Flood Protection and Climate Change Adaptation in the Copenhagen Capital Region

Takeaways from the Danish Real World Lab during the DIRECTED General Assembly

Authors: Julia Kraatz and Martin Pontius

The Danish Real World Lab

With its extensive and picturesque coastline stretching 7300 km along the North and Baltic Sea, Denmark is a desirable place to live and visit. It is estimated that 40 percent of the Danish population lives within 3 km of the coast, which includes urban areas, holiday homes, and recreational areas (1).

However, as global emissions rise and extreme weather events increase in both their frequency and intensity, much of Denmark’s coastal populations are under threat. During the DIRECTED General Assembly, held in the Copenhagen Capital Region of Denmark, from September 2-4, 2025, we were able to take a closer look at how one such area, the Roskilde Fjord, faces the challenges posed by extreme weather events. By meeting stakeholders on the ground, we were able to further examine how technical developments might help municipalities along the Fjord with their climate change adaptation (CCA) plans, to create a more cohesive, informed, and safer future.

Field trip: The Halsnaes and Roskilde Municipalities

In December 2013, Storm Bodil hit Northern Europe, causing extreme damage to the Isefjord and Roskilde Fjord in Denmark (2), with water rising in the Roskilde Fjord more than two meters (3).

The Municipality of Halsnaes, located along the Roskilde Fjord, is one such place that was heavily affected by Storm Bodil. In the city of Frederiksvaerk, located in the Halsnaes Municipality, flood waters reached the city center, the city’s high school, historic buildings, and the city’s campground (4). Thus, in 2017, the Halsnaes Municipality and Halsnaes Utility Company came together in a joint effort to construct a floodgate in Frederiksvaerk; to this day, the floodgate continues to be a key protective measure against storm surge and resulting coastal flooding. We were able to visit the floodgate in Frederiksvaerk. Representatives from the Halsnaes Municipality and Halsnaes Utility Company told us how the gate continues to operate in times of high storm surge warnings and actual coastal flooding events.

Figure 1. The floodgate in the city of Frederiksvaerk, a key protective measure against storm surge and resulting coastal flooding.

Another important aspect of Disaster Risk Management (DRM) in the Roskilde Fjord is the efforts of emergency response workers. During extreme weather events, such as Storm Bodil, the need for aid and assistance is high, and responders must act promptly and work very intensely until the coast is, quite literally, clear. To help train responders in such emergency situations, the Roskilde Fire Department opened the Water Management Center in 2024. The center consists of a cement basin spanning 20 meters in width and 1.8 meters in depth, which is able to simulate real-life flood scenarios in a controlled environment. The center enables responders to test existing tools from all over the country against large water masses, as well as provide insight into how researchers and companies can develop new solutions (5). Emergency response workers can additionally answer questions such as, “How long does the measure take to implement?” and “How many people does it take to set-up?”, without the fear of being in a live, highly stressful, situation.

We were able to visit the Roskilde Fire Department and Water Management Center and see the basin in action. During the visit, emergency water blockades were demonstrated against a flow of water in the basin.

Figure 2. The Water Management Center at the Roskilde Fire Department.

Figure 3. The Water Management Center in a live demonstration, with emergency response water blockades.

Roskilde Harbour, located in the southern area of the Roskilde Fjord, has also implemented various CCA measures and mitigation strategies since the Storm Bodil event. One point of particular concern post-Bodil was the Vikings Ship Museum. While the flood waters did not reach the museum, if another event were to occur, there is no guarantee that the museum and the cultural heritage within it would be spared.

On our final stop in the Roskilde Fjord, we were able to visit the Vikings Ship Museum to hear about plans to relocate the museum. Additionally, we heard from a hydrologist from the Roskilde Municipality about current measures used to combat coastal flooding in Roskilde Harbour. This includes concrete walls which can be built-up, i.e., to increase height, or taken down, depending on the warning or severity of the projected storm surge. This ensures that houses located on the coast are protected from storm surge, and also maintain their view of the Fjord.

Figure 4. Concrete wall with emergency built-up adaptation measure capabilities in the Roskilde Harbour.

Figure 5. The view from inside the Vikings Ship Museum in the Roskilde Harbour.

A Look into the Data Fabric

Having learned a lot about the challenges of CCA, how can technical solutions like the Data Fabric support stakeholders in making decisions?

One approach is to adopt a Multi Criteria Analysis (MCA) to compare different adaptation options. In order to understand how this could be applied to the Roskilde Fjord, a tabletop exercise led by the partners from ETH was conducted as part of the General Assembly. The idea of an MCA is to compare different options; in this case adaptation measures, such as a sea barrier or relocation of critical infrastructure with respect to a set of possibly conflicting criteria, such as public approval or the time it takes to implement such a measure. The ranking of the options then depends on the “importance,” otherwise known as weighting, of each criterion.

In the exercise, we considered the following adaptation measures: building new barriers, relocation, changing building codes (i.e., implementing green or protective measures depending on the location and building type), and launching an early warning system.

The first step in the tabletop exercise was to have participants decide on a ranking for the measures based only on their costs and benefits. This demonstrated how decisions can be made solely on economic figures – i.e. the cost of the measure vs. how much it saves in the long term; however, this step highlighted the importance of other criteria. In other words, how important it is to consider factors besides economic impact, such as how many peoples’ lives the measure saves, how long it lasts through time, etc.

The second step was to have participants split up into groups, and decide on weights for a set of criteria (measure cost, monetary averted risk, averted risk for people, averted risk for nature, public approval) and compare the resulting ranking with the previous one. This step highlighted how the “best” measure is dependent on what criteria you consider important, with the result varying drastically between different groups (just as it usually does in real-life decision making processes).

In the last step, participants were asked to identify new criteria which could be integrated into the analysis. From this discussion, additional criteria such as the following were listed as important by the different groups: ecological impact, health (cost, number of lives), social cohesion (happiness index), political controversy, public acceptance, time for implementation, risk of failure/power outage, adaptability/scalability (in lens of climate change), and social value (i.e. jobs created), among others.

A first version of the MCA has already been integrated into the Data Fabric. In its current state, a fixed number of adaptation measures and criteria are considered. Users can then decide on weights for the criteria and see the resulting ranking (see Figure 6).

Closing Remarks

Overall, the GA in Copenhagen was an informative and insightful experience. It enabled us to gain a better understanding of the entire DRM and CCA landscape in the Roskilde Fjord, and hear first-hand from the people who participate in this important work. Developments in this Real World Lab (RWL) have been carefully constructed with the feedback and information from the stakeholders and RWL hosts alike. Thus, the hope is that the end result is something that can be used to help bridge any communication and information needs in the Roskilde Fjord and possibly beyond.

Check out the latest version of the Data Fabric coming soon!