[A-HW23] Tracer Hydrology: Advances in Measurement and Modelling

[AHW23-02] Mt. Fuji’s Watershed Under the Lens: Advancing 3D Hydrogeological Models for Climate Resilience

*Stephanie Lisa Musy¹, Horst Dresmann¹, Yasuhiro Tawara², Yama Tomonaga^1,3, Yuji Sano⁵, Oliver S. Schilling^1,4 (1.Hydrogeology, Department of Environmental Sciences, University of Basel, Basel, Switzerland, 2.Geosphere Environmental Technology Corporation, Tokyo, Japan, 3.Entracers GmbH, Duebendorf, Switzerland, 4.Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, Switzerland , 5.Center for Advanced Marine Core Research, Kochi University)

Keywords:Numerical Model, Fujisan, Hydrogeology, Tracers

Mount Fuji in Japan is a very important watershed that is home to millions of people who rely on its groundwater for drinking water, agriculture, and industry. The region is particularly known for producing tea, wasabi, and sake, and its groundwater is globally recognized for its high Vanadium content. However, increasing industrial and agricultural activities, coupled with over-extraction driven by rising domestic and tourism demand, have resulted in concerns about both groundwater quality and availability. These anthropogenic pressures, combined with the accelerating impacts of climate change, underscore the urgent need to better understand the origin, flow paths, and residence times of groundwater and integrative manage water at the scale of the entire catchment.

Here, an updated framework for constructing high-resolution 3D geological and integrated hydro(geo)logical models of volcanic aquifer systems, on the example of Mt. Fuji watershed, is presented. The region’s complex subsurface, shaped by successive lava flows and tectonic activity, has been systematically classified into hydrogeologically relevant hydrofacies using lithographic, stratigraphic, and borehole data. We demonstrate how the framework enables the integration of these hydrofacies into state-of-the-art Integrated Surface–Subsurface Hydrological Models (ISSHM), providing a seamless representation of surface water-groundwater flow dynamics.

The resulting model and framework will be openly accessible to support sustainable groundwater management planning and hydrological climate change projection simulations using the latest IPCC climate change scenarios, offering a valuable tool for sustainable groundwater management. With increasing anthropogenic pressures and climate variability, understanding and modeling complex underground volcanic environments, which are particularly vulnerable and for which Mount Fuji represents an internationally recognizable example, is essential for long-term water security, risk assessment, and climate resilience.