INVESTIGATION OF THE INFLUENCE OF URBAN BUILDINGS ON TSUNAMI ARRIVAL TIME IN TSUNAMI INUNDATION SIMULATIONS

Abstract

 In urban tsunami inundation calculations, the influence of buildings is often indirectly considered by assigning roughness values. However, in order to accurately assess the tsunami arrival time and temporal variations in flow velocity at any given location, explicit consideration of buildings is necessary. In this study, we conducted high-resolution tsunami inundation calculations for Osaka Prefecture, explicitly considering buildings using the 3D urban model PLATEAU developed by the Ministry of Land, Infrastructure, Transport and Tourism. We investigated the changes in maximum inundation depth and tsunami arrival time due to the inclusion of buildings. The results showed that in calculations that considered buildings, an increase in maximum inundation depth was observed at 45.5 % of the grid points within the entire inundation area. Furthermore, the tsunami arrival time was earlier at 53.1 % of the grid points within the calculation domain due to the consideration of buildings. These trends were particularly significant in coastal areas and near rivers, which can be attributed to the concentration of overflow flow at grid points without buildings.