Drought monitoring in south Bihar region using standard precipitation index

摘要

The Bihar state is divided by the river Ganga into two parts as north Bihar and south Bihar. Where the north Bihar has to face flood events every year, the south Bihar is more prone to drought. In the present research work the drought events has beendetermined over the entire south Bihar, using standard precipitation index (SPI) for fifty grids. Thereafter the monitoring of the creeping natural hazards has been carried out for the grids facing maximum number of drought events in the period of 1902 to 2016 (i.e., for 115 years) with durations equal to or greater than three months. The complete analysis has been performed for two scales of SPI of 3- and 6-months as an indication of agriculture and hydrological drought respectively. The grid 25 and 2is found to suffer maximum number of the drought events of 73 and 58 based on SPI-3 and SPI-6 computation respectively. The analysis concludes that the Gaya district of Bihar, comprising the two grids (25,2) faces maximum numbers of soil moisture as wellas the surface-water drought events in the study period. The onset, termination, magnitude and intensity of all drought events have been computed to have a clear picture of the pattern of the drought prevailing in the study area. The agriculture droughtevents are found to be more dominating as compared to hydrological drought events. The SPI is proofed to be very effective in drought monitoring with the advantage of being flexible in its application for multi-timescales and considering rainfall data as a single input variables.