River

:For the Second World War frigate class, see River class frigate. For the state of Nigeria, see Rivers State.

Management

In its natural state a river may be inconvenient to man in a variety of ways. Rivers in inhabited areas have therefore been managed or controlled to make them more useful and less disruptive to human activity.

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• The river channel may be dredged to make it deeper for navigation or to prevent flooding.
• Dams (see above) or weirs may be built to control the flow, store water, or extract energy.
• Levees may be built to prevent flooding.
• Sluice gates provide a means of controlling flow and adjusting river levels.
• floodways may be added to draw off excess river water in times of flood.
• Canals connect rivers to one another for water transfer or navigation.
• River courses may be modified to improve navigation, or straightened to increase the flow rate.

River management is an ongoing activity as rivers tend to 'undo' the modifications made by man. Dredged channels silt up, sluice mechanisms deteriorate with age, levees and dams may suffer seepage or catastrophic failure.

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