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It is described by the fact that the discharge through a river of an approximate rectangular cross-section must, through conservation of mass, equal Q = u ¯ b h {\displaystyle Q={\bar {u}}bh} where Q {\displaystyle Q} is the volumetric discharge, u ¯ {\displaystyle {\bar {u}}} is the mean flow velocity, b {\displaystyle b} is the channel ...
The theory is based on the concept of dynamic equilibrium in which streamforms balance between physical parameters, such as width, depth, velocity, and sediment load, also taking into account biological factors. [2] It offers an introduction to map out biological communities and also an explanation for their sequence in individual sections of ...
However the grains will continue to be transported even if the velocity falls below the entrainment velocity due to the reduced (or removed) friction between the grains and the river bed. Eventually the velocity will fall low enough for the grains to be deposited. This is shown by the Hjulström curve.
Rapids of Kern River, California, USA. Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Flow, gradient, constriction, and obstacles are four factors that are needed for a rapid to be created.
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 ...
For particles with a small settling velocity, diffusion will increase the complexity of the particle's path to the bottom and the time it takes to settle compared to particles with high settling velocities. The settling velocity (also called the "fall velocity" or "terminal velocity") is a function of the particle Reynolds number.
The critical velocity for deposition, on the other hand, depends on the settling velocity, and that decreases with decreasing grainsize. The Hjulström curve shows that sand particles of a size around 0.1 mm require the lowest stream velocity to erode. The curve was expanded by Åke Sundborg in 1956.
The river's discharge at that location depends on the rainfall on the catchment or drainage area and the inflow or outflow of groundwater to or from the area, stream modifications such as dams and irrigation diversions, as well as evaporation and evapotranspiration from the area's land and plant surfaces. In storm hydrology, an important ...