Spatio-temporal drought assessment and comparison of drought indices under climatic variations in drought-prone areas of Pakistan

Climatic variations cause droughts which badly affect the environment. To assess the agricultural droughts, a newly developed agricultural Standardized Precipitation Index (aSPI) was calculated which was not used earlier in Balochistan. The widely recommended Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) were used for meteorological drought assessment. Drought indices comparison was also investigated to check the applicability. Rainfall, maximum temperature, and minimum temperature data (1992-2021) were utilized to calculate SPI, aSPI, and SPEI at different timescales (3, 6, 9, and 12 months) using DrinC software and SPEI calculator. Analysis of indices revealed the following extreme drought years: SPI - 1996, 1998, 2000, 2001, 2003, 2004, 2008, 2012, 2014, and 2017; aSPI - 1997, 2001, 2003, 2005, 2013, and 2021; and SPEI - 1993, 2000, 2005, 2006, 2015, 2017, 2018, and 2019. It was determined that Dalbandin, Quetta, Sibi, Kalat, Khuzdar, and Zhob experience higher extreme drought frequencies. Both long-term and short-term drought durations were observed. A comparison of indices showed that the SPI is the efficient drought index as compared to aSPI and SPEI. This study will be helpful for water management strategies in perspective of drought mitigation in the Balochistan province due to climate change.