Numerical experiments on effect of river mouth morphology on tsunami behavior in rivers

Yuta Mitobe, Hitoshi Tanaka, Kazuya Watanabe, Neetu Tiwari, Yasunori Watanabe

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

In the 2011 Tohoku Earthquake Tsunami, run-up of the tsunami along rivers expanded the damaged area into more inland areas far from the coast. High water level in rivers was kept for more than several times of the wave period in the 2011 event, while more simple periodical oscillations of the water level superposed on the tidal motion was observed in the 2010 Chile Tsunami event. The difference of behaviors of tsunami in rivers was discussed with related to the magnitude of tsunami and river mouth morphology through two numerical experiments in this paper. In the first numerical experiments, the run-up of historical tsunamis was simulated along Kitakami River. It was found that the discharge of tsunami flow across the river mouth was proportional to third power of water depth if overflow of the sand spit occurred, and that caused unbalance of water volume coming into and going out from the river channel. Through the second numerical experiment with simple model bathymetry and sinusoidal waves, it was found that discharge during both tsunami run-up and run-down across river mouths is reduced by sand spits at the river mouths and the reduction effect is more significant during flow rushing into the rivers than that during return flow.

Original languageEnglish
Pages (from-to)516-531
Number of pages16
JournalCoastal Engineering Journal
Volume60
Issue number4
DOIs
Publication statusPublished - 2018 Oct 2

Keywords

  • Tsunami run-up in rivers
  • breaching of embankment
  • movable-bed
  • sand spit
  • shallow water equation

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Modelling and Simulation
  • Ocean Engineering

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