The variable nature of rainfall in India has forever plagued the Indian agriculture and economy. Approximately 73.7 per cent of the total area of the country is rain dependent12. And rain fed agriclture is practised in 58 per cent of this area. Despite the importance of agriculture in the Indian economy irrigation is restricted to some regions only and the productivity potential in these areas have been scaled.
Henceforth, any further rise in agricultural production has to come from the rainfed regions, the potential of which remains untapped.
To revitalize these marginal lands for enhanced agricultural production, the erratic nature of the rainfall has to be understood in the context of Indian agriculture.
Rainfall in India is essentially a result of the southwest monsoon. Over 73.3 per cent of the rains in the various metecrological sub divisions are received between June-September by the Southwest monsoon12. Only Tamil Nadu and Bay Islands receive rains from the northeast returning monsoons, which accounts for 2.6 per cent of the total annual rainfall for the entire country.
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Pre-monsoon and post-monsoon rains account for 10.4 and 13.3 per cent of annual rainfall respectively13.
Seventy two per cent of the entire country receiving a rainfall of 100-1150 mm, experience vast variations in the amount of rainfall received. Droughts and floods occur frequently and the study of rainfall data foT the last 110 years (1871-1981) did not indicate any definite trend.