Managing flood risk at Stockholm's schools

Patrik Jansson, Technical Land Administrator at SISAB, has been using Scalgo Live and DynamicFlood to understand and address the flood risk around these critical public buildings.

"We use Scalgo Live to analyse flooding around our existing properties," Patrik explains. "We always combine the analyses with site visits and discussions with the property manager. The goal is to assess whether any action is needed in the short or long term—or if we should do nothing."

The expected lifespan of the building is a key factor when evaluating flood risk and mitigation needs. "Preschools may only be in use for 20 to 50 years, while schools are often expected to last up to 100 years. That naturally affects how we prioritise our actions," Patrik says.

So far, the SISAB team has analysed flooding for around 200 sites and conducted in-person evaluations at approximately 40 of them.

"Using DynamicFlood, we can already do some very good assessments that help us make the best possible decisions."

Patrik Jansson, SISAB

Aspudden School: Identifying where action is needed

One of the sites Patrik assessed was Aspudden School. "We begin by looking at the terrain and flood risk using the standard Scalgo Live analyses. We also check conditions downstream to make sure our properties don’t create problems for others."

At each building, Patrik and his team mark potential points of water intrusion and take note of expected water levels. These locations are then visited and closely examined.

"For example, we identified a door (p.5) where water could rise as high as 65 cm. That clearly requires action—possibly by adjusting the slope slightly so water doesn’t flow into the building," he explains.

At another location on the property (p.7), water stands along the foundation, raising concerns about the long-term exposure of the building walls. "This is where the input from the site manager becomes important. Can the building handle this?"

All findings from the site visit are compiled into a table that helps evaluate the overall risk and clarify which adjustments should be made.

"We do this for all our properties. The full evaluation will take around three years. After that, we’ll start implementing improvements to reduce flood risk," Patrik says.

Hägerstenshamnen School: Testing measures with DynamicFlood

Patrik has also assessed flood risk around Hägerstenshamnen School, a more recently built property from 2017. "Here, the issue is clear," Patrik notes. "Water enters from a municipal park, flows through the schoolyard, and even gets into the building."

For these more complex situations, SISAB uses DynamicFlood to simulate flood events in more detail. In the simulation, they added a curb between the park and the schoolyard to test the effect of such a measure. "We could quickly see that this had a positive effect—even if it didn’t completely solve the problem."

Another issue was a shed placed exactly where water would ideally exit the property.

Patrik describes: "That shed ended up blocking the water. We removed it in Scalgo Live and ran a DynamicFlood simulation, and we could see that it made a big difference."

DynamicFlood also allowed the team to estimate how much water was diverted by the measure—useful for evaluating cost-effectiveness.

"We could ask: is it cheaper to remove the shed or do something else?"

Supporting better decisions

"We still have a lot to learn," Patrik concludes, "but using DynamicFlood, we can already do some very good assessments that help us make the best possible decisions."

With more schools to assess and more simulations to run, SISAB’s work with Scalgo Live is proving to be a valuable part of Stockholm’s strategy for adapting the city's public buildings to climate change.