Oued Righ (Algeria): Nature-based Solutions for Canal Restoration

This Case Study is located in Touggourt municipality, in the valley of Oued Righ, a geographical entity located in south-eastern Algeria. The Oued Righ canal crosses 12 municipalities over a distance of 150 km, ultimately terminating in the Chott Merouane wetland complex. It is an artificial infrastructure, and it is mainly used for drainage for the excess water from irrigation of palm groves and the disposal of wastewater, acting as a main collector.

Oued Righ is the richest part of Sahara Desert of Algeria in aquatic ecosystems. The presence of various wetlands in the region - e.g. canals, irrigation and drainage networks, salt lakes and salt marshes - create high suitable habitats for wildlife species. Fauna is therefore rich, especially regarding insects, reptiles and birds. Agricultural activity in the region is centred around date palm cultivation, often intercropped with vegetables and fruit trees. The socio-economic fabric of the area depends heavily on this oasis-based agriculture, which is increasingly threatened by declining water quality and salinization. The Oued Righ region has an arid climate, where summers are sweltering, arid, and clear, and the winters are cold, dry, and mostly clear. 

The canal faces significant environmental challenges, being one of the most important ones, water pollution. In the region there is only one wastewater treatment plant (WWTP), and it treats about 20% of the wastewater of the city of Touggourt, while, the rest of urban wastewater and agricultural drainage are discharged directly into the canal. The canal system suffers from eutrophication, sedimentation, and declining groundwater levels—partly due to drainage operations and historical mining activities. These pressures are further intensified by the impacts of climate change, threatening both ecosystem integrity and human well-being.

Other challenges include soil degradation (they are poor in organic matter and are very influenced by the water table), biodiversity loss, and inefficient wastewater management.

The main objective of this case study was the Improvement of the water quality of Oued Righ canal by reducing the discharge of wastewater and agriculture run-offs.

NATMed project, EU-funded project through the PRIMA Programme (n. 2221)

• Improved water quality in the Oued Righ canal through the reduction of untreated domestic wastewater discharges, supporting the recovery of aquatic ecosystems.
• Effective secondary treatment of domestic wastewater using constructed wetlands, enhancing the overall performance of the existing wastewater management system.
• Stabilisation of canal banks and reduced erosion through the combination of bioengineering techniques and civil works, protecting critical local infrastructure and improving hydromorphological conditions.
• Enhanced habitat quality and biodiversity supported by revegetation with native and halophytic species adapted to saline and arid conditions.
• Increased local awareness and capacity regarding sustainable water management and the role of NbS, supported by monitoring activities and stakeholder engagement.
• Strengthened resilience of the canal system to climate change impacts, including high temperatures, evaporation and variable flows.

• Constructed Wetlands implementation: Installation of a pilot-scale constructed wetland system based on a French vertical flow design to provide secondary treatment of domestic wastewater, improving effluent quality before discharge into the Oued Righ canal and supporting the performance of the existing WWTP.
• Canal banks restoration: Application of a hybrid solution combining nature-based and civil engineering measures, including dry-stone protection and revegetation with native and halophytic species, to stabilise canal banks, prevent erosion and protect critical infrastructure.
• Green infrastructure integration: Establishment of herbaceous and woody vegetation along canal banks and within the canal bed to enhance soil stability, habitat provision and natural water purification processes.
• Monitoring and impact assessment: Deployment of a comprehensive monitoring framework to assess water quality, soil quality, biodiversity and evapotranspiration.
• Stakeholder engagement: Active involvement of local stakeholders through co-design sessions to address local needs, barriers and long-term management considerations.

• A robust baseline diagnosis is essential for designing effective NbS. When site-specific data are limited, establishing an initial monitoring framework provides critical evidence to support informed design.
• NbS must be climate-adapted in arid environments. Arid climates with highly variable flows and high evapotranspiration require flexible designs and complementary measures (shading, windbreaks, alternative water sources) to maintain performance.
• Hybrid designs increase performance under complex pollution conditions. Combining natural treatment processes (phytofiltration, microbial degradation, and sorption) with engineered features (settling zones, aeration) increases robustness when pollution sources are mixed.
• Governance and local ownership determine long-term viability. Early community engagement and clear land-use arrangements reduce risks (grazing, vandalism, misuse) and improve maintenance continuity.
• Economic and scaling success depends on valuing co-benefits and institutional alignment. Life-cycle valuation, together with synergies with national/regional strategies and phased scaling plans, strengthens investment cases and supports replication.

Scientific and Technical Research Center for Arid Regions (Case Study Leader)

NBSCLIMATE (IUCN Assessment Leader)

CARTIF Technology Center (Project Coordination)

Khaled Amiri (CRSTRA), Nora Bouchahm (CRSTRA), Naçeur Eddine Bekkari (CRSTRA), Meïada Khellou (CRSTRA), Claudia Sánchez (NBSCLIMATE), Raquel Marijuan (CARTIF)