Abstract

In this study, field surveys along the coasts of Wakayama Prefecture, Japan, were first conducted to investigate the coastal damage due to storm surges and storm-induced waves caused by the 2018 Typhoons Jebi and Trami. Special focus was placed on the characteristic behavior of nearshore waves through investigation of observed data, numerical simulations, and image analysis of video footage recorded on the coasts. The survey results indicated that inundation, wave overtopping, and drift debris caused by violent storm-induced waves were the dominant factors causing coastal damage. Results of numerical simulations showed that heights of storm-induced waves were predominantly greater than storm surge heights along the entire coast of Wakayama in both typhoons. However, computed gradual alongshore variations in wave and surge heights did not explain locally-concentrated inundation and run-up heights observed along the coasts. These results indicate that complex nearshore hydrodynamics induced by local nearshore bathymetry might have played a significant role in inducing such local wave characteristics and the associated coastal damage. Analysis of video footage recorded during Typhoon Jebi, for example, clearly showed evidence of amplified infragravity wave components, which could enhance inundation and wave run-up.

Highlights

  • Tropical cyclone disasters are one of the major natural disasters in the world, as cyclone-induced winds, rain, waves, and surges cause catastrophic damage in urban areas (e.g., Hurricanes Katrina, Sandy, Irma, and Maria, and Typhoon Haiyan) [1,2,3,4,5]

  • Among the collected video footages, this study focused on two videos that clearly captured the behavior of nearshore waves at different sites (Figure 10) and image analyses were conducted to extract quantitative characteristics of the captured nearshore hydrodynamics

  • We investigated damages along the coast of Wakayama, induced by storm surges and storm-induced waves during Typhoons Jebi and Trami, and estimated how waves appeared near the shore and caused damage

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Summary

Introduction

Tropical cyclone disasters are one of the major natural disasters in the world, as cyclone-induced winds, rain, waves, and surges cause catastrophic damage in urban areas (e.g., Hurricanes Katrina, Sandy, Irma, and Maria, and Typhoon Haiyan) [1,2,3,4,5]. Individual damages induced by past tropical cyclones in each region should be thoroughly investigated to understand the mechanisms of damage generation and develop better disaster mitigation plans and strategies for the future. Japan has suffered major disasters induced by storms such as Typhoons Vera, Nancy, and Mireille [8,9,10,11]. Storm surges and storm-induced waves during a typhoon, as well as winds and rain, largely affect the country’s long coastlines. WwakeraeybamasaedPorenfeJacptuarne.MReetdeoaronldogbilcuael Aingdeinccayt,eJMTyAph[1o6o]n. sThJeebyiealnlodwTsrqaumair,esreisnpdeiccatitveetliyd.eTghaeugtyepshtaotoionns paatthKsuwsherime boatose, SdhoirnaJhaapmaan,MGoebteoo,rWolaokgaiycaalmAag, aenndcyK, oJMbeAfr[o1m6].thTehseoyuetlhlo, awndsqtuhaeryeesllionwdictraitaentgildees ginaduigcaete staNtiaotniosnawtidKeuOshciemaontWo,aSvheirinahfoarmmaa,tiGoonbfoo,r WPoarktaaynadmHa,AarnbdorSK(oNbeOWfroPmHAthSe) sstoautitohn, saantdShthioenyoemllioswaki, triKaonmglaestsiunsdhiicmatae, NanadtioKnowbeidferoOmcethane sWouavthe. information for Port and HArborS (NOWPHAS) stations at Shionomisaki, Komatsushima, and Kobe from the south

Damage Caused by Typhoon Jebi
Damage Caused by Typhoon Trami
Comparison of Inundation Characteristics of Jebi and Trami
Analysis of Tide Gauge Records
Image Analysis of Video Footage Recorded at the Coast
Video Footage Recorded at Kushimoto Town
Video Footage Recorded at Yura Town
Findings
Discussion and Conclusions
Full Text
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