Success and limiting factors:
The project was successful due to the synergies of various functions (storm water management and storage and control of pollutants) and other indirect benefits (related to traffic safety – the project reduces the number of traffic lanes – and urban landscape). The project has shown that it is possible to implement climate change adaptation measures that blend well into the city landscape.
Due to the space limitations of the existing built environment, it was not possible to fully respond to the future climatic conditions with the dimensioning of the canal. However, the canal has served as a partial solution to the current and short-term climate variability, by increasing the capacity of the storm water management system. In new development areas, storm water management facilities are planned to fit both current and future climate changed conditions. Also, potential locations for new storm water management facilities have already been identified on a map and can be built in the future as long as they can be fitted to the city budget. Some solutions to storm water management in the existing city structure have already been implemented in other areas of the city of Växjö to further improve the capacity of the drainage systems. For example, storm water retention ponds underneath a football field and a parking place contribute to management of surface runoff in the city (SMHI).
Budget, funding and additional benefits:
The whole investment cost nearly 2,000,000 €, of which about 15% was funded by the Swedish Government via the Swedish Local Investment Program for Sustainable Development. The remaining part was funded by the Technical Department of the City of Växjö. Thanks to the investment, this part of the city is now mostly protected from floods after heavy rainfalls. The canal is dimensioned to manage the worst rainfalls estimated to currently occur only once every ten years.
Since the construction of the canal, there have been a few floods, but less severe and not as often as before. So, this kind of storm water storage and delay system has proven to be efficient. Due to the projected future amount of rainfall there is a need for further improving measures to prevent flooding in Växjö. Experiences gained within this project will help to develop improved solutions and will provide a valuable example for other municipalities around Europe.
One direct co-benefit of the canal has been that it has contributed to increased traffic safety in the street. The Linnaeus Canal is situated in the middle of the street, outside a secondary school. Before, there was a bigger risk for accidents between cars and people crossing the four-lane street. Now, there are only two lanes and people have the possibility to wait on bridges over the canal before moving on to cross the other traffic lane. Moreover, the canal and the connected sedimentation lagoons contribute to the reduction of the flow of storm water to the lake, and also have a positive effect on the water quality by reducing the amount of pollutants ending up in the lake. The canal is not only an important part of Växjö’s storm water management. The open water body is a beautiful element within the city and also refers to the historic Växjö where a stream was originally situated in this area.