Assessment of groundwater resources potential using geoelectrical method and slug test in Tegal District, Central Java Province, Indonesia

Water resources are essential to support everyone in the world, and one of its sources is groundwater. Many areas in Indonesia rely on groundwater to meet their daily needs due to the lack of surface water resources. However, not all-districts have detail information about groundwater resources such as in Tegal District, Central Java Province, Indonesia. Land use planning without the support of information on water resources will cause many problems. Therefore, this study aims to assess groundwater resources in Tegal District using the geoelectrical method and slug test. The research was conducted by geoelectrical survey in 8 locations, measuring groundwater level from the nearest point, and two slug tests. The result of the survey shows that five types of materials in the area are clay, silt, sand, breccia, and lava. The sand layer is an aquifer, and it consists of two layers. The sand layer has a permeability of 6.68 m d-1. However, the clay has a permeability of 1.46 × 10-3 m d-1. The moderate potential of groundwater resources with transmissivity value of more than 50 m2 d-1 lies in the middle of the district.