Geophysical mapping of saltwater intrusion in the Kerpan coastal area, Kedah

Author : Abdul Rahim Samsudin, Bashillah Baharuddin, Masrita Mustapa & Sanisah Soed
Publication : Bulletin of the Geological Society of Malaysia
Page : 135-138
Volume Number : 45
Year : 2002

Bulletin of the Geological Society of Malaysia, Volume 45, May 2002, pp. 135 – 138


Geophysical mapping of saltwater intrusion in the Kerpan coastal area, Kedah

Abdul Rahim Samsudin1, Bashillah Baharuddin2, Masrita Mustapa1 and Sanisah Soed1

1Pusat Pengajian Sains Sekitaran & Sumber Alam, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor

2Institut Penyelidikan Teknologi Nuklear Malaysia, Bangi, 43000 Kajang, Selangor, Malaysia

Abstract: The salinity of the ground water in the coastal alluvial aquifer between Kerpan-Air Hitam and Sanglang area in Kedah was investigated using both vertical geoelectrical sounding (VES) and 2-D geoelectrical resistivity imaging techniques. The resistivity measurements were made using ABEM SAS 300C and SAS4000 terrameters. A total of 61 VES stations were established over an area of approximately 100 km2 of Quaternary alluvium. The 2-D imaging was used to study the lateral and vertical changes in resistivity of the alluvial sediments. Salinity of the ground water was interpreted based on the apparent resistivity values. Ground water with resistivity values less than 5 ohm-m is considered as saline and those of greater than 100 ohm-m is fresh water. The resistivity values ranging from 5 to 100ohm-m is for brackish water. The VES and imaging results show that the ground water has resistivities ranging from 0.53 to 670.5 ohm-m. The results of spatial distributions of apparent resistivity indicate that the ground water is mainly brackish with the salt-water affected aquifer confined to the coastal part of the study area. Vertical variations of the resistivity values plotted along profiles perpendicular to the coastal line, indicate that the saltwater has significantly affected the ground water at depth and far away from the coastal area.