JpGU-AGU Joint Meeting 2017

Presentation information

[EJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS09] [EJ] tsunami deposit

Tue. May 23, 2017 9:00 AM - 10:30 AM 201A (International Conference Hall 2F)

convener:Tetsuya Shinozaki(Center for Research in Isotopes and Environmental Dynamics (CRiED), University of Tsukuba), Takashi Chiba(Institute of Seismology and Volcanology, Hokkaido University), Daisuke Ishimura(Department of Geography, Tokyo Metropolitan University), Kazuhisa Goto(International Research Institute of Disaster Science (IRIDeS),Tohoku University), Chairperson:Tetsuya Shinozaki(Center for Research in Isotopes and Environmental Dynamics (CRiED), University of Tsukuba)

10:00 AM - 10:30 AM

[MIS09-05] Features of erosion and sedimentation due to the September 2015 flooding of the Kinu River, central Japan

★Invited papers

*DAN MATSUMOTO1, Yuki Sawai1, Yuichi Namegaya1, Koichiro Tanigawa1, Atsunori Nakamura1, Masaki Yamada2, Tetsuya Shinozaki2, Daisuke Takeda2, Shigehiro Fujino2, Jessica Pilarczyk3 (1.National Institute of Advanced Industrial Science and Technology, 2.University of Tsukuba, 3.The University of Southern Mississippi)

Keywords:Flood deposit, Erosion, Sedimentation, diatom analysis, September 2015 flooding, Kinu River

Fluvial flooding is among the most destructive natural disasters comparable to tsunamis. An accurate identification between flood and tsunami deposits still remains controversial, which complicates appropriate future risk assessments for these disasters. Enhancing descriptive data on modern flood and tsunami deposits is one of the basic approach to the problem. In this study, we describe the patterns of erosional scour and sedimentary deposition generated by the September 2015 flooding of the Kinu River in Joso City, Ibaraki Prefecture, central Japan. During the flooding event, water levels in the Kinu River rose rapidly due to heavy rain that ultimately overtopped, and subsequently breached a levee, causing destructive flooding on the surrounding floodplain. Distinctive erosional features are found near the breached levee, with sandy crevasse-spray deposit distributed adjacent to them. Based on the observation in conjunction with grain-size and diatom analyses, the deposit can be divided into three sedimentary units. The vertical and lateral changes of these sedimentary features might be the result of temporal and spatial changes associated with flow during the single flooding event. These observations and quantitative data provide information that can be used to reveal the palaohydrology of flood deposits in the stratigraphic records, leading to improved mitigation of future flooding disasters.