Development of drought severity–duration–frequency curves for identifying drought proneness in semi-arid regions

Abstract The effectual estimation of meteorological drought parameters such as severity, duration and frequency to plan suitable drought mitigation measures is challenging owing to the complex relationship among these parameters. The present study endeavored to assess the drought proneness of various districts of chronic drought prone Saurashtra region of Gujarat state (India). The district wise Drought Severity Duration Frequency (DSDF) curves were developed using Standardized Precipitation Evapotranspiration Index (SPEI) based on 40 years (1980 to 2019) data. The monthly drought severities of SPEI for various return periods ranging from 2 to 100 years were estimated by testing 10 probability distributions. The DSDF curves revealed that severe droughts were more prominent for shorter durations and identical severities were observed for 1 to 4 month drought duration for smaller rerun periods. As drought mitigation measures vary according to drought severity and duration, the study employed a novel approach of ranking the districts based on three criteria as proneness to higher severities for longer drought durations, high severities with short drought duration, and low severities with long drought duration. Rather than relying on rainfall or drought index-based judgement, the present study demonstrated the better alternative for drought risk assessment, resilience planning, and mitigation.