Simulation of Seawater Intrusion Range in Coastal Aquifer Using the FEMWATER Model for Disaster Information

The FEMWATER model is a three-dimensional finite element model that can simulate both groundwater flow and mass transport at the same time, and so by using this FEMWATER model seawater intrusion was simulated and the results were compared to observation data. By using the observation data, a conceptual model was made of 3 layers based on the type of soil, and the hydrogeological parameter was selected. There are two types of dispersivities: longitudinal dispersivity and transverse dispersivity. Longitudinal dispersivity was calculated by Xu and Eckstein's method (1995 Xu , M. and Y. Eckstein . 1995 . Use of weighted least-squares method in evaluation of the relationship between dispersivity and field scale . Ground Water 33 ( 6 ): 905 – 908 .Crossref], Web of Science ®] , Google Scholar]) and the transverse dispersivity was put at 3/10 of the longitudinal dispersivity for the simulation. The electrical conductivity suggested by Freeze and Cherry (1979 Freeze , R. A. and J. A. Cherry , J. A. 1979 . Groundwater . Eaglewood Cliffs , NJ : Prentice-Hall . Google Scholar]) and the correlation with total dissolved solids, TDS, was used to classify the state of the water. Upon analyzing the depths at 15 m, 30 m, 60 m, and 90 m, occurrence of seawater intrusion near the ground surface was limited to the vicinity of the coastline, but as the depths became deeper, seawater intrusion expanded inland. From these results we can come to the conclusion that in order to prevent seawater intrusion there needs to be sufficient preliminary examination.