Operating and optimising multifunctional urban flood protection - Lake Phoenix Dortmund

Abstract

Lake PHOENIX in the heart of the city of Dortmund simultaneously fulfills many functions. In terms of city planning the lake is very significant. First and foremost it serves the local recreation of the citizens. The district of Hörde has been greatly upgraded and nowadays a very attractive construction area exists within the middle of the city. Ecologically, a 24.5-hectare mesotrophic shallow-water lake was created, which is sensitive to organic pollution due to its conditions. Third, this lake also fulfills a flood protection function. The river Emscher bypasses the Lake. Only if discharge is more than a HQ20, the Emscher flows into the lake. Lake PHOENIX offers a flood volume of 235,000 m³ and is able to reduce the flood discharge from HQ20 up to HQ100. During the first years of operation, it became evident that natural succession along the river causes many questions about the dimensioning and operation of the plant. This report describes the results of the intensive measurement campaign and the findings from the renewed. Last but not least, the effects on flood risk management are described and discussed.