A Study on the analysis of groundwater flow using thermal and hydrochemical data of groundwater and surface water in the karst area of Samcheok, Korea

In this study, a study on groundwater flow analysis was conducted using hydrochemical and thermal data to find out the flow of groundwater and pollutant behavior in the karst area and to secure countermeasures for problems related to water quality and water resource stability. The flow characteristics were identified using the study area's overall topographic slope and groundwater map. It is more vulnerable to groundwater pollution because it belongs to the discharge stand where groundwater from the west is discharged into the sea. The vertical hydraulic gradient was measured to confirm the direction of recharge and discharge of groundwater and surface water, and it can be seen that the inflow and outflow of groundwater-surface water is active. In both Gyogokcheon (Gyogok-ri) and Sohancheon (Hamaengbang-ri), the recharge of groundwater tends to be more dominant, and in the case of Sohancheon located in Hamangbang-ri, the recharge of groundwater in summer and winter was more active than in spring and fall. In addition, the residence time of groundwater and the recharge and mixing of surface water according to the flow of groundwater and the behavior of pollutants were analyzed using hydrochemical data. There was a distinct difference in radon concentration values between Gyogokcheon (gneiss-based rock) and Sohancheon (limestone-based rock). In the case of Hamaengbang-ri, radon concentration values were not significantly divided according to surface water, groundwater-surface water mixing section (hyporheic zone), and cave water. In the case of Gyogok-ri, radon concentration was used as one of the indicators to estimate the mixing ratio of groundwater and surface water in the hyporheic zone. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant numbers 2019R1I1A2A01057002 and 2019R1A6A1A03033167). This subject is supported by Korea Ministry of Environment as "The SS(Surface Soil conservation and management) projects; 2019002820004.