Flood management seeks to reduce the frequency and magnitude of flooding, and therefore, to limit the damage that floods cause. Flood protection can be achieved by the following hard engineering methods:
- banks and/or channel can be modified to enable the river to carry a larger volume of water. Artifically raised and strenghtened banks form a significant part of this strategy. In some cases, parallel lines of flood banks act as a double form of protection - if the river overtops the first barrier, then it has difficulty rising over the second bank some distance behind. The removal of large boulders from the bed of the river reduces roughness, therefore increasing the velocity of flow.
- dams and weirs can be built to regulate the rate at which water passes down a river.
- diversion channels can be constructed to divert rivers away from areas vunerable to flooding.
- dredging can be used to create a deeper channel so that greater volumes of water pass through.
- the height of the floodplain can be increased by dumping material on it.
- retention basins and balancing lakes can be constructed into which water is diverted at times of high discharge.
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