Evaluation of drought events using multiple drought indices under climate change in the Upper Indus Basin

Spatiotemporal variations in drought events were examined through multiple drought indices in the Upper Indus Basin (UIB) during the 1980-2020 period using observed climate data of precipitation, temperature (T max., T min., and T mean), and potential evapotranspiration (PET) from 16 meteorological stations. Software like ClimPACT2 (to quality check data and generate SPI, SPEI, and CDD drought indices), DrinC (to generate AI, eRDI and PD drought indices), CMhyd (to bias correct NASA POWER gridded data), and ArcGIS (to map extreme drought years) were used in this study. It was revealed that precipitation decreased at 30 mm/decade and maximum and minimum temperatures increased at 0.132 °C/decade and 0.23 °C/decade, aridity increased by decreasing aridity index at 0.15/decade, and number of consecutive dry days increased at 2 days/decade. All drought indices reflected decreasing trends, indicating a warming and drying climatic regime. The eRDI drought index analysis revealed that droughts have occurred for 12.6 years in the last four decades, and mild droughts (15%) are more common, followed by moderate droughts (9.4%), severe droughts (4.7%), and extreme droughts (2.4%). The study provides comparisons of drought patterns under changing climate in three distinct climatic and physical regions of UIB, i.e., Jammu, Kashmir, and Ladakh, and reveals that the UIB is not free from droughts.