Arga. Mejora Ambiental del meandro del Plantío
Arga. Mejora Ambiental del meandro del Plantío
Key features of the case study
Attention: The following text is a partial translation of the Project Summary (available in Spanish).
This project is the result of an initiative from the municipalities of Mañeru and Mendigorría. Gestión Ambiental, Viveros y Repoblaciones de Navarra S.A. in collaboration with Centro de Estudios y Experimentación de Obras Públicas del Ministerio de Fomento(CEDEX) designed the "Environmental Improvement of El Plantío meander".This work was framed within the Interreg IIIa TURN-IMER Comprehensive Management of European Rivers.The Department of Rural Development and Environment of the Navarra Government carried out the execution of the works.
An old meander has been used during years for agriculture, livestock and forestry, with low economic returns. These drivers changed the structure and composition of the riparian forest, being reduced to small patches or bands along the main channel. The meander and the floodplain around suffered morphological changes as a result of levelling.
Site description
The Arga river, tributory of the Aragon river, is one of the main rivers of the Ebro basin. The middle stretch of the Arga river is characterized by a meandering planform, flowing through Oligocene sandstone escarpments, with an annual contribution in natural regime 1450 Hm3 and a catchment area of 2290 km2. The riparian forest is composed by vegetal communities of willow, poplar, elm and tamarisk. The wildlife associated to this habitat has a great value for conservation purposes. Among the diversity of species we can find several mustelids, and species of diurnal and nocturnal birds of prey.
Measures selection
The objectives of the project were:
- Ecological restoration of the central subreach, subjected to lower anthropic pressure.
- Environmental recovery of the other subreaches, enabling some areas for Public Use.
- Improvement of the paths that connect the meander with Mendigorría and Mañeru, for its integration in the environmental education program linked to the values of the Arga river.
The first stage of the project comprised morphological naturalization of the area: recovering the old meander channel for recconect it with main channel, lowering the banks and restoring the topography of the old agricultural zones, giving them a more irregular look and enlarging the flooding. Apart from the ecological benefits, this would contribute for flood control.Also, two pools were established, and woody debris were placed in certain areas.
The second stage of the project had two objectives.The first one was helping the natural establishment of the riparian vegetation. The spread of vegetal propagules takes place naturally with the floods, but in order to accelerate the process, several techniques were used for revegetation: installation of biorolls, stakes, cuttings, rhizomes and plantations. Eight types of stands with and area lower than 1 hectare were defined, composed by different riparian species. Exotic species were removed for facilitate the establishment of native species and improve the composition of the riparian corridor.
The second objective of this phase is enhance the environmental education and awareness. For this purpose, volunteering activities took place during the plantation works. Of the 24 hectares object of the restoration, a 4 % is going to be adapted for recreational use through the installation of banks, information panels, and wildlife watching areas.
The third stage, consists of silvicultural treatments,irrigation works, and monitoring the evolution of the restored meander and the riparian corridor.
Success criteria
Ecological response
So far its too early to have ecological results, as the works finalised few weeks ago.
Hydromorphological response
Since the end of the works, the old meander has been flooded by two ordinary high flows, the 9th of November, 2009 (633 m3/s and T=2) and the 15th of January, 2010 (782 m3/s and T=4), so, until now the results can be considered positive.
Monitoring before and after implementation of the project
In collaboration with the University, a monitoring program will assess the effectiveness of the revegetation techniques, and other ecological and hidromorphological factors. Its duration is projected to last for 8 years, and the conclusions will be useful for the design of future restoration projects
Socio-economic aspects
The project was divided in three stages:
- Morphological restoration. Realised in 2009 with a budget of 129.916,97 euros in a period of 2 months.
- Revegetation of the riparian zone and Public Use adaptation. the budget is of 127.495,10 euros and the duration of the works of 5 months.
- Maintenance and Environmental Monitoring.
- Morphological restoration. Realised in 2009 with a budget of 129.916,97 euros in a period of 2 months.
The project emerged from the Town Council of Mendigorria and Mañeru, as an example for spread the benefits of river restoration. the municipalities participated in the design of the project. Also, the Public Participation was taken into account for incorporate technical proposals and suggestions of the diffrent social actors, and find a solution that reach together the objectives of the project and local preferences.
Contact person within the organization
- Fernando Magdaleno
- fernando.magdaleno@cedex.es
- Roberto Martínez
- roberto.martinez@cedex.es
- Área de Ingeniería Ambiental del CETA–CEDEX
- Centro de Estudios y Experimentación de Obras Públicas del Ministerio de Fomento
Extra background information
This area of Navarra frequently suffers inundations and flooding. The ecological restoration of different reaches at the low Arga river and Aragon river is linked to flood control. The ecological objectives (increasing the connectivity, improving habitats of great ecological value, creating longitudinal and lateral corridors, increasing the heterogeneity of the fluvial system and improving its hydromorphological conditions) are parallel to the protection of certain critical areas (mainly human settlements)[1].
More restoration projects have already been realised in the area, while others are planned of in progress.
References
Summary of the project in pdf format (Spanish) Media:Mejora ambiental meandro el Plantio.pdf
Pictures of the situation before, during and after the works, and plan of the actions (slides 9 - 11): Media:El Plantio remeandering.pdf
NEWS:
Related Measures
- Remeander water courses
- Develop riparian forest
- Revegetate riparian zones
- Construct semi-natural/articificial wetlands or aquatic habitats
