The Numerical Simulation of the Freshwater-Seawater Mixing in the Single Phase Coastal Aquifer

The interaction between freshwater and seawater usually occurs in the coastal aquifer. To simply explain this condition, describing the interface between them is conducted. This approach is a multiphase condition. Unfortunately, this condition is on immiscible condition, whereas the miscible condition should be obtained. The miscible condition of freshwater and seawater along coastal aquifer occurs on the single phase. This condition neglects the concept of the interface between them. The purpose of this research is to simulate the mixing of freshwater and seawater in the coastal aquifer by using the numerical method. Groundwater flow equation is governed involving the effect of contaminant concentration. On the other hand, the conservative groundwater contaminant transport equation is used. The discretization process uses the Finite-Difference Method. Coupling two equations will obtain the spreading of contaminant concentration along the model domain. The result shows that the freshwater-seawater interface does not appear and the change of concentration can be reviewed in every section and every point of the computational domain.