SEAWATER INTRUSION AFFECTED BY BOUNDARY CONDITIONS IN UNCONFINED AQUIFERS

The characteristics of seawater intrusion are examined on the various aquifer conditions. Numerical positions of fresh-saltwater interface are obtained with using Residual Flow Procedure that was proposed originally to solve unconfined groundwater flow. A simulated result of fresh-saltwater interface is confirmed by sand model test in case of two-layered aquifer. From the simulated results, the followings are clarified, that is; seawater easily intrude to the two-layered aquifers in case that the high permeable layer overlies on the low permeable layer. The intruded saltwater region is relatively small in case of both the stratified aquifers separated by a semi-permeable layer and the anisotropic aquifers having low permeability in vertical direction, but that is relatively large in both the two-layered aquifer and the stratified aquifer of which the upper layer is closed by the impermeable wall.