Groundwater aquifer study on coal mining area: a case of North Samarinda, Indonesia

Abstract

One of the sectors supporting the economy of Indonesia is the mining industry. In East Kalimantan, coal mining activity has been done widely. Coal-mining open-pit activities play a significant role in the economic growth and the advancement of technology for Indonesia. Therefore, it is necessary to study every critical aspect including the hydrological and hydrogeological studies but especially aquifers, so that mining activities can be well managed and the impact on the environment can be overcome. The study of the aquifer from the study area was based on the resistivity value of the materials obtained through one of the geophysical methods that are the geoelectrical resistivity method, by using Wenner-Schlumberger configuration. In this study, geoelectrical resistivity method was performed in order to find out the condition of the subsurface by injecting two electrodes into the soil using direct current (DC) with certain distance so that potential difference can be known and resistivity information of subsurface layers can be obtained. The obtained resistivity value of the material was then interpreted so that the type of aquifer in the study area can be known. The interpretive results of the resistivity values of the materials in the study area showed that the distribution of aquifers based on measurement of a geoelectrical line of line number one, two and three, ware semi-confined aquifers. Meanwhile, the distribution of aquifers of line number four was confined aquifers. Based on the results of hydrological studies, the area of study has an annual rainfall of 3,053.704 mm/year with a watershed area of 16.586 km 2 . The evapotranspiration value of the study area is 1,784.21 mm/year, the surface run-off is 913.51 mm/year, and groundwater recharge is 355.98 mm/year.