지하수관측망 자료를 이용한 밀양시 지하수 수질특성 및 해수침투 가능성 규명

Abstract

The characteristics of groundwater quality and the possibility of sea water intrusion around Miryang area were evaluated from data analyses of 31 local groundwater monitoring wells in Miryang county, Korea. Major cation and anion concentrations including TDS and EC in each well were measured two times per year from 2015 to 2016. The vertical EC logging for five monitoring wells, at which the sea water intrusion was doubted, were additionally performed. TDS, Cl- concentration, the Cl-/HCO3- mole ratio, and Cl-/NO3- concentration ratio were compared for 31 monitoring wells to identify the sea water intrusion and the artificial pollution for groundwater in Miryang area. From the water quality analyses of monitoring wells, groundwater in Miryang were divided into two groups: the first group was affected by the sea water intrusion and the second group was represented as fresh groundwater. Results of data analysis for TDS, Cl- concentration, the Cl-/HCO3- mole ratio, the Cl-/NO3- concentration ratio, and EC logging data showed that five monitoring wells (OB-3, OB-6, OB-9, OB-11 and OB-20) in Miryang county were considered to be in the first group, which were affected by the sea water intrusion from Miryang river and Nakdong river. The Cl- and Na+ concentration og the first group have increased for 2 years but its NO3- concentrations were lower than those of the second group. The EC logging data showed that the increase pattern of EC value was similar to those of monitoring wells in Kyoungnam province, which were identified as the sea water intruded groundwater. From the study, five wells in Miryang county, located in Sangnam, Hanam and Samrangjin area, were considered to be affected by sea water intrusion even though the Nakdong river estuary dam has prevented a counter flow of the sea water from the ocran due to the tidal effect.