GROUNDWATER AGE ANALYSIS USING TRITIUM IN GNEISS OF THE SAMKWANG MINEIN KOREA

Travel times of the groundwater in the gneiss near Samkwang mine in Ko rea were estimated through the field hydraulic tests, the development and the application of a mathematical model, and the analysis of triti um concentration of the groundwater sampled in the study positions. Re sults of this study are follows: (1) Through the field hydraulic test, the hydraulic conductivity in the gneiss of the syudied area is 1.7 x 10(-5) x Z(-1.3) m/sec (Z:depth from the surface, (m)) and the longit udinal dispersivity is 9.8 m. (2) The mathematical model to calculate the age of groundwater was developed considering the tritium concentra tions of rainfall precipitated in the studied area for period 1961 - 1 993. (3) The ages of the groundwater in the tunnel 44, 92, 102, and 20 5 m below the earth surface were estimated at 2.0, 4.0, 4.5, and 9.0 y ears, respectively. These results were verified by the data on the tri tium concentrations of the groundwater in the tunnel for period 1990 t o 1993.