Propagation of meteorological drought to groundwater drought in India

Groundwater drought poses a growing threat to water security in India, as groundwater supplies support agriculture, ecosystems, and domestic use. Although meteorological and hydrological droughts and their propagation have been studied, the propagation of drought into groundwater systems in India has not been examined. In this study, we employed Standardized Precipitation Index (SPI), the CGWB-based Standardized Groundwater Index (SGI), and the GRACE-based Groundwater Storage Anomaly (GWSA) to investigate meteorological drought and groundwater drought across the Indian region. We estimated drought propagation duration, recovery duration, mean drought duration, and maximum drought duration. The results show that regions in the north, northwest, northeast, and a few regions in southern India have the longest propagation time from meteorological to groundwater drought, while other zones, such as central India, have relatively shorter propagation times. We also find that regions in northeast and northwest India recover faster from groundwater droughts than other regions. Our results also show that the Dryness Index (DI), Seasonality Index (SI), and Land Surface Controls (NDVI, soil moisture (SM), and Evapotranspiration (ET)) play a significant role in the propagation time of meteorological to groundwater droughts across different zones. Overall, understanding the propagation and recovery plays a vital role in aiding effective management and planning of groundwater resources in India.