FIELD RESEARCH ON THE TIDE-INDUCED VARIATION OF SALINE WATER INTRUSION INTO A COASTAL AOUIFER

Abstract

The time-dependent mechanisms of saline water intrusion into a coastal aquifer were investigated through systematic field observation that covers the duration of more than half of the tidal cycle. The investigation included three measurements for water table height, vertical distribution of electric conductivity at various testing wells and water levels of the tidal river at a few selected bridge points. It was found that the mixing region between the fresh-saline water bodies is fairly dynamic, and it shifts the depth corresponding to the variation of sea water level. The tide-induced variations of saline water intrusion were analyzed with relation to the variations of sea water level and groundwater level at various testing wells. The mean depths of a mixing region at testing wells appeared more shallowly than the depth predicted by the Ghyben-Herzberg's law.