The Hydrogeological Conceptual Model of Makassar Coastal Area, South Sulawesi, Indonesia

Abstract The rapid industrial growth and urban development of Makassar City, located on the edge of the Makassar Strait, have led to a significant reliance on groundwater pumping. Understanding the hydrogeological conceptual model is crucial due to the consequences of groundwater exploitation. Therefore, this study aimed to establish the hydrogeological conceptual model of Makassar coastal area. The methods involved gathering both primary and secondary data to define study area boundaries and determine hydrostratigraphic systems, aquifer characteristics, and hydrological conditions. The result showed 3 types of boundary conditions, namely river (Tallo, Jeneberang, and Salo Sinrijala Rivers), constant head (Makassar Straits), and no-flow boundaries (lithological contact between coastal alluvium, the Camba Formation, and the Baturape Cindako Volcanics). The hydrostratigraphic system includes an unconfined aquifer, an aquitard, a semi-unconfined aquifer, and an aquiclude layer. The study area’s hydrological conditions included an annual precipitation of 3,145 mm, evapotranspiration of 1,762 mm, runoff of 532 mm, and groundwater recharge or infiltration of 851 mm. This hydrogeological conceptual model is crucial for future groundwater modeling in the Makassar coastal area.