The recovered space corresponding to the relief channel in the La Roza area will have a riparian corridor configuration with more continuity, complexity and diversity for habitats and species of flora and fauna of interest.
As part of the works for the morphological adaptation of the Ebro River in the area, completed in December 2023, a relief channel was built, 800 meters long and 100 meters wide.
But what is a relief channel? It is one of the types of interventions carried out for the recovery of the fluvial dynamics.
The relief channel temporarily brings forward, with a low-impact intervention, the flooding of the meander, allowing the water to enter it with less flow in circulation.
Relief channels are branches of the river that come into operation during floods:
馃敼 They can be artificial branches, excavated in the ground, or partially natural, when they connect with old branches of the river that have lost their functionality.
The relief channel is excavated at a higher level than the riverbed, so that when the water level rises, it flows through the two available routes.
馃敼 This intervention increases the width of the river when needed (in floods), reducing the height of the flowing water.
馃敼 It also makes it possible to direct water to areas of interest, to reduce pressure on the defenses of urban centers or to promote the functionality of bridges.
馃敼 It also increases the number of days of meander flooding, favoring the implementation and development of riverine habitats in a predominantly arid environment.
Restoration of vegetation in the relief channel.
The plant restoration of this relief channel is essential for several environmental reasons, among them, being in a Red Natura 2000 area.
How is this restoration being carried out? The Ebro Hydrographic Confederation is restoring the vegetation of this riverbed with plantations of native riverside species that will support the natural colonization of this area.
- Step 1: The relief channel slopes were seeded at the same time as the recessed mote in late 2023. Planting was by hand and broadcast with a mixture of herbaceous seeds that has been very successful in taking root.
- Step 2: plantings, started in February and still in progress, are carried out along the edge of the relief channel, in two longitudinal strips, to recreate the character of the vegetation corridor. A sufficiently large central area remains for spontaneous environmental restoration and for the seeding, to be carried out by the Government of La Rioja, of the final third of the riverbed with Festuca arundinacea, mainly.
The fact: in these strips, between plants and cuttings, more than 1,000 riparian species will be planted, using both mechanical and manual means.
The main species: shrub willows (Salix fragilis, Salix purpurea and Salix triandra), typical of the thickets of the middle stretch of the Ebro, and tamarisk (Tamarix gallica), a species that shares with the willows the first lines or banks of these riparian environments. Tree species such as Salix alba will also be used at the end of the relief channel to give continuity to the existing riparian forest. These species are resilient to the passage of floods.
Coordination and cooperation: all plant material to be used comes from forest nurseries managed by partners of the LIFE Ebro Resilience P1 project. Specifically, the willow cuttings and stakes are from the Marcilla nursery, managed by Gesti贸n Ambiental de Navarra (GAN). The tamarix plant comes from the nursery of Gurrea de G谩llego, managed by the Government of Arag贸n.
The LIFE Ebro Resilience P1 Project, through the Ebro Hydrographic Confederation, organized an informative planting with students of the Forestry Cycle of the Gonzalo de Berceo High School in Alfaro, La Rioja.
They learned about the project, its objectives and proposals for river restoration.
Restoration of the La Roza meander
Together with this intervention in the relief channel, the Government of La Rioja is carrying out, in this case, the environmental restoration of the entire meander of La Roza.
A total of 4,650 specimens of species typical of the Ebro riverbank and its groves will be introduced, imitating the natural growth of riparian vegetation and occupying an area of 12 hectares.