Fluvial and ecosystem restoration of the Arga-Aragon Rivers, Spain

National Id
Site name
Ebro River Basin, lower reaches of the Arga River and lower and medium reaches of the Aragón River, Comunidad Foral de Navarra
Fluvial and ecosystem restoration of the Arga-Aragón Rivers systems by combining measures.
This initiative (partially carried out within the framework of the Mink Territory LIFE+ Project), implemented at the lower reaches of the Arga River and lower and medium reaches of the Aragón River (two of the main tributaries of the Ebro River, Comunidad Foral de Navarra, NE Spain), included a combination of measures involving meanders, wetlands, floodplains, riparian buffers and riverbed restoration and creation.
The in-depth description of the case study
Comunidad Foral de Navarra
RBD code
Data provider
Fernanda Milans (IMDEA Water) in close cooperation with Fernando Magdaleno Mas (CEDEX) whose valuable contribution is acknowledged and very much appreciated.
Climate zone
warm temperate dry
Mean annual rainfall
900 - 1200 mm
Mean rainfall unit
Average temperature
Mean runoff
Mean runoff unit
450 - 600 mm
Case Study Info
Light or indepth?
Monitoring impacts effects
Performance impact estimation method
Edge of Field/Plot
Performance impact estimation information
An external team made by independent assesos is in charge of the assessment. The assessors willl prepare a report which serve as a source to determine the degree of compliance with the objectives. The final outcome is the strict and meticulous monitoring of the project based on the reports required to assess the evolution of the measurable indicators defined in each of the actions.
Application scale
River Basin
Area (ha)
Area subject to Land use change or Management/Practice change (ha)
Favourable preconditions
- The low population density (60 inhabitants/km2 on average), the small and compact urban centres and the fact that buildings are fairly concentrated facilitate the needed intervention works. (Source: Anuario Estadí­stico, Instituto de Estadí­stica de Navarra, (2012))
- Natural and physical conditions allow N5, N4 and N8 to be carried out in the months of August and September, taking advantage of the low river flow during those months. Also N2, N3 and F1 can be easily carried out during those months when there is no plant growth (from November to February), in order to guarantee the plantation success.
- The fact that most of the compromised lands are publicly owned facilitates the negotiation with landowners to acquire the plots and make possible the restoration activities.
- Since the selected case-study site comprise not very productive lands (most of them poplar plantations) make cheaper the compensation required for the loss of profits derived from giving up the activities developed in the floodplains to be restored.
- The relatively high GDP per capita (29,071 in euros) of the area inhabitants and the fact that The Navarre Regional Government has its own financing capacity influence positively in the development of the planned intervention activities. (Source: Anuario Estadí­stico, Instituto de Estadí­stica de Navarra, (2012))
- The existence of a large riverside dimension and the large floodplains allows and facilitate the recovery of the river natural space.
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
Regional Government of Navarre
Government of Navarre with authority for environmental matters
TRAGSA (public company of the Spanish State)
Spanish public company.
Ministry of Agriculture, Food and the Environment (Spain)
Agriculture, Food and Environment - National authority
Regional / sub-national water authority
Ebro Basin Authority
Public company dependent of Navarre†™s regional government†™s environmental department. Its mandate includes environmental protection, conservation management and environmental education. Responsible for the technical administration and management of the LIFE+ project at stake in this case study, and also for project co-ordination.
The Navarran Environmental Resource Centre is a nonprofit foundation established on the initiative of the Government of Navarra and some public companies. Promotes public participation in issues of environmental and social inters.
Determination of design details of the measure
The Applied Techniques Research Centre (CETA) depends on CEDEX (Centre for Research and Experimentation of Public Works) and focuses its activities on studying the natural and human induced conditions and risks on the environment.
Key lessons
NWRMs are essential to fully integrate WFD, FRD, BHD and other related Directives.
GES, ESS, and other relevant concepts are all advancing in parallel paths, but have to be adequately interconnected through NWRMs.
Mediterranean Basins need NWRMs to avoid collapse (desertification, CC, anthropogenic impacts).
Med-rivers need intensive hydrogeomorphological restoration to support natural water retention.
Cost-benefit analyses commonly drive to NWRMs, but have to be developed on a truly scientific basis.
NWRMs require active public participation and best possible coordination
NWRMs help people and ecosystems, while committing legislation and optimizing our natural heritage.
Success factor(s)
Success factor type Success factor role Comments
Specific incentives for stakeholder involvement
main factor

Farmers commitments since they are the primarily affected by flooding events

Financing possibilities
main factor

Area of high ecological value (included in the LIC) and funding availability; LIFE+, LIFE-GERVE, INTEREG IIIAa GIRE-IMER and Regional Government of Navarre

Public participation
secondary factor

Most of the compromised lands are from municipal property and Navarre Regional government has its own financing capacity

secondary factor

Low population density and relatively high GDP per capita

Financing type Comments
EU-funds: LIFE+
National funds
Ministry of Agriculture, Food and the Environment (Spain)
Local funds
Regional Government of Navarre
Local funds
Ebro River Basin Authority.
Barrier type Barrier role Comments
Lacking coordination between authorities
main barrier
Differences in timings when developing the actions along the rivers
secondary barrier
Lack of knowledge of the actual functioning of the river system
Limited staff and consultant knowledge
secondary barrier
Lack of knowledge of specific preferences of flora and fauna, and interactions between habitats and species
secondary barrier
Lack of information about extreme hydrologic events
secondary barrier
Lack of post-project hydrogeomorphological behaviour
Driver type Driver role Comments
Balancing different objectives
main driver
The lower reaches of the Aragí³n and Arga rivers forms one of the Sites of Community Importance (SCI) included in the Natura 2000 network. The project area hosts a fifth of the species population in Navarra and two-thirds of the Iberian population; hence the importance of restoring the river ecosystems of the lower reaches of these two rivers for the global strategy of the species conservation.
Past flooding events
main driver
Give solution to the endemic flood challenges of the river system - shift from traditional paradigms
Financing share
Financing share type Share Comments
Policy description
The lower reaches of the Aragón and Arga rivers form one of the Sites of Community Importance (SCI) included in the Natura 2000 network. The area´s importance is mainly due to the presence of Mediterranean river forest habitats (Mediterranean poplar and willow forests) and species such as the European mink, otter (Lutra lutra), European pond turtle (Emys orbicularis) and night heron (Nycticorax nycticorax). In the past, dikes and breakwater defences were built to defend agricultural and forestry plantations along the rivers´ floodplains, and the Arga River was canalised to protect downstream towns from floods. These defence infrastructures have diminished the dynamics of these two rivers, resulting in a decrease in natural habitats, a reduction in biodiversity, losses of ecohydrological connectivity, deterioration of the role of the natural habitats as traps for water and sediments and decrease the functionality of the flow regime to contribute to good status of rivers and floodplains. The project comprises the lower reaches of the Arga River (from the mouth of the Salado River until the confluence of the Arga and Aragón Rivers) and the middle-lower reaches of Aragón River (from Carcastillo Village until the confluence of the Aragón and Ebro River).
Stability does not exist in these sections, major flooding events occured in February 2003 (Arga Q=930.2 m3/s T=15), in April 2007 (Arga Q=910 m3/s T= 10 Aragón Q= 1394 m3/s T=25) and in January 2010 (Aragón, Q= 806 m3/s Arga, Q= 730 m3/s T= 3-4).
The restoration of the floodplains and the natural habitats, will permit the coordinated application of the three European river management related Directives: the Habitats Directive (1992/43); the Water Framework Directive(2000/60); and the Flood Prevention Directive (2007/60). This also goes in line with the EU Biodiversity Strategy to 2020 (COM (2011) 244) seeking to address the protection and restoration of biodiversity and associated ecosystem services.
Part of wider plan
Policy target
Target purpose
Peak-flow reduction
Improved Biodiversity
Increase Water Storage
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
Environment & Biodiversity
Natura 2000 Network - SIC: ES2200035 / lower reaches of the Arga and Aragí³n rivers
National Plan of Rivers restauration / Hydrological connection of the lower reaches of the Arga and Aragí³n Rivers
INTERREG IIIa - GIRE "Integrated Management of European Rivers"
Environment & Biodiversity
Life project "GERVE - Ecosystemic Management of Rivers with European Mink"
Policy requirement directive
Requirement directive Specification
Direct benefits information
Flood risk reduction (Increasing water storage capacity)
Habitat and biodiversity conservation (recovering and increasing the European mink population)
Clear water (achieving the good ecological status (GES) according to the WFD).
Ancillary benefits information
Flood risk reductions avoid future economic losses arising from down stream flooding events.
Data from the 2003 flooding in Navarra indicate that the economic losses, including production losses and infrastructure damages, where estimated in more than 9 millions euros. In the case of the flooding event in 2007 the total amount of damages in public and private infrastructure and agricultural production losses were quantified in more than 8 millons euros. (Source: Gobierno de Navarra (2010)).
Local socio- economic benefits when developing the measures in terms of employment and local consumption
The provision of clear water in turn yields social benefits as recreational services and amenity (increased demand for recreation or increased number of visitors) and clean drinking water
Habitat and biodiversity conservation perform numerous ecosystem functions that provide multiple co-benefits as in the case of storing and fixing carbon, serving as wildlife habitats and ecological corridors, stabilizing stream banks, providing shade, organic matter, retaining sediments and filtering chemicals applied on agricultural sites on upslope regions.
Costs total
Costs total information
The total for the project Life+ Mink territory + total cost phase I and II for the project INTERREG IIIa GIRE-IMER restoring the "El Plantío"meander + total cost for the Life project GERVE restoration of the "Barranco Vallacuera"
Ecosystem improved biodiversity
Information on Ecosystem improved biodiversity
The measures seek to improve the overall river ecosystem, leading to the recovery and increase of forest habitats (Mediterranean poplar and willow forests), species such as the European mink, otter (Lutra lutra), European pond turtle (Emys orbicularis) and night heron (Nycticorax nycticorax) and its habitats in the area, together with a decrease in the main threats to this species.
Ecosystem provisioning services
Ecosystem impact climate regulation
Impact on GHGs (net emissions and storage) including soil carbon
Information on Ecosystem impact climate regulation
Climate control is another hydrologic function of wetlands and floodplains, by storing and capturing carbon. Also wetlands return in average, over two-thirds of their annual water inputs to the atmosphere through evapotranspiration (Richardson and McCarthy 1994). Wetlands also act to moderate temperature extremes in adjacent uplands (Brinson 1993).
Information on increased water storage
The measures enhance the water storage capacity since they can act as buffers. As in the case of wetlands and floodplains, both having the capacity to temporarily store flood waters, during high runoff events.
Information on runoff reduction
Wetlands and floodplain as the vegetation on the riparian area have the capacity to intercept and reduce the runoff. Also there is a reduce runoff from agricultural land since they should be reallocated.
Water quality overall improvements
Positive impact-WQ improvement
Information on Water quality overall improvements
The floodplain and wetlands contribute to nutrient retention, sedimentation and de-nitrification (retention of nitrogen and phosphorous) improving the water quality.
Soil quality overall soil improvements
Positive impact-SQ improvement
Information on Soil quality overall soil improvements
The plants that grow in wetlands and riparian areas are especially adapted for the high water levels, and high water flow energies. These plants have strong roots that helps to hold the soil in place, their leaves and stems help to protect the soil surface during high flow events. Then, they seek to conserve soils and its quality by reducing accelerated erosion.


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