Restoration of river Hermance, France

General

National Id:

France_02

Site name:

Hermance river

Summary:

Hermance is a French/swiss transboundary river. From 2006, in the frame of a transboundary river management program, the SYMASOL has been implementing restoration measures along river in order to decrease flood risk downstream, supported amongst other by Geneva Canton. The river mouth have been widenned, the river has been remeandered, 2,3km of the river have been renaturated and vegetation have been planted back on banks. The Mermes marshland water retention power has been exploited through the creation of a retention pond. In addition to flood risk reduction for a hundred houses, the renaturation and restoration of a path along the river provided social benefits: people happen to appropriate again their river.

NUTS Code:

Rhône-Alpes

RBD code:

FRD

Transboundary:

Data provider:

Anaí¯s HANUS, ACTeon

Source(s):

Contrat de rivières transfrontalier du sud-ouest lémanique 2006-2012, Etude, bilan, évaluation et prospective, phase 1: état des lieux initial et final

www.symasol.fr

Contrat de rivières transfrontalier du sud-ouest lémanique 2006-2012, Etude, bilan, évaluation et prospective, phase 2: bilan technique et financier

NWRM(s) implemented in the case study:

Re-meandering

Stream bed re-naturalization

Riverbed material renaturalization

Natural bank stabilisation

Longitude:

6.273155

Latitude:

46.271137

Site information

Climate zone:

cool temperate moist

Mean rainfall:

1150

Mean rainfall unit:

mm/year

Average temperature:

Type:

Case Study Info

Light or indepth?:

Light

Vegetation class:

Predominant vegetation classes are crops and forests

Monitoring maintenance

Monitoring impacts effects:

Monitoring location:

In-Stream

Monitoring parameters:

Water quality (pesticides, nitrogen and metals) is monitored. Water flow and ecological quality are measured punctually

Monitoring upstream station:

There is a project of settling down a station upstream

Monitoring downstream station:

HER 379 and HER380

Performance

Performance impact estimation method:

Catchment outlet

Performance impact estimation information:

Comparison to the state before the implementation of the measure

Biophysical impacts

Water quality overall improvements:

Negative impact-WQ deterioration

Information on Water quality overall improvements:

Water quality has decreased during the implementation of the measure, but his can be linked to other factors (pressures...). Only hydrobiological quality (downstream) and metals (mouth) have stayed at the same level.

Soil quality overall soil improvements:

Not relevant for this application

Lessons, risks, implications...

Key lessons:

The case study provides an example of a bundle of measures which can be implemented to achieve several purposes; it does not gives much facts on biophysical impacts but provides interesting elements about succes and barrier factors; in this case as in many others, dealing with private owners in order to implement the measures on their properties have been the main difficulty.

Financing mechanism:

Financing difficulties:

Success factor(s):

Type	Role	Comments
Other	main factor	Contractors change for the different works; the SYMASOL considers that it is a good thing
Successful coordination between authorities	main factor	coordination between stakeholders, particularly in a transboundary watershed, was essentiel to guarantee the success of the implementation
Financing possibilities	main factor	Existing financing posibilities, including one from Geneva Canton, was a main succes factor

Financing:

Type	Comments
Sub-national funds	Sub-national funds were provided by water authority (Agence de l'Eau) and other authorities (Conseil régional rhí´ne Alpes, conseil général Haute Savoie).
Local funds	Local funds are water authority funds (SYMASOL) and other local authority funds (Canton of Geneva, Thonon town)
EU-funds: Rural development funds	EU contributed through FEADER fund
EU-funds: Cohesion and regional development funds	It also contributed through PSADER fund

Barrier:

Type	Role	Comments
Attitude of relevant stakeholders	main barrier	The main barrier has been dealing with land property; private owners were not ready to give away constructible lands and even in the case of existing regulations, they would not take away their fences. Negociations with private owners had to be done.
Attitude of the public	secondary barrier	At the beginning of the project, people were not convinced; after several achievements, they understand better.
Other	secondary barrier	The property issue has been considered to late; it needs to be anticipated.
Limited staff and consultant knowledge	secondary barrier	The design consultant was not aware of the local context in terms of vegetation for instance; it proposed to plant trees which were not adapted to the local climate

Driver:

Type	Role	Comments
Balancing different objectives	main driver	Local authorities decided to deal with their rivers management after some studies that showed the pressure of urbanisation and the need to restore water quality. They made a first preliminary dossier that led them to implement a River contract and create the SYMASOL
Legal obligations	secondary driver
		Objectives fixed by the SDAGE asked for implementing a management strategy

Financing share:

Share type	Share	Comments
European funds	3
National funds	97

Socio-economic

Direct benefits information:

The main benefit is social: people walk along the river and walkaways enable them to link the two sides of the city. People seem to make again the river their own and to became more aware of river management issues.

Costs investment:

357800

Costs investment information:

343800€ have financed the creation of retention areas along the Hermance river

Costs land acquisition:

64000

Costs land acquisition unit:

€ (total value)

Costs operation maintenance:

237300

Costs operation maintenance:

About 96000€ have been spent for restoring the banks of the Hermance river and 1000800€ have been spentto restore and renature the riverbed. 134331€ have been spent for widenning a discharge section. 5128€ have been spent for implementing grass buffer strips in the vineyards above the river, 10 000e/year are spent on haying in retention ponds.

Costs operational:

211300

Costs operational information:

About 96000€ have been spent for restoring the banks of the Hermance river (9,63€/m), corresponding to about 16 000€/year during six years. 166800€ have been spent per year during six years to restore and renature the riverbed. 134331€ have been spent for widenning an discharging section, that is to say 22400€ per year. About 100€/year have been spent on supporting grass buffer implementation in the vineyards above the river

Costs maintenance:

26000

Costs maintenance information:

About 96000€ have been spent to manage the newly planted vegetation along the Hermance riverbanks. Moreover, haying in retention ponds require about 10 000€/year.

Costs total:

1831600

Compensations annual:

2500

Compensations annual information:

About 14000€ have been received by farmers for income losses

Compensations nr beneficiaries:

Compensations nr beneficiaries information:

Farmers

Information on Economic costs - income loss:

Famers have received indemnisations for yield losses

Ecosystem improved biodiversity:

Information on Ecosystem improved biodiversity:

The river renaturation, banks restoration and riverbed works have benefited to natural habitats; fish population status have improved along the river: it passed from disturbed to excellent in one station, and to good in another one, between 2002 and 2011. Moreover, new plants can now be observed along the river.

Ecosystem impact climate regulation:

No information available

Ecosystem erosion control:

Policy, general governance and design targets

Policy description:

Main targeted problem is flood risk in urban areas downstream; erosion and habitats protection are also targeted

Quantified objectives:

The objectives are renaturing 4,4km of artificialised river, improving water retention capacity of a 5ha marshland

Part of wider plan:

Policy pressure:

Policy requirement directive:

Policy impact:

Policy wider plan:

Wider plan type	Wider plan focus	Name	Comments
Local	Water	Contrat de rivière transfrontalier Sud Ouest Lémanique	The plan defines water maagement strategy on rivers located in a watershed
Regional	Water	SDAGE Rhí´ne Méditerranée	The SDAGE defines the main objectives and strategies necessary to reach the good status for water bodies in 2021

Policy area:

Policy target:

Target purpose
Peak-flow reduction
Increase Water Storage
Erosion Control
Improved Biodiversity
Oher Societal Benefits

Design & implementations

Application scale:

River

Installation date:

2006

Lifespan:

100

Age:

Performance timescale:

1 - 4 years

Area (ha):

4320

Area subject to Land use change or Management/Practice change (ha):

7,5

Size:

13,5

Size unit:

Constraints:

No performance evaluation has been done after the measure was imlemented. Effects are hard to assess.

Favourable preconditions:

Areas relevant to retain water have been identified; the Mermes marshland appeared as an interesting retention place.

Management change from:

artificialised courses

Management change to:

natural courses / change in management practices in order to improve water retention

Crop rotation:

crops are mostly vineyards and fruit plantations without rotation

Outflow volume:

0,439999997615814

Outflow volume unit:

m3/sec

Peak flow rate:

42,5

Public consultation:

Contractural arrangements:

Design contractual arrangement:

Arrangement type	Role	Responsibility	Name	Comments
Contractual agreement			Contracts with private owners	Contractual arrangements have been signed with private owners about banks management

Design consultation activity:

Activity stage	Name	Key issues	Comments
Design phase	Information letters
Screening phase	Private interviews
Screening phase	Public meeting
Implementation phase	Public meeting

Design land use change:

Land use change type
Water courses

Design authority:

Authority type	Role	Name	Comments
Local water authority	Implementation	SYMASOL	Local water authority created to manage weter in the concerned watershed and impelement the River contract
	Monitoring
Other	Financing	Canton de Genève DIAE	swiss Canton of Geneva

Last updated: 12 Jan 2015 | Top

Miscellanous

Main menu

Restoration of river Hermance, France

Partners