华北滨海平原海水入侵时空变化规律与驱动机制分析OACHSSCD

In recent years,the issue of seawater intrusion caused by excessive groundwater extraction in the North China Coastal Plain has garnered widespread attention from water resource management departments and scholars in the field of groundwater research.To investigate the dynamic variation patterns of seawater intrusion in the coastal plain and quantitatively analyze the impact of groundwater over-extraction on seawater intrusion,this study constructed a three-dimensional variable-density coupled flow and solute transport model(SEAWAT),to reveal the spatio-temporal evolution patterns of seawater intrusion under the synergistic effects of multiple factors by combining with the Random Forest method,and quantitatively evaluate the contribution of controlling factors.The research indicates that:1)From 2018 to 2023,the chloride ion(Cl-)concentration in the North China Coastal Plain showed significant zonal distribution.Seawater intrusion exhibited a polarized pattern of"inland suppression-coastal intensification",with Cl-concentration increasing from＜250mg/L in inland to＞5000mg/L near the coast.The area of the intrusion zone expanded at an average annual rate of 8.8％.2)Groundwater extraction(importance 23％)is the primary driving factor for seawater intrusion.Groundwater over-exploitation causes hydrodynamic imbalance,leading to the landward migration of the freshwater-saltwater interface.In contrast,extreme precipitation in recent years(importance 21％)has played a certain inhibitory role against seawater intrusion by raising groundwater levels and enhancing freshwater displacement.3)Groundwater over-extraction control measures can cause the saltwater front in the coastal zone to retreat seaward by 1.8-2.5km.This research can provide data support and a management basis for groundwater eco-environment monitoring and water resource management in the coastal areas of the North China Plain.