• 7 min de lectura
• 7 min de lectura
“The obvious answer is sea-level rise, but it is broader than that. We are facing increasingly severe storm surges, waves, flooding and erosion, often all at once. On the other hand, natural coastal buffers are under pressure. Ecosystems like dunes, wetlands and mangroves absorb wave energy, trap sediment and provide room for a coastline to respond dynamically. When these systems disappear, or get squeezed between the sea and fixed infrastructure, we lose part of the coast's natural capacity to adapt.“
"Future-proofing is about making sure the coastal protection solution performs safely today, while leaving room to adapt it later."
Vicky Stratigaki
Lead Engineer Project Development and Conceptual Design at Jan De Nul
“The key concept is adaptability. We cannot predict with absolute certainty what the sea level, storm climate or coastal landscape will look like at one particular location several decades from now. Future-proofing therefore does not mean selecting one future scenario. It is about making sure the solution performs safely today, while leaving room to adapt it later. Monitoring is an important part of that. Design, observe, adapt. That principle is key.”
“Take the Prince Hendrik Sand Dike on the Dutch island of Texel. Instead of simply making the existing concrete dike higher and stronger, we placed 5.5 million cubic metres of sand in front of it, creating a new dune landscape and salt marsh. The result is a coastal defence system with two hundred hectares of new nature that works with natural processes: sand, wind and water can continue to shape the landscape, while the dune system protects the island against storms and flooding.”
“It is. But we do not turn this into a discussion of grey versus green. It is a spectrum of solutions, with at one end conventional engineering: dikes, seawalls, breakwaters and storm-surge barriers. They can provide very high and predictable levels of protection and remain indispensable in many locations. Then there are softer measures such as beaches, nourishments and dunes. Further towards the nature-based end of the spectrum are ecosystems like wetlands, salt marshes and mangroves. Increasingly we are working in between, with hybrid solutions that deliberately combine both hard and soft measures. They are different tools in the same toolbox.”
“The most important thing is that we do not start from a technology. We start from the coastal system and the problem that needs to be solved. What level of protection is required? What are the dominant waves, water levels and erosion processes? How much space is available? Is sediment available and can it move through the system? These are some of the questions we need to answer before working towards a solution.”
“Absolutely. Coastal protection does not have to start at the exact line between land and sea. A coastline is influenced by waves, currents and sediment transport across a much larger coastal profile. Intervening offshore or in the nearshore zone can therefore sometimes reduce the wave energy reaching the shoreline or influence the way sediment is transported towards and along the coast. That is one of the reasons why we often incorporate submerged breakwaters or different types of reefs, such as oyster, mussel or coral reefs, into our solutions.”
Vicky Stratigaki, Lead Engineer Project Development and Conceptual Design at Jan De Nul
“Our capabilities at Jan De Nul cover a very wide spectrum: dredging and sediment management, beach nourishment, coastal structures, hydraulic engineering, design and modelling, and increasingly ecosystem restoration and nature-based solutions. That means we do not have to argue that every coastline needs a nature-based solution. Sometimes a storm-surge barrier is the appropriate answer. In another location it may be a beach nourishment. Somewhere else it may be a dune-dike, wetland, reef or mangrove system. And very often the optimum will be a combination.”
“They can combine the reliability of engineering with the ability of natural systems to evolve and adapt. A hard structure can provide a clear safety line. A dune, wetland or other natural component in front of it can interact with waves, currents and sediment and may reduce the loads reaching the engineered structure and contribute to seabed stabilization. At the same time, it can provide habitat, recreation and other ecosystem services. This creates a layered defence rather than relying on a single element. But a hybrid solution does not automatically come with lower costs or is not maintenance-free. It is attractive because you can get several functions out of one coastal system.”
“Yes, but scalability does not mean copying the same design everywhere. You cannot take the dimensions of a dune in Texel and simply reproduce them on another coastline. What you can scale, is the approach. How do we characterise the site? Which processes matter? What data do we need? How do we design, monitor and adapt the solution? That is also the idea behind the blueprint for hybrid dune-dike solutions we created within the project DuneFront : we turn the experience from individual projects into a method that can be used elsewhere, while keeping the actual solution site-specific.”
“Completely maintenance-free coastal protection is probably not realistic, certainly not when people's safety depends on it. But nature can do part of the work for us. Vegetation can trap sand. Dunes can develop and act as a protective buffer. Wetlands and mangroves can capture sediment and evolve over time. A recent example is our AquaForest project. We built a mangrove island from scratch with dredged sediment from the nearby port access channel. The mangrove habitat is now developing towards a self-sustaining ecosystem, with strong tree growth and biodiversity colonisation. But ecological self-sustainability is not the same thing as guaranteeing a coastal protection standard without any future monitoring or management. Zero maintenance is not a realistic objective. The more interesting ambition is to create systems in which natural processes contribute to maintaining and adapting the protection.”
“Exactly. Understanding natural processes. Understanding how water, waves, currents, sediment and ecosystems behave and seeing whether we can use natural processes as part of the solution. A recent project of Jan De Nul in Itapoá, Brazil, illustrates this very clearly. We dredged the access channel to improve navigation and beneficially reused the recovered sand to widen a nine-kilometre stretch of beach, with dunes planted with 300,000 native plants to hold the sand in place. One sediment operation addressed both port accessibility and coastal resilience. That is working with nature: engineering the conditions in such a way that natural processes can start working with you.”
Vicky Stratigaki,
Lead Engineer Project Development and Conceptual Design at Jan De Nul
