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Determination of Groundwater Recharge Area based on Isotope data in Makassar Coastal Area, South Sulawesi, Indonesia (a) Student Master of Geological Engineering, Faculty of Engineering, Gadjah Mada University, Yogyakarta, 55281 Abstract The government recently improved the Makassar metropolitan area in South Sulawesi, Indonesia, to support the main food supplier for Indonesia^s new capital city of Nusantara (IKN) in East Kalimantan. These improvements will impact the increase in population and the need for fresh water. The people in this metropolitan area, especially Makassar, the main and core city, still use groundwater daily. Groundwater availability is closely related to water infiltration and the amount taken. Therefore, finding a groundwater recharge area in the Makassar Coastal area is necessary to manage groundwater resources for sustainability. This research aims to determine the groundwater recharge area of the Makassar coastal area using isotope methods. Nineteen isotope water samples, including rainwater, groundwater, river, and seawater samples, were taken to the laboratory. The analysis of the comparison diagram between the δ-18O and δ-D isotope water samples shows that the groundwater in the Makassar coastal area has the same genesis and still comes from rainwater. In contrast, some of the groundwater samples are affected by seawater or experienced seawater intrusion. The groundwater recharge area is located at an altitude between 4.88 to 49.92 masl. Based on the type of aquifer, the groundwater recharge area in the unconfined aquifer is located between 4.88 and 49.92 masl. In comparison, the semi-unconfined aquifer is located at an altitude between 20.75 to 37.92 masl. Keywords: groundwater, recharge area, isotope, coastal area Topic: Hydrology, hydrogeology, and geology engineering |
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