NUMERICAL-SIMULATION OF SALTWATER INTRUSION IN A GROUNDWATER BASIN

The spatial and transient behavior of the coupled mechanism of saltwat er and freshwater how throughout the Erzin, Turkey, groundwater basin was analyzed to forecast the position of the interface under a particu lar set of recharge and discharge conditions. The density-driven saltw ater intrusion process was simulated with the use of a finite-element model. Physical parameters, initial heads, and boundary conditions of the basin were defined on the basis of available field data, and an ar eal, steady-state groundwater model was constructed to calibrate the o bserved head values corresponding to the initial development phase of the aquifer. Initial and boundary conditions determined from the areal calibration were used to evaluate the aquifer's dispersivities and th e porosity in a steady-state, cross-sectional analysis. Consequently, the initial position of the salt concentration distribution was calibr ated under steady-state conditions. The initial concentration distribu tion was then marched through time under discharge and recharge condit ions, and the present-day position of the interface was predicted. In the cross-sectional simulation, the saltwater front was predicted to m ove inland during the discharge period, whereas in the recharge period the heads were pre dieted to recover to their initial positions with no significant movement of saltwater. The present-day distribution of salt concentrations was estimated via a 25-year simulation. Results in dicate that the width of the dispersion zone has increased during this period and the saltwater encroachment has gradually been slowed down, tending toward a new steady-state position.