Analytical and numerical model of saltwater intrusion in Jeneponto Regency, South Sulawesi Province Indonesia

Abstract

This paper assesses the extent of saltwater intrusion (SWI) in coastal aquifers in two sub-districts of Jeneponto Regency, Indo-nesia, for the first time using an analytical method in the form of a sharp-interface approach and numerical dispersive simulation of a finite difference solution developed by SEAWAT, based on field observations and secondary field data. In general, the SWI extents obtained from the analytical solutions for four aquifers in the region are around 30% greater than numerical solutions. The results show that the maximum SWI extent occurs in the Binamu2 aquifer in Jeneponto Regency, where the analytical solution and numerical simulation produced SWI extents of 850.4 m and 510 m, respectively. The higher results in the sharp interface model compared to the numerical model are most likely due to the pushing seaward effect caused by the presence of circulating flow inside the saltwater wedge below the freshwater-saltwater interface, which is considered in the numerical solution but not in the analytical solution, as explained in the previous SWI study. The results also revealed that the SWI conditions in Jeneponto Regency are still within reasonable limits, but groundwater exploitation control is critical in the region to maintain this situation.