Multimedia Gallery. Park Passes. Technical Announcements. Employees in the News. Emergency Management. Survey Manual. These are all names for water flowing on the Earth's surface. Whatever you call them and no matter how large they are, they are invaluable for all life on Earth and are important components of the Earth's water cycle. Glacier melting in springtime causes high streamflows. They are all names for water flowing on the Earth's surface.
As far as our Water Science site is concerned, they are pretty much interchangeable. I tend to think of creeks as the smallest of the three, with streams being in the middle, and rivers being the largest. Most of the water you see flowing in rivers comes from precipitation runoff from the land surface alongside the river. Of course, not all runoff ends up in rivers. Some of it evaporates on the journey downslope, can be diverted and used by people for their uses, and can even be lapped up by thirsty animals.
Rivers flow through valleys in the landscape with ridges of higher land separating the valleys. The area of land between ridges that collects precipitation is a watershed or drainage basin. Most, but not all, precipitation that falls in a watershed runs off directly into rivers - part of it soaks into the ground to recharge groundwater aquifers , some of which can then seep back into riverbeds. A river forms from water moving from a higher elevation to a lower elevation, all due to gravity.
When rain falls on the land, it either seeps into the ground or becomes runoff , which flows downhill into rivers and lakes, on its journey towards the seas. In most landscapes the land is not perfectly flat—it slopes downhill in some direction.
Flowing water finds its way downhill initially as small creeks. As small creeks flow downhill they merge to form larger streams and rivers. Rivers eventually end up flowing into the oceans. Flowing over ground as runoff or underground as groundwater, water finds its way to a stream and then eventually to the sea. Why do rivers continue to flow, even when little or no rain has fallen? Much of the water feeding a stream runs slowly underground through shallow aquifers.
They encountered a group of natives who all appeared to be women, or so the story goes. The explorers called the people Amazon s, after female warriors described in Greek myth ology. The name Amazon was later given to the river. The region has abundant and unusual wildlife, including flesh-eating fish called piranha s; huge fish called pirarucu , which can weigh more than kilograms pounds ; and giant snakes called anaconda s.
Some Amazon tribes remain independent of Western culture. The Tagaeri people, for instance, continue to live a nomad ic life based around the Amazon and its tributaries in the rain forest of Ecuador. Because of the demand for timber from the rain forest, the land of the indigenous people of the Amazon is shrinking.
Today, there are fewer than Tagaeri living in the rain forest. Rivers provide energy to many South American communities. The huge reservoir formed by the dam supplies water for drinking and for irrigation. The two join at Khartoum, Sudan. Because the area where the tributaries meet is close to the two sources of the Nile, the area is called the Upper Nile , even though it is farther south geographically.
The Lower Nile runs through Egypt. One of the earliest civilizations in the world developed along the Lower Nile. Ancient Egyptian civilization arose about 5, years ago.
It was directly related to the Nile and its annual flooding. Each year, the river overflowed, spreading rich sediment across its broad flood plain. This made the land extremely fertile. Egyptian farmers were able to grow plentiful crops. Egyptians also used the Nile as a major transportation route to both the Mediterranean and the African interior. A tall, white crown shaped like a bowling pin represented the lands of the Upper Nile.
This crown was combined with a pointy red crown that had a curly wire protruding from the front. The red color symbolized the red soils of Lower Egypt, while the curly wire represented a honeybee.
When putting on the Pschent, an Egyptian ruler assumed leadership for the entire Nile. The Nile provided enterprising Egyptians with material to form a powerful civilization. From papyrus , a tall reed that grew in the river, Egyptians made a sort of paper, as well as rope, cloth, and baskets. Egyptians also built great cities, temples, and monuments along the river, including tombs for their monarchs, or pharaoh s.
Many of these ancient monuments are still standing. The Congo River flows across the middle of Africa, through a huge equatorial rain forest, before emptying in the Atlantic Ocean. The Congo is second only to the Amazon in terms of water flow. It is the deepest river in the world, with measured depths of more than meters feet.
Huge urban areas, including the capital cities of Brazzaville, Republic of Congo, and Kinshasa, Democratic Republic of Congo, sit on the banks of the river. In the Democratic Republic of Congo, the river is the principal highway for transporting goods such as cotton, coffee, and sugar. Boats traveling the river range from dugout canoe s to large freighter s.
The river also supplies an abundance of fish to central Africa. Fishermen use baskets and nets hung from high poles across rushing falls and rapids to catch fish. They also use more traditional nets operated from either onshore or on boats.
Rivers of Australia Much of Australia is arid , but rivers still run through it. The Murray flows some 2, kilometers 1, miles from the Snowy Mountains to a lagoon on the Indian Ocean. Near the town of Wentworth, the Murray is joined by the Darling, a 2,kilometer 1,mile river that flows from the highlands of the eastern coast. Indigenous Australians placed great importance on the Murray River. The Murray valley had the greatest population density on the continent before the arrival of Europeans in the s.
By the mids, European farmers had settled along both rivers and some of their tributaries. Most Australian farmers raised sheep and cattle. Riverboats began plying the waters, and towns grew up along the banks.
Polluted Rivers For centuries, people have depended on rivers for many things. Rivers have provided waterways for shipping, convenient construction sites for cities, and fertile land for farming.
Such extensive use of rivers has contributed to their pollution. River pollution has come from directly dumping garbage and sewage , disposal of toxic waste s from factories, and agricultural runoff containing fertilizer s and pesticide s. Their waters became unsafe for drinking, swimming, and other uses.
One of the most famous examples of a polluted river was the Cuyahoga. The Cuyahoga is a busy river in the U. It is a major highway for goods and services from the Midwest to the Great Lakes. In , the oily pollution in the Cuyahoga was so great that the river actually caught fire—something it had done more than a dozen times in the 19th and 20th centuries.
Since the fire, stricter laws have helped clean up polluted rivers. The laws have restrict ed the substances factories can dump into rivers, limited the amount of agricultural runoff, banned toxic pesticides such as DDT , and required treatment of sewage.
Although the situation in some parts of the world has improved, serious problems remain. The Citarum River in Indonesia, for instance, is often cited as the most polluted river in the world.
Textile factories near the Citarum dump toxic wastes into the river. The garbage floating on top of the river is so thick that water is invisible. Even after communities have limited river pollution, toxic chemicals may remain.
Many pollutants take years to dissolve. Toxic chemicals may cling to algae , which are eaten by insects or fish, which are then eaten by larger fish or people. In parts of North America and Europe, there is also the severe problem of acid rain. Acid rain develops when emission s from factories and vehicles mix with moisture in the air. The acid that forms can be toxic for many living things. Acid rain falls as rain and snow.
It builds up in glaciers, streams, and lakes, polluting water and killing wildlife. Environmentalists, governments, and communities are trying to understand and solve these pollution problems.
To provide safe drinking water and habitats where fish and other wildlife can thrive, rivers must be kept clean. Dams A dam is a barrier that stops or diverts the flow of water along a river. Humans have built dams for thousands of years. Dams are built for many purposes. Still others provide water supplies for nearby rural or urban areas. Many dams are used to provide electricity to local communities.
Since then, thousands of hydroelectric plants have been built on rivers all over the world. These plants harness the energy of flowing water to produce electricity.
About 7 percent of all power in the United States, and 19 percent of power in the world, comes from hydroelectric plants. Hydroelectric power is renewable because water is constantly replenished through precipitation.
Because hydroelectric plants do not burn fossil fuel s, they do not emit pollution or greenhouse gas es. However, hydroelectric power does have some negative effects on the environment.
Dams and hydroelectric plants change the flow and temperature of rivers. These changes to the ecosystem can harm fish and other wildlife that live in or near the river.
Decay ing plant material emits carbon dioxide, a major greenhouse gas, into the atmosphere. Dams also have an effect on people living near the rivers.
For example, more than 1. Human rights organizations claim that many of these people did not receive the compensation they were promised in return for being displaced. In addition, dams can affect fish populations and the fertility of flood plains.
Is it simply that it takes very a long time for the water at its source and the sources of all its tributaries to reach the point I'm observing from? It seems there's a constant supply of water when I would have expected the network of rivers to start draining, and the drying up starting from the source the moment the rain stopped. The rivers are generally fed by water that percolated into the ground, it takes longer for that water to work its way down to the stream so the streams and rivers keep flowing long after the initial rain.
A river's primary of source of water is precipitation, surface water run off, and shallow groundwater discharge within the drainage basin the river is located. The size of the drainage basin really determines if a river may run dry during drought conditions. Some river basins are so large that drought conditions are unlikely to persist over the entire basin at any given moment. With the Colorado river, scarce rainfall and over-usage leads to a greatly diminished flow at discharge into the into the Gulf of California Sea of Cortez.
Glaciars and snow in mountains act as natural dams for many rivers. That's why several rivers have an increase of their flow during hot times, when the snow melts and the river moves more water compared to other times of the year. Since many mountains keep part of their snow and glaciars the whole year, the rivers that start there will have water for a long time.
Finally, snow that falls in mountains is by far more than the rain that falls in the valley below, so each rain you see in the valley is a storm up in the mountains. Sign up to join this community.
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