2002 Volume 32 Issue 4 Pages 135-147
In this study, we estimated the mean recharge altitudes of springs and hot springs on the southeast slope of Mt. Ontake, Japan. Water samples were collected from precipitation, springs, hot springs and ponds, and were analyzed on the oxygen and hydrogen stable isotopic ratios. The altitude effects of the precipitation of δD and δ18O were calculated at－0.95 ‰/100 m and －0.14 ‰/100 m, respectively. The altitude effects of springs of δD and δ18O were calculated at －0.97 ‰/100 m and －0.13 ‰/100 m, respectively. Considering that these results were consistent, it was concluded that the ratio of evaporation to precipitations didn’t change from the base to the top of the southeast slope. The estimated ratio of evaporation to precipitation was about 10 % under condition of annual mean temperature. Using the recharge-water line, mean recharge altitudes of springs and hot springs were estimated. Each mean recharge altitude of the three springs is estimated nearby its discharge altitude. By contrast, each mean recharge altitude of hot springs is higher than its screen altitude.
