A flood is an overflow of water, whenever the magnitude of flow of waterexceeds the carrying capacity of the channel within its banks.
CAUSES OF FLOODS
- Heavy rainfall, melting of snow (ice), sudden release of water from dams often causes floods in the low lying coastal area.
- Prolonged heavy rainfall can also cause the overflowing of lakes and rivers resulting in floods
- Reduction in carrying capacity of river channels due to accumulation of sediments or obstructions built on flood ways.
- Deforestation, overgrazing, mining increases the run-off from rains causing floods.
- Removal of dense and uniform forest cover over the hilly zones leaqds to occourrence of floods.
EFFECT OF FLOODS:
Due to floods:
- Water spreads in the surrounding areas and submerges them
- Plain surfaces get eroded and silted with mud and sand thereby affecting cultivable land areas.
- Extinction of civilization in some coastal areas also occurs.
- Floods can be controlled by constructing dams or reservoirs
- Channel management and embankments also control floods
- Encroachment of flood ways should be banned
- Flood hazard may be reduced by forecasting or flood warning
- Flood hazard may be reduced by reduction of runoff and this can be achieved by increasing infiltration through appropriate afforestation in the catchment area.