Time-lapse resistivity investigation of salinity changes at an ex-promontory land: a case study of Carey Island, Selangor, Malaysia

Baharuddin, Mohamad Faizal Tajul and Taib, Samsudin and Hashim, Roslan and Zainal Abidin, Mohd Hazreek and Ishak, Mohd Fakhrurrazi (2011) Time-lapse resistivity investigation of salinity changes at an ex-promontory land: a case study of Carey Island, Selangor, Malaysia. Environ Monit Assess, 180 (1). pp. 345-369. ISSN 0167-6369

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Official URL: http://www.dx.doi.org/10.1007/s10661-010-1792-x

Abstract

Time-lapse resistivity measurements and groundwater geochemistry were used to study salinity effect on groundwater aquifer at the ex-promontory-land of Carey Island in Malaysia. Resistivity was measured by ABEM Terrameter SAS4000 and ES10-64 electrode selector. Relationship between earth resistivity and total dissolved solids (TDS) was derived, and with resistivity images, used to identify water types: fresh (ρe > 6.5 nm), brackish (3 n m < ρe < 6.5 n m), or saline (ρe < 3 n m). Long-term monitoring of the studied area’s groundwater quality via measurements of its time-lapse resistivity showed salinity changes in the island’s groundwater aquifers not conforming to seawater-freshwater hydraulic gradient. In some aquifers far from the coast, saline water was dominant, while in some others, freshwater 30 m thick showed groundwater potential. Land transformation is believed to have changed the island’s hydrogeology, which receives saltwater pressure all the time, limiting freshwater recharge to the groundwater system. The time-lapse resistivity measurements showed active salinity changes at resistivity-image bottom moving up the image for two seasons’ (wet and dry) conditions. The salinity changes are believed to have been caused by incremental tide passing through highly porous material in the active-salinity-change area. The study’s results were used to plan a strategy for sustainable groundwater exploration of the island.

Item Type:Article
Uncontrolled Keywords:salinity; groundwater chemistry; time-lapse resistivity; ex-promontory land
Subjects:G Geography. Anthropology. Recreation > GB Physical geography
Divisions:Faculty of Civil and Environmental Engineering > Department of Infrastructure and Geomatic Engineering
ID Code:8120
Deposited By:Normajihan Abd. Rahman
Deposited On:10 Jan 2017 12:16
Last Modified:10 Jan 2017 12:16

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