Using DynamicFlood for flood mitigation at a sports arena
- DynamicFlood
The Larvik Sports Arena, built in 2009, has experienced several damaging floods since it was taken into use. The most recent flood, in 2023, caused damages amounting to millions of Norwegian kroner. The municipality, which owns the arena, was eager to find a solution to reduce flood risk.
Mariann Sæbø Wagner, Head of Stormwater Management at Asplan Viak, and her team were asked to assess the situation and identify potential measures to reduce flooding at the site.
"The arena is at the bottom of a catchment that is mostly built-up residential areas," Marianne explains. "This makes it particularly vulnerable, as there is very limited space for managing surface water."
The sport arena in Larvik, Norway, has been flooded several times since it was built in 2009
In Scalgo Live, it was immediately clear that the arena is exposed to significant flooding.
"We could see right away that the arena is in a depression in the terrain, and there’s also a railway embankment that prevents water from flowing towards the river," Marianne says.
The arena itself was built before Scalgo Live was developed, but with the platform it is today easy to see that the arena is built in a problematic location.
"But it’s too late now. The arena is built, so we need to find a way to improve the situation."
"In Scalgo Live, we could see that some of the flow paths initially were heading straight for the arena, and adding these simple measures to the terrain helped redirect the water."
Mariann Sæbø Wagner, Asplan Viak
The arena is located in a low area and has a large catchment that drains water towards the arena.
Small but strategic measures
The team considered redirecting water to an old, unused ice hockey rink next to the sports arena. However, space was limited due to the presence of a nearby road and the need to maintain sufficient parking. The stormwater team collaborated closely with a road engineer to explore whether the road layout could be adjusted to redirect water without significantly affecting parking capacity.
"We looked at simple measures like adding a speed bump and elevating the curb," Marianne explains. "In Scalgo Live, we could see that some of the flow paths initially were heading straight for the arena, and adding these simple measures to the terrain helped redirect the water."
"With DynamicFlood, we could run simulations for a 100-year event and quickly realised that our measures weren’t enough."
Mariann Sæbø Wagner, Asplan Viak
The mitigation measure (black) was added to the elevation model in Scalgo Live. With the static Scalgo Live analyses, the team could see that water was redirected towards the old hockey ring (green line) instead of flowing straight towards the building (orange line).
Testing the limits with DynamicFlood
While these minor adjustments seemed promising, Marianne’s team wanted to know if they would hold up under more extreme conditions.
"We were curious to see if these small interventions would work for larger events as well," Marianne says. "With DynamicFlood, we could run simulations for a 100-year event and quickly realised that our measures weren’t enough. The water started to overflow towards the arena, and it was clear that the small curb and speed bump couldn’t contain rain events with such high peak flows."
The client, however, kept asking if these measures would have helped during the flood they experienced in 2023.
"We decided to dig into rain data from several gauges and figure out what kind of event that had been. It turned out that the 2023 event had a much smaller peak, lower intensity, and longer duration. When we simulated that event in DynamicFlood, we could see that our small measures could actually handle it," Marianne explains.
Above: 100 year CDS rain event with a very high peak flow. The water starts overflowing towards the arena. Below: a simulation of the rain event in 2023 that caused flooding in the arena. The measure can manage the water.
Looking ahead
"So, for now, these small measures will help," Marianne concludes. "The client has a limited budget, but at least they can reduce the risk of flooding in the coming years while they plan for more extensive flood mitigation investments."
This approach highlights an important point: large, expensive infrastructure isn’t always necessary to reduce flood risk in existing urban areas. Sometimes, small, cost-effective interventions can provide meaningful protection and buy time for more substantial long-term solutions.
Learn more about how DynamicFlood can be used for flood mitigation!
Watch this webinar with more user stories or book a demo with one of our market managers.
