Assessment of seawater intrusion using multivariate statistical

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May 3, 2018 - 21 the hydrochemical data, seawater intrusion into coastal aquifers in this ... In the coastal aquifer, seawater lies under fresh water since fresh ... In addition, the VES technique can be enabled in large areas as it is less time-consuming ..... The pseudo cross-section C-C' (Figure 6c) consisted of 12 VES as ...

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

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