PROJECT DESCRIPTION
BACKGROUND
The stream of Usserød in the northern part of Sealand, Denmark, is receiving increasing amounts of water from storms and sewage systems as a consequence of climate change and the gradual expansion of urban areas in the municipalities of Rudersdal, Hørsholm and Fredensborg. The 8 km-long stream flows from the Lake of Sjælsø in the west to the Strait of Øresund in the east. In Denmark, strong individual rain events and periods of heavy rain over several days (the “renewable rain” phenomenon) can lead to flooding, as was the case in Fredensborg in the summer of 2010 when more than 70 houses were directly affected. Run-off from precipitation is generally expected to become more extreme in Denmark in the coming years, increasing the climate change challenge. It is therefore necessary to assess the entire water cycle to identify solutions for the years to come. Additionally, alternative thinking is needed to create solutions and methods that embrace and include all three municipalities – as water does not respect boundaries.
OBJECTIVES
The Stream of Usserød project’s key objective was climate change adaptation. Specifically, the project aimed to reduce the risks of critical floods along the stream of Usserød in Denmark, and to reduce the risk of damage and associated economic, societal and human costs if floods are not avoided. In addition, the project aimed to increase awareness of the stream and its resources among citizens, politicians and civil servants; and to create a basis for all parties to implement proactive and holistic actions around the maintenance of the stream, making it a unifying positive element for the municipalities.
RESULTS
The Stream of Usserød project developed an inter-municipal approach to managing a stream running through three municipalities in Denmark, and implemented a series of flood prevention measures. It succeeded in significantly reducing the flood risk of the stream of Usserød in urban areas. The approach is highly relevant for climate change adaptation, with methods that can be transferred to similar situations across Europe.
The project team established a permanent inter-municipal organisation for coordinating the management of the stream of Usserød, comprising the local authorities in Fredensborg, Hørsholm and Rudersdal, and three water utility companies; and developed a joint emergency plan in case of flooding events. A water flow metering system was created and this feeds data into a real-time computer model, which enables water flow in the stream to be continuously monitored. The water flow data can be accessed online and anyone can monitor the water level of the stream via the project’s website.
Measures were established by the project that can be implemented to adjust the water level in the stream of Usserød during periods of heavy rainfall. The project team successfully demonstrated these measures and conducted emergency training exercises, to ensure key personnel could use the measures effectively when needed.
The project team created a wet meadow at Blårenden/Mortenstrupvej, with a storage capacity of 9 000 m3 of water, which extends the natural water retention capacity of the wet meadows in the area by five times. This will be important for preventing flooding in the municipalities, even if climate change effects are much larger than currently foreseen. Among the other measures, the project improved lock management at Sjælsø Lake to gain better control of water flow, by incorporating an automatic system to replace a dated manual system. Project calculations also showed that the lake’s water retention capacity was better than previously thought in cases of heavy rainfall.
The project team determined that the measures would significantly reduce the risk of flooding and flood-related damage to nearby housing in a 100-year scenario, and could continue to offer protection to the municipalities for up to 200 years. The project team presented their modelling data in a series of easy-to-understand flood risk maps.
The project team published a manual to inform citizens of the municipalities about flood risks and the measures implemented to reduce those risks. It is potentially of interest to anyone living in flood-prone areas and is freely available on the project website. The project’s main conference was on methods for inter-municipal cooperation on climate change adaptation and water management.
Collaborations initiated by the project will remain operational and will be further developed in the future. The intensive work on organisation and collaboration performed during the project will pave the way for further inter-municipal cooperation in other fields. In fact, two project partners (Fredensborg and Rudersdal) have already launched cooperation on wastewater administration with joint and shared specialist staff to achieve mutual benefits.
Solutions implemented in the project are expected to contribute to the long-term improvement of climate change adaptation and environmental actions for the stream of Usserød catchment area. The prevention of flood events will have positive economic impacts by reducing the damage to houses, and subsequent compensation payments to homeowners, as a result of flooding events.
The project has direct relevance for the 7th EU Environmental Action Programme, specifically climate change adaptation.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
