Case study:Creation of flood channels and restoration of exchanges between the flood plain and the low-flow channel on the Vezouze
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site||http://www.onema.fr/IMG/EV/publication/rex_VezouzeGB.pdf|
|Themes||Flood risk management, Habitat and biodiversity, Hydromorphology, Monitoring, Social benefits, Urban|
|Main contact forename||Josee|
|Main contact surname||Peress|
|Main contact user ID||User:Josee Peress|
|Contact organisation web site||http://www.onema.fr/Hydromorphologie,510|
|Parent multi-site project|
| This is a parent project
encompassing the following
The work consisted of widening the river’s middle water channel in some places. For this, a protective levee has been levelled on the left bank. Two flood channels, measuring one metre on average over 6 hectares, have been dug, involving the removal of 60,000 m3 of material. Within these flood channels, wetland environments such as ponds and side channels have been created. Trees have been planted on the banks as well as helophytes in flood channels. In addition to these actions on the environment, work on the rainwater system has also been undertaken: check valves and pumping stations have been set up.
The Vezouze maintenance syndicate manages the removal of blockage and debris as required.
Monitoring surveys and results
A pre-restoration monitoring was carried out by a consultancy in 2000 and again in 2003, 2004 and 2005 on the hydraulic component. Investigations were required to study the hydrography, hydrology, topography and geology of the land. A bibliographic study was used to describe the biological component of the aquatic environment. Post-restoration ecological monitoring (habitats, species) began in 2010 and will continue until 2014. This monitoring consists of describing the natural environment and assessing the impacts (positive and / or negative) of operations on animal and plant life, specifically targeting the restored flood plain and side channels created. The hydromorphology and biological communities living in the lowflow channel (fish, aquatic invertebrates, etc.) are however not investigated in this work.
The first results of 2010 and 2011 highlight several outstanding species for Lorraine, including insect and plant species. It will therefore be very interesting to monitor the evolution of these species on the site. Particular attention will be paid to plants receiving protected status, as these species were most likely to have been introduced during the restoration work.
The ecological evolution of the site is very satisfactory. The results of monitoring attest to the positive effects of the work on biodiversity with the presence of wildlife characteristic of wetlands and the presence of outstanding species in terms of flora and insect life. The evolution and diversification of the side channels, which have a dense vegetation of helophyte-type plants, are also very conducive to pike reproduction (even though there is no monitoring of this aspect, side channels here show strong potential).
Hydraulically, the results are equally satisfactory. Upstream to the restored area, height and surfaces of areas flooded in Lunéville have significantly diminished.
As the primary objective of this restoration is flood defence, the explanation to elected representatives of the benefits of preserving the flood storage area and diversifying habitats in the flood plain has led to the setting up of a project that reconciles hydraulic and ecological objectives. Cross-cutting objectives particularly motivated elected representatives who were thus able to meet the expectations of the local population in terms of safety and landscaping issues. These developments make it possible to combine flood management and improvement of the ecological status of the river.
In addition, a pedestrian path has been created in the area and its regular use reflects the renewed interest of local people for the site. Previously, they tended to avoid this unattractive, unsightly sector. The work thus helped to enhance “nature” in a peri-urban area.
Catchment and subcatchment
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos