en.wikipedia.org

River regime - Wikipedia

From Wikipedia, the free encyclopedia

This article is about the mathematical relationship between the river discharge and its width, depth and slope. For the annual pattern of a river's discharge, see Discharge regime.

The river regime generally refers to the mathematical relationship between the river discharge and its width, depth and slope. Thus, "river regime" describes a series of characteristic power-law relationships between discharge and width, depth and slope[1]

It is described by the fact that the discharge through a river of an approximate rectangular cross-section must, through conservation of mass, equal

{\displaystyle Q={\bar {u}}bh}

where {\displaystyle Q} is the volumetric discharge, {\displaystyle {\bar {u}}} is the mean flow velocity, {\displaystyle b} is the channel width (breadth) and {\displaystyle h} is the channel depth.

Because of this relationship, as discharge increases, depth, width, and/or mean velocity must increase as well.

Empirically derived relationships between depth, slope, and velocity are:[1]

{\displaystyle b\propto Q^{0.5}}
{\displaystyle h\propto Q^{0.4}}
{\displaystyle u\propto Q^{0.1}}

{\displaystyle Q} refers to a "dominant discharge" or "channel-forming discharge", which is typically the 1–2 year flood, though there is a large amount of scatter around this mean. This is the event that causes significant erosion and deposition and determines the channel morphology.

  1. ^ a b Luna B. Leopold; M. Gordon Wolman; John P. Miller. (1995). Fluvial processes in geomorphology. New York: Dover Publications. ISBN 0-486-68588-8.