Extreme sea level events are more likely to occur more frequently in the future due to climate change. Therefore, new approaches to flood risk management must be explored. Instead of following a solely defence-dominated engineering approach, improving resilience has become increasingly popular and more desirable. Nature-based solutions (NBS) are actions inspired by, supported by or copied from nature that simultaneously help societies address environmental, social and economic challenges. Therefore, they have the potential to contribute to a more resilient Flood Risk Governance (FRG). However, implementing new perspectives will inevitably widen the scope and increase the number of stakeholders involved in the decision-making process. The idea of more collaborative and participatory governance has gained increased interest among researchers. Nevertheless, influential stakeholders often prefer solutions that cost less and hold fewer management complications and risks, even if other, more multi-functional solutions might be more beneficial for the other stakeholders and society. To further contribute to the knowledge of FRG and the implementation of NBS, this thesis aims to explore how the current FRG can be enhanced for the implementation of nature-based flood defence systems.

The chosen approach is a qualitative study. In addition to reviewing related literature, a first round of interviews explores the current FRG. Furthermore, a multiple-case study was selected as a research method. Data was gathered through interviews and document review in a thematic analysis. Both barriers and enablers for the design and implementation of NBS were identified. Ultimately, the research discovered that barriers and enablers are deeply interconnected, which was depicted in a framework. Moreover, the framework was categorised into three levels of governance. From there, recommendations are given to relevant stakeholders.

The Netherlands can reflect on a long history of living with water, leading to a well-defined FRG with clearly divided responsibilities. Nevertheless, this historical and cultural background also made the system somewhat rigid, making the integration of novel approaches, such as NBS, rather difficult. Several barriers and enablers for wider NBS implementation have been identified within the case studies. Moreover, potential solutions were extracted.

Based on the framework, the study provides a set of policy recommendations targeted at Rijkswaterstaat and other stakeholders of the Dutch FRG. These recommendations focus on enhancing governance flexibility, fostering interdependencies, and creating incentives to overcome risk aversion and promote nature-based approaches. Additionally, the study suggests revising existing legislation to accommodate adaptive management practices better and integrating long-term monitoring and evaluation to support continuous learning and improvement.

The study concludes that better integration of NBS in FRG requires addressing distinct areas of responsibilities, encouraging adaptive and flexible governance arrangements, and promoting collaborative approaches to policymaking. By enhancing stakeholder engagement and providing adequate financial and regulatory support, the Netherlands can improve the resilience of its flood protection system while harnessing the multiple benefits offered by NBS.