Case study:Restoration of the Erft-river in Weilerswist

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Location: 50° 45' 5", 6° 49' 54"
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Project overview

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Status Complete
Project web site
Themes Economic aspects, Fisheries, Flood risk management, Habitat and biodiversity, Hydromorphology, Monitoring, Spatial planning, Water quality
Country Germany
Main contact forename Volker
Main contact surname Gimmler
Main contact user ID
Contact organisation Erftverband
Contact organisation web site http://www.erftverband.de/
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Before (left) and after (right) restoration

Project summary

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The Erft River was heavily trained in the 1960s to provide a higher discharge capacity for flood prevention and to make it easier to mechanically maintain the river. High dams were built along the river banks and the river bed was secured with large rocks. This river training resulted in a river with few structures ans a low morphological diversity. The restoration project has been implemented in Cooperation of the Landesbetrieb Straßen NRW (the state road authority) and the Erftverband (water board in the Erft watershed) to compensate the impact on nature and environment caused by the construction of a new road. The measure has been necessary to reach the Good Ecological State of the Erft required by the WFD. By adressing the need for compensation with a river improvement measure, inefficiencies in public spending has been avoided. The project started in April 1995 and aimed at developing a structure-rich, ecologically permeable stretch of the river with regularly flooded meadows and a high potential for self-development. About 10 hectares of cropland were bought and turned into a meadow on the left hand side of the river, towards the lowest part of the valley. The dam along the Erft separating this meadow from the river has been removed. The rocks securing the river bed on that side have been removed and groynes have been built in the river bed to add morphological diversity and initiate lateral erosion. The groynes have been designed in cooperation with the local fishery association, and according to their observation, young fish which have been drifted away by floods in the past are now able to stay in the area.

Monitoring surveys and results

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Lessons learnt

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Image gallery


Erf I Lateral erosion.jpg
Erf II Lateral erosion.jpg
Erf III Lateral erosion.jpg


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Catchment and subcatchment



Site

Name
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body
National/international site designation
Local/regional site designations
Protected species present
Invasive species present
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 100
100 m
0.1 km
10,000 cm
Project started 2002/04/01
Works started
Works completed
Project completed 2009/12/31
Total cost category 500 - 1000 k€
Total cost (k€) 717000
717,000 k€
717,000,000 €
Benefit to cost ratio
Funding sources Landesbetrieb Straßen NRW (the state road authority) and the Erftverband (water board in the Erft watershed)

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure Flood risk management
Hydromorphology Quantity & dynamics of flow, Continuity for organisms, Continuity of sediment transport
Biology Macrophytes, Macrozoobenthos
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Macrophytes No Yes No Yes No
Invertebrates No Yes No Yes No
Angiosperms No Yes No Yes No

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

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Supplementary Information

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