TITLE:
Saltwater Intrusion in Jizan Coastal Zone, Southwest Saudi Arabia, Inferred from Geoelectric Resistivity Survey
AUTHORS:
Saad Mogren
KEYWORDS:
Geoelectric Resistivity, Seawater Intrusion, Jizan Area, Saudi Arabia
JOURNAL NAME:
International Journal of Geosciences,
Vol.6 No.3,
March
26,
2015
ABSTRACT: This work focuses on the
causes of water quality deterioration in the coastal plain of Jizan area,
southwest Saudi Arabia using vertical electrical sounding (VES) surveys.
Schlumberger electrode array is used in the study with the current electrode
spacing ranging from 400 to 600 m to delineate the thickness of the shallow
aquifer and its possible interaction with the sea water. The differences in
resistivity are associated with the variations in lithology and groundwater
saturation and salinity. The interpretation of VES curves reveals low
resistivity zones characterizing the study area. These zones reflect saline
water intrusion in the coastal aquifer. Generally, it is observed that the
resistivity of saturated zone decreases towards the sea, indicating the
influence of seawater. Based on the interpretation of the constructed
resistivity pseudo-sections and 1-D sequential inversion models, three factors
are identified to control the seawater intrusion into the shallow groundwater
aquifers: 1) presence of faults that contribute extensively in the seawater
intrusion as the seawater invades the coastal aquifers through the crushed
rocks in fault zones related to the Red Sea rifting, 2) over-withdrawal of
groundwater from the coastal aquifers, resulting in saline water intrusion from
the sea into the freshwater aquifer, and 3) the lithological variation where
the alluvial sediments of the ancient buried wadi (dry valley) channels provide
potential pathways for saltwater intrusion and make a hydraulic connection
between the aquifer and the sea water.