VARIATIONS OF SALT WATER INTRUSION IN A UNCONFINED AQUIFER NEAR THE TIDAL RIVER

Salt water intrusion in a coastal aquifer varies corresponding to the sea level and rainfalls. The influence of tidal river might be added to the behavior of salt water intrusion when the aquifer locates near the tidal river. Consequently it is easy to understand that the behavior of salt water bodies in such a situation will be quite complicated. The present study describes the findings about the salt water intrusion on the basis of the long-term field measurements conducted near a tidal river. Following findings were obtained: 1) The interface of fresh-salt water bodies in an aquifer consists of a wide mixing zone. 2) The depth of mixing zone varies cyclically and more largely during a spring tide than a neap tide. 3) Rainfalls may have the possibility to uplift the upper mixing zone remarkably for a short period after the rainfall event. Such possibility has to be verified in the future