Abstract
The seawater intrusion in coastal aquifers has long been attracting attention of researchers for the management of coastal water resource and environmental protection. As the saltwater intrudes into the freshwater aquifers, the quality of salt groundwater will depend on the length of its residence time in aquifers and the geo-chemical composition of the aquifer material. This paper presents the estimation of residence time of freshwater and saltwater in the coastal aquifers and their characteristics. This study utilized the data from the borehole taken from Saitozaki, Fukuoka City. The method of stream function was applied in evaluating the residence time both in the saltwater and freshwater. It was found out that the residence time at saltwater region is longer than that in the freshwater region.
