How to stop groundwater drawdown in North China Plain? Combining agricultural management strategies and climate change

The global crisis of groundwater depletion is becoming a challenge in irrigation agriculture. How to optimize the agricultural system amidst climate change is crucial for groundwater and food security around the world. In this study, the multiple cropping index (MCI) reducing strategy and irrigation-limiting strategy were assessed using the SWAT-GW model in the piedmont plain of the Taihang Mountains of North China Plain (NCP). Model calibration and validation were conducted using field data for spring maize (SPM) with a target NRMSE below 25%, alongside previously calibrated parameters for winter wheat (WW), summer maize (SUM), evapotranspiration, and groundwater levels. Historical simulations (1993-2012) indicated that a two-year-three-crop cropping system (WW-SUM -> SPM) with 82 mm of irrigation quota (3H2Y_O, "double-reducing strategy") maintained shallow groundwater levels while accepting a 27% yield reduction. Future simulation (2030-2049) suggest that increased groundwater recharge due to climate change might allow shallow groundwater balance through the irrigation-limiting strategy alone ("single-reducing strategy"), with crop yields expected to rise by 5.8%-6.9% for wheat and 1.2%-2.3% for maize. By 2070-2089, enhanced precipitation could lead to sufficient groundwater recharge, enabling equilibrium under a double-cropping system (WW-SUM) with full irrigation scheme ("non-reducing strategy") in most areas. Wheat yields may increase by 9.7%-10.5%, but maize yields could fall by 1.1%-10.9%. This study could provide detailed data for groundwater recovery planning in China's grain-producing regions, and offer a methodological framework for the trade-off between water scarcity and food security for other over-exploited groundwater areas worldwide.