Propagation dynamics from meteorological to groundwater drought and their possible influence factors

The propagation of meteorological drought in a complete water cycle is not limited to hydrological and agricultural droughts, but also involves groundwater drought. Moreover, the intensification of water cycle under the background of global warming may also affect the time of drought propagation. Therefore, studying the dynamic propagation and possible influence factors from meteorological to groundwater drought is helpful to monitor and assess the risk of groundwater drought. Here we use terrestrial water storage anomalies observations from the Gravity Recovery and Climate Experiment satellites and simulated soil moisture and runoff variations from the Global Land Data Assimilation System to show that the groundwater storage anomalies in the Pearl River Basin (PRB). The standardized precipitation index and drought severity index were used to characterize meteorological and groundwater drought, respectively. Results indicated that: (1) the propagation time of meteorological to groundwater drought in the PRB during 2002-2015 was 8 months, and that in spring and summer was shorter than that in autumn and winter; (2) the time of drought propagation has a significant deceasing trend (p < 0.01), indicating that the water cycle in the PRB was accelerating; (3) increasing soil moisture accelerates the response of groundwater to precipitation in the surplus period due to the stored-full runoff mechanism, whilst intensifying evapotranspiration rate and heat wave facilitate the drought propagation in the deficit period; (4) compared with Arctic Oscillation and El-Nino Southern Oscillation, Pacific Decadal Oscillation is the main driving force to accelerate drought propagation in the PRB.