Revetments are generally more cost-effective and environmentally friendly compared to sea walls. This is because revetments are designed to absorb and dissipate wave energy rather than reflecting it, as sea walls do. This energy-absorbing design reduces the impact on the surrounding areas and causes less disruption to the natural sediment transport processes. In terms of construction, revetments are often made from more natural materials like rock, rubble, or wooden slats, which can be less expensive and more environmentally harmonious than the concrete typically used in sea walls. Additionally, revetments can be constructed to blend with the natural environment, thereby minimising the visual impact on the landscape. However, it's important to note that while revetments are less intrusive, they may not provide the same level of protection as sea walls, particularly in areas with high-energy wave action.

Breakwaters are often more preferable than sea walls in scenarios where indirect protection of the coastline is needed, particularly for creating calm water zones for harbours, marinas, and beach preservation. Unlike sea walls, which are built directly on the shoreline, breakwaters are constructed offshore and are designed to break the force of incoming waves before they reach the shore. This makes them particularly effective in protecting areas from wave action while preserving the natural appearance of the coastline. Additionally, breakwaters are beneficial in areas where the direct impact of a rigid structure like a sea wall on the shoreline needs to be avoided, either due to environmental concerns or to maintain the natural aesthetics of the beach. They are also preferable in areas with deep water close to the shore, where sea wall construction might be impractical or too costly.

Implementing hard engineering solutions like sea walls, groynes, breakwaters, and revetments can have significant social and economic implications for coastal communities. On the positive side, these structures can protect coastal areas from erosion and flooding, thereby safeguarding homes, businesses, and public infrastructures. This protection can enhance property values and attract tourism, which is economically beneficial. However, the construction and maintenance of these structures can be very costly, often requiring substantial public or private investment. Moreover, their presence can alter the natural appearance and accessibility of the coastline, potentially affecting local livelihoods dependent on tourism and recreation. Socially, there can be a sense of loss among communities as natural beaches and coastlines are replaced with man-made structures. Additionally, the redistribution of erosion and sediment caused by these structures can lead to conflicts between different community groups or neighbouring areas affected differently by these changes.

The long-term sustainability of groynes in coastal management is a concern due to their impact on natural sediment transport processes. Groynes, by design, interrupt the flow of sediment along the coast, leading to accumulation on one side while causing erosion on the other. This can result in a need for continuous maintenance and potential restructuring over time, which is both costly and labour-intensive. Additionally, as the coastal environment is dynamic and constantly changing, the effectiveness of groynes may diminish over time, necessitating further interventions. The interference with natural coastal processes can also have downstream ecological impacts, such as habitat loss and changes in the coastal ecosystem. This raises questions about the long-term viability and environmental sustainability of relying heavily on groynes for coastal management.

Sea walls can significantly impact coastal ecosystems, particularly concerning biodiversity. By altering the natural shoreline dynamics, sea walls can change the habitat conditions. For instance, the hard structure of a sea wall can replace sandy beaches and rocky shores, which are critical habitats for various species. This leads to a loss of biodiversity as species that depend on these natural habitats are displaced. Additionally, the reflection of waves off sea walls can result in increased turbulence in the water, affecting marine organisms' feeding and breeding patterns. The change in sediment transport dynamics can also impact the downstream areas, leading to habitat loss in those regions. Thus, while sea walls are effective in protecting coastal infrastructure, they can significantly disrupt the natural coastal habitats, leading to a decrease in biodiversity.