Identification of Confined Aquifer Layers Using the Electrical Logging Method in Artesian Wells in Parepare City, South Sulawesi

Abstract Groundwater utilization in Pare-Pare City has been intensive since 2017 until now. A case study of groundwater exploitation in Pare-pare City shows that there are 3 artesian wells. However, there is still a lack of references regarding the identification of aquifer layers in these 3 wells. An important first step in improving groundwater management is to develop an understanding of the subsurface groundwater system. Geological structures, and climatological conditions are important to study comprehensively to understand the aquifer layer system. The electrical logging measurement method (SP log and resistivity) is a method used to see in detail the vertical rock lithology. The tool used for electrical logging measurements is the Naniura Model NRD112P mini logger. The results of electrical logging show that the lithology of the 3 artesian wells consists of layers of massive and fractured volcanic breccia rock, as well as layers of lapilli tuff. Of the 3 artesian wells observed, the layer of lapilli tuff and breccia, which has a fracture structure, acts as a confined aquifer layer, while the massive volcanic breccia acts as an aquifuge layer. The resistivity value of the tuff layer is 60 - 140 Ωm, while the volcanic breccia layer with a fractured system is 150 - 190 Ωm. The confining layer is a massive volcanic breccia layer with a resistivity value of 210 - 390 Ωm.