Investigation of Seawater Intrusion in Coastal Aquifers of Kelantan, Malaysia using Geophysical and Hydrochemical Techniques

Abstract

Seawater intrusion is known to be a major source of groundwater quality deterioration in coastal regions globally. The high population and the modern living standards demand more water, which has put the coastal aquifers under huge stress. Approximately 60% of water production in Kelantan is sourced from groundwater where groundwater abstraction for potable water supply is at its forefront. It is shown that the high rate of water abstraction from shallow and deep wells has put the coastal aquifer under stress to meet the increasing demand, as a result the movement of seawater accelerates fast towards the land which will cause mixing of groundwater with seawater. With this background, an integrated approaches using ERI and in-situ physical and hydrogeochemical technique is used to evaluate the nature and extend of seawater intrusion of shallow aquifers in coastal parts of Kelantan. A total of eight resistivity profile with a line spread of 200 meter each has been established to provide the subsurface resistivity values. The resistivity results showed low resistivity values ranging from 0.1 – 10.0 Ω m indicating that the groundwater is considered brackish or saline. Salinity results of the water analysis showed the value of 0.1, 4.1 and 6.0 parts per thousand (ppt) which considered as saline water zones. The electrical conductivity analysis values also reveal a value ranging from 200 – 2000 µs/cm suggest that aquifer is slightly brackish. Based on the result obtained, it is clear that saline water was detected in the shallow aquifer of the study area.