Last updated: March 2025
In 2020, the Metropolitan City of Cagliari launched a project to enhance flood resilience and ecological integrity in the Mannu-Cixerri river system in southern Sardinia. The river traverses several communes within the metropolitan area, ultimately feeding into the Santa Gilla Lagoon, a vital wetland ecosystem west of the city. The project, with a budget of €21 million, focuses on three key communes: Assemini, Decimomannu, and Uta. Rather than solely emphasizing structural flood defenses, the initiative integrates nature-based solutions (NbS) to mitigate flood risks while restoring riverine ecosystems. The Metropolitan City of Cagliari, in collaboration with the Sardinian Regional Public Works Department, is responsible for its implementation. Key interventions include reinforcing and revegetating embankments, improving water flow along the Rio Mannu, and constructing new levee sections in a manner that enhances natural water retention. Additionally, the project involves upgrading bridges to facilitate better floodwater management. These measures align with the Sardinian Flood Risk Management Plan (PGRA) and aim to reduce flood hazards while promoting ecological benefits. The project timeline began with a two-year preparation phase for the Preliminary Design Document, followed by a year-long tendering process for construction. These efforts represent a crucial step toward long-term flood resilience and environmental sustainability in the region. (Ref. 1, 2, 3)
vegetation-takes-over
https://pianogestionerischioalluvioni.regione.sardegna.it/documenti/1_617_20211222120316.pdf
Overview
Nature-based solution
- Blue infrastructure
- Rivers/streams/canals/estuaries
- Riverbank/Lakeside greens
Key challenges
- Climate action for adaptation, resilience and mitigation (SDG 13)
- Climate change adaptation
- Green space, habitats and biodiversity (SDG 15)
- Green space creation and/or management
- Water management (SDG 6)
- Flood protection
- Stormwater and rainfall management and storage
- Inclusive and effective governance (SDG 16)
- Disaster-risk reduction
Principal problems in Functional Urban Area (FUA)
- Climate-Related Hazards
- River flooding
- Extreme weather events (e.g. storms, hurricanes)
- Land use and Socio-economic change
- Economic losses due to disasters and environmental degradation
Key priorities
Climate action (adaptation and/or mitigation)
Focus
Creation of new green areas, Creation of any other green urban spaces, Management and improved protection of rivers and other blue areas, River rehabilitation/ restoration, Restoration, protecion and sustainable manage floodplains, Restoration of riparian vegetation, Ecological restoration of ecosystems, Soil remediation and revegetation, Strategy, plan or policy development, Development of disaster-risk prevention strategies (e.g.fire management, flood alleviation scheme)
Project objectives
To reduce flood damage, particularly in areas surrounding the Santa Gilla Lagoon.
To improve the response to flash floods. As climate change causes shifts in weather patterns, leading to more intense and unpredictable rainfall, the project aims to mitigate the impact of these events.
To strengthen and raise existing levees, improve the water flow capacity of the Rio Mannu, and construct new sections of levees and riverbanks where necessary, and maintain existing riverbanks. These upgrades are designed to manage water levels during heavy rain and reduce the risk of overflow.
To reinforce and complement the Flood Risk Management Plan of Sardinia (PGRA), a strategy that aims at mitigating flood hazards and enhancing resilience in vulnerable areas. (Refs. 1, 2, 3, 5, 6, 8 & 9).
Implementation activities
The project is ongoing. In 2020, an agreement was signed between the Department of Public Works of the Sardinia Region and the Metropolitan City of Cagliari. From 2020 to 2022, the project focused on preparing the Preliminary Design Document. After consultation with regional offices, this document will be submitted for approval by the Metropolitan Mayor, paving the way for the tender procedure to begin. In 2023, the tendering process for the assignment of construction work was set to be completed.
Planned activities include creating, raising, and reinforcing riverbanks and embankments, which will allow vegetation to cover and stabilize the land. The project may also involve removing certain bridges to enable natural vegetation growth. Additional activities include maintaining existing banks, constructing flood discharges, creating overflow thresholds, reorganizing flood-prone hydraulic networks near existing banks, and improving the flow capacity of the Rio Mannu. (Refs. 1, 2, 3, 5, 6, 8 & 9)
Climate-focused activities
Climate change adaptation:
- Implement measures that prevent/manage desertification, soil erosion and landslides
- Implement sustainable urban drainage schemes to manage stormwater
- Restore rivers and other fresh water bodies to reduce flood or drought risk
Communities vulnerable to environmental hazards or climate change impacts
Yes
Specification of climate or environmentally vulnerable communities
Riverfront communities, Communities located in floodplains
Main beneficiaries
- Citizens or community groups
- Food producers and cultivators (i.e. farmers, gardeners)
Governance
Management set-up
- Co-governance with government and non-government actors
Type of initiating organisation
- Regional government
- Local government/municipality
Participatory approaches/ community involvement
- Co-planning (e.g. stakeholder workshops, focus groups, participatory mapping)
- Joint implementation (e.g. tree planting)
- Co-management/Joint management
Details on the roles of the organisations involved in the project
The Metropolitan City of Cagliari is tasked with managing and executing the project, which includes the design, planning, and coordination of the various interventions aimed at reducing flood risks in collaboration with local municipalities affected and with private actors charged with construction work or rehabilitation of the river. Overseeing the initiative is the Sardinian Regional Department of Public Works, which ensures that all activities align with regional policies and established flood risk management plans. The project is funded by CIPESS (the Interministerial Committee for Economic Planning and Sustainable Development). ( (Refs. 1, 2, 3 & 11)
Project implemented in response to ...
... an EU policy or strategy?
Yes
(The intervention is related to the regional Flood Risk Management Plan, envisaged by Directive 2007/60/EC which aims to reduce the negative consequences of floods on human health, the environment and society (Ref. 7).)
... a national policy or strategy?
Yes
(Legislative Decree 49/2010, which aims to reduce the negative consequences of floods on human health, the environment and society (Ref. 7).)
... a local policy or strategy?
Yes
(Il Piano di Gestione del Rischio Alluvioni della Sardegna (PGRA) (1))
Type of enablers
Change agents (individual with major role influence on launching), City network or regional partnerships focused on climate change, sustainability, GI or NBS in the city, Funds, subsidies or investment for GI/NBS in the city (available for the city or provided by the city)
Financing
Total cost
More than €4,000,000
Source(s) of funding
- Public national budget
Type of funding
- Direct funding (grants, subsidies, or self-financed projects by private entities)
Non-financial contribution
Unknown
Impacts and Monitoring
Environmental impacts
- Climate change
- Strengthened capacity to address climate hazards/natural disasters
- Expected strengthened capacity to address climate hazards/natural disasters
- Environmental quality
- Improved stability of slopes
- Expected improved stability of slopes
- Water management and blue areas
- Increased protection against flooding
- Expected increased protection against flooding
Economic impacts
- Unknown
Socio-cultural impacts
- Safety
- Improved community safety to climate-related hazards
- Expected improved community safety to climate-related hazards
Type of reported impacts
Presence of formal monitoring system
Yes
Presence of indicators used in reporting
Yes
Presence of monitoring/ evaluation reports
No evidence in public records
Availability of a web-based monitoring tool
No evidence in public records
Potential risks of implementation and trade-offs
Unknown
References
1.
L'Unione Sarda (2020). Rio Mannu-Cixerri, 21 milioni per la mitigazione del rischio idraulico. Accessed on September 12, 2024, [Source link];
2.
Cagliari Post (2020). Rio Mannu-Cixerri, al via progetto per la mitigazione del rischio idraulico. Accessed on September 12, 2024, [Source link];
3.
Casteddu Online (2020). Rio Mannu-Cixerri, al via progetto da 21 milioni di euro per la mitigazione del rischio idraulico. Cagliari: Casteddu Online, Accessed on September 12, 2024, [Source link];
4.
Regione Autonoma della Sardegna (2020). Ordinanza Commissario di Governo N.55 protocollo n. 1096 del 27/05/2020. Accessed on September 12, 2024, [Source link];
5.
Regione Autonoma della Sardegna (n.d.). Normativa. Accessed on September 12, 2024, [Source link];
6.
Regione Autonoma della Sardegna (2021). Piano di gestione del rischio di alluvioni . Accessed on September 12, 2024, [Source link];
7.
Giunta regionale Sardegna (2020). RISCHIO IDROGEOLOGICO, SOLINAS: OLTRE 160 INTERVENTI FINANZIATI. AL VIA LA PROGETTAZIONE DELLE OPERE SUL RIO MANNU-CIXERRI PER 21 MILIONI. Accessed on September 12, 2024, [Source link];
8.
Regione Autonoma della Sardegna (2021). Scenari di intervento strategico e coordinato: Rio Cixerri . Accessed on September 12, 2024, [Source link];
9.
Regione Autonoma della Sardegna (2021). Scenari di intervento strategico e coordinato: Flumini Mannu . Accessed on September 12, 2024, [Source link];
10.
Regione Autonoma della Sardegna (2023). MANUTENZIONE DEGLI ALVEI NATURALI E CANALIZZATI PRESSO LE SEZIONI IDROMETRICHE DELLA RETE DI MONITORAGGIO METEOROLOGICO E IDROPLUVIOMETRICO DELLA REGIONE SARDEGNA . Accessed on September 12, 2024, [Source link];
11.
Dipartimento per la programmazione e il coordinamento della politica economica (n.d.). Il Comitato interministeriale per la programmazione economica e lo sviluppo sostenibile. Accessed on September 12, 2024, [Source link];
12.
Comune di Cagliari 2022 (2022). Atlante Demografico di Cagliari 2022. Accessed on September 12, 2024, [Source link];
embankment
https://pianogestionerischioalluvioni.regione.sardegna.it/documenti/1_617_20211222120316.pdf
aerial-view
https://pianogestionerischioalluvioni.regione.sardegna.it/documenti/1_617_20211222120316.pdf
Information about this nature-based solution was collected as part of the Naturescapes project funded by the European Union under Grant Agreement No 101084341.