Alzette river restoration in the "Am Brill" nature reserve, Luxembourg
Year of issue
2025
Summary
The Alzette river restoration at “Am Brill” (Schifflange) reversed earlier channelisation that had uniformised the river and impoverished habitats. The project re-meandered the channel (+140 m length), raised and widened the bed (summer/winter profiles), and removed an artificial dyke to reconnect the river to existing ponds; a new pond was also created. Works were delivered in 2000 over ~600–700 m as part of the LIFE-Nature project “Ecological valorisation of the upper Alzette.” Reported outcomes include ≈30 cm reduction of high-water levels, ~20,000 m³ of floodplain storage, a delayed flood peak (~15 min) and shorter peak duration (42→24 min), together with improved self-purification capacity and habitat diversity. Since completion, the site has been opened to the public via a 3 km interpretive nature trail (2005), and in 2024 it was incorporated into the nationally protected “Brill – Am Pudel” reserve, confirming its long-term conservation status and management.
Photo Gallery
Location
49.509026, 6.007891
Project
NWRM
National ID
Lux_03
Sector
Hydromorphology
Installation Date
2000-2001
Implementation status
Completed
Overview
Location of the project
The project area extends between the bridge providing access to the motorway and the pedestrian bridge downstream of the ARBED railway in the locality "Am Brill" in Schifflange.
Country
Luxembourg
NUTS2 Code
Luxembourg
Sponge measures implemented in the case study
Re-meandering
Reconnection of oxbow lakes and similar features
Objectives
Restore natural planform and floodplain, reconnect ponds, enhance habitats for farmland/wetland birds; locally +140 m river length, ~20,000 m³ flood storage, ~30 cm reduction in peak stage; part of a corridor where 41 ha were purchased and >5 km restored by 2006.
Involved partners
| Authority type | Authority name | Authority role | Authority responsibility |
|---|---|---|---|
| Local water authority | Municipal council of Schifflange | Initiation of the measure | Responsible |
| National water authority | Ministry of the Interior - Water Management Services | Implementation | Responsible |
| National water authority | Ministry of the Environment - Nature Conservation Service | Initiation of the measure | Responsible |
| Architects / Engineers | Micha Bunusevac design office | Determination of design details of the measure | Responsible |
Site Information
Climate Zone
Cool temperate moist
Precipitation
853.00 mm
Temperature (°C)
9.20 °C
Elevation range
285 m
Vegetation class
Restored wet meadows (6510, 6410 Molinia meadows), alluvial alder/ash riparian forest (91E0), and hydrophilous tall-herb fringes (6430), with ponds/oxbows. Extensive grazing is used for management.
WFD Ecological status
Bad
WFD Chemical status
Failing to achieve good
Water quality status
Historic channelisation, urban/industrial pressures and wastewater/CSO impacts; locally the Alzette was “relatively polluted,” hence ponds are connected only during floods to avoid low-flow contamination.
Design and Implementation
Project scale
Micro
Project scale specifications
Single, site-specific reach at Schifflange (~700 m between the motorway access bridge and the footbridge below the ARBED railway), with local hydromorphological works and pond reconnection.
Size
700.00
Size unit
m
Constraints
No main constrain identified.
Financing
Total cost
700.00 €
Total cost information
The investments were essentialy dedicated to filling and clearing works.
Costs investment
600000.00 €
Costs investment information
The investments were essentialy dedicated to filling and clearing works.
Costs operation maintenance information
No information available
Policy and Governance
Policy description
A flood in Schifflange happened in 1998. A proposition for a project was elaborated afterwards. The main objective was to restore the natural reserve "Am Brill" and to prevent flooding.
Land ownership
Mixed ownership: communal (Schifflange) plus other owners; parcels were also acquired by Fondation Hëllef fir d’Natur under the LIFE Alzette project; the area is now a national nature reserve (“Brill–Am Pudel”).
Policy targets
Peak-flow reduction
Improved Biodiversity
Target remarks
The sponge measure tackles floodplain disconnection, flood risk at Bestgen Mill, and ecological impoverishment from channelisation.
Part of a wider plan
No
Public consultation
No
Has contractual arrangements
No
Impacts and Monitoring
Impact Assessment Methodology
Performance impact assessment method
Unknown
Socio-economic Impacts
Direct benefits information
No information available
Ancillary benefits information
No information available
Biophysical impacts: Hydrology
Retained water
60000.00
Retained water unit
m3/day
Information on retained water
The water storage restoration contributed to 15 mintutes delay of the peak flow. The maximal flow duration were reduced frome 42 to 24 minutes. Documented: increased storage (~20,000 m³), ~30 cm decrease in high-water levels locally, slower velocities, later/shorter flood peaks downstream, +140 m channel length and reconnection of ponds to the flood regime.
Increased water storage
20000.00
Increased water storage unit
m3/year
Reducing flood risks quantity change
Lowering of the high water level by approximately 30 cm. Flood delay and shortening of the duration of maximum flow downstream.
Information on peak delay effects
Significant. The peak flow is delayed by 15 minutes.
Biophysical impacts: Biodiversity
Improved biodiversity
Yes
Information on improved biodiversity
Biodiversity improvement was expected.
Biophysical impacts: Water & Soil Quality
Water quality overall improvements
Positive impact-WQ improvement
Information on water quality overall
Positive effects on water quality are expected due to the restoration of the ecosystem self-purification, but no assessment has been realised yet.
Soil quality overall improvements
N/A info
Biophysical impacts: Others
Ecosystem impact climate regulation
No information available
Lessons Learned
Key lessons
The Alzette river restoration project aimed at erasing the effect of the river chanelling, which caused the river uniformisation and an ecological impoverishment.
The project consisted in a remeandering, increase of the base level of the river, widening of the riverbed, reconnection of the river to existing ponds and creation of a new pond. The project contributed to restore the flood plain, to prevent flooding and erosion, to restore the natural functionning of the river, to improve the self purification capacity, to improve biodiversity and to intergrate the river in the natural landscape.
Its success lead to further renaturation for the river, for example in the city Steinsel (Alzette and its tributary river Pétrusse) in 2023.
The project consisted in a remeandering, increase of the base level of the river, widening of the riverbed, reconnection of the river to existing ponds and creation of a new pond. The project contributed to restore the flood plain, to prevent flooding and erosion, to restore the natural functionning of the river, to improve the self purification capacity, to improve biodiversity and to intergrate the river in the natural landscape.
Its success lead to further renaturation for the river, for example in the city Steinsel (Alzette and its tributary river Pétrusse) in 2023.
Drivers
| Driver type | Driver role | Comments |
|---|---|---|
| Past flooding events | Main driver | A flood event occurred in Schifflange in 1998. |
Transferability
Highly transferable to channelised lowland rivers with floodplain space and off-line ponds. Key enablers: land purchase/exchange, multi-benefit design, public access. Cautions: stakeholder/landowner negotiations can be complex; ensure water-quality is considered in (dis)connecting wetlands.
Sources
Sources