In recent years, climate change has led to increasingly extreme precipitation, including in the Netherlands. Municipalities are therefore wise to prepare for this type of flooding. The climate stress test developed by the Municipality of Dronten in collaboration with Tygron shows how this can be done in a smart way.
Water
Together with Tygron, the municipality of Dronten developed a method to provide local insight into waterlogging and explore potential measures. During the Tygron Community of Practice, hydrologist Ward van Laatum and water, sewerage, and climate adaptation policy advisor Michel van der Ploeg presented a climate stress test as a tool enabling employees to work independently.
Ward van Laatum
Michel van der Ploeg
Want to know more about the Community of Practice?
Read the report of the Community of Practice and watch the accompanying presentations for more insights and practical examples.
From heat stress to waterlogging
The reason is clear: extreme precipitation is becoming more frequent and can lead to significant damage. Yet, until recently, residential areas were designed to handle relatively limited amounts of rain. Van Laatum explains: “Sewage systems in the Netherlands are designed for a 'shower 8' (bui 8), in which 20 millimeters of water falls in an hour. But alongside shower 8, we now have a new challenge: the low probability of an extreme precipitation event. Low probability, but with major consequences. And municipalities have to deal with that.” The Delta Plan on Spatial Adaptation (DPRA) therefore asks government bodies to map out their vulnerabilities and work toward a climate-resilient and water-robust layout by 2050.
For Dronten, this was a reason to no longer completely outsource stress tests. The municipality had previously gained experience with the Tygron Platform when mapping heat stress, which gave Michel van der Ploeg the idea to use the same tool for waterlogging. Being able to perform analyses themselves provides a great deal of freedom when identifying issues and devising an action plan. “I can see for myself what happens, whenever I want and whenever I have time,” says Van der Ploeg. "And the great thing is that, as a municipality, we can also devise measures ourselves and view the effects immediately.”
Concrete research questions
An important part of the approach is translating general policy questions into concrete research questions. Take the question of whether emergency services can still drive through the city during extreme rainfall. A model cannot simply work with that directly. First, it must be clear what is meant exactly. How much water is allowed on the street? What water depth is still acceptable for an ambulance? And for how long may a road potentially be inaccessible?
Van Laatum emphasizes that from such a concrete question, you then determine the necessary analyses, baseline assumptions, and data. Are those data available and reliable enough to build a usable model? That step is essential. Without proper assumptions and data, even advanced models yield few actionable insights.
Collaborative approach
The municipality expressly opted for a collaborative approach. Van der Ploeg: “Of course, I don't do this alone. Policy officers contributed their knowledge of the various challenges, asset managers tested the model results against their practical outdoor experiences, and the GIS specialist handled the analyses.” From Tygron, hydrologist Ward van Laatum helped set up the model and document the assumptions in a template.
That template forms the basis for reuse within the municipality. The same assumptions and analytical methods can be applied to different areas without having to start from scratch every time. According to Van Laatum, the collaboration between the GIS specialist and the domain expert remains vital: “One understands the data and software, the other knows what happens in practice.”
What is a template?
A template is a pre-configured workflow in which data, model settings, analyses, dashboards, and visualizations are already defined. As a result, employees do not have to rebuild a model or establish baseline assumptions every time. The same approach can be directly applied to new areas, scenarios, or measures, allowing analyses to be carried out more quickly and consistently. This reduces the risk of errors, accelerates projects, and ensures that specialized knowledge remains available within the organization for new challenges.
Supporting decision-making
The results of the stress tests are not only intended to make problems visible, but above all to support decision-making. The municipality can present various scenarios and measures to the board, including the associated costs and risks. Ultimately, it is up to the municipal council to determine which investments are justified. Van der Ploeg is enthusiastic: “Fantastic! In the past, we just had a map with some notes written on it. That was it. Now everyone can see in the system what happens when we make adjustments.”
How do you connect climate adaptation with other spatial challenges?
A climate stress test is just one component of area development. Discover how to integrally investigate water, green spaces, housing, and accessibility, and better substantiate spatial choices.
