OPTIMIZATION BASED SOLUTION OF DENSITY DEPENDENT SEAWATER INTRUSION IN COASTAL AQUIFERS

The numerical simulation of seawater intrusion with a considerable transition zone requires simultaneous solution of the discretized ground-water flow and transport equations. A nonlinear optimization method for solving the embedded governing equations for simulation of seawater intrusion is proposed. The main advantage of this optimization based method is that sequential iterative solution of the flow and transport equations is not necessary. Also, simultaneous solution of the flow and transport equations using the optimization approach uniquely suits the transformation of this simulation approach to a management model. Both steady-state and transient simulations are performed by using this methodology. The solutions obtained by using the proposed methodology are compared with results reported by other researchers. The obtained solutions compared satisfactorily with the known solutions. The formulation and solution of a nonlinear optimization model for maximizing total sustainable yield from specified locations of the aquifer, while satisfying stipulated salinity constraints, are presented to demonstrate the feasibility of integrating this simulation approach within a coastal aquifer management model.