Pilot description

Area description

Vejle is a medium sized Scandinavian city and municipality. With its 111,000 inhabitants, Vejle is the 6th largest municipality in Denmark.The city itself is the 9th largest with 54,000 citizens (Municipality Vejle, 2016).

Location of city of Vejle in Denmark (from Municipality Vejle, 2016).

Relevant characteristics of the water system: Vejle is located at the mouth of a fjord, at the bottom of a steep valley where two rivers discharge into the fjord. These geographic characteristics make it naturally prone to flooding. Furthermore, the impact of climate change has increased the frequency and severity of flooding as rainfall events get more intense, average sea level continue to rise and storms surges become more frequent. Historically, Vejle has frequently suffered from flooding due to intense rainfall either in the city or over the river catchments, and by high water level – caused by storm surges – in the fjord (DHI, 2019).  The rivers flow through a sluice before they discharge into the fjord (interview pilot manager, 2019).

Flood risks

Usually, flooding from the river when heavy rainfalls happen and from the sea when there are storm surges events with a return period of 1:20. The flooding coming from rivers are more common than the flooding coming from the sea. However, last winter there were 2 events. The situation becomes problematic  when both events (heavy rainfall and storm surge) happen at the same time. Vejle is one of the 14 high risk areas in Denmark as defined in the EU Floods Directive (interview pilot manager, 2019).

There was a big event in 1872 that flooded the southeast of the fjord and people still remember that.

Referenties

• Improved flood control and water quality with a smart water solution, DHI, 17 februari 2020.
• Vejles resilience strategy, Municipality Vejle, 1 januari 2016.