Présentations Colloques

Session 8.11: Hydrogeodesy: new surface tools to characterize and monitor active and managed groundwater systems
Litang (orateur)
Evaluation of regional groundwater storage variations in China using GRACE data
Countries with severe groundwater depletion problems have limited information on spatial and temporal variability in groundwater storage, as monitoring networks for groundwater systems are generally limited and it is difficult to regionalize point-based measurements. Water scarcity is a critical issue in China. The Gravity Recovery and Climate Experiment (GRACE) satellite mission provides approximately monthly changes in terrestrial water storage (TWS) on the basis of measurements of the Earth’s global gravity field. With auxiliary information of soil moisture, snow water, and surface water, groundwater storage can be isolated from TWS. This study evaluate the ability of the GRACE satellite to monitor groundwater storage variations. Auxiliary data, such as soil moisture and snow water equivalent, were simulated by the Global Land Data Assimilation System (GLDAS) and used to isolate groundwater item. In situ groundwater storage (GWS) changes were evaluated using measured records from Water Resources Bulletin of China and Monthly Groundwater Dynamic by the Ministry of Water Resources, China. Results show GWS changes derived from GRACE-GLDAS compared favorably with results calculated by measure data in China and first grade unit of water resources, and the correlation coefficient (r) is 0.84 in China. Furthermore, comparison of annual GWS changes from measured data agreed with GRACE-derived annual GWS both in Song-Liao Plain and North China, and the correlation coefficient is 0.70 and 0.57, respectively. GWS depletion rate is estimated in China and 38 provinces from 2003 to 2012 , which shows that the GWS is estimated to decrease at a rate of 24.9 cm yr 1 in China and Beijing has the largest depletion rate (-1.16 cm yr-1) among these representative provinces. This trend, if sustained, will lead to a major water crisis in this region when this non-renewable resource in exhausted.