Numerical Analysis of Seawater Intrusion and Dispersion in Coastal Aquifers

Abstract

Water resources on small islands depend greaty on coastal groundwater. For the purpose of monitoring and predicting groundwater quality, it is important to analyse seawater intrusion and dispersion processes in these coastal aquifers. This paper describes a numerical method which evaluates the salt concentration distribution in coastal groundwater in response to the tide. Numerical solutions obtained by the numerical method were compared with numerical solutions obtained previously by the finite element method. Tidal effects on the mixing zone between freshwater and seawater were numerically investigated for a two-layered aquifer with different permeability coefficients. The numerical results can explain the behavior of the mixing zone in response to tidal change which was observed under the field condition. It is concluded that this numerical method is a practical one for analysing seawater intrusion and dispersion in coastal aquifers.