Concrete is a widely used construction material for coastal and marine infrastructure such as ports, coastal defence structures and waterfronts. In fact, concrete accounts for more than 70% of such infrastructure globally . In this article, we will explore the various aspects of the role of concrete in coastal protection.
The Need for Coastal Protection
Coastal areas are important for a variety of purposes such as tourism, fishing, industry, trade and transport . However, they are also vulnerable to natural phenomena such as storms, waves and flooding. The effects of climate change, including sea level rise, are exacerbating the problem. Hence, it is crucial to protect the coasts and the areas behind them from the harmful effects of these phenomena.
Concrete as a Coastal Protection Material
Concrete is a popular choice for coastal protection structures such as sea walls, revetments, breakwaters and groynes. It is hardwearing and durable and provides excellent protection against waves and flooding . However, it is also susceptible to damage from the corrosive environment of the coast, particularly due to the presence of chloride ions in seawater and the presence of oxygen in zones subject to sea spray and splash .
Best Practices for Using Marine Concrete
To increase the lifespan of coastal defence structures, it is essential to adopt best practices for using marine concrete. The UK government has published guidance on all aspects of design, construction, inspection, monitoring and maintenance to lessen the impact of concrete degrading . The guidance covers issues such as the selection of materials, mix design, placement, curing, protection and repair.
Eco-Friendly Alternatives to Ocean Concrete
The use of concrete in coastal protection has environmental impacts, particularly in terms of its carbon footprint and effects on marine ecosystems. Concrete structures typically support low biological diversity and are dominated by nuisance and invasive species . Therefore, researchers are exploring alternative materials such as eco-concrete, which incorporates recycled materials and promotes the growth of marine organisms .
Coastal Protection Strategies
Various coastal management strategies are employed to protect the coast, each with its own advantages and disadvantages . Coastal protection structures such as sea walls and breakwaters provide direct physical protection, but they can have negative effects on coastal ecosystems and may be costly to construct and maintain. Soft engineering techniques such as beach nourishment and dune restoration are more environmentally friendly, but they may not provide sufficient protection against severe storms and flooding.
Surface Protection of Concrete
To protect concrete structures from damage due to environmental factors such as corrosion and chemical attacks, it is necessary to apply surface protection methods such as coatings, sealers and membranes. These methods can help to reduce the permeability of water/moisture, prevent chemical attacks and improve durability.
Types of Coastal Protection Structures
Coastal protection structures can be classified into different types based on their purpose and design. Sea walls are concrete barriers built along the seafront that deflect waves back to sea and protect the land behind them from flooding . Breakwaters are offshore structures that reduce the energy of incoming waves and protect harbours and other structures . Groynes are wooden or concrete barriers built perpendicular to the shore to prevent longshore drift and accretion . Revetments are sloping structures built along the shore to prevent erosion and protect the coastline .
The Role of the State in Coastal Defence
Over the last century, the State has assumed a more significant role in coastal defence, including coast protection from erosion and permanent occupation of the land by the sea . The primary legislation in the UK for coast protection is the Coast Protection Act 1949 (CPA). The CPA establishes the roles and responsibilities of local authorities, government agencies and other stakeholders in coastal defence.
The Role of Coral Reefs in Shoreline Protection
Coral reefs play an important role in shoreline protection by reducing the energy of waves and promoting the deposition of sediment . Studies have shown that coral reefs can reduce wave energy by up to 97%, depending on the depth and morphology of the reef. Artificial reefs are also being designed for coastal protection, taking into account the local conditions and environmental factors.
Concrete is a crucial material for coastal protection, providing hardwearing and durable structures that protect the coast and the areas behind it from the harmful effects of storms, waves and flooding. Best practices for using marine concrete and eco-friendly alternatives are being explored to reduce its environmental impact. Other coastal protection strategies, such as soft engineering techniques and the role of coral reefs, are also important considerations in coastal defence.