Aquifer Mapping Using Geo-Electrical Resistivity Survey for Seepage Mitigation in Kuwil Kawangkoan Dam, North Minahasa, North Sulawesi, Indonesia

Abstract

The dam built in an area with a productive aquifer system has potential seepage, influenced by groundwater presence. Seepage can cause instability in the main dams or slopes around the dam. An initial assessment of subsurface geological conditions needs to be done to identify groundwater potential as information in mitigating seepage potential in the dam. Kuwil Kawangkoan Dam is located in the Manado groundwater basin with a high groundwater potential. The 2D electrical resistivity approach with the Wenner configuration was applied in this study. Geoelectric data was acquired on 12 lines spread across the dam area. The measurement results show a resistivity value of less than 300 Ωm, indicating the layer is composed of unconsolidated pyroclastic sediments in the form of sand–gravel. This layer has a depth of around 35 m from the surface. The lithology found is dominated by tuff lapilli with pumice fragments that have the potential as an aquifer.