MOVEMENT OF RESIDUAL SALTWATER IN SUBSURFACE DAM TO PREVENT SALTWATER INTRUSION

Abstract

In coastal areas, a subsurface dam has been planed to ensure a constant extraction of water without causing saltwater intrusion into fresh groundwater. The movement and removal of residual saltwater in the storage area of the subsurface dam have not been investigated because of difficulties in monitoring and predicting saltwater dynamics under ground. Experimental and numerical studies were performed to understand the fundamental mechanism of saltwater movement after the dam construction. Experimental results indicate that the residual saltwater in the storage area is gradually flushed out under the conditions of freshwater overflow above the cut-off wall. Numerical results show that the circulation flow is appeared in the residual saltwater region immediately after the installation of the cut-off wall, and then the diluted saltwater in the freshwater-saltwater mixing zone is transported with freshwater flow into the sea side. The results obtained in this study will be a useful guideline to manage groundwater in subsurface dam.