The impact of climate change on coastal erosion in Southeast Asia and the compelling need to establish robust adaptation strategies.

Climate change alters the climate condition and ocean environment, leading to accelerated coastal erosion and a shift in the coastline shape. From previous studies, Southeast Asia's coastal region is suffering from severe coastal erosion. It is most sensitive and vulnerable to climate change, has broad and densely populated coastlines, and is under ecological pressure. Efforts to systematically review these studies are still insufficient despite many studies on the climate change linked to coastal erosion, the correlation between coastal erosion and coastal communities, and the adaptative measures to address these issues and their effectiveness in Southeast Asia. Therefore, by analyzing the existing literature, the purpose of this review was to bridge the knowledge gap and identify the link between climate change and coastal erosion in Southeast Asia in terms of sea-level rise, storm surge, and monsoon patterns. The RepOrting standards for Systematic Evidence Syntheses (ROSES) guided the study protocol, including articles from the Scopus and Dimension databases. There were five main themes considered: 1) climate change impact, 2) contributing factors to coastal erosion, 3) coastal erosion impact on coastal communities, 4) adaptation measure and 5) effectiveness of adaptation measure using thematical analysis. Subsequently, nine sub-themes were produced from the themes. Generally, in Southeast Asia, coastal erosion was reflected by the rising sea level. Throughout reviewing past literature, an interesting result was explored. Storm surges also had the potential to affect coastal erosion due to alterations of the atmospheric system and seasonal monsoon as the result of climate change. Meanwhile, an assessment of current erosion control strategies in relation to the relative hydrodynamic trend was required to avoid the failure of defence structures and the resulting danger to coastal communities. Systematically reviewing the existing literature was critical, hence it could significantly contribute to the body of knowledge. It provides valuable information for interested parties, such as authorities, the public, researchers, and environmentalists, while comprehending existing adaptation practices. This kind of review could strategize adaptation and natural resource management in line with coastal communities' needs, abilities, and capabilities in response to environmental and other change forms.

Environmental impacts of shore revetment.

Coastal structures, especially revetments, have been widely implemented to protect properties and infrastructures from erosive waves during storms. While being incompatible with nature-based solutions, revetments have still been constructed due to their effectiveness in solving coastal erosion. One of the most crucial concerns that should be considered as part of a revetment implementation is how to diminish and manage its possible impacts on the environment. Thus, a thorough understanding of how the revetments affect the surrounding environment must be achieved. This article critically reviews and summarizes their economic considerations, and environmental impacts on beach morphology, hydrodynamics, ecology, aesthetics, beach accessibility, beach recreation, and other notable aspects. Coastal practitioners and researchers, who are involved with the revetments, may increase their environmental awareness before implementing them. The revetments can be an excellent option to protect the eroding shoreline, if their possible environmental consequences are well-understood and properly managed.

Adaptation of coastal defence structure as a mechanism to alleviate coastal erosion in monsoon dominated coast of Peninsular Malaysia.

The complexity of the coastal environment and the advent of climate change cause coastal erosion, which is incontrovertibly a significant concern worldwide, including Peninsular Malaysia, where, the coast is threatened by severe erosion linked to anthropogenic factors and monsoonal wind-driven waves. Consequently, the Malaysian government implemented a mitigation plan using several coastal defence systems to overcome the coastal erosion problem. This study assesses coastal erosion management strategies along a monsoon-dominated coasts by evaluating the efficacy of coastal protection structures against the coast. To this end, we analysed 244 km of the coastline of Terengganu, a federal state located on the east coast of Peninsular Malaysia. Due to a higher frequency of storms and the ensuing inception of high wave energy environments during the northeast monsoon (relative to southwest monsoon), the study area is the most impacted region in Malaysia with regard to coastal erosion. Fifty-five (55) coastal defence structures were detected along the Terengganu coastline. The Digital Shoreline Analysis System (DSAS) was utilised to compute changes in the rate statistics for various historical shoreline positions along the Terengganu coast to assess the efficacy of the defence structures. Additionally, this study acquired the perception of the existing coastal management strategies through an interview session with the concerned stakeholders. The rate statistics revealed the effectiveness and impact of the coastal defence structure on the coastline. Assessing the functionality of the coastal defence structures shed light on the present scenario of coastal erosion management. Greater efficacy and lower impact of coastal defence structures are prescribed for coastal erosion management strategies across the monsoon-dominated coast.

Jeopardizing the environment with beach nourishment.

Beach nourishment is not a permanent solution against beach erosion, as periodic renourishment will be needed to maintain its effectiveness. Numerous publications show that it may potentially affect the entire marine ecosystem, yet it is still being implemented nowadays, and its use is predicted to expand. The environmental impacts of beach nourishment are often underestimated or neglected. Thus, a thorough understanding of how beach nourishment affects the environment is needed to answer the question "Is beach nourishment a less impacting strategy for opposing coastal erosion?". This article compiles key findings from published studies, highlighting how nourishment activities disturb and alter the surrounding environment at both borrow and nourished sites. Present findings highlight the need for coastal practitioners and researchers to prudentially consider the sustainability of beach nourishment as a coastal protection measure, in light of its irreversible deleterious impacts on the environment.

Environmental impact of submerged and emerged breakwaters.

Coastlines are constantly threatened by erosion. Effective coastal defense structures with the least environmental impacts are increasingly required. Submerged and emerged breakwaters have been implemented globally, while positively or negatively creating impacts on the environment. One of the most significant concerns in applying breakwaters is how to minimize their undesirable consequences on the environment. Thus, a thorough understanding of how submerged and emerged breakwaters affect the surrounding environment must be achieved. This article critically reviews and summarizes their environmental impacts on beach morphology, hydrodynamics, ecology, tourism, and recreation, as well as other notable impacts. This is a review article that may help coastal practitioners to manage coastal erosion with breakwaters more sustainably.

Detached breakwaters: communities' preferences for sustainable coastal protection.

Detached breakwaters have been implemented for coastal protection. As society evolves and community livelihood has been acknowledged as an ingredient for sustainable coastal development, the breakwaters must do more than just dissipate wave forces. Using detached breakwaters in Nakhon Si Thammarat province, Thailand as a case study, this research provides empirical proof of such a concept. Interviewing coastal communities who have lived with the breakwaters revealed numerous expectations. Since each community's requirement might be entangled with other functions and incur more costs, coastal engineers had to prioritize preferences. Seven breakwater scenarios were synthesized based on the interview results. For each scenario, the shoreline position was simulated using calibrated LITPACK software, the construction cost was estimated, and a set of illustrations was drawn in order to standardize respondents' perceptions. An analytical hierarchical process (AHP) was applied. The AHP results suggested that the preferred breakwater scenarios were those that promoted the existing ways of life. Other aspects such as construction practice, environmental, and social aspects should also be thoroughly considered.