Case study:Bocq river (Walphy - LIFE project)

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Location: 50° 19' 21.02" N, 5° 0' 30.92" E

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Project overview

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Status	Complete
Project web site	http://walphy.be
Themes	Habitat and biodiversity, Hydromorphology, Monitoring
Country	Belgium
Main contact forename	Alexandre
Main contact surname	Peeters
Main contact user ID	User:AlexBE
Contact organisation	Service Public de Wallonie (SPW)
Contact organisation web site	http://walphy.be
Partner organisations	University of Liege, University of Namur
This is a parent project encompassing the following projects	Eau Blanche River (Walphy - LIFE project)

Overview of the restoration projects undertaken on the Bocq catchment

Project summary

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In the context of fulfilling the Water Framework Directive requirements, the LIFE+ project Walphy allowed experimental restoration projects to be undertaken on two medium-size catchments of the Meuse basin in Wallonia (Belgium) between 2009 and 2014: the Bocq catchment and the Eau Blanche Catchment. This five-year long project was funded by the European Union and the Service Public de Wallonie (SPW). It involved three institutions: the SPW was in charge of the experimental restoration projects while the Universities of Liège and Namur were responsible for evaluating the success of the restoration projects.

The Bocq is a medium-size gravel-bed river which has been strongly impacted by numerous barriers, impeding the free movement of fish and bedload (an average of one weir every 1.8 km). In addition, some river reaches have been straightened over the last few centuries, which has led to significant loss of habitat.

A multi-scale assessment of hydromorphological conditions of the Bocq catchment has led to a large-scale restoration project implemented mainly in the lower and middle course of the Bocq River itself. 22 barriers (mainly old weirs of an average height of 1.35 m) have been removed or modified in order to reconnect the Bocq with the Meuse and to improve access to areas of spawning grounds. To date, only two barriers remain in the middle Bocq. In addition, 13,3 km of modified reaches were improved through a wide range of rehabilitation techniques such as designing sinuous channels, re-instating spawning grounds, improving fish shelters, improving culvert bed, etc.

Monitoring surveys and results

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The success of the restoration projects was evaluated on the basis of a multi-disciplinary monitoring.

Hydromorphology was evaluated on five restored sites using microhabitat survey and three indices of physical quality. For all sites, hydromorphology was significantly improved 10-20 months post-rehabilitation, through the diversification of flows (depth, substrate, water velocity) and the creation of habitats (e.g. fish shelters, spawning areas and woody debris).

Biological quality, based on macroinvertebrates and fish communities, has generally showed a status quo or a slight increase 10-20 months post-completion. Nevertheless, ambitious rehabilitation measures such as weir removal and meanders restoration have resulted in the most positive effects, while less ambitious measures such as habitat diversification have led to more contrasted results. In addition, restoration of the longitudinal connectivity was beneficial for Grayling, designated as Natura 2000 species, and for eels, concerned with the Benelux convention.

The geomorphological monitoring has focused on the effect of barriers on sediment transport and the effectiveness of spawning gravel rehabilitation.

Lessons learnt

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- Despite the short period of time (5 years) of this project, we realized afterwards the importance of achieving a multi-scale assessment and an initial state (pre-restoration) prior to restoration work.

- We implemented a wide range of demonstration techniques and we compared them in terms of cost-effectiveness (see the Manual of River Restoration Techniques on http://www.walphy.be/index.php?page=guide-technique).

- Most of the restoration projects could be implemented without acquiring the land but rather through negociations with the local community. This underlines the importance of engaging the local community.

- The time span of the project allowed us only 1-2 years of monitoring (post-restoration). Fortunately, the SPW funded a long-term monitoring (>3 years), which is crucial for accurate evaluation of success, especially for biological indicators.

- Finally, we hope the project to give a boost to future restoration projets in Wallonia.

Image gallery

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Bocq: Rehabilitation projects

Barriers location on the Bocq catchment pre and post Walphy project

Bocq at Yvoir: Pre-barrages

Bocq at Spontin: Weir removal

Bocq at Braibant: Bypass channel

Bocq at Yvoir: Fish passage

Leignon at Ciney: Habitat diversification

Bocq at Emptinale: Designing sinuous channel

Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district Meuse River basin Meuse Subcatchment River name Bocq Area category 100 - 1000 km² Area (km2) 237237 km² <br />23,700 ha <br /> Maximum altitude category 200 - 500 m Maximum altitude (m) 305305 m <br />0.305 km <br />30,500 cm <br /> Dominant geology Limestone, sandstone Ecoregion Western Plains Dominant land cover Grassland, cropland, forest Waterbody ID MM28R and MM30R Site Edit 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 Edit project background Reach length directly affected (m) Project started Works started Works completed Project completed 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 Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Hydromorphology Biology Physico-chemical Other reasons for the project Measures Edit 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 Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit 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 Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information