A sensitivity analysis of '2D-FED', a model for seawater encroachment in leaky coastal aquifers

In a previous study, a two-dimensional finite element model for dispersion (2D-FED) was developed and verified for some previously published problems. The model was applied to predict the shape of equiconcentration and equipotential lines in coastal aquifers. In this paper, the 2D-FED model is used to study the effect of several parameters on the simulated dispersion zone and flow pattern in leaky coastal aquifers. The aquifer thickness greatly affects the dispersion zone as well as the equipotential lines. Except for certain ranges, the effects of isotropic and anisotropic permeability coefficients and anisotropic dispersivities are relatively small. Cyclic flow is found near the shore boundary in many cases. Selection of a proper mesh size especially near the seaside is found to be very important to avoid instability problems.