Spatial Distribution of Groundwater Quality in the Coastal Plain and Its Relationship with Land Use and Seawater Intrusion

Studying the spatial distribution characteristics of groundwater quality in the coastal plain and its relationship with land use and seawater intrusion is of great significance for maintaining the stability of the coastal groundwater environment, rationally using land and preventing seawater intrusion in international community. Taking Longkou, Shandong Province as an example, through field surveys and sampling monitoring, and using methods, such as semi-variogram and Kriging interpolation, the spatial distribution characteristics of groundwater quality in the study area and the coupling relationship with land use and seawater intrusion were analyzed. The results show that the main chemical types of groundwater in Longkou are the HCO3·Cl–Na·Ca·Mg and HCO3·Cl–Na·Ca types. Spatial distribution characteristics of groundwater quality are closely related to land use and seawater intrusion, and the mass concentration of most ions gradually decreases from the coast to the inland. The spatial variability of Cl− and Na+ is greatly affected by seawater intrusion. The spatial distribution of NO3− is closely related to the distribution of agricultural land and residential land. We should constantly monitor the scope of seawater intrusion and the total amount of sewage discharged from agriculture and domestic life to effectively prevent the further deterioration of coastal groundwater quality.