National Id
Switzerland_03
Site name
Chêne Bougeries
Summary
This case study is located in Switzerland, in the city of Chênes Bourgerie. It presents one of the natural water retention measures that can be implemented in urban areas to reduce runoff and flood risks. A retention pond is implemented on a plot to retain about 450m3 of water, which contribute to retain water at the watershed scale (279m3 for 3,1ha). The pond also provides a "natural" area which can be used as recreative area for neighboring private owners and contributes to reduce mosquitos density.
Light or indepth?
Light
NUTS Code
Ticino
RBD code
CH50
Transboundary
0
Data provider
Anais Hanus, ACTeon
Source(s)
Chemin du Vieux-clos: étang de rétention et biotope
NWRM(s) implemented in the case study
Retention Ponds
Longitude
6.187778
Latitude
46.197778
Climate zone
cool temperate moist
Mean rainfall
942
Mean rainfall unit
mm/year
Average temperature
10,1000003814697
Mean runoff
54
Mean runoff unit
0 - 150 mm
Average runoff coefficient
0,25
Type
Case Study Info
Average slope range
1-2%
Monitoring impacts effects
0
Performance impact estimation method
Unknown
Performance impact estimation information
null
Application scale
Plot
Installation date
1995
Lifespan
100
Performance timescale
< 1 year
Area (ha)
3,09999990463257
Area subject to Land use change or Management/Practice change (ha)
0,0299999993294477
Size
300
Size unit
m2
Design capacity description
The pond itself can retain 460m3; the estimated volume of retained water for the whole watershed is 279m3
Max water retention capacity
0,469999998807907
Max water retention capacity unit
m3/sec
Runoff treatment capacity unit
mm/month
Constraints
No particular constraint
Favourable preconditions
No particular favrable conditions
Public consultation
0
Contractural arrangements
0
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
Water bodies
Design authority
Authority type Role Responsibility Name Comments
Other
Initiation of the measure
Chêne Bougerie town
Financing
Architects
Private property owners
Determination of design details of the measure
Solfor SA
Architects
Private property owners
Implementation
Jacquet SA
Engineers
Key lessons
Example of how to retain water in urban areas
Financing mechanism
0
Success factor(s)
Success factor type Success factor role Comments
Attitude of relevant stakeholders
main factor

Since private owners are responsible for maintaining vegetation on their plots, the measure efficiency partly depends on their attitude
Legal obligations
secondary factor

Legal obligations can lead stakeholders to implemnt measures to retain water in urban areas
Financing
Financing type Comments
Local funds
Private funds
Barrier
Barrier type Barrier role Comments
Expected maintenance needs
secondary barrier
Private owners are responsible for maintaining vegetation on their plots
Driver
Driver type Driver role Comments
Other
main driver
The main driver which led to consider the measure was the new status of the land which became available to be constructed; water management became a major issue.
Other
main driver
The measure was estimated cheaper than another project (re-build existing infrastructures)
Legal obligations
main driver
The federal law on water protection requests rain water infiltration in urban areas through retention measures
Organisation committed to it
secondary driver
Geneva Canton elaboraed recommandations regarding water retention in urban areas
Financing share
Financing share type Share Comments
National funds
Private funds
Private owners finance vegetation maintenance
Policy description
The main targeted problem is the management of rainwater on a plot that is going to be constructed
Part of wider plan
0
Policy target
Target purpose
Increase Water Storage
Improved Biodiversity
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
National
Water
federal law on water protection, 24 january 1991
Local
Water
Cantonal law on water (L 2 05)
Policy requirement directive
Requirement directive Specification
Direct benefits information
The pond reduce runoff in the area and the damages it can generate
Ancillary benefits information
The pond provides a &quot;natural&quot; area which can be used as recreative area for neighboring private owners. It also contributed to reduce mosquitos density.
Costs operation maintenance
49000
Costs total
49000
Ecosystem improved biodiversity
1
Information on Ecosystem improved biodiversity
The pond provide habitat for fauna and flora, including aquatic flora
Ecosystem provisioning services
0
Ecosystem water supply
0
Ecosystem impact climate regulation
No information available
Increased water storage
90
Increased water storage unit
m3/ha
Information on increased water storage
279m3 can be retained at the watershed scale (3,1ha)
Water quality overall improvements
Not relevant for this application
Soil quality overall soil improvements
Not relevant for this application