Groundwater depletion intensified by irrigation and afforestation in the Yellow River Basin: A spatiotemporal analysis using GRACE and well monitoring data with implications for sustainable management

Study region: Yellow River Basin. Study focus: This study analyzes trends in groundwater storage (GWS) changes and their influencing factors in the Yellow River Basin (YRB) using GRACE satellite data and groundwater level measurements. The Soil-Water-Balance model was developed to simulate groundwater recharge (GWR), quantifying the discrepancies between GWS and GWR at the basin scale. Spatiotemporal changes in GWS and GWR are critical indicators for identifying regions at risk of depletion and evaluating groundwater sustainability. New hydrological insights for the region: The results indicate that between 2002 and 2022, the YRB experienced a reduction of 52.28 Gt in terrestrial water storage, with the GWS losing 77.02 Gt. Except for the significant increase in GWS in the source region, GWS decreased at a rate of 5.56 Gt/yr for entire basin. The annual GWR in the YRB was 103 mm/yr, showing a steady increase of 8.5 mm/decade. However, in the middle and lower reaches of the YRB, GWR failed to compensate for consumption. Approximately 73.71 % of the YRB area was identified as a groundwater risk zone. In the source region, natural factors such as precipitation and snowmelt are the primary drivers of groundwater changes. In contrast, afforestation and irrigation play key roles in the middle reaches, while agricultural is the dominant factor in the lower reaches.