Very Short Paragraph on Floods!
Floods and droughts both are natural hazards and are related with rainfall. If there is heavy rain in the catchment area of a river, flood occurs.
On the other hand, if there is less rain or failure of monsoon, drought occurs. In both the situations their impact on environment creates problems and also affects the regional ecosystem.
Flood is a hydrological phenomenon that can occur in any drainage basin. Its magnitude and frequency varies primarily on the precipitation conditions in the catchment area. Most of the river valleys are subjected to varying degrees of flood incidences, either creating minor damages or devastating havoc at times.
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Such calamities of floods pose a serious problem to the whole environmental set-up of a region, bringing about some phenomenal changes in the physical environment ushering in accelerated erosional transportional and depositional activities of the river with the consequent effects on soil. The devastating effects of flood can be seen on vegetation, agricultural, industry settlement, sometimes causing loss of human and animal lives and of material also.
The main cause of flood is excessive rainfall but its occurrence is also due to earthquakes, deforestation in the upper catchment areas, failure of dams, excessive snow melting, etc. The beneficial effects of floods have been established beyond doubt in the form of fertilisation of soil. But, it’s devastating effects far exceed the benefits.
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In India, the problem of flood is of gigantic magnitude, because of: typical seasonal rainfall, and erratic nature of tropical cyclones and rainstorms. Besides in last few years, most parts of the country, including metropolitan cities like Mumbai, have been badly affected by floods—the reason being unplanned development. In August-September, 2008, devastating flood has been occurred in parts of Bihar. This was due to excess water release in rivers originated in Nepal.
The following are the areas which may be termed as flood-prone:
(a) Upper catchment and piedmont zone of the Himalayan river basins.
(b) Ganga river valley—upper, middle and lower deltaic zone.
(c) Brahmaputra valley and its tributaries.
(d) Deltaic region of Mahanadi, Godavari, Cauvery and Krishna rivers.
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(e) Narmada and Tapti basins.
The common measures of the flood control could be:
(i) Control of erosion in upper catchment areas.
(ii) Construction of dams and reservoirs at suitable sites.
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(iii) Prevention of overflow in channels.
(iv)Construction of multiple channels for distribution of the excess river water
(v) Development of shelters in flood-prone areas.