Abstract
The North China Region (NCR), a typical grain base and highly populated area in China, is a well-recognized global groundwater funnel. Severe water shortage has been threatening and limiting sustainable development in the region over the past decades. Previous studies have reported the depleted water resources in the NCR and attributed the major driver to intensified agricultural water use, hardly considering the effects of the large-scale implementation of ecological restoration (ER) programs. As terrestrial water storage (TWS) is a critical indicator for measuring and evaluating regional water resources, understanding its spatial and temporal dynamics and responses to ER programs is significant for sustainable water management in the NCR. Here, we examine the interannual variations and trends of TWS in the NCR during 2002-2016 by using Gravity Recovery and Climate Experiment (GRACE) satellite data and the Google Earth Engine cloud computing platform. We find the significantly (p < 0.01) decreasing TWS (-8.9 mm/yr) and identify a hotspot with the most rapid depletion (-12.7 +/- 0.45 mm/yr) in the western NCR, where interannual variations and spatial patterns of TWS depletion are consistent with those of ER-induced greening. Attribution analyses of TWS depletion by considering precipitation, evapotranspiration, and runoff suggest increasing evapotranspiration induced by afforestation as the major driver for TWS depletion in the ER regions. Our study highlights ER is posing a new threat to water security in the NCR, and taking ecological water usage into account would be necessary for the synergy of food, water, and ecological securities and regional sustainable development.