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. Light or indepth? In-depth The in-depth description of the case study cs-it-02-final_version.pdf NUTS Code Veneto RBD code ITA Transboundary 0 Data provider Gloria De Paoli, ACTeon Source(s) Interventi estesi di riqualificazione fluviale lungo gli affluenti del medio corso del Fiume Dese Phone interview Italy Bruno Boz was actively involved in the design and implementation of these measures, as well as the other applications implemented by the Consorzio NWRM(s) implemented in the case study Buffer strips and hedges Wetland restoration and management Re-meandering Riverbed material renaturalization 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. 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 Local water authority Initiation of the measure Consorzio Acque Risorgive Consorzio di bonifica: local water authority in charge of managing and maintaining the irrigation network as well as the provision of irrigation water Local water authority Implementation Consorzio Acque Risorgive Other Financing Veneto Region Provincial Administration - Funding (through the †œPlan for diffuse pollution prevention and restoration of water in the draining basins of the Venice Lagoon†) Determination of design details of the measure Ingegneria 2P e Associati External consulting firm (contractor) - design of measures Other Bruno Boz †“ free-lance professional and member of CIRF External Consulting (design, implementation and evaluation) Monitoring University of Bologna 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. Financing difficulties 0 Success factor(s) Success factor type Success factor role Comments Other main factor Other main factor Attitude of the public secondary factor Other secondary factor Financing possibilities main factor 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. Barrier Barrier type Barrier role Comments Other secondary barrier The design of intervention was contracted to an external engineering firm, which did not have a capillary knowledge of the area and the territory, so this created some problems Other secondary barrier In some cases, negotiations for expropriations posed some challenges Other secondary barrier After implementation, there were some little problems with farmers: in some cases, trees and plants cast shadows on crops. 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 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 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 Information on Water quality Improvements (N) Expected impact (forecast based on experimental parameters from previous applied studies) Total N reduction: 12.73 t/year Full Context Pathway(aka Context) Default view Area(aka Level or Site) ALL