As climate change accelerates and sea levels rise, coastal regions face unprecedented threats. Traditional methods of coastal protection are evolving to meet the challenges of the 21st century. Enter the dune-dike solution: a hybrid, nature-based approach that combines natural dunes with man-made dikes to offer resilient, adaptable, and sustainable coastal protection. This method is gaining traction across Europe where the need for long-term, adaptable coastal defense strategies is paramount. DuneFront, a newly launched European research project, is leading the way to expand the use of nature-based coastal protection across Europe and beyond.
Aerial view on the dune-dike system at Raversijde (Belgium) (Photo: Glenn Strypsteen)
Rethinking coastal protection in the age of climate change
Traditional coastal protection systems — such as concrete seawalls and dikes — are increasingly proving inadequate against the growing threat posed by climate change. Rising sea levels, more intense storms, and accelerated coastal erosion demand new, adaptive solutions. One such innovation is the dune-dike solution, a hybrid system that pairs the natural buffering capacity of sand dunes with the strength of engineered dikes.
This approach offers an adaptable and sustainable means of coastal protection, allowing nature to play a key role in shielding coastlines from extreme weather while also supporting local ecosystems. Across Europe, regions vulnerable to the impacts of sea-level rise are adopting these nature-based solutions, recognizing that they offer long-term protection with fewer environmental downsides than traditional hard infrastructure.
How do dune-dike solutions work?
The principle behind dune-dike systems is simple yet effective. Natural dunes act as the first line of defense, absorbing the energy from storm surges and high water levels and waves. Behind these dunes, already existing engineered dikes provide additional protection, ensuring that even during extreme weather events, inland areas remain safe. This two-tiered approach maximizes resilience, leveraging the strengths of both nature and human engineering.
Moreover, these systems are designed to be self-sustaining. Dunes can develop when vegetation captures the wind-blown sands. This vegetation not only keeps the sand in the system by preventing erosion, but it also ensures an efficient, natural regeneration after storm surge impacts. Over time, these natural processes enhance the dunes' ability to protect the coast. This reduces the need for constant maintenance and repairs, unlike conventional dikes, which often require costly investments and upgrades as sea levels rise.
Expanding the use of dune-dike systems across Europe
While coastal nations like the Netherlands have long been pioneers in coastal defense, the dune-dike solution is now gaining traction in many parts of Europe. The Netherlands, but als countries like Sweden, Denmark, Germany, Belgium, France, and Portugal are exploring this hybrid approach, applying it to vulnerable coastal zones that are increasingly at risk from rising seas.
Dune-dike systems along the Belgian coast
While coastal nations like the Netherlands have long been pioneers in coastal protection, the 'dune-dike' solution is now gaining popularity in other parts of Europe. Countries such as Sweden, Denmark, Germany, Belgium, France, and Portugal are exploring this hybrid approach for vulnerable coastal areas that are increasingly at risk due to rising sea levels.
Along the Belgian coast, several dune-dike pilot projects are already underway. The Agency for Maritime and Coast Services (MDK), in collaboration with the city of Ostend, began constructing such a project in Raversijde in spring 2021. Spanning 750 meters, MDK planted various zones of brushwood hedges and marram grass in front of the dike, each with a different arrangement (see cover image).
Using highly sensitive measuring equipment, researchers can assess how well the dune strip captures sand and determine the optimal construction methods for such dunes. These dunes help prevent blowing sand from settling on roads and tram tracks. Insights gained from monitoring dune growth and construction will also enhance coastal protection against sea storm surges.
A little further along the beach stands a concrete structure: an artificial test dike measuring 20 by 20 metres. From this ‘Raversijde research dike’, scientists can study the impact of waves during a simulated extreme storm event. The ultimate goal is to better understand how severe storms affect coastal defences, making Flanders’ coastal protection even more effective and secure. The research dike was developed from a conceptual idea by Ghent University. MDK, in collaboration with Jan De Nul, was responsible for its construction and equipped it with monitoring instruments. Ghent University and the Hydraulic Engineering Laboratory analyse the collected data to gain further insight into wave overtopping and wave forces.
Together with the ‘dune-dike’ pilot project, the research dike forms part of the ‘Living Lab Raversijde’, established by MDK in partnership with the Hydraulic Engineering Laboratory and VLIZ.
The Research Dyke on the Beach of Raversijde (Agency for Maritime Services and Coastal Affairs)
Another pilot project is underway in Middelkerke-Westende. Middelkerke's sea dike is the longest on the Belgian coast and susceptible to damage during heavy storms. In partnership with the municipality of Middelkerke, MDK pursued a solution that balances coastal protection with enhancing coastal experiences. Rather than traditional hard renovations involving concrete and other rigid structures, they opted for a green grass dike in residential areas and a wave-damping structure in central zones. This approach not only enhances coastal safety and climate resilience but also creates space for walking, cycling, and leisure activities along the sea dike.
Environmental and economic benefits
One of the standout advantages of dune-dike systems is their ability to protect both people and nature. By preserving and enhancing natural landscapes, these solutions contribute to the restoration of highly threatened habitats and species, while maintaining and reinforcing the aesthetic and recreational value of coastlines. This is particularly important in tourist-dependent regions, where beaches and dunes are integral to the local economy.
In addition, the long-term economic benefits are significant. Traditional sea walls and concrete dikes require substantial investment for construction and ongoing maintenance. Dune-dike systems, in contrast, rely on natural processes to renew and stabilize themselves, making them possibly more cost-effective over time. This economic advantage is becoming increasingly attractive to policymakers across Europe, especially as governments face the challenge of financing large-scale climate adaptation projects.
Adapting to a future of rising seas
As climate models project a future of rising seas and more frequent storm events, European countries are looking for coastal protection systems that are not only robust but adaptable. The dune-dike solution provides a flexible response to an uncertain future. While dikes can be raised incrementally as needed, dunes offer a natural buffer that can evolve in tandem with changing environmental conditions.
This flexibility makes dune-dike systems an ideal choice for countries with long coastlines, where the scale and scope of protection require a solution that can be fine-tuned over decades. By working with nature, rather than against it, these nature-based systems are helping Europe stay ahead in the race to protect its shores from climate-related threats.
DuneFront: a European research project leading the way
One of the most exciting developments in the field of coastal protection is the launch of DuneFront, a collaborative European research project aimed at advancing the science and implementation of dune-dike solutions. Funded by the Horizon Europe program, DuneFront brings together experts from leading European research institutes. Together, they will test and refine these hybrid systems in real-world conditions.
DuneFront’s Project Leader, Prof. Dr. Dries Bonte (Ghent University, Belgium): “The project's goal is to develop new models and strategies for integrating natural and engineered measures, focusing on creating resilient coastlines that can adapt to sea-level rise while enhancing local biodiversity. By experimenting with innovative designs and materials, DuneFront hopes to expand the use of nature-based coastal protection across Europe and beyond.”
DuneFront gathers and evaluates data from 12 different existing dune-dike systems across six different countries. The project aims to provide valuable data and insights that inform national and regional policies, ensuring future coastal protection is both effective and sustainable.
