A two-dimensional finite element model for dispersion (2D-FED) in coastal aquifers

A two-dimensional finite element model is developed to simulate the saltwater intrusion phenomena in confined and leaky coastal aquifers under steady state conditions. The governing equations are combined into two nonlinear coupled partial differential equations in only two variables, namely, the concentration and the equivalent freshwater piezometric head. The Galerkin technique is employed, with the computation scheme based on the relaxation method. Heterogeneity and anisotropy of the aquifer are considered. The dispersion coefficient is taken to be velocity dependent. The model is verified on two prepublished problems. Unlike existing models, this model is also applied to simulate saltwater intrusion in a large aquifer - the Nile Delta aquifer in Egypt. Equiconcentration and equipotential lines are constructed in the Nile Delta aquifer.