Fluvial Landforms

Fluvial landforms result from erosion by water flowing on land surfaces. Fluvial landforms include the following:

• ait—a small island in a river.

• alluvial fan—a fan-shaped deposit formed where a fast-flowing stream flattens, slows, and spreads, typically at the exit of a canyon onto a flatter plain.

• anabranch—a section of a river or stream that diverts from the main channel or stem of a watercourse and rejoins the main stem downstream.

• arroyo—usually dry creek bed or gulch that temporarily (or seasonally) fills with water after a heavy rain.

• bayou—a small, slow-moving stream or creek, or a lake or pool that lies in an abandoned channel of a stream.

• braided river—one of a number of channel types and has a channel that consists of a network of small channels separated by small and often temporary islands called braid bars.

• Carolina Bay—elliptical depressions concentrated along the Atlantic seaboard within coastal Delaware, Maryland, New Jersey, Virginia, Georgia, North Carolina, South Carolina, and north-central Florida.

• drainage basin—an extent of land where water from rain or snowmelt drains downhill into a body of water, such as a river, lake, reservoir, estuary, wetland, sea, or ocean.

• exhumed river channel—a ridge of sandstone that remains when the softer floodplain mudstone is eroded away.

• gully—landform created by running water eroding sharply into soil, typically on a hillside.

• lacustrine plain—a plain that originally formed in a lacustrine environment, that is, as the bed of a lake from which the water has disappeared, by natural drainage, evaporation, or other geophysical processes.

• lake—a terrain feature, a body of liquid on the surface of a world that is localized to the bottom of a basin and moves slowly if it moves at all.

• levee—a natural or artificial slope or wall to regulate water levels.

• meander—a bend in a sinuous watercourse.

• oasis—an isolated area of vegetation in a desert, typically surrounding a spring or similar water source.

• oxbow lake—a U-shaped body of water formed when a wide meander from the mainstem of a river is cut off to create a lake.

• pond—a body of water smaller than a lake.

• proglacial lake—a lake formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice.

• rapid—a section of a river where the riverbed has a relatively steep gradient causing an increase in water velocity and turbulence.

• riffle—a shallow stretch of a river or stream, where the current is below the average stream velocity and where the water forms small rippled waves as result.

• rock-cut basin—cylindrical depressions cut into stream or riverbeds, often filled with water.

• spring—any natural occurrence where water from below the surface of the Earth flows onto the surface of the Earth and is thus where the aquifer surface meets the ground surface.

• stream—a flowing body of water with a current, confined within a bed and stream banks.

• stream terrace—relict feature, such as a floodplain, from periods when a stream was flowing at a higher elevation and has downcut to a lower elevation.

• swamp—a wetland featuring temporary or permanent inundation of large areas of land by shallow bodies of water.

• wadi—Arabic term traditionally referring to a valley.

• waterfall—a body of water resulting from water, often in the form of a stream, flowing over an erosion-resistant rock formation that forms a nickpoint, or sudden break in elevation.