Effect of bed roughness on tsunami bore propagation and overtopping

Journal article (2020)

Authors

Miguel Esteban Waseda University
Kotaro Iimura Waseda University
Bas Hofland Hydraulic Structures and Flood Risk - CEG
J.D. Bricker Hydraulic Structures and Flood Risk - CEG
Hidenori Ishii Waseda University
Go Hamano Waseda University
Tomoyuki Takabatake Waseda University
Tomoya Shibayama Waseda University
Research Group
Hydraulic Structures and Flood Risk (CEG) (TU Delft)
Copyright: © 2020 Miguel Esteban, Jochem Jan Roubos, Kotaro Iimura, Jorrit Thomas Salet, Bas Hofland, J.D. Bricker, Hidenori Ishii, Go Hamano, Tomoyuki Takabatake, Tomoya Shibayama
DOI
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https://doi.org/10.1016/j.coastaleng.2019.103539
Evacuation Dykes Dam break Tsunami overtopping
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Published Date

2020

Language

English

Reuse Rights

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Faculty

Civil Engineering & Geosciences

Department

Hydraulic Engineering

Research Group

Hydraulic Structures and Flood Risk

Abstract

The accurate modelling of overtopping of coastal defences by tsunami waves is of vital importance for the formulation of disaster management strategies. To improve knowledge of this phenomena the authors conducted experiments on coastal structure overtopping using bores that were generated by a dam-break mechanism. Three types of structures were tested, namely a coastal dyke, a wall, and a wall of infinite height. The results highlight the necessity to consider the energy present in a bore to determine if a structure will be overtopped or not. As a result of these experiments an empirical formula to determine the height of overtopping given the incident bore height and velocity was validated. The study highlights the importance of clearly modelling the velocity and Froude number of a tsunami. Such experiments should be conducted on rough beds, for which a suitable Manning's n seems to be around 0.06 sm-1/3. The study also contrasted the results obtained to those of the ASCE7 method, and concludes that the Manning's n values recommended in ASCE7 are probably too low.