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

It is possible to plan suitable measures to mitigate the ill effects of droughts if the severity, recurrence interval, and frequency of droughts can be estimated efficiently. The present study was conducted to assess the drought proneness of various districts of the Saurashtra region of Gujarat state (India) by developing the drought severity-duration-frequency (DSDF) curves using the Standardized precipitation evapotranspiration index (SPEI) using rainfall and temperature data of 40 years (1980-2019) of 36 stations. The drought severities for various return periods ranging from 2 to 100 years were estimated using the best -fit probability distributions to derive district-wise DSDF curves for various districts for durations of 1-4 months. The results revealed that severe droughts are expected to occur once in 29-44 years for various districts of Saurashtra. The districts were ranked based on criteria such as proneness to higher severities for longer drought durations, high severities with short drought duration, and low severities with long drought duration. The finding of the study and DSDF curves can serve as a convenient tool for risk assessment, planning various crop cultivation and irrigation interventions, preparedness, and mitigation against droughts.