Monday, September 30, 2013

Disaster management - Floods

Increased rainfall or rapid snow melting causes more flow of water in the streams. This excess water flow in a stream covering the adjacent land is called a flood. Floodplain is defined in terms of a flood frequency. Flood frequency is referred as 10-year flood, 100-year flood, etc. A 10-year flood at any point in a stream is that discharge of water which may be expected to occur on average once in 10 years. Floodplains are generally fertile, flat and easily formed.
CAUSES OF FLOOD
Heavy rainfall
Construction of buildings in a flood plain
Removing vegetation
Paving roads and parking areas
Deforestation
Urbanisation
Earthquakes

EFFECTS OF FLOOD
Erosion of top soil and vegetation
Damage and loss to land, house and property
Spread of endemic waterborne diseases
Interruption of basic facilities of community such as highways, railways, telephone, electricity and day-to-day essentials
Silting of reservoirs and dams

FLOOD CONTROL
Construction of flood control dam
Deepening, widening and straightening of streams
Lining of streams
Banning of construction of buildings in floodplains
Converting flood-plains into wildlife habitat, parks, and recreation areas.

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