A National Ecological Security Pattern for Groundwater sustainability in China: Implications for sponge city planning

Groundwater, a critical resource underpinning China's ecosystems and socio-economic stability, faces widespread overexploitation, threatening water security, food production, and ecological balance. This study proposes a National Ecological Security Pattern for Groundwater Preservation (NESP-GP) to assess groundwater security across China. To construct the NESP-GP, we integrated groundwater-level records from the China Geological Survey, provincial water-supply and utilization statistics, and natural, hydrological, and socio-economic factors, and applied the Analytic Hierarchy Process to delineate five security levels. Separately, GRACE-derived groundwater storage changes were compared with monitoring-well groundwater-level changes across five spatial supports during 2006–2016 to assess cross-source consistency rather than to validate the NESP-GP. The comparison showed significant, scale-dependent positive associations: Spearman's ρ increased from 0.127 at the native GRACE grid scale to 0.396 at the 16 × 16 aggregation scale, while directional agreement ranged from 59.9 to 68.1%. Results reveal pronounced regional disparities, with security generally increasing from northwest to southeast. Northwest China exhibits extremely low to very low security associated with limited precipitation, weak recharge conditions, and strong groundwater dependence, whereas the North China Plain shows relatively low security associated primarily with historically intensive groundwater utilization and high agricultural and population pressures. By contrast, the Qinghai–Tibet region exhibits relatively higher security in many areas despite limited recharge, reflecting comparatively low groundwater utilization intensity and socio-environmental pressure. The resulting NESP-GP provides a national-scale representation of groundwater ecological security by integrating recharge conditions, utilization pressures, and socio-environmental impacts, and offers a groundwater-informed spatial reference for groundwater protection and sponge city planning.