We have known for some time that prolonged droughts—just like devastating floods—will occur more frequently in the future. The Living Lab action plan is a step towards transforming the valley into a more resilient system. In the castle’s foyer, a mini-exhibition visualized the intensive process that led to the action plan. Joachim Declerck and Patrick Willems guided Flemish Minister for Environment and Agriculture Jo Brouns, Flemish Brabant Governor Jan Spooren, and Limburg Provincial Deputy Laura Olaerts through the panels and the interactive scale model of the landscape (made by CLUSTER, the landscape designers that supported the coalition). They explained how the process consistently fostered solidarity between sectors and subzones of the territory, resulting in collectively supported local water security goals. The Minister emphasized the power of territorial coalitions—and the urgency of making landscape transformation a political priority—also in his opening speech: “The work happening here in the Herk and Mombeek valley could serve as a blueprint for future water policy in Flanders.”

That a future-oriented water policy is not a luxury but a necessity became even clearer through the figures presented by Professor Patrick Willems. As part of the Living Lab, he launched a cost-benefit analysis. His calculations show that water-related damage in this area already amounts to €20 million per year. Without further action, this could increase to €34 million per year by 2050. Altogether, that means a cumulative damage of €600 to €700 million by 2050—excluding ecological losses like peatland drying, declining biodiversity, and more.

Doing nothing is not an option. The coalition formulated a set of water goals that serve as the basis for the first sponge action plan. This includes an investment of €1.5 million in measures to increase the valley’s resilience. However, this amount covers only a small fraction of the total risk. The true cost of a resilient valley is estimated between €45 and €70 million (excluding €200 million in residual risk). Yet even this higher investment is still far less than the massive damages under a business-as-usual scenario. The cost-benefit analysis shows a clear positive outcome: investing in sponge landscapes pays off!

How far can €1.5 million take us? Achieving maximum impact with just 2% of the needed funding requires a smart spatial strategy. That’s why the action plan clusters the measures to better grasp their cumulative effect, as Joep Fourneau (Regional Landscape Haspengouw & Voeren) explained during his presentation: “We have been working in the Herk and Mombeek valley for years. The first actions were spread out across the landscape. To maximize on-the-ground impact, weare now focusing resources in two field labs. There, we are working on a story where 1 + 1 equals 3.” An afternoon walk led participants to the field lab in Piringen, where deeply incised streams, dry arable plateaus, and promising grasslands alternate.

The panel discussion also emphasized the importance of a wide array of nature-based sponge measures. Piet Debecker from INBO explained: “The Mombeek valley is currently focused on rapid water drainage. Naturally, a river’s sinuosity—or meandering—should be 2.5 times greater in the lower reaches, which helps slow down peak flows. But humans have dramatically reshaped this landscape over centuries through deforestation, straightening of streams, drainage of farmland, and urbanization.” Nature-based solutions not only address water quantity but also tackle other challenges, such as erosion on sloped fields or poor water quality in deep-cut waterways. Maarten De Jonge from VMM also stressed the cumulative effect of sponge measures: “What sets this Living Lab apart for me is the large-scale implementation of many small actions. I’m glad to see many infiltration measures because they also help with erosion and prevent nutrient runoff.”

Rolling out many small actions on a large scale requires mutual understanding and collaboration. That is the core message of the documentary we made together with Storyrunner for this Demer Day. The importance of joining forces was also central in the closing panel discussion. The Living Lab Herk and Mombeek builds on years of on-the-ground work by organisations such as Regional Landscape Haspengouw & Voeren, the ‘bekkenwerking’ of the Demer (the organisation responsible for the catchment basin) and the Province of Limburg. Over time, the Living Lab’s dynamic has continued to grow. Steven Beyen from the Province of Limburg observed: “Our territorial coalition, which has been in place for years, continues to evolve. We’re welcoming more partners and seeing an increased willingness to listen to one another.” Patrick Willems also highlighted this in his talk: “Going through the process with all stakeholders helped us better understand both our own and each other’s risks. The modeling results gave us insight into how the system functions and where the remaining risks lie.”

To scale this work across Flanders, we must keep investing in both new and existing coalitions. As Liesbeth Gellinck, programme coordinator for Water+Land+Scape, emphasized: “A coalition does not appear overnight—and it does not function effectively overnight either. Building that connection and chemistry between actors takes effort.” Bringing diverse actors to the table around a shared goal requires time, customization, and a strategic approach. The Living Lab experience shows that the quality of the territorial coalition is one of the greatest success factors.

“Nine years ago, we deliberately focused on building a strong territorial coalition in the Herk and Mombeek valley—one where partners share roles, mandates, and leadership,” concluded Joachim Declerck in his closing remarks. “Today, we have clear goals on the table, and the local coalition is ready to take action. It is a promising step toward putting the 'Resilient Waterland' vision into practice.” The optimism felt during Demer Day carries forward in the enthusiasm for implementation: the coalition is ready! At the same time, true resilience across Flanders is still far off. To get there, we must move beyond today’s practices: “We’re looking for new frameworks in which supra-local actors and local territorial coalitions collaborate more closely to implement effective, integrated, and landscape-wide sponge action plans—not just through one-off project calls, but embedded in everyday policy. If we don’t make room for this shift, many valuable trajectories risk coming to a halt.” We need a policy-level breakthrough, so that strong local initiatives don’t dry up—but instead, grow into a structurally resilient landscape!