ABSTRACT The mountain recharge has highlighted the crucial role of groundwater replenishment in alluvial deposit areas. However, this issue remains understudied in Japan. Yamanashi prefecture, Japan, is a typical mountainous area with considerable potential for mountain groundwater recharge. Herein, the sources of the mountain groundwater recharge were identified by analyzing the ratios of stable isotopes (18O and 2H) and chloride concentration in groundwater samples combined with end-member mixing analysis. The geological model was constructed using a p-wave survey and geological borehole data. The groundwater flow was simulated using the groundwater flow models implemented in COMSOL Multiphysics. Three primary sources of groundwater recharge in the Yamanashi prefecture were identified: mountain front, mountain block, and precipitation/hill-slope run-off recharge. The contribution of each source in different regions was determined as well. The results indicate the effect of geothermal sources on the groundwater basin and chloride concentration in groundwater. The findings reinforce the importance of deep subsurface water storage in sustainable groundwater usage, especially in regions where aquifers are at risk of depletion or contamination. The obtained results can contribute to the development of sustainable policies for the regulation of groundwater use, mountain forest protection, and alleviation of health risks related to drinking water.
Nguyễn et al. (2025) studied this question.