Abstract
The unsteady state two-dimensional hydrodynamic dispersion model is used to simulate the seawater intrusion into confined coastal aquifers in response to the tide and to the sudden change in discharge of groundwater in the upstream region.
The main results are as follows : 1) Salt water intrudes most inland at the mean sea level in the ebb tide stage, as in the case of the fresh-salt water interface model by KISHI and INOUCHI (1984), and the transition zone from fresh water to salt water becomes widest at that sea level. 2) The movement of isocontours of concentration induced by the sudden change in groundwater discharge retreats faster than it advances and that movement is comparable with the fresh-salt water interface movement computed by the interface model of KAKINUMA et al. (1984). 3) The concentration distribution in response to the tide computed with higher values of the storage coefficient of the confined aquifer is somewhat different from the one obtained by using PINDER and GRAY'S (1977) approximation to the mass conservation equation. This difference, however, is negligible in field situations, with lower values of the storage coefficient.
