Analysis of the Seawater Intrusion Process Based on Multiple Monitoring Methods: Study in the Southern Coastal Plain of Laizhou Bay, China

Affected by natural factors and human activities, seawater intrusion has become a geo-environmental problem, significantly impacting production life. Seawater weakens coastal areas’ carrying capacity, limiting industry commerce development potential. On the other hand, it may provide convenient deep resources for aquaculture development. Therefore, how to quantitatively analyze intrusion’s process, scope, influencing hotspot hydrogeological researchers. This study uses chemical sampling analysis, environmental isotope, fixed-point, geophysical methods monitor long-term in southern plain of Laizhou Bay. According monitoring data, type fresh groundwater changes from Ca·Mg-HCO3 Na-HCO3·Cl, Na·Ca-HCO3·Cl south north, changing trend brackish is Mg·Na·Ca-HCO3, Mg·Ca-HCO3 Na-Cl·HCO3, Na·Mg-Cl. Saline mainly Na-Cl Na·Mg-Cl type. Brine Cl-Na The relationship between 18O, 2H, Cl− shows that was affected evaporation, dissolution, mixing runoff process. water level TDS wells at different locations depths confirms existence seasonal variations layered phenomena recharge sources. From July 2018 December 2019, north retreat rates were approximately 213.3 m/a 105.9 m/a, respectively. August 2016 front on Dawangdong profile generally retreated northward 27 m/a. results this can scientific basis utilization local Comparative analysis mutual verification multiple basic ideas constructing multi-source system intrusion.