河道の水理

[II-170] Evaluation method of river improvement in a gravel bed river in case study on the Nenotani River

〇Hidekazu Nagai¹, Tatsuhiko Uchida¹, Yoshihisa Kawahara¹, Humiya Yagi², Mitsutaka Nakano³ (1.Hiroshima university,Civil and Environmental engineering, 2.Tokyo Construction Consultant, 3.Ministry of Land, Infrastructure, Transport and Tourism)

Keywords:flood analysis, river improvement , gravel bed river , Quantitative evaluation method, Qualitative evaluation method

At the Nenotani River in the Ota River basin, the maximum discharge was recorded during the heavy rainfall of H26.8, causing heavy damage. Although the channel development had been improved after the flood, the revetment was damaged again during the heavy rain at 2018.7 In this study, two floods caused by the heavy rainfalls at 2014.8 and heavy rainfall 2018.7 were analyzed using the river channel before and after the river improvement by BVC method. In addition, the effect of river improvement was evaluated quantitatively and qualitatively with water levels and turbulence energy distribution. The methods showed the ability to examine the effect of river improvement quantitatively and qualitatively.