Abstract
In order to clarify groundwater environment in the Kurobe River alluvial fan (KRAF), the residence time and recharge area were estimated by environmental isotope, dissolved ions and hydraulic conductivity. As a result of principal component analysis using 10 dissolved ions, it was estimated that lower or middle basin of the Kurobe River basin was recharge area. Tritium concentration of groundwater above 87 m depth in the KRAF was 3.0-4.3 TU, which was estimated 35-39 years as residence time. These results were the same as calculated by hydraulic conductivity. A a result, the recharge area was estimated the middle basin of the KRAF from river mouth to 13.4-26.4 km.
