SUBGRID SCALE MODELING OF STORM SURGE INUNDATION IN COASTAL URBAN AREA CONSIDERING VOLUME OF BUILDINGS

The increasing intensity of typhoons associated with climate change is projected leading to a higher risk of coastal inundation in Japan’s three major metropolitan areas. Therefore, assessing the long-term risk of the coastal urban flooding and its impact on human lives and assets has become a significant challenge in Japan’s coastal hazard mitigation. Therefore, it is essential to understand the fluid dynamic characteristics during inundation using numerical models. In recent years, numerical modeling has been performed using high-resolution topography data of less than 10 m resolving buildings (e.g., Takagi et al., 2016). However, inundation simulations at resolutions of O(10) to O(100) m are still important from a computational load perspective. Fukui et al. (2022) have developed an urban inundation model using a subgrid model of iDFM (individual Drag Force Model) to represent buildings within grid cells and provide feedback on the drag force of building groups to the fluid flow. They conducted flood simulations at resolutions ranging from 20 m to 50 m. However, addressing the consideration of building volumes in the mass conservation equation remains a challenge, which is the aim of this study.