[H-GG12] 2015 September heavy rainfall disaster in Kanto and Tohoku area, Japan

[HGG12-P08] Particle size analysis of natural levee deposit and flood sediment around the dike-broken site, Kinugawa River

*Hiroshi, P. Sato¹ (1.College of Humanities and Sciences, Nihon University)

Keywords:Flood, Natural levee, Sediment

The flood on 10 Sep 2015 broke the dike in Kinugawa River, and the protected inland was covered with huge amount of flood sediment. The inland locates on natural levee, field survey revealed that natural levee deposit is finer than this flood sediment in particle size. I sampled both deposit and sediment, which were sieved and diveded at one-phi interval from -2 phi to less than 4 phi. As a result, it was found that fine sand of 4 phi notablly exists in natural levee deposit, but medium sand of 2-3 phi notablly exists in this flood sediments. This infers that contribution of scouring of natural levee is quite low for supplying this flood sediment. This study was supported by Promotion Grant of Special Study, Grant-in-aid Scientific Research (Grant number: 15H06923; Principal Researcher: Prof. Shigenobu Tanaka, Kyoto Univ).