Seawater Intrusion Assessment in Palu Bay, Central Sulawesi of Indonesia
Catur Nilawardani (a*), Wahyu Wilopo (b), Wursito Adi Baskoro (c)

a) Student Master of Geological Engineering, Faculty of Engineering, Gadjah Mada University, Yogyakarta 55281, Indonesia
*caturnilawardani[at]mail.ugm.ac.id
b) Department of Geological Engineering, Faculty of Engineering, Gadjah Mada University, Yogyakarta 55281, Indonesia
c) Ministry of Public Works and Housing, Jakarta 12110, Indonesia

Abstract

Palu Bay is a body of water covering the mainland of Palu City and Donggala Regency. The phenomenon has made groundwater the primary source of clean water supply in the city by contributing 65.63% of total drinking water which is estimated at 2.7 million m3. The community also uses shallow or deep wells equipped with pumping systems to fulfill daily needs but some have reported a brackish taste in water. Therefore, this research aimed to assess the possibility of seawater intrusion in the area. This was achieved by analyzing the values of Electrical Conductivity (EC), Total Dissolved Solids (TDS), chloride ion concentration (Cl-), plotting Cl/Br (bromide) vs Cl, Simpson ratio, sodium chloride ratio, and Base Exchange Index (BEX). The results showed that several areas around Palu Bay, including Mantikulore and West Palu Districts experienced seawater intrusion.

Keywords: Saltwater intrusion- groundwater- geochemistry

Topic: Hydrology, hydrogeology, and geology engineering