[A-OS14] Continental Oceanic Mutual Interaction - Planetary Scale Material Circulationn

[AOS14-11] Hydrogeological modeling and regional groundwater flow and heat transport analysis of the Kyoto Basin

*Shun Yamamoto¹, Koki Kashiwaya², Yoshiaki Kawashima², Katsuaki Koike², Youhei Uchida³, Yosuke Alexandre Yamashiki¹ (1.Graduate School of Advanced Integrated Studies in Human Survivability Kyoto University, 2.Graduate School of Engineering, Kyoto University, 3.National Institute of Advanced Industrial Science and Technology (AIST))

Keywords:groundwater flow analysis, heat transport analysis

Groundwater is the most abundant freshwater resource outside of ice and snow, and its quality is more stable than surface water. It is expected to become even more important in the future as climate change alters precipitation patterns and potentially destabilizes the amount of available surface water. Understanding groundwater flow is important for sustainable groundwater use, as it is essential to counteract declining groundwater levels and water pollution. In addition, geothermal heat is a renewable energy source that can be used regardless of weather or region. Geothermal air conditioning systems are expected to mitigate the heat island effect and save energy as a countermeasure against global warming, since there is no heat emitted into the atmosphere. When implementing geothermal systems, efficient system design can be achieved by considering local groundwater flow conditions.
To accurately determine groundwater flow conditions, it is necessary to construct a model that adequately represents the hydraulic properties. However, geological and groundwater information in deep areas is limited compared to shallow areas, which poses a challenge in creating a comprehensive groundwater flow model that covers a wide area and includes deep areas. In addition, when marine clay layers are distributed in alluvial plains and basins, it is important to model the distribution of marine clay layers as a structure that regulates groundwater flow.
In this study, the Kyoto Basin, where the Osaka Group marine clay layers (Ma) are distributed deep underground, was used as a model site to construct a hydrogeological model of the entire groundwater basin, including the deep part, and to understand the groundwater flow conditions. A hydrogeologic model was constructed from the surface to the depth of the basement by applying geostatistics into its geologic information obtained from multiple boreholes and reflection seismic surveys. Numerical simulations using this model are used to estimate groundwater flow conditions throughout the Kyoto Basin, including the deeper layers.