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
1
Data provider
Anaí¯s HANUS, ACTeon
Source(s)
NWRM(s) implemented in the case study
Longitude
6.273155
Latitude
46.271137
Site information
Climate zone
cool temperate moist
Mean rainfall
1150
Mean rainfall unit
mm/year
Average temperature
10
Type
Case Study Info
Light or indepth?
Light
Vegetation class
Predominant vegetation classes are crops and forests
Monitoring maintenance
Monitoring impacts effects
1
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
Design & implementations
Application scale
River
Installation date
2006
Lifespan
100
Age
6
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
km
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
1
Contractural arrangements
1
Design contractual arrangement
| Arrangement type | Responsibility | Role | Comments | Name | |
|---|---|---|---|---|---|
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Contractual agreement
|
Contractual arrangements have been signed with private owners about banks management
|
Contracts with private owners
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Design consultation activity
| Activity stage | Key issues | Name | Comments | |
|---|---|---|---|---|
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Design phase
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Information letters
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Screening phase
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Private interviews
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Screening phase
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Public meeting
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Implementation phase
|
Public meeting
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Design land use change
| Land use change type | |
|---|---|
|
Water courses
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Design authority
| Authority type | Role | Responsibility | Name | Comments | |
|---|---|---|---|---|---|
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
0
Financing difficulties
0
Success factor(s)
| Success factor type | Success factor role | Comments | |
|---|---|---|---|
|
Successful coordination between authorities
|
main factor
|
coordination between stakeholders, particularly in a transboundary watershed, was essentiel to guarantee the success of the implementation |
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Financing possibilities
|
main factor
|
Existing financing posibilities, including one from Geneva Canton, was a main succes factor |
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Other
|
main factor
|
Contractors change for the different works; the SYMASOL considers that it is a good thing |
Financing
| 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).
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Local funds
|
Local funds are water authority funds (SYMASOL) and other local authority funds (Canton of Geneva, Thonon town)
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EU-funds: Rural development funds
|
EU contributed through FEADER fund
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EU-funds: Cohesion and regional development funds
|
It also contributed through PSADER fund
|
Driver
| Driver type | Driver 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
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Legal obligations
|
secondary driver
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Objectives fixed by the SDAGE asked for implementing a management strategy
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Financing share
| Financing share type | Share | Comments | |
|---|---|---|---|
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
1
Policy target
| Target purpose | |
|---|---|
|
Peak-flow reduction
|
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Increase Water Storage
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Erosion Control
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Improved Biodiversity
|
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Oher Societal Benefits
|
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 | |
|---|---|---|---|---|
|
Local
|
Water
|
Contrat de rivière transfrontalier Sud Ouest Lémanique
|
The plan defines water maagement strategy on rivers located in a watershed
|
|
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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 requirement directive
| Requirement directive | Specification |
|---|
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
3
Compensations nr beneficiaries information
Farmers
Information on Economic costs - income loss
Famers have received indemnisations for yield losses
Ecosystem improved biodiversity
1
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
Biophysical impacts
Ecosystem erosion control
1
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
