Within a country as large as the U.S., a number of different regions contain different forms of river ecosystems, with the geographic differences of each region affecting the temperature and flow of the rivers within them. In many areas, river ecosystems begin at high altitudes many miles above sea level where levels of precipitation are high and persistent, the American Rivers Association reports. The level of water and speed of flow is usually seasonal in river ecosystems and is linked closely to the level of precipitation runoff events. An ecosystem provides a habitat for plants and animal life to survive, with the climate of an ecosystem affecting the type of life that can survive within it.
An area, such as the southeast region of the U.S., contains a large variety of river types. The Southeast contains high-gradient, clear-flowing headwater streams and unique types of blackwater streams and rivers. These are commonly found in the coastal plain regions of the Southeast, in contrast to the clear-flowing streams of the Southeast, blackwater streams have a low gradient and flow at a slower speed. Blackwater river ecosystems were created with sandy bottoms that do not support life found in other river ecosystems, and have broad floodplains that are covered each year by large amounts of flood water.
The water of the rivers flowing through the Midwest is warmer than in other regions, and is smaller than cold water streams. Warm water streams begin at lower altitudes than cold water streams, and commonly contain shallow waters. Warm water rivers are characterized by their lack of features and very few warm water ecosystems include cascades, waterfalls and boulders, the American River Association reports. Desert areas can contain cold spring streams in the cold desert regions of the Western states. These cold desert river ecosystems contain cold water streams flowing into deep, warm water rivers, which allow a wide variety of vegetation to grow within the ecosystem.
Large river ecosystems are found throughout the world, with a large number located in the western states. Large U.S. river systems include the Rio Grande, Snake, Yellowstone and Columbia rivers. These rivers have large headlands and have had their ecosystems damaged by humans damming these rivers for hydroelectricity and irrigation demands.
