Index Anillo Verde de Vitoria-Gasteiz

Development of Zadorra park in the Gamarra section 

Brief description
Situated at the confluence between the rivers Alegría and Zadorra, the park covers a surface area of approximately 10 hectares. It consists of 2700 m of pedestrian and cycle paths and contains the Gamarra sports complex.

Gamarra section is the result of the first stage of the overall development project of the river Zadorra. The section in which work has been completed runs between the bridge in Gamarra Mayor and the bridge on the A-1 dual carriageway, where this passes through Gamarra Menor. This work has been carried out through a Special Plan to prevent the flooding of the river Zadorra in the city centre of Vitoria-Gasteiz.

Initial status. Problem
As it flows through Vitoria-Gasteiz, the river Zadorra runs over an alluvial plain, which, before the construction of the reservoirs upstream, acted like a natural flood meadow, absorbing the floodwaters generated in the river basin.

The urban development of Vitoria-Gasteiz and the regulation of flows through the reservoirs were causing the progressive occupation of part of the flood plain. As a consequence of this situation, recently there have been several floods causing severe material damage in the city and on a number of roadways in the surrounding area, as well as in the villages of Gamarra Mayor and Gamarra Menor. The Gamarra industrial estate, near the place where the river Alegría flows into the river Zadorra, is one of the places which has been flooded most frequently in the past.

The development process
The aims of the Zadorra preparation plan, which includes the development of Gamarra section, are as follows:

• Reduce the effects of the periodic overflowing of the river Zadorra
• Recover the river ecosystem and in this way obtain a real biological corridor along the entire length of the river on which work is being done
• Provide the Green Belt, which surrounds the city of Vitoria-Gasteiz, with a sense of continuity, by preparing the river environment for use by the public

Within this overall project, the Special Plan for the defence against flooding along the section that runs from Gamarra bridge to the bridge on the A-1 dual carriageway, aimed to increase the hydraulic capacity of the river Zadorra as far as possible. The solution adopted consisted of digging a flood channel for the river Zadorra, leaving the present channel for ordinary flows and for the floodwaters of the river Alegría.

The environmental implications involved in its execution were taken into consideration at all times. An attempt was made to reduce as far as possible the negative effects and to maximise its positive effects. In this way, an attempt was made to take advantage of the possibilities offered by the area adjacent to the river Zadorra and the new channel as areas for leisure pursuits and recreation, as well as allowing visitors to gain firsthand knowledge of the rivers situated near the city.

The work affected 100,722 m2 and consisted of the following:

• The construction of a diversion dam in the river Zadorra, downstream from the bridge on the A-1 dual carriageway, integrated within the landscape of the land adjacent to the river
• Preparation of a new flood channel for the river Zadorra, adapted to the spontaneous vegetation and existing terrain, whose excavation was carried out in a natural manner through the formation of a low-water channel and the replanting of herbaceous species, trees and bushes
• Building of 2 asphalted roads to allow visitors access
• Replacement of the bicycle lane of the green way of the Vasco-Navarro railway with the installation of a metal lattice bridge with a wooden surface
• Widening of the river Zadorra downstream from the Gamarra bridge, in order to improve the drainage capacity of the river in this area

The total investment amounted to 3 million euros, of which 85% was provided by a cohesion fund of the European Union through the state company Aguas de la Cuenca del Ebro S.A. and the remaining 15% was provided by the Town Hall of Vitoria-Gasteiz.