INVESTIGATION ON THE FLOW OF GROUNDWATER AROUND KAORE DAM AND KAORE-ANBU DAM AT THE TIME OF INITIAL FILLING BY USING WATER QUALITY AND ISOTOPES

Abstract

In order to evaluate the permeability of bedrock in the area of Kaore Dam and Kaore-anbu Dam, the quality of groundwater and the behavior of isotopes around the dams were investigated at the time of initial filling. The travel time of the groundwater to move from the reservoir to the boreholes in the inspection gallery of Kaore Dam, obtained from the change of ion concentration, was as long as 7 to 20months. This result indicated that the permeability of the base rock of the dam was sufficiently improved by grouting. Also, the result of multivariate analysis using isotopic data showed the arrival of the reservoir water to the temporary drain tunnel. It was suggested that electric conductivity and nitrate that can be measured in the field were effective as indicators of the arrival of the reservoir water.