> River Emscher


River Emscher River Emscher


The Emscher is a tributary of the river Rhine catchment, running through the densely populated Ruhr area in Germany. Its catchment covers 865 km². Since the 19th century the Emscher and its tributaries were systematically developed as open wastewater sewers due to industrialisation and extensive hard coal mining. 40% of the area became polders because of subsiding surface due to hard coal mining. The bed of the Emscher and its tributaries were lowered, meanders were cut off and dykes were built over long stretches, in order to protect the cities from flooding. Now, the integrated river basin management for the Emscher region aims at the revitalisation of the Emscher and its tributaries as a nature-like urban river system.

River Emscher


The Emschergenossenschaft started within the frame of the IBA Emscherpark (international architecture exhibition) from 1989 on with the re-vitalization of the total Emscher system. This meant installing 400 km new waste water sewers and re-naturalizing 350 km of water bodies, previously used for the discharge of mixed water, to become more natural creeks and rivers.

To allow these changes, a well working flood prevention system for the whole catchment is paramount. Besides a wide range of decentralized retention measures and cooperation projects for the infiltration and storage of storm water on private, public and business sites, large flood storage projects had to be developed at the river Emscher. Examples of these large storage projects are lake Phoenix in Dortmund, the floodplain in Dortmund/Castrop-Rauxel and the basin in the Zoo of Gelsenkirchen.

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River Emscher


Planned measures in the Emscher catchment include physical implementation of stepping stones to develop natural retention sites close to the river, an emergency polder for floods on (private) farmlands close to settlements in combination with public involvement and ‘land art’ development:

  • Practical planning combined with ecological and design projects (e.g. land art)
  • Development and use of instruments as formal or informal planning tools
  • Public involvement
  • Physical implementation to develop wetlands close to the river
  • An emergency polder for floods with a return interval of > 200 years on (private) farmlands and close to settlements

Goals of the Emscher case

  • Flood prevention over a 40 km stretch downstream of the project area with a positive effect on water levels in the river Rhine
  • Develop tools to tackle safety levels that are not in focus yet (here: > 200 years return interval) with reference to the EU Flood Risk Management Directive
  • Exchange experiences and techniques for running an emergency polder with a minimum of energy and resources and a maximum of operational reliability
  • Address and sensitise politicians and authorities to close the ranks in flood management aspects
  • Strengthen both the role of public services and private precaution

project by ALFA partner(s):

Emscher Genossenschaft