Variability in rainfall and meteorological drought over the Banas River Basin under climate change scenarios

This study explores the historical and future variability in rainfall and meteorological drought over the semi-arid Banas River Basin in Rajasthan, India. For this, both historical (1981-2020) and projected (2021-2100) gridded rainfall data have been collected from the India Meteorological Department (IMD), Pune, and the Coordinated Regional Downscaling Experiment (CORDEX) under Representative Concentration Pathways (RCPs) 2.6, 4.5, and 8.5, respectively. The collected data have been analyzed using descriptive statistics (mean, minimum, maximum, skewness, kurtosis, coefficient of variability, and standard deviation) and trend tests (Mann-Kendall and Sen's slope). The severity of drought has been evaluated using the Standardized Precipitation Index (SPI) at multiple time spans (1-, 3-, 6-, 9-, and 12-month). The findings reveal a reduction in the quantity of annual rainfall in the near (2021-2060) and far (2061-2100) future as compared to the historical time period, particularly under RCP4.5 and RCP8.5 scenarios. In the future, the duration, severity, intensity, and frequency of drought will intensify despite the increasing (non-significant) trends in annual rainfall. The maximum frequency has been estimated for mild droughts, followed by moderate and severe droughts. The longest duration of drought (12 years) will occur at the SPI 9-and 12-month scale in the near future (RCP8.5). These findings will be valuable for researchers, water resource managers, agricultural stakeholders, and policymakers in developing effective strategies related to systematic management of water resources and drought over the Banas River Basin, India.