논문 상세보기
pp.253-259
The purpose of this study is to investigate the physicochemical characteristics of salinization of groundwater at the estern area of Cheju island. For this purpose, the major ions of groundwater. spring water are analyzed. The concentration of Cl- and Na-+K- contained in the groundwater at near the coastline are higher than those at inland area away from the coastline. The water quality components of groundwater observed at this area can be classified into 4 types such as Na-Cl, HCO3, Na-Cl-HCO3 and Ca-HCO3. The concentration ratio of SO4- to Cl- is 0.1354(R2=0.972) at this area. This value is very similar with Dittomer's ratio of 0.13. For Na-, K-, and Mg2+ versus Cl-, their ratios also show a significant relationship between sea water and groundwater in this area. From the chloride-bicarbonate ratio, it can be estimated that the intrusion distance of seawater from coastline to inland area is 2.8km at Onpyung-Nansan, Sangdo and Pyungdae areas, and 5.4㎞ at Kosung-Susan area.
The mixing ratio between seawater and fresh water by the intrusion of seawater is decreased with the distance toward inland from coastline. This ratio(fresh water : seawater) is 80:20 in spring water adjacent the coastlines, Onpyung area and 99.8:0.2 in the well at No.3 of Susan located at inland away from the coastline. The concentration of Na- observed at field is 25∼45% lower than that theoretically calculated by this mixing ratio. Based on the data of EC, the equipotential line of 500μmhos/㎝ is located at 4∼5㎞ point at Kosung-Susan area and 2.5㎞ point at the other area. The equation of correlation between Cl- concentration and EC values is Cl-=0.1927EC-16.683 for the area lower than 500μmhos/㎝ and Cl-=0.2773EC for the area beyond 500 μmhos/㎝.
