General
National Id
Italy_02
Site name
Draining basin of the Venice Lagoon - Venice province
Summary
The case study is located in the draining basin of the Venice Lagoon. It is characterized by intensive agriculture and by a web of drainage channels discharging into the rivers. This case study, in particular, includes measures on the drainage channels discharging into the Dese river, one of the main water bodies of the Venice Lagoon basin.
The Veneto Region, through the “Plan for diffuse pollution prevention and restoration of water in the draining basins of the Venice Lagoon” financed measures of re-calibration of riverbeds aimed at the renaturation of the hydraulic web, to increase the time of permanence of water and phytodepuration processes in the draining basin. In this framework, the Consorzio Acque Risorgive implemented a series of extended interventions on the area under its responsibility. This case study was implemented as part of these interventions.
In particular, it aimed at re-structuring the effluents of the mid course of the Dese river (Rio S. Martino, Rio S. Ambrogio and Scolo Desolino). Such effluents are mostly draining channels, draining water from agricultural fields to the Dese river. The primary objective was the reduction of the amount of N and P reaching the Venice lagoon through phytodepuration. However, at the same time the project carried out the restoration of the draining channel web aimed at reducing flooding issues affecting the area. Over the years, the area has in fact been subject to massive urban development (new residential and industrial areas), with consequent soil sealing and culverted effluents: this had a devastating effect on the hydrological system. The strong floods of 2006 and 2007 on the city of Mestre, for example, were a consequence of this.
The following measures were implemented: (i) Riparian buffer zones; (ii) Creation of wetlands; (iii) River bed enlargement; (iv) Creation and reconnection of floodplain and new buffer strips; and (v) Channel naturalization, creation of new meandering channel.
The ability of the measures to address two pressing environmental issues in the area was a key success factor. The measures proved in fact very effective in reducing nitrogen loads in effluents and, ultimately, into the Venice Lagoon, as well as mitigating flood risk in the area. During the implementation phase, some residents complained for the annoyance (e.g. the dust lifted by the machinery). However, during the first intense precipitation, the rivers/ channels did not overflow (they would have before implementation), so residents understood the key role of measures for flood mitigation. Furthermore, the overall decrease of N levels in the Venice lagoon, which followed the implementation of these and other similar measures in several sites within the draining basin, contributed to gain a positive public perception of these measures.
The Veneto Region, through the “Plan for diffuse pollution prevention and restoration of water in the draining basins of the Venice Lagoon” financed measures of re-calibration of riverbeds aimed at the renaturation of the hydraulic web, to increase the time of permanence of water and phytodepuration processes in the draining basin. In this framework, the Consorzio Acque Risorgive implemented a series of extended interventions on the area under its responsibility. This case study was implemented as part of these interventions.
In particular, it aimed at re-structuring the effluents of the mid course of the Dese river (Rio S. Martino, Rio S. Ambrogio and Scolo Desolino). Such effluents are mostly draining channels, draining water from agricultural fields to the Dese river. The primary objective was the reduction of the amount of N and P reaching the Venice lagoon through phytodepuration. However, at the same time the project carried out the restoration of the draining channel web aimed at reducing flooding issues affecting the area. Over the years, the area has in fact been subject to massive urban development (new residential and industrial areas), with consequent soil sealing and culverted effluents: this had a devastating effect on the hydrological system. The strong floods of 2006 and 2007 on the city of Mestre, for example, were a consequence of this.
The following measures were implemented: (i) Riparian buffer zones; (ii) Creation of wetlands; (iii) River bed enlargement; (iv) Creation and reconnection of floodplain and new buffer strips; and (v) Channel naturalization, creation of new meandering channel.
The ability of the measures to address two pressing environmental issues in the area was a key success factor. The measures proved in fact very effective in reducing nitrogen loads in effluents and, ultimately, into the Venice Lagoon, as well as mitigating flood risk in the area. During the implementation phase, some residents complained for the annoyance (e.g. the dust lifted by the machinery). However, during the first intense precipitation, the rivers/ channels did not overflow (they would have before implementation), so residents understood the key role of measures for flood mitigation. Furthermore, the overall decrease of N levels in the Venice lagoon, which followed the implementation of these and other similar measures in several sites within the draining basin, contributed to gain a positive public perception of these measures.
Light or indepth?
In-depth
The in-depth description of the case study
NUTS Code
Veneto
RBD code
ITA
Transboundary
0
Data provider
Gloria De Paoli, ACTeon
Source(s)
NWRM(s) implemented in the case study
Longitude
12.0629
Latitude
45.343
Site information
Climate zone
warm temperate moist
Mean annual rainfall
600 - 900 mm
Mean rainfall unit
mm/year
Average temperature
13
Type
Case Study Info
Average slope range
0-1%
Monitoring maintenance
Monitoring impacts effects
1
Monitoring location
Unknown
Monitoring parameters
Monitoring is supposed to be carried out by the Regional Agency for Environmental Protection, but actually little has been done so far. The Consorzio carried out some monitoring in some sites, but these data were not shared.
Specific monitoring of N retention was carried out in another site, where similar measures were also implemented by the Consorzio, in the experimental site NICOLAS.
Specific monitoring of N retention was carried out in another site, where similar measures were also implemented by the Consorzio, in the experimental site NICOLAS.
Performance
Performance impact estimation method
Catchment outlet
Performance impact estimation information
Unclear - In general, discharge measurements
Design & implementations
Application scale
Field Scale
Installation date
2009-05
Age
5
Performance timescale
< 1 year
Design capacity description
The measures were designed and modeled to protect from flood events generated by precipitations with a 30-years return time.
Basis of design
The measures were designed and modeled to protect from flood events generated by precipitations with a 30-years return time.
Constraints
No info
Favourable preconditions
No info
Outflow volume
25
Outflow volume unit
m3/sec
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 |
|---|---|---|---|---|
Lessons, risks, implications...
Key lessons
The visible positive impact and effectiveness of the measures was a key success factor, as well as a key element to increase environmental awareness in the area. In particular:
- The ability of the measures to address two pressing environmental issues in the area, while raising environmental quality at the same time, is a key success factor.
- Flooding events significantly decreased after the implementation of measures.
- The measures created pleasant natural environments and residents are now using the area for recreation (walking, biking). This has a great value in an area otherwise dominated by monoculture, with very little natural spaces.
- The ability of the measures to address two pressing environmental issues in the area, while raising environmental quality at the same time, is a key success factor.
- Flooding events significantly decreased after the implementation of measures.
- The measures created pleasant natural environments and residents are now using the area for recreation (walking, biking). This has a great value in an area otherwise dominated by monoculture, with very little natural spaces.
Financing difficulties
0
Success factor(s)
| Success factor type | Success factor role | Comments |
|---|---|---|
|
Other
|
main factor
|
The main success factor is the evident effectiveness of the measures! During the implementation phase, some residents complained for the annoyance (e.g. the dust lifted by the machinery). However, during the first intense precipitation, the rivers/ channels didn't overflow (they would have before implementation), so residents understood the key role of measures for flood mitigation. |
|
Other
|
main factor
|
The ability of the measures to address two pressing environmental issues in the area, while raising environmental quality at the same time, is a key success factor. |
|
Attitude of the public
|
secondary factor
|
The measures created pleasant natural environments and residents are now using the area for recreation (walking, biking). This has a great value in an area otherwise dominated by monoculture, with very little natural spaces. Furthermore, the possibility of doing recreational activities has raised residents' awareness and interest towards the importance and role of measures, as well as on the importance and value of natural areas. |
|
Other
|
secondary factor
|
The overall decrease of N levels in the Venice lagoon, which followed the implementation of these and other similar measures in several sites of the draining basin, contributed to gain a positive public perception of these measures. |
|
Financing possibilities
|
main factor
|
Availability of funds for this type of measures created by the Plan for the Venice Lagoon |
Financing
| Financing type | Comments |
|---|---|
|
National funds
|
The Veneto Region, through the "Plan for diffuse pollution prevention and restoration of water in the draining basins of the Venice Lagoon" financed measures of re-calibration of riverbeds aimed at the renaturation of the hydraulic web, to increase the time of permanence of water and phytodepuration processes in the draining basin.
|
Driver
| Driver type | Driver role | Comments |
|---|---|---|
|
Availability of subsidies
|
main driver
|
The Plan for the Venice Lagoon subsidized interventions to reduce eutrophication. The Consorzio chose NWRM because these measures also address flooding issues, quite common in the area
|
|
Other
|
secondary driver
|
Financing share
| Financing share type | Share | Comments |
|---|
Policy, general governance and design targets
Policy description
The project tackles two problems at the same time:
- Retain part of the N and P loads from agricultural activities in the basin through phytodepuration ,thus reducing the amount of nutrients reaching the Venice Lagoon (the Lagoon is affected by serious eutrophication issues)
- Reduce the incidence and intensity of flood events in the area. Flooding issues had increased in the decades before the interventions mainly because the sections of the drainage channels were too narrow to contain water discharges in critical periods of the years. When the channels were built, their size was sufficient to contain high discharges, but then the landscape had changed: urban sprawling increased impermeable land, and also agricultural drainage practices (e.g. tubular drainage)had changed increasing discharge into channels.
According to the project's authors, in the framework of integrated landscape planning these two objectives proved to be totally synergic
- Retain part of the N and P loads from agricultural activities in the basin through phytodepuration ,thus reducing the amount of nutrients reaching the Venice Lagoon (the Lagoon is affected by serious eutrophication issues)
- Reduce the incidence and intensity of flood events in the area. Flooding issues had increased in the decades before the interventions mainly because the sections of the drainage channels were too narrow to contain water discharges in critical periods of the years. When the channels were built, their size was sufficient to contain high discharges, but then the landscape had changed: urban sprawling increased impermeable land, and also agricultural drainage practices (e.g. tubular drainage)had changed increasing discharge into channels.
According to the project's authors, in the framework of integrated landscape planning these two objectives proved to be totally synergic
Quantified objectives
Expected impact on water quality (forecast based on experimental parameters from previous applied studies, caluclated in the design phase)
Total N reduction: 12.73 t/year
Total P reduction: 0.64 t/year
Total N reduction: 12.73 t/year
Total P reduction: 0.64 t/year
Part of wider plan
1
Policy target
| Target purpose |
|---|
|
Pollutants Removal
|
|
Peak-flow reduction
|
|
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 |
|---|---|---|---|
|
Plan for diffuse pollution prevention and restoration of water in the draining basins of the Venice Lagoon
|
The "Plan for diffuse pollution prevention and restoration of water in the draining basins of the Venice Lagoon" (entered into force in 2000) is aimed at addressing the serious eutrophication issues affecting the Venice Lagoon. The draining basin of the Venice Lagoon is in fact characterized by intensive agriculture, responsible for the discharge of large amounts of nutrients (N and P) into the lagoon. The Veneto Region, through the "Plan for diffuse pollution prevention and restoration of water in the draining basins of the Venice Lagoon" financed measures of re-calibration of riverbeds aimed at the renaturation of the hydraulic web, to increase the time of permanence of water and phytodepuration processes in the draining basin.
|
Policy requirement directive
| Requirement directive | Specification |
|---|
Socio-economic
Direct benefits information
Information not available
Ancillary benefits information
Information not available
Costs investment information
Information not available
Costs operation maintenance
Information not available
Costs total
4131655
Costs total information
Total financial costs
Compensations scheme information
Measures were implemented on private land, which was thus expropriated. Expropriation involves compensation for landowners, although the price paid is lower as compared to a purchase of land on the market.
Ecosystem improved biodiversity
1
Information on Ecosystem improved biodiversity
Overall, the environmental quality has increased, and new habitats were created. However, data on biodiversity improvements are not available
Ecosystem provisioning services
0
Information on Ecosystem provisioning services
Although measures have had a positive impact on water quality, water from rivers and channels is not used for human consumption, so "provision of clean water" has not been included in the list of ecosystem services.
Ecosystem impact climate regulation
Increased permanent biomas
Information on Ecosystem impact climate regulation
In buffer zones (but limited area)
Biophysical impacts
Information on Peak flow rate reduction
Overall, the peak flows discharged by rivers and channels to the Dese river decreased from 29 m3/s to 25 m3/s (13.8% overall reduction of peak flows into the Dese river)
Information on Ecosystem flood control volume
Overall, the peak flows discharged by rivers and channels to the Dese river decreased from 29 m3/s to 25 m3/s (13.8% overall reduction of peak flows into the Dese river)
Water quality overall improvements
Positive impact-WQ improvement
Information on Water quality overall improvements
Water quality improvements: the simulation conducted in the design phase indicate that a significant amount of nutrients can be retained by the measures. In addition, this is just one intervention areas, as similar measures were implemented in several other sites by the Consortium, as part of the Plan for the Venice lagoon: and, overall, since these interventions started the N content in the lagoon has actually decreased.
Information on Water quality Improvements (P)
Expected impact (forecast based on experimental parameters from previous applied studies)
Total P reduction: 0.64 t/year
Total P reduction: 0.64 t/year
Information on Water quality Improvements (N)
Expected impact (forecast based on experimental parameters from previous applied studies)
Total N reduction: 12.73 t/year
Total N reduction: 12.73 t/year