Drought can occur in any area regardless of the amount of rainfall the area may receive or irrespective of its scientific and social advancement, it can occur in small pockets or over a large area. Drought can occur at any time and cause scarcity of water for drinking, irrigation, industry and urban needs. Drought causes deficiency in soil moisture and makes the land unproductive.
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This causes damage to the crops. Droughts are caused due to failure of monsoon or when it is delayed or arrives early or withdraws without giving rain. These circumstances have produced a continuing expansion in India’s drought prone areas. Drought is no longer a natural disaster; it is a direct consequence of human activity. The resulting human suffering is enormous and growing.
Classification of Droughts:
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The National Commission on Agriculture in India defines three types of droughts.
1. Metrological Drought is defined as the deficiency of precipitation from expected on normal Level over on extended periods of time. It is furthers classified as moderated drought if the rainfall deficit is 26-50% and severe drought when the deficit exceeds 50% of the normal.
2. Hydrological Drought is best defined as deficiencies in surface and subsurface water supplies leading to a lack of water for normal and specific needs.
3. Agricultural Drought usually triggered by metrological and hydrological droughts Occurs. When soil moisture and rainfall are inadequate during the crop growing seasons causing extreme crop stress and wilting.
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The Irrigation Commission (1972) set up by Ministry of Water Resources, Government of India (Gol) has defined those areas that experience meteorological drought in 20 percent of years as drought prone areas and those experiencing meteorological drought in more than 40 percent of years as chronic drought prone areas.
The National Commission on Agriculture recognized an agricultural drought when at least four consecutive weeks receive less than half of the normal rainfall (<5 mm) during kharif or six such consecutive weeks in Rabi.
Hanumatha Rao Committee (1994) suggested climatic variables as well as irrigated area and source of irrigation be used to redefine drought prone districts. In addition, one could use variables given in Table below in demarcating drought prone districts.
Geographical Spread of Drought:
Large parts of the country perennially reel under recurring drought: over 68-70% of India is vulnerable to drought. 33% classified as “chronically drought prone area” receive less than 750 mm of rainfall, while 35%, classified as “drought prone areas” receive rainfall of 750-1125 mm. The drought prone areas of the country are confined to peninsular and western India. Primarily arid, semi-arid and sub humid regard.
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The main cause of drought is the inadequate and uneven distribution of rainfall. West and central India face an uncertainty of rainfall which they receive in the monsoon season; the rainfall is inadequate as well.
The scarcity of rainfall triggers off hydrological and agricultural drought. About 19 per cent of the total area of India experiences drought with 12 per cent of the population being affected by it. Drought is a perennial feature in some states of India. About 30 per cent of the country’s total area is drought prone, affecting 50 million people and 68 per cent of total sown area annually. There are three types of drought prone areas, namely extreme, severe and moderate.
It has been observed that the impact of droughts differs widely between developed and developing countries because of the influence of such factors as water supply and water-use efficiency. The majority of the estimated 500 million rural poor in the Asia-Pacific region are subsistence farmers occupying mainly rain- fed land. The drought-prone countries in this region are Afghanistan, Iran, Myanmar, Pakistan, Nepal, India, Sri Lanka and parts of Bangladesh.
In India, about 33 per cent of the arable land is considered to be drought-prone (i.e. about 14 percent of the total land area of the country) and a further 35 per cent can also be affected if rainfall is exceptionally low for extended periods. Nepal has been subjected to severe droughts in the past. The Philippines, Thailand, Australia and the Pacific islands of Fiji, Vanuatu and Samoa also contain drought-prone areas.
Reducing Impact of Drought:
Planning for mitigation of drought may be taken up on war footing. Various devices of remote sensing, satellite mapping and GIS (Geographical Information System) may be used for identifying water aquifers. Integrated water harvesting programmes with active peoples’ participation may also be useful. Inter- basin transfer of river waters from surplus to deficit areas can also mitigate water crisis to some extent.
Some other measures may be building of small dams for collection of water, afforestation and use of drought resistant crops. The Pani Panchayat in Maharashtra and the Sukhmajari experiment in Haryana are some of the well-known efforts made by the people of counter drought. A drought Atlas for India is being prepared by the National Atlas and Thematic mapping Organisation (UATMO).