Hydrochemical of Groundwater and the Potential of Sea Water Intrusion in Tanah Laut, South Kalimantan

Abstract

The Tanah Laut area in South Kalimantan Province is a rapidly developing area, in line
with the plan to relocate the country's capital. Therefore, the need for groundwater as a water
resource in community life in that area needs to be supported by various studies. This research is
intended as a hydrogeological survey in Tanah Laut District, to determine the local groundwater
hydrochemistry and its potential for sea water intrusion. The research was conducted in the field by
collecting data on the physical properties of groundwater in 155 dug wells and 50 artesian wells.
Several groundwater samples representing free and confined aquifers were tested for
physical/chemical properties in the laboratory. The analysis was performed based on groundwater
table, pH, electrical conductivity (EC) and groundwater facies. The results showed that free
groundwater has a pH of 6.1 - 8.4 and a total dissolved solid (TDS) ranged from 20.3 - 964 μS/cm,
while the confined groundwater had a pH of 4.01 - 9.95 and a TDS of 28 – 2,670 μS/cm.
Groundwater facies vary widely, generally dominated by Na and bicarbonate ions. Brackish
groundwater was found in confined aquifers in two locations, namely Asam Jaya and Mekar Sari,
indicating that the research area has the potential of sea water intrusion.