Tordera - Restoration of a secondary channel of the Tordera River
Tordera - Restoration of a secondary channel of the Tordera River
Key features of the case study
Between 2001 and 2003 a LIFE project was carried out to promote the sustainable management of the alluvial aquifer of the River Tordera. Few years after at the same place, a levee was removed and an old meander was restored to recover the lateral and longitudinal connectivity, restore habitat diversity and riparian vegetation communities while reducing the risk of flooding to flood return periods of 10 years.
Site description
Like in many Mediterranean rivers, water scarcity together with overexploitation of water resources leads to the fall of the water table and longer dry periods. Groundwater quality declines and supply sources for domestic use are contaminated. Protected wetlands dry up and biodiversity is lost, with consequent problems for conservation. Also, the proximity of urban areas caused the morphological and ecological degradation of a lateral meander that was filled with debris and rubble.
Measures selection
Both projects had multiple objectives. Water reuse serve as a pioneer example of sustainable management for other communities that may manage their water resources in similar ways. This initiative improved the wastewater system (soft treatments, wastewater treatment plant supplied by renewable energy) while the recycled water was allocated for conservation uses (aquifer recharge, wetland conservation, groundwater quality). Also, the morphological restoration brought multiple benefits: recover the original river path and the flivial space, based on the Guiding Image from 1967; rrecover the habitat diversity while improving flood control. Complementary actions were necesary to achieve these objectives: removing a lateral levee for rrestore lateral connectivity and increase flooding areas for water storage and flood control. Removing rubble for improve the composition of the riverbed was aalso a required measure.
Success criteria
Achievement of a good status of riparian vegetation, recover of the water table and water quality, enrichment of habitat diversity.
Ecological response
Hydromorphological response
Visits to the site after the restoration showed a good response for flow rising and self-maintenance of the meander.
Monitoring before and after implementation of the project
The Agencia Catalana del Agua developed a protocol for monitoring before, during, and after the implementation of the project. It comprised a diagnose and characterisation os PEF (Fluvial Space Planning), diagnose of the initial environmental status. Other indicators such as presence of exotic species, IVF (Riparian Vegetation Index) or biological indicators were used.
Socio-economic aspects
As an example of renewable energy and water resources sustainable management these projects may bring social, cultutal and educational benefits asides from ecological benefits. The enlargement of water storage and retention areas brings social benefits derived from avoided costs from flooding damages.
Contact person within the organization
Generalitat de Cataluña − Departamento de Medio Ambiente Lluis BALAGUER Dr. Roux, 80 08017 Barcelona
Extra background information
References
Related Measures
- Recycle used water
- Remeander water courses
- Remove hard engineering structures that impede lateral connectivity
- Construct semi-natural/articificial wetlands or aquatic habitats
