Inter-Basin Water Transfer Effectively Compensates for Regional Unsustainable Water Use

Globally, a persistent decline of freshwater availability has been identified over a number of intensively irrigated agricultural regions. Large-scale inter-basin water transfer (IBWT) has been suggested as a key tool for stabilizing regional terrestrial water storage (TWS). However, IBWT projects are prohibitively expensive, and their large-scale cost effectiveness remains unclear. Here we quantify the IBWT impacts on TWS trends in the North China Plain (NCP), a global hotspot for TWS depletion and IBWT. Based on in-situ observations, remote sensing, and water balance principles, we provide a framework to disentangle complex climate and anthropogenic impacts on NCP TWS. Results show that the NCP TWS depletion rate was significantly attenuated in 2015-2021, which is primarily attributable to recently enhanced IBWT. Otherwise, the average NCP TWS would currently be 94.9 +/- 4.9 mm (or 12.2 +/- 0.6 km3) lower. However, the positive effect of IBWT is partly offset by increased crop water consumption (-24.1 +/- 5.2 mm or -3.1 +/- 0.7 km3). IBWT and agricultural management (i.e., reducing crop density) are both necessary for stabilizing future NCP TWS. Otherwise, a TWS declining trend exceeding 100 mm/year may occur under elevated CO2 conditions. As such, this study verifies the feasibility and effectiveness of IBWT for mitigating regional water shortages, as well as the crucial role of agricultural management in stabilizing regional TWS. A new framework for reconstructing terrestrial water storage (TWS) is proposedThis framework physically distinguishes climate and human impacts on TWS anomaly variationsInter-basin water transfer and agriculture management are critical for stabilizing TWS over the North China Plain