Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-137 Manuscript under review for journal Hydrol. Earth Syst. Sci. Discussion started: 3 May 2018 c Author(s) 2018. CC BY 4.0 License.
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Assessment of seawater intrusion using multivariate statistical, hydrochemical and
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geophysical techniques in coastal aquifer, Cha-am district, Thailand
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Jiraporn Sae-Ju1, Srilert Chotpantarat1, 2, 3, 4, and Thanop Thitimakorn1,3
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Department of Geology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
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Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Bangkok, Thailand.
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Research Program on Controls of Hazardous Contaminants in Raw Water Resources for Water Scarcity Resilience, Center of Excellence on Hazardous Substance Management (HSM), Chulalongkorn University, Bangkok, Thailand. 4
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Research Unit of Green Mining (GMM), Chulalongkorn University, Bangkok, Thailand.
Corresponding author. Tel.: (662)2185442; Fax.: (662)2185464; Email:
[email protected].
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Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-137 Manuscript under review for journal Hydrol. Earth Syst. Sci. Discussion started: 3 May 2018 c Author(s) 2018. CC BY 4.0 License.
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ABSTRACT
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Seawater intrusion in coastal areas is one of the important environmental problems, causing negative impact
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on groundwater resources in the future. To assess and mitigate the seawater intrusion, the affected aquifers
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need to be characterized. By integrating geophysical investigation and multivariate statistical analysis of
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the hydrochemical data, seawater intrusion into coastal aquifers in this area could be evaluated. The study
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conducted 80 locations of the vertical electrical sounding (VES) survey; then selected 47 VES to create
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four pseudo cross-section lines in a west-east direction, running perpendicular to the coast in Cha-Am
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district, Thailand, which is negatively affected by this problem. The geophysical results were described
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together with the hydrochemical analysis of 57 groundwater samples. The results revealed that seawater
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intrusion occurred in the Qcl aquifer with an average depth of 50–60 meters and presented more obviously
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near the coastal line. The resistivity value of 50 m3/hour. The TDS ranged widely from 300 to >1200 mg/L. The consolidated aquifers
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are composed of 40% of the study area as described follows. The Silurian-Devonian metamorphic aquifer
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(SDmm) was found in a small area in the lower west. The average depth of the SDmm aquifer is 30–35
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meters with a groundwater level of approximately 3–5 meters deep. Well yield ranged from