The ACCREU Adaptation Decision Type workshop on “Transformative Coastal Flood Adaptation in Europe: barriers and success stories” aimed to distil key insights on transformative adaptation, major barriers and enablers for successful implementation. The workshop took place as part of the ACCREU project activities, on the 14th of April 2025 and targeted scientists, coastal authorities, regional and national policy makers, NGOs, and consultants. Around 15 stakeholders, excluding ACCREU project partners, participated in the workshop.
Some of the stakeholders present were familiar with ACCREU already, through their involvement in the co-creation case studies of ACCREU on coastal flood adaptation: one along the Baltic Sea Coast and one in North-Holland, the Netherlands. Other stakeholders were new to the ACCREU project.
Above figure shows the background of the workshop participants.
Due to sea-level rise and coastal flood risks, there is a need for coastal adaptation in Europe. We introduced the four archetypical strategies for coastal adaptation to participants: 1) protect; 2) accommodate; 3) retreat; 4) advance (Glavovic et al. 2022). We discussed the first three of these archetypes more in-depth through case studies. Firstly, protect was discussed by a description of the first ACCREU case study on a multifunctional dike—a dike with housing on top—in the Netherlands. This case study assessed whether a robust dike that combined functions would be a suitable measure in the long-term, in light of the reduced flexibility that multifunctional measures tend to have. The case study results suggest that building on top of a robust dike could be beneficial in urban areas, as long as sea-level rise does not exceed the design threshold. However, such a measure would only provide flood related benefits for the area behind the dike when implemented in larger areas; and there are political and cultural barriers that could hamper the implementation of such a novel approach.
Secondly, we discussed retreat through the second ACCREU case study on managed realignment in Europe and the German Baltic Sea coast. The suitability of managed realignment is modelled for the European coastline through the DIVA model, in particular by assessing in which areas restoration and managed realignment would be cost-efficient. This measure could bring further benefits than a structural protection measure, like biodiversity, carbon sequestration, or ecotourism. Moreover, it could also bring financial benefits, through reduced maintenance costs in the long-run. Besides these success factors, several barriers were also highlighted in the discussion, such as the lack of data on effectiveness of nature-based solutions, or the social opposition to such measures.
Thirdly, we discussed accommodate with an external case study unrelated to the ACCREU project: the Sigma Plan in the Scheldt Estuary (Belgium, Netherlands). This plan entails both accommodate and protect measures, like flood retention zones, quay walls, wetlands. Some success factors discussed were the comprehensive economic assessment conducted, or the stakeholder consultation from early on that helped overcome stakeholder opposition to flood control areas.
With stakeholders, we subsequently discussed the presented case studies and whether they knew of other innovative or transformative case studies in Europe related to coastal flood adaptation. Based on this discussion, we collected more information on case studies from other European projects (e.g. Rest-Coast) as well as practical examples.
Further, we discussed the list of barriers and success factors we had already identified based on the literature and whether they recognized this list and had additions. See the Table below. Stakeholders brought up the strong focus in the table and presentations on ensuring a good business case, but that there are other success factors that are of relevance, such as knowledge generation or monitoring.
Based on the provided input on other cases and practices in Europe, enabling conditions, and the previously collected information on innovative flood adaptation cases in Europe, we will be working on synthesizing this information into practical insights for decision-makers in Europe on this topic.