[M-IS10] Mountain Science

[MIS10-09] Surface water and groundwater interaction in mountain systems: results and prospects in the Japanese Northern Alps

★Invited Papers

*Koichi Sakakibara¹, Mayu Fujino², Anji Kanai³, Maki Tsujimura⁴, Keisuke Suzuki¹ (1.Department of Environmental Sciences, Faculty of Science, Shinshu University, 2.Graduate School of Life and Environmental Sciences, University of Tsukuba, 3.Graduate School of Science and Technology, Shinshu University, 4.Faculty of Life and Environmental Sciences, University of Tsukuba)

Keywords:Northern Alps, Surface water and groundwater interaction, Rainfall-runoff process, Water storage

Mountainous areas with large amounts of precipitation and snow cover are regions where various phenomena associated with water transport (e.g., sediment transport, topographic change, and vegetation formation) dynamically occur. Climate change may alter precipitation regimes, such as changes in precipitation amount and snow-rainfall rates. Therefore, rapid environmental shifts related to water transport are likely to occur in mountainous areas; hence, it is important to understand the hydrological cycle in these regions. Surface water and groundwater interaction, i.e., infiltration of surface water into the subsurface area and discharge of groundwater to the ground surface, is one of the most fundamental hydrological processes in hydrology and environmental science. Mountainous areas have large hydraulic gradients due to their steep topography, sedimentary conditions with various grain sizes and characteristics, and a geological structure dominated by fractures. However, it is not fully understood how these conditions affect the surface water and groundwater interaction in mountainous areas.

The presenters have conducted field observations to elucidate the surface water and groundwater interaction in the Northern Alps and its downstream areas. The results have revealed that mountain groundwater plays a role in maintaining the base flow of mountain streams, that the mechanism of peak runoff during precipitation differs depending on whether the basin has exposed base rock or a variety of deposits, and that the existence of soil layers in alpine areas provides a water storage function. In this presentation, we will review the hydrological processes in mountainous areas, and present the results and prospects regarding research on surface water and groundwater interactions in the Japanese Northern Alps.