IMAU Colloquium - Bas Borsje (University of Twente) - in person/ online

Living Dikes ‐ Realising Resilient and Climate‐Proof Coastal Protection

Climate is changing rapidly and to protect ourselves against flooding, hard structures are used worldwide as coastal protection measures. These structures are static and will not withstand rising sea levels and increase in storminess. In the Netherlands alone, it would cost billions of Euros to heighten these asphalt-covered dikes in the coming years. Instead, I propose a game changer in coastal protection: the construction of coastal wetlands in front of existing dikes. Wetlands are much cheaper to construct compared to heightening hard structures and more effective, since wetlands grow with rising sea levels and buffer storms. I call these biophysical systems ‘living dikes’.

A breakthrough in this emerging and multi-disciplinary field of research is hampered by a fundamental lack of knowledge about the behaviour of constructed living dikes during their design lifetime (50 years) under extreme hydro-meteorological events. The challenge of the Living Dikes project is to acquire a thorough understanding of the resilience and tipping points of constructed living dikes.

My team intends to accomplish this through a combination of laboratory experiments, field campaigns, data-mining techniques and model studies. We will lift full-grown wetlands into a water tank containing the most powerful wave generator in the world, and expose them to extreme wave conditions (up to a storm that occurs once every 10,000 year). We will deploy Wetland Umbrellas to induce extreme drought-like conditions. Next, we will integrate the results by developing a numerical model, able to predict (the uncertainty in) 50 years of wetland behaviour. Strong cooperation with 20 end-users is embedded in our living lab to guarantee the implementation of the findings in practice by constructing a 50 km long living dike. The project will provide the knowledge and experience required for the construction of living dikes as safe and cost-effective alternative in coastal protection.