Cloudburst road in Karlstad

When a street in Karlstad was to be renewed, the municipality took the opportunity to make climate adaptations to part of the street in order to deal with flooding by making it into what is known as a cloudburst road. The V-shaped cloudburst road leads water away in the event of torrential rain in order to prevent properties along the street being flooded. Thanks to the cloudburst road, the risk of flooding is now much lower.

In the future, climate change is expected to cause more rain, sometimes torrential. This is leading to an increased risk of flooding in many towns and cities. In Karlstad, as in other cities in Sweden, this risk arises when the city’s surface runoff drainage system cannot cope with the large quantities of water. The risk of flooding is worsened by the fact that Karlstad has low-lying areas that sometimes lack runoff, which makes them even more sensitive in the event of torrential rain.

The cloudburst road as a solution to flooding

One of the streets in an industrial area of Karlstad, Sågverksgatan, and its water and sewerage system, were in great need of renewal. In conjunction with the planning of the northern part of the street, the municipality had the idea of adapting this part to climate change in order to reduce the risk of flooding. The solution was what is known as the cloudburst road.

Karta område Karlstad
Red marker shows the cloudburst road. The blue arrows show the direction of water towards the street's low point. Green marker shows pedestrian and bicycle path AND-green / gravel area located next to Klarälven river. Illustration Karlstads kommun Enlarge Image

How does the cloudburst road work?

The street is designed so that water that exceeds the capacity of the surface runoff drains and thus collects on the street is led away along the surface into the Klarälven river. This prevents flooding in properties along the street. The design of the street has two main principles: the street is V-shaped along its centre line and it leans in towards a low point on the street. This design means that the water first runs towards the low point, where there is a pedestrian and cycle path that has been designed in the same way. The pedestrian and cycle path leads the water on from the low point to a green/gravel area alongside the Klarälven, where the water finally runs out into the river. 

V-formen skyfallsväg
The picture shows the V-shape of the cloudburst road. The V-shape directs the rain water toward the street center line. Illustration Ramböll Enlarge Image

Costs

The ordinary reconstruction of Sågverksgatan, including the street’s water and sewerage system, has a preliminary cost of about SEK 18 million, of which SEK 500 000 was the additional cost of making the street a cloudburst road. There is not yet an exact figure for the final cost of the cloudburst road as some work in the form of small adjustments remains to be completed.

More examples of climate adaptation

This is one of many examples of climate adaptation. There are more in the collection of ideas being built up by the Swedish National Knowledge Centre for Climate Change Adaptation at the Swedish Meteorological and Hydrological Institute (SMHI). The collection of examples has the aim of sharing experiences and providing ideas to everyone who works with climate adaptation. Examples describe concrete measures and challenges in several subject areas. They show how different actors have worked to adapt their activities to the climate changes that are already being noticed today and those that we cannot prevent in the future.