Spatio-Temporal Dynamics of Groundwater Drought in the Cauvery Basin Under Variable Climatic Conditions

Groundwater drought is a critical issue in regions dependent on groundwater for water supply. This study investigates the spatio-temporal dynamics of groundwater drought in the Cauvery Basin using satellite- based groundwater storage data from NASA’s GIOVANNI platform. The Standardized Groundwater Drought Index (SGDI) is computed at a monthly grid scale over 21 years to assess groundwater depletion and classify drought severity. The SGDI is correlated with the Standardized Precipitation Index (SPI) to validate its reliability in capturing drought conditions. To examine the persistence of groundwater drought, the Hurst exponent (H) is applied, revealing long-term memory in drought patterns. Singular Spectrum Analysis (SSA) is then performed on sub-basin SGDI to identify long-term trends and the most severe drought years. Spatial mapping of SGDI highlights the distribution and severity of drought impacts across the basin. Furthermore, the influence of large- scale climate patterns El Niño-Southern Oscillation (ENSO), Southern Oscillation Index (SOI), and Indian Ocean Dipole (IOD) on groundwater drought is analysed using wavelet-based methods. This approach identifies the dominant teleconnection f actor driving drought variability in the region. The findings enhance drought monitoring capabilities and provide actionable insights for groundwater management and early warning systems in the Cauvery Basin.