Crop Seasonal Meteorological Drought Severity Assessment using SPI Indices

Droughts are major natural disasters of many parts of world. Dry areas, where precipitation pattern is seasonal, or is otherwise highly variable, are the most susceptible. Unlike most natural disasters, drought onset is difficult to identify. In the recent decade, semi-arid regions are subjected to frequent droughts due to climate change. The information about frequency, duration and intensity of historical drought is essential for planning suitable policies and measures to control land degradation. The principal objective of the study is to assess the meteorological drought severity on crop seasonal basis by Standard Precipitation Index (SPI) using monthly rainfall data for timescale of 3 months. Thirumanimuthar Sub-basin located in semi-arid region of Tamil nadu, India is chosen as the study area which is predominantly affected by drought over few decades. The results from SPI indices show that there is no drought during Thaipattam but there is frequency of occurrence of drought in last decade in Chittaraipattam, Adipattam and Puratasipattam. During different crop seasons the normal average drought is observed once in 3 years till 2002. Later it was observed that the drought frequency is once in 1 or 2 years till 2014.