Reconstruction of the hedgerow on the Léguer basin | Natural Water Retention Measures

General

National Id

France_15

Summary

The Léguer River catchment is one of the most hedged areas in Brittany. However, this territory has suffered a decline in its hedgerow mesh as a result of agricultural mechanization and land consolidation operations. Faced with the degradation of the Leguer's water quality observed in the 1990s, elected officials in the Leguer's watershed became aware of the need to preserve the hedgerow to stop this degradation, and to consider its restoration to improve water quality. Since 1999, the Leguer's watershed committee undertook awareness-raising of the watershed population, before experimenting with the restoration of hedges and embankments in several pilot basins. This work was then extended to the entire watershed, leading to the restoration of 300 kilometers of hedges and embankments. This action is still ongoing today, and aims in particular to ensure the sustainability of existing linear thanks to urban planning tools and the promotion of hedged farmland.

Light or indepth?

In-depth

The in-depth description of the case study

mnre_rex04_bassin_versant_du_leguer.pdf

Location description

The Leguer is a coastal river of the Côtes d'Armor that flows into the Bay of Lannion, and whose basin has a historically dense hedgerow mesh. Hedges and embankments are distributed heterogeneously throughout the watershed and are threatened in several sectors by changes in maintenance practices and the gradual disappearance of certain linear areas.
In Bretagne, 80% of drinking water comes from surface water pumping, which makes this resource fragile and sensitive to diffuse or point pollution. Several water intake points were closed in the mid-1990s due to significant water quality degradation. Due to the positive influence that hedgerow can have on the quality of surface water, policies for the preservation and restoration of hedgerow have emerged in BrIttany.

NUTS Code

Bretagne

RBD code

FRG-La Loire, les cours d'eau côtiers vendéens et bretons

Transboundary

Source(s)

Rapport de présentation, état initial de l’environnement

Retour d'expérience - Le programme Breizh Bocage au service de la restauration de l’eau

L’eau en Loire Bretagne, les trophées de l’eau en Loire Bretagne 2009

Le suivi de la qualité de l’eau

Bocage

Bocage et cultures : un mariage harmonieux sur le Kervulu

Le projet Léguer Bocage

NWRM(s) implemented in the case study

Buffer strips and hedges

Longitude

-3.3920

Latitude

48.5865

Monitoring maintenance

Monitoring parameters

The project does not implement monitoring of the flow and water level of the Leguer.
Study of a pilot sub-basin
In the 2000s, the Comité du Bassin Versant du Léguer (CBVL) conducted a study of the Kervulu watershed (pilot basin) to assess the effect of hedgerow restoration and changes in practices on water quality.
Physico-chemical and chemical monitoring
A water quality monitoring network on pesticide parameters has been implemented since 2007, in addition to the existing monitoring network (WFD network).
Biodiversity monitoring
The Leguer hedgerow project, led by INRA (UMR BAGAP), aims to evaluate the role of the hedge as a shelter for auxiliary fauna, both through the in situ assessment of hedge biodiversity at the hedge and farm levels, and through the analysis of the ecological connectivity of the landscape and the establishment of ecological networks in planning documents.

Performance

Performance impact estimation method

Catchment outlet

Performance impact estimation information

A pre-configuration study was conducted to assess the effect of hedgerow restoration and practice changes on water quality.

Design & implementations

Project scale

Large

Project scale specification

The project is covering the entire Léguer river basin and specific research were conducted on sub-catchments.

Application scale

River Basin

Installation date

1999-2019

Area (ha)

50 000 ha

Area specifications

300 km of planted or restored hedges and embankement

Favourable preconditions

The planting of hedges helps to fight against erosion and improve the quality of surface water. The many co-benefits of this measure have contributed to the progressive extension of the restoration program to the entire watershed.

Design contractual arrangement

Arrangement type	Responsibility	Role	Comments	Name

Design consultation activity

Activity stage	Key issues	Name	Comments

Design land use change

Land use change type

Design authority

Authority type	Role	Responsibility	Name	Comments
Other	Initiation of the measure	Responsible	Lannion Trégor Communauté (LTC)	this is a mutli municipality administration, common organisation in France to gather resources to manage technical topics such as water, waste and other topics.
Local water authority	Initiation of the measure	Responsible	Comité bassin versant du Léguer (CBVL)

Lessons, risks, implications...

Key lessons

The area was primarily the subject of consolidation actions to increase size of fields by agriculture authorities. This led to an important destruction of hedgerows and some farmers were therefore reluctant to replant hedges shortly after. The fact a wood energy sector using wooden chips elaborated using recovered wood from the maintenance of hedges has helped convince local stakeholders to engage at such a large scale. Almost 300km of hedgerows and embankments have been restored in the basin. A reduction of chemical and nutrient pollution has been found. the research conducted showed the habitat role of hedgerows for agriculture auxilaries, made possible in oparticular with a diverse and good stratified hedge. The project has created a common dynamic towards preservation and restoration of hedges and embankment beyond farmers, including citizen and elected officials and created a territorial identity. The project leader underline is important to watch not only the increase of the hedgerows but also their maintenance.

Success factor(s)

Success factor type	Success factor role	Comments
Financing possibilities	main factor	The emergence of the wood sector (grove wood, production of wood chips to supply boilers) has been a real opportunity for farmers to find an economic interest. The gradual structuring of an energy wood sector allowing the valorization of wood from the maintenance of hedges in the form of logs or wood chips has helped convince the territory actors commit themselves on such a scale. Finally, the project benefited from the regional dynamics linked to the Breizh Bocage scheme.

Financing

Financing type	Comments
Local funds

Barrier

Barrier type	Barrier role	Comments
Attitude of relevant stakeholders	secondary barrier	Some farmers were reluctant to plant hedgerow lines soon after participating in land consolidation actions.

Driver

Driver type	Driver role	Comments

Financing share

Financing share type	Share	Comments

Policy, general governance and design targets

Policy description

The Léguer River is labelled a Wild River. Its catchment area is one of the most hedgerow territory in Brittany, with an average 150 meters of hedge per hectare. However, this hedgerow has been gradually eroded as a result of agricultural mechanization and land consolidation, as well as the phasing out of hedge and slope maintenance seen as a cost without any benefit. This decline was estimated at a loss of 3 linear meters per hectare per year.
The main objective of the project was to improve water quality and control erosion. Limiting runoff allows water to stay longer before reaching the watercourses, giving time to natural processes to occur to purify the water by soil microorganisms or light.
Secondly, the restoration of hedged land is of interest for biomass supply, biodiversity conservation, carbon sequestration, renewable wood production, for the wind-breaking role of hedges, livestock protection and landscape restoration.

Policy target

Target purpose

Policy pressure

Pressure directive	Relevant pressure

Policy area

Policy area type	Policy area focus	Name	Comments

Policy impact

Impact directive	Relevant impact

Policy wider plan

Wider plan type	Wider plan focus	Name	Comments
Regional	Environment & Biodiversity	"Breizh bocage"	The programme aims at the Brittany region level to enhance protection and restoration of hedgerow landscapes.

Policy requirement directive

Requirement directive	Specification

Biophysical impacts

Hydrological effects

The hydrological response to rain event seems longer than river basins with no action on hedgerows. Farmers also report complete stop of mud flows in lower areas of the fileds which were previously common problem.

Information on Water quality overall improvements

The study carried out in the Kervulu basin showed that the sub-basins that had been the subject of restoration of the hedgerow coupled with the adoption of rationale weed control practices contributed less to pollution (in particular phosphorus and pesticides) of surface water than the other basins.
Since the 2000s, an improvement has been observed on the nitrate parameter, while it was increasing in the 1990s.

Information on Reducing flood risks, quantity

During floods, it was observed that the hydrological behaviour of the Leguer appeared less reactive than that of other nearby rivers that had not been the subject of such a restoration program.
In addition, farmers report that they have noticed the disappearance of mud flows on the lower part of their fields following the creation of hedges that break the slope.

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