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Stream capacity, while linked to stream competency through velocity, is the total quantity of sediment a stream can carry. Total quantity includes dissolved, suspended, saltation and bed loads. [3] The movement of sediment is called sediment transport. Initiation of motion involves mass, force, friction and stress.
In this equation w s is the sediment settling velocity, g is acceleration due to gravity, and D is mean sediment diameter. is the kinematic viscosity of water, which is approximately 1.0 x 10 −6 m 2 /s for water at 20 °C.
The sediment-carrying capacity of flowing water depends on the velocity of the water. When the river overflows its banks, the velocity decreases as the water flows away from the river bed, particularly where it flows through a built-up area. The slower-moving water can no longer carry the sediment loads associated with the mid-stream velocities ...
Stream power, originally derived by R. A. Bagnold in the 1960s, is the amount of energy the water in a river or stream is exerting on the sides and bottom of the river. [1] Stream power is the result of multiplying the density of the water, the acceleration of the water due to gravity, the volume of water flowing through the river, and the ...
Sediment in rivers is transported as either bedload (the coarser fragments which move close to the bed) or suspended load (finer fragments carried in the water). There is also a component carried as dissolved material. For each grain size there is a specific flow velocity at which the grains start to move, called entrainment velocity.
The capacity of a stream or river is the total amount of sediment a stream is able to transport. This measurement usually corresponds to the stream power and the width-integrated bed shear stress across section along a stream profile. Note that capacity is greater than the load, which is the amount of sediment carried by the stream.
The suspended load of a flow of fluid, such as a river, is the portion of its sediment uplifted by the fluid's flow in the process of sediment transportation. It is kept suspended by the fluid's turbulence. The suspended load generally consists of smaller particles, like clay, silt, and fine sands.
Terraces are sediment storage features that record an alluvial river's past sediment delivery. [3] Many changes in boundary conditions can form terraces in alluvial river systems. [3] The most basic reason for their formation is that the river does not have the transport capacity to move the sediment supplied to it by its watershed. [3]