Studies on Isotope Hydrology of Korea

Abstract

An environmental isotope investigation of the groundwater stored in the shallow alluvium and underlying crystalline rock aquifer, and of the interaction between surface water and groundwater has been undertaken in the karst area of the Han River Valley. The data collected during this study have confirmed that groundwater in the metropolitan area is recharged by the river water and that the groundwater in the non-urbanized region of the Valley is replenished by infiltrating precipitation. Additionally proven has been the fact that the crystalline rock aquifers which occur as geologic structure such as faults, fracture zone and other forms of secondary porosity are recharged by the shallow groundwater from overlying unconsolidated alluvial deposits. The survey on karst area has shown that the groundwater which fills wells installed in limestone is of the same origin as the stream water. This indicates that water flowing in the stream channel is percolating through or onto solution with the limestone, forming a type of groundwater. This groundwater then appears further downstream as a spring. Isotope analysis of the groundwater at Cheju Island has proven helpful in interpreting the general hydrologic and hydrogeologic relations and in developing a model of the groundwater flow system in the permeable volcanic rocks of the island. The groundwaters uribium and stable isotope (D-18O) level provided a basis for modelling the groundwater flow regime.