2018 Volume 60 Issue 2 Pages 205-221
Highly - turbid water had been observed from the beginning of May 2015 due to a huge landslide event in the Tedori River Basin, Ishikawa Prefecture. The significant decrease of the groundwater level during the irrigation period near the river was also observed. To investigate impacts of quantitative changes of the river water - groundwater interaction on the shallow groundwater, we conducted hydrological data analysis and regular field observations of stable isotopes. Hydrological data showed the groundwater recharge from the river decreased due to low river discharge. It was clarified that the reduction of groundwater recharge from the river increased the contributions of groundwater recharge from the paddy fields to the groundwater along the left bank and the middle stream area of the river. Our analysis revealed that decrements of groundwater recharge from both the river and paddy fields caused large groundwater drawdown at the right bank area.
