From smart sensors to medieval cultural heritage: A new chapter in Bruges' water identity with Blue4Green

I find myself on a red boat, following two swans (a species which is treated like royalty, according to Bruggelingen, the inhabitants of Bruges), exploring Bruges' connection to water. What may sound like a dream has a much more serious backdrop: Flanders, Bruges‘ region, is exposed to high risks of water shortages and droughts¹.

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Yet, as I learn more about how the city merges data-driven decision-making and nature-based solutions with activities like public swimming—and how all of this ties into a medieval pipe system beneath the streets—one could sum it up like this: Bruges is adding yet another layer to its identity shaped by water, one that has been evolving for over 1,000 years.

The background: Bruges – A city is reinterpreting its relation to water… and green spaces.

To fully understand today’s ambition of Bruges around water and green infrastructure, we need to have a look at the city’s history. The proximity of the city to the waterways was one key factor in the founding and development of Bruges in the 9^th century. By the 12^th century, the city became a prominent international trading hub. Depending on the source, estimates suggest between 50,000 and 125,000² people lived in Bruges, making it one of Europe’s largest cities in the medieval period.

“Due to its waterways and connection to the North Sea, Bruges functioned as an international trade hub in the 12^th century. Goods sold here came from as far as China”, explains Frederic Roelens, the City of Bruges’ archaeologist (yes, they have this job in Bruges!) as he shows the augmented reality installation Bruges and the sea in City Hall.

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Bruges’ global importance in trade declined in the late 15^th century due to the cutting off of the city’s water connection to the sea. However, the picturesque medieval architecture in the city centre, a UNESCO World Heritage Site, combined with the Reien (the canals that run through the city centre) are the main reasons for the attractiveness for tourists worldwide. Exploring the city on foot or by boat is like a journey back in time: an experience that over 8 million tourists seek annually³.

Bruges’ challenges today: The climate catch-up

When visiting the city by boat, being guided by swans and enjoying a scenic atmosphere throughout the city centre, the main challenges of the city related to its blue and green infrastructure might go unnoticed.

A lack of water buffer capacity: The city is increasingly suffering from water and drought stress caused by the climate crisis, as Astrid Stroobandt (Blue4Green’s Project Manager) and Eva Gheselle (the city’s hydrologist) explain to me as our boat navigates the canals inaccessible for tourist boats. Changes in rainfall patterns lead to water shortages. 16% of the surfaces in Flanders are paved, which is among Europe’s highest numbers⁴. With heavy rainfalls occurring, infrastructure needs to be in place to deal with the surplus water. “We are extremely good at flushing the water out of the city when it rains, yet we would need it right here in dry periods,” says Jonas Lagrou, policy officer at the City of Bruges, highlighting the current dilemma with the water.

Unstable water quality in the Reien: Low and fluctuating water levels in the city’s canals do not only bear challenges for the many tourist boats, they also significantly threaten the water quality by supporting the toxic algal blooms. Additionally, trees and plants in the green areas of the city are under stress from long periods of drought. The canals of Bruges are a closed system. Currently, the water levels of all the inner-city canals are controlled by hand via one inlet and one outlet (the Sluices). While this nostalgic process might fit well with the medieval charm of the city, it is highly impractical, especially to address the city’s current challenges.

Lack of predictive data on water availability: “Currently, we don’t have the real-time data needed to manage water intelligently,” notes Astrid Stroobandt. Key variables such as water levels, overflows, water quality, and plant stress are not yet systematically monitored. The result is a reactive system where decisions are taken only after the occurrence of an event and the fluctuation has already taken place.

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Blue4Green: Adding a chapter to Bruges’ water identity

The City of Bruges decided to address these challenges head-on by adding a new chapter on the connection with the water. One that brings together technological solutions, cultural changes in the local public administration, using the regenerative power of nature, experimenting with ancient pipes and wells, which are occasionally found when excavating, and not least, by creating a renewed awareness of water throughout the city. The chapter’s title: Blue4Green, which is an Innovative Action funded by the European Urban Initiative. Over the project’s running time of three and a half years, the City of Bruges, together with key partners, will effectively connect water to the green by weaving together activities and innovations that will become the new chapter.

A smart water balancing system: Bruges will say goodbye to its manual system to regulate the water levels in the canals, which an automated system will replace. In the last years, Diane Patfoort took care of the water level and the current on the Reien, after the retirement of the last Reienmeester of the City of Burges. She has unique knowledge about the water in Bruges. While the shift from a manual to an automated system might sound like a simple technological implementation project on paper, it requires significant considerations and calculations in practice. For example, if the water level rises too high, it could flood buildings along the canals, as many of the doors that in medieval times provided direct access to the boats sit just a step above the waterline. They now pose a serious risk of allowing water to enter the houses. At the same time, if water levels are too high, the low bridges are a significant risk for tourists who go on the popular boat rides through the canals. No one wants to take a head injury (or worse) home as a souvenir from a visit to Bruges. In December 2026, the automated system will be in place.

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A Blue4Green dashboard to improve decision making: Bringing together different data streams to improve decision making is at the project’s heart and will significantly contribute to the city’s sustainability and climate robustness. Combined with the automation of the water balance system, the dashboard will equip the city with an easy overview to make faster decisions on various aspects, including the water levels in all canals.

Smart sensors for decision making… aka giving a voice to trees: Sensors will measure the water levels in the Reien and identify potential heat stress in trees. “We are currently experimenting with one tree sensor in Astridpark already. These sensors will allow us to listen to the needs and requirements of the trees. For example, if we see that trees in a certain neighbourhood are suffering from heat stress, we can irrigate them on demand, without the risk of overwatering.”says Astrid Stroobandt when I asked what the sensors on the trees do. The trees are only one source of data, which will be fed into the dashboard. Once in full effect, it will develop simulation models, building a digital twin.

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Bridging past and present: Storing water for hard times: Blue4Green addressed the challenges observed by Jonas Lagrou (see above) and will use the Reien but also an cultural heritage for storing water when there is a surplus. The automated system, combined with the policy dashboard, will allow for raising the water levels in the canals when water is available, for example during and after rainfalls. In this sense, as the Reien are an almost fully cut-off system, the canals become buffers where water can be stored during or after rains and used, for example for irrigating plants/trees, during heatwaves.

Additionally, the City of Bruges is looking centuries back to store even more water: “There is a medieval system of dwells and pipes which brought fresh water from the outside to the city centre. Most of these networks are unmapped and we find them by chance in reconstruction processes,” the city’s archaeologist Frederic Roelens explains and continues, “In Blue4Green, we will experiment with opening up part of this medieval system as additional water storage.” Using medieval cultural heritage and infrastructure to address the challenges of the 21^st century is yet another innovative aspect. At the end of Blue4Green, the water buffer capacity of the inner city will be increased by 10,000 cubic meters, which equals 74% of the needed capacity to mitigate climate change by 2050 in the city.

Letting nature do its magic: Using nature-based solutions to improve the water quality. In the summer months, the canals of Bruges are prone to toxic algae bloom, which is caused primarily by hot weather and nutrients in the water. With climate change, the water temperature in the Reien tends to increase in hot months of the year, combined with the nutrients from animal excrements (do not blame, their highness, the swans!), the conditions for toxic algae bloom are good, and thus, water quality suffers.

Professor Peter Goethals from the University of Gent is leading the experiments with nature-based solutions to improve the water quality. From June 2025 onwards, there will be a floating infrastructure in place. Besides providing potential nesting grounds for water birds on top, this raft will filter nutrients from the water. The effectiveness will be regularly monitored.

Connecting people to the water and creating awareness: “You need fun for water” Lieven Symons and Simon Thys from Waterland point out when describing how they will work with residents and communities throughout Blue4Green. Over the running time of the project, Waterland will work with creative concepts and communication activities to engage the residents in Bruges and develop awareness and a cultural shift. Besides the co-creation activities, Blue4Green will organise workshops with schools, events such as the Open Garden Days and Reien Festival 2026 and much more. Blue4Green aims to inspire lasting connections between people and the city’s water landscape.

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The City of Bruges is reshaping the future of climate-resilient cities

Developing this new chapter of the City of Bruges is much more than collecting data, implementing technological solutions and creating awareness among the residents. It is also a process to change internal, historically grown structures, cultures and work processes in the city administration. “When working on Blue4Green, we need to develop this new chapter together with different city departments. This is a challenge of running any innovative and integrated project in a city: we are constantly confronted with old processes that do not match the ambitions of the project. Introducing innovative processes and ways of working into how a city is run is a long road,” says Astrid Stroobandt when asked how Blue4Green will contribute to transformation in different departments.

Blue4Green has three more years to fully unfold, and many cities across Europe and the world should look closely at what is happening in Bruges. As water and green spaces have received increasing attention in policy, Blue4Green can lead the way on how to combine water-related questions and challenges with urban nature, greening and biodiversity. Too often, these systems are treated as separate, whereas integrating, planning and considering the closer interrelations will allow to contribute to policies such as the Urban Agenda for the EU, the EU Green Deal, the EU Climate Adaptation Strategy, the EU Mission on Climate Adaptation and many more.

As Bruges writes a new chapter in its centuries-old relationship with water by adding green elements, Blue4Green offers a living laboratory. By bringing together ancient infrastructure with digital innovation, and cultural heritage with ecological regeneration,combined with co-creation and participation of residents the project sets an innovative example for weaving together water, biodiversity and nature in cities. Bruges reminds us that innovative approaches for climate resilience may include a rediscovery of the past by combining it with technologies, knowledge and approaches of today.

Are you asking yourself how the swans like all of that? You might find out in future publications and episodes on Portico, the Urban Voices and Cities Reimagined Podcast.

Bibliography

¹ MIP4Adapt (2024) The Blue Deal: Tackling drought and water scarcity in Flanders, Belgium. Retrieved from: https://climate-adapt.eea.europa.eu/en/mission/solutions/mission-stories/the-blue-deal-mission-story12

² Dumolyn, J., Ryckaert, M., Deneweth, H., Devliegher, L., & Dupont, G. (2018). The Urban Landscape II: c.1275–c.1500. In A. Brown & J. Dumolyn (Eds.), Medieval Bruges, c. 850–1550 (pp. 152–195). Cambridge University Press.

³ https://www.vrt.be/vrtnws/en/2025/03/20/bruges-introduces-tax-on-cruise-and-coach-tourists-from-2027/#:~:text=Last%20year%2C%20a%20record%20number,the%20city%20and%20its%20residents.

⁴ MIP4Adapt (2024) The Blue Deal: Tackling drought and water scarcity in Flanders, Belgium. Retrieved from: https://climate-adapt.eea.europa.eu/en/mission/solutions/mission-stories/the-blue-deal-mission-story12