Coastal Protection in a Changing Climate: Innovative Dune-Dike Solutions European research project 'DuneFront' with TU Braunschweig on adaptation to rising sea levels

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 21^st 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. Technische Universität Braunschweig is also part of the project.

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.

Rethinking coastal protection in the age of climate change

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.”

Prof. Dr. Nils Goseberg, Head of the Leichtweiß Institute for Hydraulic Engineering and Water Resources at TU Braunschweig, explains:

“Using natural processes such as wind-driven sand transport to feed the dunes in summer and build up white dunes to protect against storm surges and high seas in winter is an intelligent, sustainable and nature-friendly solution. It follows the approach of ‘working with nature, not against it’.”

Dr. Oliver Lojek, sub-project leader of the DuneFronts project, adds: “Our experimental research activities and the development of simulation methods will help to make dune-dike combinations more predictable. This will provide planning practitioners with direct tools.”

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.

Dune models in the wave flume

Within DuneFront, the Leichtweiß-Institute develops numerical models of European sites and investigates erosion and accretion processes under different boundary conditions and potential future climate scenarios. The goal of this research is to identify site specific strengths to filter for potential transfer functions across Europe to increase natural resilience of dune-dike-hybrid systems and make them fit(er) for climate change related challenges.

Furthermore, the Leichtweiß-Institute will conduct extensive physical experiments in its hydraulic lab. For this experimental campaign, 1:5 dune models will be created in collaboration with the Technical University of Berlin. The experiments are complemented by other lab campaigns conducted at Ghent University and Flanders Hydraulic and the Technical University of Delft. At the Leichtweiß-Institute live dune vegetation will be cultivated on the live bed dune models for extended periods of time. These dune models are then installed in a 90 metre long wave flume at the institute and exposed to storm surge conditions to monitor and assess their erosion behaviour. Aim of this complex research chain is to advance the knowledge on potential vegetation related erosion reduction impacts. The lab-data will serve as basis for refining and advancing numerical models of the demonstrator sites across Europe.

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.

For example, in the Netherlands, the “Sand Motor” project – a massive man-made peninsula designed to nourish beaches and dunes over time – illustrates how sand and sediment can be used dynamically to protect coastlines. Other European regions are adopting similar methods, reinforcing natural dunes while combining them with the structural support of dikes.

In Germany, “Sankt Peter-Ording” comprises a natural grey dune called “Maleens Knoll”, that provides storm surge protection along 1.4 kilometre and is laterally connected to dikes. In front of the Dune-in-Dike system, a wide salt marsh lagoon is situated, which’s seaward side is bounded by an extensive white dune chain further adding natural storm surge protection running out into a flat nearly 2 kilometres wide white beach towards the North Sea. The natural character of this site with minimal man-made structures offers unique insights into natures potential to build dunes and consolidate them through vegetation. The extensive white dune chain stretches for approximately 10 kilometres protecting the salt marsh and adjacent dune-in-dike system and its people living in the adjacent town from the rough North Sea, was not there in 1986. Due to aeolian sediment transport and dune vegetation it has been growing ever since without much intervention, reaching 11,5 metre above sea level in most places.

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.