Are submerged and emerged breakwaters efficient on coastal zones?

An article by Saengsupavanich, Ariffin, Yun, and Pereira, summarises and critically reviews beach morphology environmental impacts. The aim of the article is to manage coastal erosion with breakwaters to help coast practitioners to be sustainable in this field. Coastal zones have a value to human services and needs such for tourism, fishery industries, shipping, economic benefits, and protection against floods. The coastal zones are, however, susceptible to climate change as they are vulnerable to storm surges, cyclones, sea-level rise, and flooding. It is not just extreme natural events that are affecting coastal zones but also human-induced actions such as urbanization, land conversion and rapid population growth. Further, the article supports the rapid population growth relating to coastal areas by stating, “Nearly half of the global population currently lives within 200 km of the coast, and the projected statistics show that the population growth could reach 70% by 2025”. Having a vast population living in these coastal areas is a threat and nothing has been done about the safety of the environment and the people. The erosion caused either by human-induced actions or natural events is still affecting human well-being, infrastructures and coastal settlements. There are soft and hard protection measures that are available for coastal planners to choose from. For instance, a soft measure includes non-structural techniques involving vegetation cover, mangrove afforestation and beach nourishment. Alternatively, the hard measures include measures that do form or are implemented naturally such as timber, steel, concrete or rocks. 

A method of protecting or implementing shoreline defence is through emerged or submerged breakwaters. This method can protect the coastlines from risking the lives of coastal communities, local economic activities, and severe storm conditions. The submerged and emerging breakwater have been effective and successful in Japan, Thailand, Indonesia, and Malaysia. Although there have been many success stories, there are quite a few publications that have written negative feedback on submerged and emerged breakwaters. For instance, Saengsupavanich, Ariffin, Yun, and Pereira and have backed up their statement by reviewing  Betzold et al. (2017) argument, “Betzold et al. (2017) argued that hard coastal structures artificially fix the coastline but compromise the ability of beaches to adapt to changing conditions, leading to passive and aggressive ecological consequences. Breakwaters also significantly interrupt nearshore hydrodynamic regimes and sediment transport , affecting surrounding assemblage structures. Some researchers consider breakwaters to be non-adaptive, as they are costly to build and to maintain in response to a changing climate”. Since two sides of the story have been given, it is important to assess whether an emerged and submerged breakwaters are detrimental to the surrounding environment. The article looks into various outputs such as: hydrodynamics, coastal tourism, notable effects, beach morphology, ecology and recreation. This research that is being carried out is to assist coastal practitioners to utilise breakwaters sustainably. 

Submerged breakwaters - are structures that are built in shallow waters and are more prevalent than emerged breakwaters. There is some donut if submerged breakwater is fully understood. 

Economic considerations - is through maintaining beaches and shorelines for economic means (income), the livelihoods who use the coastal environment as a source of living and income.

The beach methodology impact - presents the structural changes of the beach such as erosional changes, sand movement from updrifts and downdrifts as well as coastline changes just to list a few.

Hydrodynamic impacts - this is where water current and wave patterns change the surrounding hydrodynamics which is resulted from submerged breakwaters. 

Ecology Impact - this is where submerged breakwater provides unnatural sheltered habitat to ecology, such as an artificial habitat.

Tourism and recreational impact - submerged breakwaters can be on hand when needed for recreational and tourism purposes. 

The conclusion of the study by Saengsupavanich, Ariffin, Yun, and Pereira, show that breakwater's environmental impacts need to be managed more carefully by coastal stakeholders. There is still a debate on whether submerged and emerged breakwater are effective and reliable as there have been success stories but also criticisms. The aim of the study is to create an awareness to coastal practitioners on ways to reduce environmental disturbances and to manage coastlines sustainably. A method of protecting or implementing shoreline defense is through emerged or submerged breakwaters.