ASSESSMENT OF NAGINA AREA OF DISTT. BIJNOR U.P. ON THE BASIS OF STANDARD PRECIPITATION INDEX (SPI) FOR DROUGHT INTENSITY

Drought is a natural and worldwide phenomenon, usually defined by periods of less than normal water availability, and is one of the major weather related hazards. Droughts have been dramatically increased in number and intensity in many parts of the world. Drought is a decrease of water availability in a particular period and over a particular area. Based on the drought analysis using the SPI criteria, appropriate crop planning and design of rainwater harvesting and storage structures in the drought affected areas can be proposed in drought affected areas. Standardized Precipitation Index (SPI) was calculated at different time scales (1, 3, 6, 12, and 24 months). The SPI is a drought index based on the probability of an observed precipitation deficit occurring over a given prior time period. The SPI, calculated for a desired period at any location, are based on the long term precipitation record (30 years or more). The positive SPI values show greater than medium precipitation, while negative SPI values indicate less than medium precipitation. The results shows that the SPI can be used for better assessment of drought as it considers larger range of moving sums of rainfall data. Since SPI uses for the running sum of rainfall values at multi-time scales (1 to 24 months) and more variables depending on the statistical distributions used, it gives better assessment of meteorological drought at multi-time scales. A proper rainwater harvesting and management program is an appropriate option for a severely-dry year, but, on the contrary, a situation of wet years with heavy rainfall during monsoon months followed by severely-dry period calls for the need of rainwater harvesting during monsoon and its proper utilization during subsequent dry periods.