Study on driftwood accumulation at bridge and prevention of bank erosion at the time of torrential rain

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K16311
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster / Disaster prevention science
• Research Institution: Kyoto University
• Principal Investigator: OKAMOTO TAKAAKI 京都大学, 工学研究科社会基盤工学専攻, 助教 (70599612)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 橋梁閉塞 / 迂回氾濫流 / 家屋破壊 / 流木 / 河岸浸食

Outline of Final Research Achievements

Large driftwood accumulates at a bridge and blocks the river, which leads to a decreased discharge capacity and increased water levels. In Uji city in August 2012, the detour flood-flow occurred around the bridge and the house along Shizugawa River was washed away. However, there is almost no detailed information about flood discharge of a detour flow around a bridge and flood damage area in a blocked river.
In this study, four kinds of flume experiments were performed. First, we conducted the driftwood accumulation tests at the model bridge to evaluate the blockage ratio of driftwood blocking. Second, we measured the flood-flow velocity in the blocked river by PIV to estimate the flood discharge on floodplains. Third, the drag force exerted on the model house on floodplain was measured using Force gauge to examine the flood damage of the nearby area. Finally, the bank erosion experiment was performed to investigate the erosion area around the bridge.

Free Research Field

防災水工学