Case study:Voorste Nete at Dessel: Difference between revisions

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{{Motivations
{{Motivations
|Specific mitigation=Barriers to fish migration,  
|Specific mitigation=Aggregate/mineral extraction,
|Hydromorphological quality elements=Channel pattern/planform, Width & depth variation, Substrate conditions, Quantity & dynamics of flow,
|Biological quality elements=Fish: Species composition, Fish: Age structure, Fish: Abundance, Invertebrates: Taxonomic composition,
|Physico-chemical quality elements=Oxygen balance,  
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{{Measures}}
{{Measures}}

Revision as of 14:42, 30 August 2012

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Location: 51° 13' 55.80" N, 5° 9' 0.77" E
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Project overview

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Status Complete
Project web site
Themes Fisheries, Habitat and biodiversity, Hydromorphology, Monitoring
Country Belgium
Main contact forename Nick
Main contact surname Elbourne
Main contact user ID User:NickRRC
Contact organisation River Restoration Centre
Contact organisation web site http://www.therrc.co.uk
Partner organisations University Hasselt, Centre for Environmental Sciences, Diepenbeek
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Source of photographs - ECRR 2008. Upper row (left and right): original reach of the Voorste Nete. Middle row (left and right): Excavation of a 5 m wide stretch for placing the bentonite mat and refilling with the original sand. Bottom row (left and right): Diverted reach of the Voorste Nete, dug out in sand filled bentonite lining with transferred substrate from the original reach, and the same stretch 6 months later during first monitoring showing the changes in dimensions caused by a summer storm in 2004.

Project summary

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In 2004 a reach of 1.3km of the small, channelized lowland brook, Voorste Nete, was diverted because of sand mining activities. The sinuosity of the newly created reach of the Voorste Nete, 1.9km in length, was based on old maps, aerial photography and field measurements. The new brook was hydrologically isolated with a bentonite mat preventing water loss due to a decline of the groundwater level. The sides of the bentonite were placed upright for 0.5m and the lining was filled with the original sand from digging out the new reach.

Originally the newly created streambed has a weak meandering channel pattern (sinuoscity 1.1), and was 1m wide at the bottom and 2m wide at the top. In August 2004, a summer storm caused severe erosion and had a noticeable impact on the profile. In the first three years, mechanical weed clearance was only conducted once in the upstream reach of the diversion in autumn 2005. In 2007, mechanical weed mowing was executed for the total stream.

Monitoring surveys and results

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Lessons learnt

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Catchment and subcatchment

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Catchment

River basin district Meuse
River basin Meuse

Subcatchment

River name Meuse
Area category more than 10000 km²
Area (km2) 465465 km² <br />46,500 ha <br />
Maximum altitude category 100 - 200 m
Maximum altitude (m) 200200 m <br />0.2 km <br />20,000 cm <br />
Dominant geology chalk and loess
Ecoregion Western Plains
Dominant land cover Intensive agriculture, Urban
Waterbody ID



Other case studies in this subcatchment: Aaijen- Removal of bank fixation, Meers - Floodplain lowering, Reméandration du Geer à Grand-Axhe, Rijkelse Bemden - River bed widening


Site

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Name Voorste Nete
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present Yes
Invasive species present No
Species of interest Spined loach, Three-spined stickelback, Nine-spined stickelback, Gudgeon, European eel (Anguilla anguilla)
Dominant hydrology
Dominant substrate
River corridor land use Intensive agriculture (arable)
Average bankfull channel width category 2 - 5 m
Average bankfull channel width (m) 22 m <br />0.002 km <br />200 cm <br />
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category 0.1 - 1.0 m³/s
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient
Average unit stream power (W/m2)


Project background

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Reach length directly affected (m) 19001,900 m <br />1.9 km <br />190,000 cm <br />
Project started 2004/04/01
Works started 2004/04/01
Works completed 2004/06/01
Project completed 2004/06/01
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources

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 University Hasselt Alain De Vocht



Reasons for river restoration

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Mitigation of a pressure Aggregate/mineral extraction
Hydromorphology Channel pattern/planform, Width & depth variation, Substrate conditions, Quantity & dynamics of flow
Biology Fish: Species composition, Fish: Age structure, Fish: Abundance, Invertebrates: Taxonomic composition
Physico-chemical Oxygen balance
Other reasons for the project


Measures

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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

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

Biological quality elements

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

Physico-chemical quality elements

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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

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


Monitoring documents

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Additional links and references

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Link Description

Supplementary Information

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