[A-OS15] Waves, Storm Surges, and Related Hazards

[AOS15-P02] Numerical Modeling of Storm Surge Inundation by Typhoon Haiyan Using Subgrid-scale Building Information

*Nobuki Fukui¹, Nobuhito Mori², Sooyoul Kim³, Tomoya Shimura², Takuya Miyashita² (1.Graduate School of Engineering, Kyoto University, 2.Disaster Prevention Research Institute, Kyoto University, 3.Kumamoto University)

Storm surge is one of the coastal disasters with devastating damage and it is important to understand the inundation risk in coastal urban areas based on numerical modeling. Although numerical simulation directly considering the buildings as topography is possible, it is difficult to employ such simulation in terms of computational cost because inundation risk analyses need huge number of ensemble simulations. The authors developed the subgrid-scale model, individual drag force model (iDFM), expressing multiple building existence in a coarser computational grid cell using total sum of drag force on buildings. The hindcast of storm surge inundation targeting typhoon HAIYAN (2013) was conducted based on the 2D shallow water models and the iDFM. Furthermore, the wind drag coefficient is changed according to building submergence to consider the wind speed reduction by buildings. The sensitivity analysis of wind drag coefficient showed more than 40% smaller inundation depth and velocity near limit of inundation than when the wind speed reduction was not considered. In addition, the validation of the iDFM using the post survey results showed that the reproducibility of inundated area was improved compared to conventional roughness model.