Author(s): Nani G. Bhowmik
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Abstract: Human interventions have altered almost all the river systems of the world.These interventionsinclude channelization,alteration of stream courses,construction of levees,building of drainage channels,construction of dams and locks,installation of river training works,flow diversions,changes in land use,and many more.River systems respond to such changes through changes in flow,stages,gradients,orsediment supplies and through attempts to attain a new dynamic equilibrium suitable to the changedconditions.However,the time frame for obtaining a new dynamic equilibrium in response to an alteredregimen ranges from a few years to decades or more.There are numerous examples of such alterations oflarge river basins and of the consequent responses of the rivers.In almost all casesthe intervention isassociated with a changed regimen of sediment delivery.The amount of sediment that is delivered eitherincreases as a result of changed land use or decreases as a result of the construction of some form ofsedimen retention devices.Such devices may be created by an act of nature or intentionally,such as inthe case of the construction of locks and dams.
Year: 1989