Drought risk evaluation based on Standardized Precipitation Evapotranspiration Index for projected climate across Tamil Nadu

Abstract Prolonged period of insufficient rainfall leads to the extreme weather event called drought. This research evaluates the drought risk during Southwest Monsoon (SWM) and Northeast Monsoon (NEM) seasons of Tamil Nadu. IMD gridded data (1991–2020) and projected global climate model (CMIP6 – EC_Earth3_Veg_LR) used for SSP245 and SSP585. It helps to assess the anticipated drought risk prone districts over Tamil Nadu using Standardized Precipitation Evapotranspiration Index (SPEI) at different time scales. The drought characteristics (drought events, duration, magnitude, intensity was computed based on SPEI. The historical, SSP245, SSP585 scenarios of the near (2021–2050) and mid (2051–2080) century period were compared and the drought risk was assessed. In future, Northeastern zone, Northwestern zone and Southern zone and parts of High rainfall zone are prone to drought during SWM. Northeastern zone is under high risk during NWM season. Under the SSP585 scenario, extreme drought risk is projected to increase significantly, particularly during the SWM season, despite an overall increase in total rainfall. Increased variability in precipitation amplifies the risk of drought. So, Tamil Nadu needs a comprehensive mitigation effort to manage the increasing drought frequency, intensity, and spatial variation expected over the coming decades.