Cascadilla Creek, near Ithaca, New York in the United States, an example of an upland river habitat.

Amazon River near Manaus, Brazil, an example of a lowland river habitat.

In studies of the ecology of freshwater rivers, habitats are classified as upland and lowland. Upland habitats are cold, clear, rocky, fast flowing rivers in mountainous areas; lowland habitats are warm, slow flowing rivers found in relatively flat lowland areas, with water that is frequently coloured by sediment and organic matter. It has been suggested that Ithaca Commons be merged into this article or section. ... Download high resolution version (640x640, 156 KB)A satellite image of the city of Manaus with surrounding rivers. ... Download high resolution version (640x640, 156 KB)A satellite image of the city of Manaus with surrounding rivers. ... A satellite image of the mouth of the Amazon River, looking south The Amazon River (occasionally River Amazon; Spanish: Río Amazonas, Portuguese: Rio Amazonas) of South America is one of the two longest rivers on Earth, the other being the Nile in Africa. ... Manaus as seen from a NASA satellite image, surrounded by the rivers. ... The word ecology is often used in common parlance as a synonym for the natural environment or environmentalism. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... The Murray River in Australia. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ...

These classifications overlap with the geological definitions of "upland" and "lowland". In geology an "upland" is generally considered to be land that is at a higher elevation than the alluvial plain or stream terrace, which are considered to be "lowlands". Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history and the processes that shape it. ... An alluvial plain is a relatively flat and gently sloping landform found at the base of a range of hills. ... Stream Terraces are features, often flood plaines, left behind from periods when the stream was flowing at a different water level. ...

Many freshwater fish and invertebrate communities around the world show a pattern of specialisation into upland or lowland river habitats.

Upland

In freshwater ecology, upland rivers and streams are the fast flowing rivers and streams that drain elevated or mountainous country, often onto broad alluvial plains (where they become lowland rivers). However, altitude is not the sole determinant of whether a river is upland or lowland. Arguably the most important determinants are that of stream power and course gradient. Rivers with a course that drops in altitude rapidly will have faster water flow and higher stream power or "force of water". This in turn produces the other characteristics of an upland river - an incised course, a river bed dominated by bedrock and coarse sediments, a riffle and pool structure and cooler water temperatures. Rivers with a course that drops in altitude very slowly will have slower water flow and lower force. This in turn produces the other characteristics of an lowland river - a meandering course lacking rapids, a river bed dominated by fine sediments and higher water temperatures. Lowland rivers tend to carry more suspended sediment and organic matter as well, but some lowland rivers have periods of high water clarity in seasonal low flow periods. A running stream. ... An alluvial plain is a relatively flat and gently sloping landform found at the base of a range of hills. ... Bedrock is the native consolidated rock underlying the Earths surface. ... This page is a candidate to be copied to Wiktionary. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ...

Classifying rivers and streams as upland or lowland is important in freshwater ecology as the two types of river habitat are very different, and usually support very different populations of fish and invertebrate species.

The generally clear, cool, fast-flowing waters and bedrock and coarse sediment beds of upland rivers encourage fish species with limited temperature tolerances, high oxygen needs, strong swimming ability and specialised reproductive strategies to prevent eggs or larvae being swept away. These characteristics also encourage invertebrate species with limited temperature tolerances, high oxygen needs and ecologies revolving around coarse sediments and interstices or "gaps" between those coarse sediments.

Lowland

The generally more turbid, warm, slow-flowing waters and fine sediment beds of lowland rivers encourage fish species with broad temperature tolerances and greater tolerances to low oxygen levels, and life history and breeding strategies adapted to these and other traits of lowland rivers. These characteristics also encourage invertebrate species with broad temperature tolerances and greater tolerances to low oxygen levels and ecologies revolving around fine sediments or alternative habitats such as submerged woody debris ("snags") or submergent macrophytes ("water weed").