Relationship between deposited sediment depth and damaged level of houses due to debris flows

Abstract

Information about damages on houses due to debris flow is one of key information to plan early-warning strategies and to predict magnitude of disasters. However, most of these information was based on the field survey in 1980s and early 1990s. So, we consider that updated information should be necessary to improve strategy of countermeasures against debris flow. Here we surveyed damaged level of houses and deposited sediment depths around these houses for 34 debris flow events occurred in 2009-2018. We surveyed more than 800 damaged houses. We classified these houses into 8 levels in terms of damaged level. We quantified relationship between deposited sediment depth and damaged level of houses. Moreover, we found that effects of catchment topography, such as drainage area and riverbed gradient, were not clear. On the other hand, peak rainfall intensity gave a large impact on relationship between deposited sediment depth and damaged level of houses.