STUDY ON BUILDING DAMAGE IN THE NARROW SECTION OF THE KUMA RIVER DUE TO HEAVY RAINFALL IN JULY, 2020 USING A COUPLED METHOD FOR RIVER AND FLOODING FLOW ANALYSIS

Abstract

 Heavy rainfall in July 2020 caused flood inundation and significant damage to many buildings in the upstream and middle basin of the Kuma River. There have been a lot of field research on the upstream area of the Kuma River, but very few on the middle area. This study aims to clarify the damage conditions of various type of buildings due to flood flows in the middle area in which the stenosis is located. The Hy2-3D model with a building sub-grid model to evaluate the hydrodynamic forces on each building was applied to the numerical simulation for river and flood flows in this area. The results showed that the velocity and inundation depth for most of the lost buildings exceeded the washout criteria. There was a statistically significant difference in these hydraulic variables between lost and no-lost buildings. These highlight the need to consider both hydraulic and structural factors in assessing building vulnerability.