abrasion

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A form of mechanical weathering that occurs when loose fragments or particles of rocks and minerals that are being transported, as by water or air, collide with each other or scrape the surfaces of stationary rocks.

alluvial fan

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Sloping triangular deposits of sediment located where a mountain stream reaches level land.

base level

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The level of the body of water into which a stream flows. The ocean is the ultimate base level.

bedload

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The larger, heavier particles that are being transported by a stream. Instead of being dissolved or suspended, these are being rolled or bounced along, spending at least part of their time in contact with the stream bottom.

 

See also: load, suspended load, dissolved load

 

carrying power

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A measure of the total amount of sediment in a stream and the size of the particles being moved by the stream.

delta

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A fan-shaped deposit of sediment formed at the mouth of a stream or river.

discharge

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The volume of water flowing past a given point in a stream at a given time.

divide

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The higher land separating two adjacent drainage basins.

drainage basin

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Area of land surface drained by a river system.

 

flash flood

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A sudden rush of water, usually caused by a single cloudburst over the narrow valley of a young mountain stream.

 

flood plain

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Wide, level area that borders a stream and is covered by it's water in time of flood.

gully

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A miniature valley formed by erosion from heavy rains.

headward erosion

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The wearing away of land at the head of a gully or a stream valley.

levees

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A long continuous ridge built along the banks of a stream to contain the water during times of high flow.  Can be natural or man-made.

 

meanders

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One of a series of broad, looking bends in a stream.

oxbow lake

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The crescent-shaped lake formed when a river meander gets cut off from the river and the ends of the original bend have silted up.

pothole

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Deep oval or circular hole cut into a stream bed by abrasion from swirling sand and pebbles.

solution

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Dissolved materials containing minerals like calcium and sodium are carried in the water.

stream piracy

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The diversion of the upper part of one stream by the headward growth of another stream.

suspension

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 The state in which rock materials carried by a river are stirred up and kept from sinking by the turbulence of stream flow.

 

water gap

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A pass in a mountain ridge through which a stream flows.

watershed

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The drainage basin includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels.

 

Other terms that are used to describe a drainage basin are catchment, catchment area, catchment basin, drainage area, river basin, water basin and watershed.