Collapse of a Coastal Revetment Due to the Combined Effect of Anthropogenic and Natural Disturbances

Abstract

Coastal structures, such as revetments, are built to protect specific areas and facilities from the attack of extreme waves. However, unexpected environmental damage could be induced from these structures when inappropriately applied. Here, we present the results of measurements carried out using a video monitoring system, indicating the rapid collapse of a coastal revetment due to the attack of storm waves. The destruction occurred in sequence; that is, it was initiated by human activities, followed by a natural disaster. First, the beach in front of the revetment was eroded, even under moderate wave conditions, because sediments transported into this area were blocked by a rip-rap jetty. After the beach width was severely reduced due to the erosion, the revetment collapsed when storm waves attacked the area. The destruction seems accidental and inevitable because it was directly caused by the storm. However, it could have been avoided by predicting and preventing the erosion due to the jetty. This study provides insights into sequential processes that lead to the failure of coastal revetments, which could be applied for prevention of similar anthropogenic disasters.

Monitoring of Recovery Process at Yeongildae Beach, South Korea, Using a Video System

“…However, large storms can cause rapid erosion locally, from which recovery may take many years or even decades if the impacts are sufficiently large [10]. In extreme cases, the damage can be irreversible if the coastal structures that are built to protect the shore are destroyed by the storms [11].…”

Numerical Simulation of the Locality of Erosional Damages by Storm Waves in Searching for Measures to Conserve Bonggil Beach, Korea

“…Although recommended, it is noted that Case 3 is still not be a perfect protection plan for the beach as it could still cause dune erosion in the southern part of the beach. Considering previous studies, hard structures might increase coastal variability and could worsen erosion ( van Rijn, 2011;Do et al, 2021a). Therefore, measures that could conserve the equilibrium condition should be more desirable in preventing unexpected side effects.…”

“…The reason for the increasing threat on the coasts by erosion may be found from the natural factors such as climate change (Zhang et al, 2004;Masselink and Russell, 2013;Mentaschi et al, 2018) and from the anthropogenic factors such as coastal structures (Syvitski et al, 2005; van Rijn, 2011;Anthony et al, 2015). For example, episodic events of severe coastal erosion would increase when the intensity of storms increases due to the warming of sea surface (Bender et al, 2010;Knutson et al, 2010), and when the equilibrium within a coastal cell could be broken by construction of coastal structures (Do et al, 2021a). Because climate change is an ongoing process and will continue unless robust actions are taken globally, and also because various engineering structures will continue to be built as the coastal communities grow worldwide, the problem of erosion may remain as a significant issue not only at present but also in the future for probably a considerable time.…”

“…However, under specific conditions such as extraordinary storm waves, the damage on the shore could be too severe so that the recovery process may take a long time of years or even decades (Forbes et al, 2004) because the high wave power under these storms could carry the sediments to the areas where the waves and currents could not affect the sediment motion under normal wave conditions (Do et al, 2019). Sometimes, the damage could hardly be recovered when the coastal structures built to protect the shore were broken (Do et al, 2021a). In order to prevent unexpected damage and to find proper protection plans for beaches of economic and cultural values, therefore, it is important to accurately predict the processes under extreme conditions, considering that the intensity and frequency of major storms may increase in the coming years due to climae change (Bender et al, 2010;Knutson et al, 2010).…”

Successful Coastal Protection by Step Concrete Revetments in Thailand

“…Every country that has experienced coastal erosion is still implementing the revetment, implying that the revetment has the greater good. Differently implementing a revetment project can have different outcomes [14]. Stakeholder participation is another important component of successful revetment implementation.…”