Hidden costs of a thriving Yellow River: Severe groundwater depletion

Groundwater storage (GWS) is essential for supporting agricultural irrigation and revegetation in the water-scarce Yellow River Basin (YRB). Early studies have mainly focused on the impacts of revegetation on GWS, and rarely consider the influences of agricultural irrigation and other human activities, rendering the driving mechanisms of GWS unclear. Here we used NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite data, the PCR-GLOBWB2 hydrologic model, and an Long Short-Term Memory (LSTM) machine learning approach to reveal changes, driving mechanisms, and future trends in GWS in the YRB. Results show that GWS in the YRB decreased by ∼101 Gt in 2003−2020, roughly 24 times the Yellow River’s flow into the sea in 2000. Notably, GWS depletion (−7.7 mm/yr) dominates the observed terrestrial water storage (TWS) losses (−6.0 mm/yr) and accounts for >100% of the net TWS decline. Storage losses are largely explained by increases in evapotranspiration (+6.0 mm/yr) driven by revegetation and agricultural irrigation. This is evident in higher evapotranspiration rates (+3 mm/yr) observed in heavily revegetated areas, with irrigation showing an estimated contribution of −6.6 mm/yr on GWS by the PCR-GLOBWB2 model. GWS losses are projected to persist until 2060 by the LSTM model, with a total storage loss of ∼237 Gt. With GWS declining and natural recharge growth lagging behind the rise in groundwater demand, the YRB confronts a future of groundwater deficits. The study suggests that although groundwater extraction for agricultural and ecological benefits might appear helpful to the region in the short term, this trajectory is physically unsustainable and detrimental to the water-scarce Yellow River.