The future of the Dutch delta is challenged by the wicked problem of climate change characterized by sea level rise and extreme weather changes as well as land subsidence and the uncertainty pertaining to these processes. This makes well-considered policy decisions a sought-after endeavor. To provide a long-term view of how the Dutch delta behaves under future conditions and how this may be influenced by solutions from different domains, Deltares initiated an exploration into the need for a ”Deltaverkenner”, a national-scale decision support tool to collect, integrate, improve, and visualize insights from disciplinary research. Decision support tools (DSTs) are developed to support decision-makers in decision-making processes by providing frameworks and models to assist in making informed decisions. The benefits of DSTs can be plentiful. However, for information to successfully transfer the boundaries between science and policy it needs to be salient, credible and legitimate.

Therefore, this thesis aims to explore, synthesize and evaluate co-produced designs for a decision-making support tool for water governance contributing to climate change adaptation in the Netherlands that best fits the needs of the stakeholders involved. Consequently, this thesis aims to answer the following research question:
“What do stakeholders perceive as a fit for purpose design for a water governance decision support tool contributing to climate change adaptation in the Netherlands?”

To do so, it takes an informed, iterative co-production approach, meaning possible designs for the DST are co-designed based on stakeholders’ needs in collaboration with stakeholders and experts. Subsequently, the potential designs are evaluated by the stakeholders. This process is informed by lessons learned from the application of previous decision support tools at the water governance science-policy interface. Additionally, the findings are analyzed in comparison to a literature-based theoretical framework regarding the requirements for successful DSTs and the trade-offs to consider at the science-policy interface.

The findings show that there is consensus on the need for a quick and aggregated tool, preferably a conceptual model like a system dynamics model or a reservoir model. This tool should be able to provide insight into the impacts (both water engineering related and societal impacts such as nature, agriculture and economics) of strategies like the ’voorkeursstrategiën’ for the Delta program. It is also clear there is no desire for a computationally detailed model. There seems to be enough information available; the challenge is to find a way to aggregate this into a quick, easy to use, informative tool that offers significant interaction opportunities in the form of dialogue between different users, as well as feedback between users and the tool based on system knowledge.

The findings were analyzed using a theoretical framework that identifies important considerations for a successful decision support tool that capable of bridging the science-policy interface. Most of the findings of this thesis align with the framework especially regarding the content and use elements for a DST. Regarding the goal and process elements, the findings and the framework are also in agreement, however more research is needed to further specify the needs from stakeholders.
While the findings offer interesting insights into the perception of stakeholders on fit for purpose designs of the ’Deltaverkenner’, they also highlight several areas where more research is necessary to further ii iii concretize the need and offer a starting point for potentially developing an approach for the ’Deltaverkenner’. Specifically the 5 W’s have to be elaborated and specified. Who should the ’Deltaverkenner’ be for, why the need for a ’Deltaverkenner’, what should it be able to do and where and when (timing, resources, process) should it be developed.

To further concretize the need for a ’Deltaverkenner’ and to ensure all elements of the theoretical framework are considered for successful decision support tools at the science-policy interface, the recommendation is to develop a meta model detailing the design of the process for developing the ’Deltaverkenner’. This framework should include criteria derived from co-production, boundary object, and decision support systems design processes. Additionally, the literature on impact pathways can inform the types of knowledge, types of research orientations, types of interactions, and the beneficiaries to ensure an effective impact on the decision making process.