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The water from which a river rises; a source.


 * Groundwater** is [|water] located beneath the [|ground] surface in [|soil] [|pore] spaces and in the [|fractures] of lithologic formations.

a landform at the mouth of a river


 * Slope** is often used to describe the measurement of the steepness, incline, gradient, or grade of a straight line.

A watershed is a geographic area from which water drains toward a common watercourse (such as a lake, stream, and ocean) in a natural basin. A **drainage basin** is an extent of [|land] where [|water] from [|rain] or [|snow melt] drains downhill into a body of water, such as a [|river], [|lake], [|dam], [|estuary], [|wetland], [|sea] or [|ocean].
 * velocity** is defined as the rate of change of position.
 * Meandering** rivers shift their positions across the valley bottom by depositing sediment on the inside of bends while simultaneously eroding the on the outer.
 * Erosion** is displacement of solids ([|sediment], [|soil], [|rock] and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement in response to [|gravity] or by living organisms.

A **riffle** (also known as a **swift**) is a shallow stretch of a [|river] or stream, where the current is above the average stream velocity and where the water forms small rippled waves as a result. An arcuate deposit of sediment, usually sand, that occurs along the convex inner edges of the meanders
 * A **cutbank** is a concave section of a tube wall formed on the outside edge of a meandering passage. ||