Evaluation of hydrochemical characteristics and hydraulic connectivity using fluorescent mineral tracer test in karst region of Samcheok, Korea

초록

Karst hydrogeology is one of the challenging fields in which hydrochemistry and hydraulic connectivity are difficult to understand due to complex flow processes. This study attempts to unveil not only the hydrochemical characteristics of cave, stream water and groundwater but also hydraulic connection through sinkholes and caves in a karst region of Korea. In most cases, the ratio of Ca2+ and HCO3- is high because the dissolution of carbonate rocks. However, the concentration of Ca2+ and HCO3- are lower than stream water and cave water. It is presumed to be affected by surface geology in the case of shallow groundwater, which affects stream and cave waters, and metamorphic rocks existing in unconformity in the case of deep groundwater. Furthermore, a newly proposed tracer test confirmed the hydraulic connectivity in an area where sinkholes, where well and surface water do not exist, are distributed. The injected fluorescent tracer was found around 903 m below a cave by a distance from the injection point. The tracer crossed the watershed and reached in a short time. It was possible to estimate the flow rate of 0.8-9 cm/s during transport. This study effectively understands hydrochemical and estimates the groundwater flow velocity in a karst environment using a fluorescent tracer test.

키워드