Dry spell analysis for effective water management planning

Abstract

Knowing the dry and wet periods with rainy seasons is essential for successful water management planning in any particular area. With this view, this study analyzed the thirty years (1975-2004) monthly rainfall data of Udumalpet station located in Parambikulam Aliyar sub basin (Tamilnadu) on annual, seasonal and monthly basis for planning a suitable water conservation management system. Sixty two per cent of the total rainfall is received from North East Monsoon and seventeen per cent from South-West Monsoon. In the study period, four years were found to be wet, four years were found to be dry and the remaining twenty two years were found to be normal years. The analysis showed that the annual and seasonal rainfall data did not clearly indicate the problem of drought in the region; whereas the monthly rainfall data indicated serious concerns to deal with drought particularly during the winter and summer months. It also revealed that the winter months were the most susceptible to severe drought conditions. Out of 30 years of study, January and February were found to be the dry months which normally facilitate for the good harvest of the kharif sown long duration crops. There is a need to adopt adequate moisture conservation measures like mulching etc. to mitigate the effect of drought spells during critical periods of crop growth, and to construct water harvesting ponds/tanks for application of pre-sowing irrigation to Rabi (winter) crops, and supplemental irrigation during periods of water scarcity.