Journal of the Geological Society of Korea (지질학회지)

The Geological Society of Korea (대한지질학회)
권호 표지

Integrated approach for evaluating the characteristics of seawater intrusion using factor analysis and time series analysis: Seocheon-Gunsan area

시계열 및 요인분석을 이용한 해수침투 특성 평가: 서천-군산 지역

Lee, B. J.;Moon, S. H.
이봉주;문상호

  • Published : 20080400

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Abstract

An intergrated approach is tried to evaluate the characteristics of seawater intrusion in Seocheon-Gunsan area using factor analysis and time series analysis. Analysis result of the molar ratios of Cl/HCO3 and Na/Cl indicates that groundwater quality in the study area is mainly affected by seawater. Relationships between molar ratios of Cl/HCO3 and contents of total dissolved solids, and Na:Cl milliequivalent ratios show that effects of seawater intrusion are relatively more remarkable in the groundwater samples from the bedrock aquifer than those from the alluvium/weathered zone aquifier. Factor analysis also reveals that the major factor for controlling groundwater chemistry in the study area is the seawater intrusion. Especially, outliers of factor scores for factor I, which represent groundwater contamination by seawater intrusion, are found much more frequently from samples of the bedrock aquifer than the alluvium/weathered zone aquifer. Spectrum analysis results show that the tidal ampli-tudes of groundwater levels in the bedrock aquifer are relatively greater than thoes of the alluvium/weathered zone aquifer. All these phenomena could be considered as the evidences to infer that the seawater intrusion may occur mainly through the bedrock aquifer rather than the alluvium/weathered zone aquifer in the study area. Consequently, the above-mentioned results show that the integrated application of hydrogeochemical and factor analyses and time series analysis can be used as an effective tool to evaluate the characteristics of the seawater intrusion in coastal area.

시계열 및 요인분석을 이용하여 서천-군산지역의 해수침투 특성을 평하였다. Cl/HCO3 몰비와 Na/Cl 몰비 관계는 연구지역의 지하수 수질이 많은 경우 해수에 의한 영향을 받은 것을 지시하며, Cl/HCO3 몰비와 TDS 함량과의 관계, Na:Cl 다량농도비 등의 결과에서는 충적/풍화대 지하수에 비해 암반 지하수가 해수의 영향을 보다 우세하게 받은 것으로 해석된다. 요인분석 결과에서도 역시 해수에 의한 영향이 연구지역 지하수 수질을 규제하는 가장 큰 요인으로 파악된다. 특히 해수에 의한 오염을 나타내는 요인 1에 대한 요인 점수의 이상치들이 충적/풍화대 대수층보다는 암반 대수층이 시료들에 집중되는 것과 충적/풍화대 대수층에 비해 암반 대수층의 지하수위 조석 변동 폭이 큰 것은 연구 지역 대수층으로의 해수 침입이 충적/풍화대 대수층보다는 암반 대수층을 통해 이뤄지고 있다는 증거로 볼 수 있다. 이러한 연구 결과는 수질분석, 요인분석 그리고 스펙트럼 분석의 통합적 적용이 해안지역 대수층의 해수침투 특성을 평가하고 해석하는데 있어 효율적인 도구가 될 수 있음을 보여준다.

Keywords

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