting in the formation of large ice lakes, which eventually burst their banks and caused the river to be diverted onto its present course through what is now London. Progressively, the channel was pushed south to form the St Albans depression by the repeated advances of the ice sheet.[23]
This created a new river course through Berkshire and on into London, after which the river rejoined its original course in southern Essex, near the present River Blackwater estuary. Here it entered a substantial freshwater lake in the southern North Sea basin. The overspill of this lake caused the formation of the Dover Straits or Pas-de-Calais gap between Britain and France. Subsequent development led to the continuation of the course that the river follows at the present day.[23]
Most of the bedrock of the Vale of Aylesbury is made up of clay and chalk that was formed at the end of the ice age and at one time was under the Proto-Thames. Also created at this time were the vast underground reserves of water that make the water table higher than average in the Vale of Aylesbury.

Ice age[edit]

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A geological map of the London Basin; the London Clay is marked in dark brown.
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The confluence of Rivers Thames and Brent. The motorised barge is heading up the River Brent. From this point as far as Hanwell the Brent has been canalised and shares its course with the main line of the Grand Union Canal. From Hanwell the Brent can be traced to various sources in theBarnet area.

The last advance from that Scandinavian ice flow to have reached this far south covered much of NW Middlesex and finally forced the Proto-Thames to take roughly its present course. At the height of the last ice age, around 20,000 BC, Britain was connected to mainland Europe by a large expanse of land known asDoggerland in the southern North Sea basin. At this time, the Thames' course did not continue to Doggerland but flowed southwards from the eastern Essex coast where it met the Rhine, the Meuse and the Scheldt[23] flowing from what are now the Netherlands and Belgium. These rivers formed a single river—theChannel River (Fleuve Manche)—that passed through the Dover Strait and drained into the Atlantic Ocean in the western English Channel.
The ice sheet, which stopped around present day Finchley, deposited Boulder clay to form Dollis Hill and Hanger Hill. Its torrent of meltwater gushed through the Finchley Gap and south towards the new course of the Thames, and proceeded to carve out the Brent Valley in the process.[24] Upon the valley sides there can be seen other terraces of brickearth, laid over and sometimes interlayered with the clays.
These deposits were brought in by the winds during the periglacial periods, suggesting that wide, flat marshes were then part of the landscape, which the new river Brent proceeded to cut down. The steepness of the valley sides is an indicator of the very much lower mean sea levels caused by the glaciation locking up so much water upon the land masses, thus causing the river water to flow rapidly seaward and so erode its bed quickly downwards.
The original land surface was around 110 to 130 metres (350 to 400 ft) above the current sea level. The surface had sandy deposits from an ancient sea, laid over sedimentary clay (this is the blue London Clay). All the erosion down from this higher land surface, and the sorting action by these changes of water flow and direction, formed what is known as the Thames River Gravel Terraces.
Since Roman times and perhaps earlier, the isostatic rebound from the weight of previous ice sheets, and its interplay with the eustatic change in sea level, have resulted in the old valley of the river Brent, together with that of the Thames, silting up again. Thus, along much of the Brent's present-day course, one can make out the water meadows of rich alluvium, which is augmented by frequent floods.

Conversion of marshland[edit]

After the river took its present-day course, much of the banks of the Thames Estuary and the Thames Valley in London was partly covered in marshland, as was the adjoining Lower Lea Valley. Streams and rivers like the River Lea, Tyburn Brook, andBollo Brook drained into the river, while some islands, e.g. Thorney Island, formed over the ages. The northern tip of the ancient parish of Lambeth, for example, was marshland known as Lambeth Marshe, but it was drained in the 18th century; it is remembered in the street name Lower Marsh.[25]
The East End of London, also known simply as the East End, was the area of London east of the medieval walled City of London and north of the River Thames, although it is not defined by universally accepted formal boundaries; the River Lea can be considered another boundary.[26] Most of the local riverside was also marshland. The land was drained and became farmland; it was built on after the Industrial Revolution. Use of the term "East End" in a pejorative sense began in the late 19th century,[25]
Canvey Island in southern Essex (area 18.45 km²; pop. 37,479[27]) was once marshy, but is now a fully reclaimed island in the Thames estuary. It is separated from the mainland of south Essex by a network of creeks. Lying below sea level it is prone to flooding at exceptional tides, but has nevertheless been inhabited since Roman times.

Wildlife[edit]

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Swan Upping – skiffs surround the swans.
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Fishing at Penton Hook Island.

Various species of birds feed off the river or nest on it, some being found both at sea and inland. These include Cormorant, Black-headed Gull, and Herring Gull. The Mute Swan is a familiar sight on the river but the escaped Black Swan is more rare. The annual ceremony of Swan upping is an old tradition of counting stocks.
Non-native geese that can be seen include Canada Geese, Egyptian Geese, and Bar-headed Geese, and ducks include the familiar native Mallard, plus introduced Mandarin Duck and Wood Duck. Other water birds to be found on the Thames include the Great Crested Grebe, Coot, Moorhen, Heron, andKingfisher. Many types of British birds also live alongside the river, although they are not specific to the river habitat.
The Thames contains both sea water and fresh water, thus providing support for seawater and freshwater fish. However, many populations of fish are at risk and are being killed in tens of thousands because of pollutants leaking into the river from human activities.[28] Salmon, which inhabit both environments, have been reintroduced and a succession of fish ladders have been built into weirs to enable them to travel upstream.
On 5 August 1993, the largest non-tidal salmon in recorded history was caught close to Boulters Lock in Maidenhead. The specimen weighed 6.5 kg or 14.5 pounds and measured 88 cm or 22 inches in length. The eel is particularly associated with the Thames and there were formerly many eel traps. Freshwater fish of the Thames and its tributaries include brown trout, chub, dace, roach, barbel, perch, pike, bleak, and flounder. Colonies of short-snouted seahorses have also recently been discovered in the river.[29] The Thames is also host to some invasive crustaceans, including the signal crayfish and the Chinese Mitten Crab.
Aquatic mammals are also known to inhabit the Thames. The population of grey and harbour seals numbers up to 700 in the Thames Estuary. These animals have been sighted as far upriver as Richmond.[30] Bottlenose dolphins and harbour porpoises are also sighted in the Thames.[31]
On 20 January 2006, a 16–18 ft (5 m) northern bottle-nosed whale was seen in the Thames as far upstream as Chelsea. This was extremely unusual: this whale is generally found in deep sea waters. Crowds gathered along the riverbanks to witness the extraordinary spectacle but there was soon concern, as the animal came within yards of the banks, almost beaching, and crashed into an empty boat causing slight bleeding. About 12 hours later, the whale is believed to have been seen again near Greenwich, possibly heading back to sea. A rescue attempt lasted several hours, but the whale died on a barge. See River Thames whale.[32]

Human history[edit]

The River Thames has served several roles in human history, being an economic resource, a maritime route, a boundary, a fresh water source, a source of food, and more recently a leisure facility. In 1929, John Burns, one-time MP for Battersea, responded to an American's unfavourable comparison of the Thames with the Mississippi by coining the expression "The Thames is liquid history".
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The Tower of London, with the Tower Bridgebuilt 800 years later.

There is evidence of human habitation living off the river along its length dating back to Neolithic times.[33] The British Museum has a decorated bowl (3300–2700 BC), found in the River at Hedsor, Buckinghamshire, and a considerable amount of material was discovered during the excavations of Dorney Lake.[34] A number of Bronze Age sites and artefacts have been discovered along the banks of the river including settlements at Lechlade, Cookham, and Sunbury-on-Thames.[35]
So extensive have the changes to this landscape been that what little evidence there is of man's presence before the ice came has inevitably shown signs of transportation here by water and reveals nothing specifically local. Likewise, later evidence of occupation, even since the arrival of the Romans, may lie next to the original banks of the Brent but have been buried under centuries of silt.[35]

Roman Britain[edit]

Some of the earliest written references to the Thames occur in Julius Caesar’s account of his second expedition to Britain in 54 BC,[36] when the Thames presented a major obstacle and he encountered the Iron Age Belgic tribes the Catuvellauni and the Atrebates along the river. The confluence of the Thames and Cherwell was the site of early settlements and the river Cherwell marked the boundary between the Dobunni tribe to the west and the Catuvellauni tribe to the east (these were pre-Roman Celtic tribes). In the late 1980s a large Romano-British settlement was excavated on the edge of the village of Ashton Keynes in Wiltshire.
In AD 43, under the Emperor Claudius, the Romans occupied England and, recognising the river's strategic and economic importance, built fortifications along the Thames valley including a major camp atDorchester. Two hills, now known as Cornhill and Ludgate Hill, provided a firm base for a trading centre, called Londinium, at the lowest possible point on the Thames, where a bridge was built. The next Roman bridge upstream was at Staines (Pontes) to which point boats could be swept up on the rising tide with no need for wind or muscle power.

Middle Ages[edit]

A Romano-British settlement grew up north of the confluence, partly because the site was naturally protected from attack on the east side by the River Cherwell and on the west by the River Thames. This settlement dominated the pottery trade in what is now central southern England, and pottery was distributed by boats on the Thames and its tributaries.
Many of the Thames’ riverside settlements trace their roots back to early times; for example, the suffix—“ing” in the names of towns such as Goring and Reading is of Saxon origin. Recent research suggests that these peoples preceded the Romans rather than replaced them.[37] The river's long tradition of farming, fishing, milling and trade with other nations started with these peoples and has continued to the present day.
Competition for the use of the river created the centuries-old conflict between those who wanted to dam the river to build millraces and fish traps and those who wanted to travel and carry goods on it. Economic prosperity and the foundation of wealthy monasteries by the Anglo-Saxons attracted unwelcome visitors and by around AD 870 the Vikings were sweeping up the Thames on the tide and creating havoc as in their destruction of Chertsey Abbey.
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A 1616 engraving by Claes Van Visschershowing the Old London Bridge, with Southwark Cathedral in the foreground.

Once King William had won total control of the strategically important Thames Valley, he went on to invade the rest of England. He had many castles built, including those at Wallingford, Rochester, Windsor, and most importantly the Tower of London. Many details of Thames activity are recorded in the Domesday book. The following centuries saw the conflict between king and barons coming to a head in AD 1215 when King John was forced to sign the Magna Carta on an island in the Thames at Runnymede. Among a host of other things, this granted the barons the right of Navigation under Clause 23.
Another major consequence of John's reign was the completion of the multi-piered London Bridge, which acted as a barricade and barrage on the river, affecting the tidal flow upstream and increasing the likelihood of the river freezing over. In Tudor and Stuart times, various kings and queens built magnificent riverside palaces at Hampton Court, Kew, Richmond on Thames, Whitehall, and Greenwich.
As early as the 1300s, the Thames was used as a means of disposing of waste produced from the city of London, effectively turning the river into an open sewer. In 1357, Edward III described the state of the river in a proclamation: "...dung and other filth had accumulated in divers places upon the banks of the river with... fumes and other abominable stenches arising therefrom."[38]
The growth of the population of London greatly increased the amount of waste that entered the river, including human excrement, animal waste from slaughter houses, and waste from manufacturing processes. According to historian Peter Ackroyd, "a public lavatory on London Bridge showered its contents directly onto the river below, and latrines were built over all the tributaries that issued into the Thames."[38]

Early modern period[edit]

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The Frozen Thames, 1677.

The 16th and 17th centuries saw the City of London grow with the expansion of world trade. The wharves of the Pool of London were thick with seagoing vessels while naval dockyards were built at Deptford. The Dutch navy even entered the Thames in 1667 in the raid on the Medway.
During a series of cold winters the Thames froze over above London Bridge: in the first Frost Fair in 1607, a tent city was set up on the river, along with a number of amusements, including ice bowling.
In good conditions, barges travelled daily from Oxford to London carrying timber, wool, foodstuffs, and livestock. The stone from the Cotswolds used to rebuild St Paul's Cathedral after the Great Fire in 1666 was brought all the way down from Radcot. The Thames provided the major route between the City of London and Westminster in the 16th and 17th centuries; the clannish guild of watermen ferried Londoners from landing to landing and tolerated no outside interference. In 1715, Thomas Doggett was so grateful to a local waterman for his efforts in ferrying him home, pulling against the tide, that he set up a rowing race for professional watermen known as "Doggett's Coat and Badge".
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Michael Faraday giving his card to Father Thames, caricature commenting on a letter of Faraday's on the state of the river in The Times in July 1855.

By the 18th century, the Thames was one of the world's busiest waterways, as London became the centre of the vast, mercantile British Empire, and progressively over the next century the docks expanded in the Isle of Dogs and beyond. Efforts were made to resolve the navigation conflicts upstream by building locks along the Thames. After temperatures began to rise again, starting in 1814, the river stopped freezing over.[39] The building of a new London Bridge in 1825, with fewerpiers (pillars) than the old, allowed the river to flow more freely and prevented it from freezing over in cold winters.[40]

Victorian era[edit]

The Victorian era was one of imaginative engineering. In the 'Great Stink' of 1858, pollution in the river reached such an extreme that sittings of the House of Commonsat Westminster had to be abandoned. The dumping of raw sewage into the Thames was formerly only common in the City of London, making its tideway a harbour for many harmful bacteria. Wells with water tables that mixed with tributaries (or the non-tidal Thames) faced such pollution with the widespread installation of the flush toilet.[41]
Thus, in the nineteenth century, four serious cholera outbreaks killed tens of thousands of people between the years of 1832 and 1865. Historians have attributed Prince Albert's death in 1861 to typhoid that had spread in the river's dirty waters beside Windsor Castle.[41]
A concerted effort to contain the city's sewage by constructing massive sanitary sewers on the north and south river embankments followed, under the supervision of engineer Joseph Bazalgette. Meanwhile, similar huge undertakings took place to ensure the water supply, with the building of reservoirs and pumping stations on the river to the west of London.
The coming of the railways added railway bridges to the earlier road bridges and also reduced commercial activity on the river. However, sporting and leisure use increased with the establishment of regattas such as Henley and The Boat Race. On 3 September 1878, one of the worst river disasters in England took place, when the crowded pleasure boat //Princess Alice// collided with the Bywell Castle, killing over 640 people.

20th century[edit]



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The Thames as it flows through east London, with theIsle of Dogs in the centre.

The growth of road transport, and the decline of the Empire in the years following 1914, reduced the economic prominence of the river. During World War II, the protection of certain Thames-side facilities, particularly docks and water treatment plants, was crucial to the munitions and water supply of the country. The river's defences included the Maunsell forts in the estuary, and the use of barrage balloons to counter German bombers using the reflectivity and shapes of the river to navigate during The Blitz.
In the post-war era, although the Port of London remains one of the UK's three main ports, most trade has moved downstream from central London.
The decline of heavy industry and tanneries, reduced use of oil-pollutants, and improved sewage treatment have led to much better water quality as compared with the late 19th and early- to mid-20th centuries, and aquatic life has returned to its formerly 'dead' stretches.
Alongside the entire river runs the Thames Path, a National Route for walkers and cyclists.
In the early 1980s a pioneering flood control device, the Thames Barrier, was opened — closed to tides several times a year to prevent water damage to London's low-lying areas upstream (the 1928 Thames flood demonstrated the severity of this type of event). In the late 1990s, the 7-mile (11 km) long Jubilee River was built as a wide flood channel through partly already watercourse-covered land in Taplow and Eton which face Maidenhead andWindsor. Other shorter cuts already existed above and below this point, however only on the non-tidal Thames hence the need for the Barrier.[42]

The active river[edit]

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Houseboats on river Thames, in the St Margarets, Twickenham district

One of the major resources provided by the Thames is the water distributed as drinking water by Thames Water, whose area of responsibility covers the length of the River Thames. The Thames Water Ring Main is the main distribution mechanism for water in London, with one major loop linking theHampton, Walton, Ashford and Kempton Park Water Treatment Works with central London.
In the past, commercial activities on the Thames included fishing (particularly eel trapping), coppicing willows and osiers which provided wood, and the operation of watermills for flour and paper production and metal beating. These activities have disappeared. There was a proposal to build a hydro-electric plant at Romney Lock to power Windsor Castle; but as of January 2008 this scheme appears to have been abandoned.
The Thames is popular for a wide variety of riverside housing, including high-rise flats in central London and chalets on the banks and islands upstream. Some people live in houseboats, typically around Brentford and Tagg's Island.

Transport and tourism[edit]

The tidal river[edit]

Main article: London River Services
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Passenger service on River Thames

In London there are many sightseeing tours in tourist boats, past the more famous riverside attractions such as the Houses of Parliament and the Tower of Londonas well as regular riverboat services co-ordinated by London River Services.

The upper river[edit]

In summer, passenger services operate along the entire non-tidal river from Oxford to Teddington. The two largest operators are Salters Steamers and French Brothers. Salters operate services between Folly Bridge, Oxford and Staines. The whole journey takes 4 days and requires several changes of boat.[43] French Brothers operate passenger services between Maidenhead and Hampton Court.[44] Along the course of the river a number of smaller private companies also offer river trips at Oxford, Wallingford, Reading and Hampton Court.[45] Many companies also provide boat hire on the river.
The leisure navigation and sporting activities on the river have given rise to a number of businesses including boatbuilding, marinas, ships chandlers and salvage services.

Aerial lift[edit]

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London's Air Line over River Thames.

The Air Line aerial cable system over the Thames from the Greenwich Peninsula to the Royal Docks has been in operation since the 2012 Summer Olympics.

Police and lifeboats[edit]

The river is policed by five police forces. The Thames Division is the River Police arm of London's Metropolitan Police, while Surrey Police, Thames Valley Police, Essex Police and Kent Police have responsibilities on their parts of the river outside the metropolitan area. There is also a London Fire Brigade fire boat on the river. The river claims a number of lives each year.
As a result of the Marchioness disaster in 1989 when 51 people died, the Government asked the Maritime and Coastguard Agency, the Port of London Authority and the Royal National Lifeboat Institution (RNLI) to work together to set up a dedicated Search and Rescue service for the tidal River Thames. As a result, there are four lifeboat stations on the river Thames at Teddington (Teddington lifeboat station), Chiswick (Chiswick lifeboat station), Victoria Embankment/Waterloo Bridge (Tower Lifeboat Station) and Gravesend (Gravesend lifeboat station).[46]

Navigation[edit]

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Pool of London looking west, from the high-level walkway on Tower Bridge. Click on the picture for a longer description
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A container ship unloading at Northfleet Hope terminal, Tilbury.
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A ship heading downstream past Coryton Refinery.
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Rubbish traps are used on the Thames to filterdebris as it flows through Central London.

The Thames is maintained for navigation by powered craft from the estuary as far as Lechlade in Gloucestershire and for very small craft to Cricklade. Between the sea and Teddington Lock, the river forms part of the Port of London and navigation is administered by the Port of London Authority.
From Teddington Lock to the head of navigation, the navigation authority is the Environment Agency. Both the tidal river through London and the non-tidal river upstream are intensively used for leisure navigation. All craft using the river Thames must be licensed.
The river is navigable to large ocean-going ships as far upstream as the Pool of London and London Bridge. Although London's upstream enclosed docks have closed and central London sees only the occasional visiting cruise ship or warship, the tidal river remains one of Britain's main ports. Around 60 active terminals cater for shipping of all types including ro-ro ferries, cruise liners and vessels carrying containers, vehicles, timber, grain, paper, crude oil, petroleum products,liquified petroleum gas, etc.[47] There is a regular traffic of aggregate or refuse vessels, operating from wharves in the west of London. The tidal Thames links to the canal network at the River Lea Navigation, the Regent's Canal at Limehouse Basin, and the Grand Union Canal at Brentford.
There is no speed limit on the Tideway downstream of Wandsworth Bridge,[48] although boats are not allowed to create undue wash. Upstream of Wandsworth Bridge a speed limit is in force for powered craft to protect the riverbank environment and to provide safe conditions for rowers and other river users. The speed limit of 8 knots (15 km/h) applies to powered craft on this tidal part and 4.3 knots (8 km/h) on the non-tidal Thames.
The Environment Agency has patrol boats (named after tributaries of the Thames) and can enforce the limit strictly since river traffic usually has to pass through a lock at some stage. There are pairs of transit markers at various points along the non-tidal river that can be used to check speed – a boat travelling legally taking a minute or more to pass between the two markers.
The non-tidal River Thames is divided into reaches by the 44 locks. The locks are staffed for the greater part of the day, but can be operated by experienced users out of hours. This part of the Thames links to existing navigations at the River Wey Navigation, the River Kennet and the Oxford Canal.

History of the management of the river[edit]

In the Middle Ages the Crown exercised general jurisdiction over the Thames, one of the four royal rivers, and appointed water bailiffs to oversee the river upstream of Staines. The City of London exercised jurisdiction over the tidal Thames. However, navigation was increasingly impeded by weirs and mills, and in the 14th century the river probably ceased to be navigable for heavy traffic between Henley and Oxford. In the late 16th century the river seems to have been reopened for navigation from Henley to Burcot.[49]
The first commission concerned with the management of the river was the Oxford-Burcot Commission, formed in 1605 to make the river navigable between Burcot and Oxford.
In 1751 the Thames Navigation Commission was formed to manage the whole non-tidal river above Staines. The City of London long claimed responsibility for the tidal river. A long running dispute between the City and the Crown over ownership of the river was not settled until 1857, when the Thames Conservancy was formed to manage the river from Staines downstream. In 1866 the functions of the Thames Navigation Commission were transferred to the Thames Conservancy, which thus had responsibility for the whole river.
In 1909 the powers of the Thames Conservancy over the tidal river, below Teddington, were transferred to the Port of London Authority.
In 1974 the Thames Conservancy became part of the new Thames Water Authority. When Thames Water was privatised in 1990, its river management functions were transferred to the National Rivers Authority, in 1996 subsumed into the Environment Agency.

The river as a boundary[edit]

Until enough crossings were established, the river presented a formidable barrier, with Belgic tribes and Anglo-Saxon kingdoms being defined by which side of the river they were on. When English counties were established their boundaries were partly determined by the Thames. On the northern bank were the ancient counties of Gloucestershire, Oxfordshire, Buckinghamshire, Middlesex and Essex. On the southern bank were the counties of Wiltshire, Berkshire, Surrey, andKent.
The 214 bridges and 17 tunnels that have been built to date have changed the dynamics and made cross-river development and shared responsibilities more practicable. In 1965, upon the creation of Greater London, the London Borough of Richmond upon Thames incorporated the former 'Middlesex and Surrey' banks, Spelthorne moved from Middlesex to Surrey; and further changes in 1974 moved some of the boundaries away from the river. For example, some areas were transferred from Berkshire to Oxfordshire, and from Buckinghamshire to Berkshire. On occasion – for example in rowing – the banks are still referred to by their traditional county names.

Crossings[edit]

Main article: List of crossings of the River Thames
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Newbridge, in rural Oxfordshire.
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The Railway bridge at Maidenhead.
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The Millennium Footbridge with St Paul's Cathedral in the background.

Many of the present road bridges are on the site of earlier fords, ferries and wooden bridges. At Swinford Bridge, a toll bridge, there was first a ford and then a ferry prior to the bridge being built. The earliest known major crossings of the Thames by the Romans were at London Bridge and Staines Bridge. At Folly Bridge in Oxford the remains of an original Saxon structure can be seen, and medieval stone bridges such as Newbridge and Abingdon Bridge are still in use.
Kingston's growth is believed to stem from its having the only crossing between London Bridge and Staines until the beginning of the 18th century. During the 18th century, many stone and brick road bridges were built from new or to replace existing bridges both in London and along the length of the river. These included Putney Bridge, Westminster Bridge, Datchet Bridge, Windsor Bridge and Sonning Bridge.
Several central London road bridges were built in the 19th century, most conspicuously Tower Bridge, the only Bascule bridge on the river, designed to allow ocean going ships to pass beneath it. The most recent road bridges are the bypasses at Isis Bridge and Marlow By-pass Bridge and the Motorway bridges, most notably the two on the M25 route Queen Elizabeth II Bridge and M25 Runnymede Bridge.
Railway development in the 19th century resulted in a spate of bridge building including Blackfriars Railway Bridge and Charing Cross (Hungerford) Railway Bridge in central London, and the spectacular railway bridges by Isambard Kingdom Brunel at Maidenhead Railway Bridge, Gatehampton Railway Bridge andMoulsford Railway Bridge.
The world's first underwater tunnel was Marc Brunel's Thames Tunnel built in 1843 and now used to carry the East London Line. The Tower Subway was the first railway under the Thames, which was followed by all the deep-level tube lines. Road tunnels were built in East London at the end of the 19th century, being the Blackwall Tunnel and the Rotherhithe Tunnel. The latest tunnels are the Dartford Crossings.
Many foot crossings were established across the weirs that were built on the non-tidal river, and some of these remained when the locks were built – for example at Benson Lock. Others were replaced by a footbridge when the weir was removed as at Hart's Weir Footbridge. Around 2000, several footbridges were added along the Thames, either as part of the Thames Path or in commemoration of the millennium. These include Temple Footbridge, Bloomers Hole Footbridge, the Hungerford Footbridges and the Millennium Bridge, all of which have distinctive design characteristics.
Before bridges were built, the main means of crossing the river was by ferry. A significant number of ferries were provided specifically for navigation purposes. When the towpath changed sides, it was necessary to take the towing horse and its driver across the river. This was no longer necessary when barges were powered by steam. Some ferries still operate on the river. The Woolwich Ferry carries cars and passengers across the river in the Thames Gateway and links the North Circular and South Circular roads. Upstream are smaller pedestrian ferries, for example Hampton Ferry and Shepperton to Weybridge Ferry the last being the only non-permanent crossing that remains on the Thames Path.

Sport[edit]

There are several watersports prevalent on the Thames, with many clubs encouraging participation and organising racing and inter-club competitions.

Rowing[edit]

Main article: Rowing on the River Thames
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Cambridge cross the finish line ahead of Oxford in the 2007 Boat Race, viewed from Chiswick Bridge.

The Thames is the historic heartland of rowing in the United Kingdom. There are over 200 clubs on the river, and over 8,000 members of British Rowing (over 40% of its membership).[50] Most towns and districts of any size on the river have at least one club. Internationally attended centres are Oxford, Henley-on-Thames and events and clubs on the stretch of river from Chiswick to Putney.
Two rowing events on the River Thames are traditionally part of the wider English sporting calendar:
The University Boat Race is rowed between Oxford University Boat Club and the Cambridge University Boat Club in late March or early April, on theChampionship Course from Putney to Mortlake in the west of London.
Henley Royal Regatta takes place over five days at the start of July in the upstream town of Henley-on-Thames. Besides its sporting significance the regatta is an important date on the English social calendar alongside events like Royal Ascot and Wimbledon.
Other significant or historic rowing events on the Thames include:
Other regattas, head races and University bumping races are held along the Thames which are described under Rowing on the River Thames.

Sailing[edit]

Main article: Sailing on the River Thames
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Thames Raters at Raven's Ait,Surbiton


Sailing is practised on both the tidal and non-tidal reaches of the river. The highest club upstream is at Oxford. The most popular sailing craft used on the Thames are lasers,GP14s, and Wayfarers. One sailing boat unique to the Thames is the Thames Rater, which is sailed around Raven's Ait.

Skiffing[edit]

Skiffing has dwindled in favour of private motor boat ownership but is competed on the river in the summer months. Six clubs and a similar number of skiff regattas exist fromThe Skiff Club, Teddington upstream.

Punting[edit]

Unlike the "pleasure punting" common on the Cherwell in Oxford and the Cam in Cambridge, punting on the Thames is competitive as well as recreational and uses narrower craft, typically based at the few skiff clubs.

Kayaking and canoeing[edit]

Main article: Kayaking and canoeing on the River Thames

Kayaking and canoeing are common, with sea kayakers using the tidal stretch for touring. Sheltered water kayakers and canoeists use the non-tidal section for training, racing and trips. Whitewater playboaters and slalom paddlers are catered for at weirs like those at Hurley Lock, Sunbury Lock and Boulter's Lock. At Teddington just before the tidal section of the river starts is Royal Canoe Club, said to be the oldest in the world and founded in 1866. Since 1950, almost every year at Easter, long distance canoeists have been competing in what is now known as the Devizes to Westminster International Canoe Race,[51] which follows the course of the Kennet and Avon Canal, joins the River Thames at Reading and runs right up to a grand finish atWestminster Bridge.

Swimming[edit]

In 2006 British swimmer and environmental campaigner Lewis Pugh became the first person to swim the full length of the Thames from outside Kemble to Southend-on-Sea to draw attention to the severe drought in England which saw record temperatures indicative of a degree of global warming. The 325 km (202 mi) swim took him 21 days to complete. The official headwater of the river had stopped flowing due to the drought forcing Pugh to run the first 26 miles (42 km).[52]
Since June 2012 the Port of London Authority has made and enforces a by-law that bans swimming between Putney Bridge and Crossness, Thamesmead (thus including all of Central London) without obtaining prior permission, on the grounds that swimmers here endanger not only themselves but other river users.[53]
Organised swimming events take place at various points generally upstream of Hampton Court, including Windsor, Marlow and Henley.[54][55][56] In 2011 comedian David Walliams swam the 140 miles (230 km) from Lechlade to Westminster Bridge and raised over £1 million for charity.[57]
In non-tidal stretches swimming was,[58] and still is a leisure and fitness activity among experienced swimmers where safe, deeper outer channels are used in times of low stream.[59]

Meanders[edit]

A Thames meander is a long-distance journey over all or part of the Thames by running, swimming or using any of the above means. It is often carried out as an athletic challenge in a competition or for a record attempt.

The Thames in the arts[edit]

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Brooklyn Museum – Houses of Parliament Sunlight Effect (Le Parlement effet de soleil) – Claude Monet
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The first Westminster Bridge as painted by Canaletto in 1746.
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Maidenhead Railway Bridge as Turnersaw it in 1844
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Monet's Trouée de soleil dans le brouillard, Houses of Parliament, London, Sun Breaking Through the Fog, 1904
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Whistler's Nocturne in Blue and Gold: Old Battersea Bridge(c. 1872–1875)
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St John's Lock, near Lechlade.
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The River Thames in Oxford

Visual arts[edit]

The River Thames has been a subject for artists, great and minor, over the centuries. Four major artists with works based on the Thames are Canaletto, J. M. W. Turner, Claude Monet, and James Abbott McNeill Whistler. The 20th-century British artist Stanley Spencer produced many works at Cookham.
The river is lined with various pieces of sculpture, but John Kaufman's sculpture The Diver: Regeneration is sited in the Thames near Rainham.

Literature[edit]

The Thames is mentioned in many works of literature including novels, diaries and poetry. It is the central theme in three in particular:
Three Men in a Boat by Jerome K. Jerome, first published in 1889, is a humorous account of a boating holiday on the Thames between Kingston and Oxford. The book was intended initially to be a serious travel guide, with accounts of local history of places along the route, but the humorous elements eventually took over. The landscape and features of the Thames as described by Jerome are virtually unchanged, and the book's enduring popularity has meant that it has never been out of print since it was first published.
Charles Dickens Our Mutual Friend (written in the years 1864–65) describes the river in a grimmer light. It begins with a scavenger and his daughter pulling a dead man from the river near London Bridge, to salvage what the body might have in its pockets, and heads to its conclusion with the deaths of the villains drowned inPlashwater Lock upstream. The workings of the river and the influence of the tides are described with great accuracy. Dickens opens the novel with this sketch of the river, and the people who work on it:
  • In these times of ours, though concerning the exact year there is no need to be precise, a boat of dirty and disreputable appearance, with two figures in it, floated on the Thames, between Southwark Bridge which is of iron, and London Bridge which is of stone, as an autumn evening was closing in. The figures in this boat were those of a strong man with ragged grizzled hair and a sun-browned face, and a girl of nineteen or twenty.