Index Anillo Verde de Vitoria-Gasteiz

Preparation of the wetlands of Salburua and restoration of their hydrological function

Brief description
Salburua park is located on the eastern fringes of the city. Salburua is a natural wetland formed by two main lakes (Arcaute and Betoño). Centuries ago, these were drained and converted into fields for farming.

Just two decades ago, it seemed that the disappearance of these lakes was inevitable. However, thanks to the recuperation work that began in 1994 and which still continues, the waters have begun to flood the area once again and the flora and fauna typical of this habitat have returned, converting Salburua into one of the most valuable wetlands in the Basque Country.

Initial status
After a gradual process of drainage begun in 1857, the state of the area in the mid Nineties was as follows:

• Betoño lake: the lake drained into the river Santo Tomás, so that in winter there was a pool that diminished rapidly with the onset of spring, making difficult for marsh plant and animal communities to establish themselves. The area around the lake showed signs of severe degradation due to the dumping of rubble into the lake, as well as illegal hunting, etc.
• Arkaute lake: this had been completely drained by a system of canals that flowed into the river Alegría. The area had been occupied mainly by crops although there was still a small mixed wood (the remains of a large oak woodland that covered the surrounding plains in the past) and a wet meadow grazed by horses, with botanical species typical of the land surrounding a lake.

In short, when the recovery work began, only a small wood had survived from the ancient, varied and rich landscape that existed to the north of Elorriaga remnant of the wetlands near Betoño where the last animals and plants typical of this medium fought for survival in an environment subject to all kinds of impact: poaching, slums, dumping of waste, etc.

The development process
Year started: 1994

Aims and criteria for the creation of Salburua park:

• Recover the environmental values and ecological functionality of the old wetlands
• Offer a "friendly" solution for the eastern boundaries of the city
• Secure the ecological and recreational continuity of the parks placed around the periphery of the city (Green Belt)
• Contribute to the work to prevent flooding in the centre of the city of Vitoria-Gasteiz
• Provide the eastern end of the city with a place suitable for the promotion of environmental awareness and the leisure activities of its citizens
• Promote scientific research in the area as a key tool to extend our knowledge of this environment as well as to facilitate the subsequent management of the wetlands

Restoration work performed

1- Environmentally-related actions

• Putting the drainage channels out of operation, construction of spillways, key dams, ridges and other structures designed to flood the lakes
• Removal of backfill materials used for construction of farm tracks
• Plant and landscape restoration actions around the lakes and along the water courses (33.25 hectares have been reforested with oak, and 2000 m of hedges have been planted)
• Diversification of environmental conditions in the creation of new biotopes (construction of islands, evacuation of basins, etc.)
• Release of a herd of deer for the maintenance of lakeside pastures
• Installation of fencing around the Arkaute lake to prevent dogs and people from gaining access to the lakes and in order to create a peaceful atmosphere for the animals

When the ecological restoration has been completed, the intention is to restore an area of more than 210 hectares, of which 60 are covered by water when the floodwaters are at their highest level.

2- Defensive actions against flooding

The restoration of Salburua has been closely linked to a project that aims to provide protection against flooding within the city of Vitoria-Gasteiz. This project plans to use the basins of the old lakes as separation pools for the extraordinarily high floodwaters (100 year return period) of the rivers Santo Tomás and Errekaleor, during which time a surface area of 83 hectares can be flooded, capable of containing water levels 1.5 m above their normal maximum height.

This involves diverting 1.2 million cubic meters of the flood volume of these rivers, which are released in a gradual and controlled manner through the spillway of the dam of the river Alegría through the Canal de la Balsa. The flow for the 100-year floodwaters into the river Alegría falls from 97 m3/sec to 22 m3/sec.

This has justified the expropriation of the private land affected by this project and the signing of an agreement with the administrative councils of Arkaute and Elorriaga, owners of a high percentage of the land, in order to cease agricultural activities and regenerate the lake complex.

3- Actions to plan and improve use by the public

• Creation of pedestrian routes and footbridges in the area surrounding the lakes
• Preparation of a sitting area with tables, benches and a fountain
• Installation of two fauna observatories
• Refurbishment of the old water tank in the village of Arkaute as a visitor reception centre with information on the services offered by the park. A television monitor has been installed to show images of a remotely controlled camera which provides images of the lake and its numerous inhabitants. These images can also be seen via the Internet

Current situation
Today, there are four floodable sectors which are, in order of size, Arcaute lake (the largest), Betoño lake, the Duranzarra lakes and lastly, Larregana lake. During periods of maximum flooding, taken as a whole, they add up to 66 hectares of water, which represents about one-third of the total surface area of the park, which, when finally completed, will occupy an area of 204 hectares.

In the rest of the park, a number of different plant communities are developed. A large portion of the park is given over to herbaceous planting, characteristic of soils with high humidity levels on the banks of lakes. There are also grassy areas suitable for public use. The wooded areas include a small oak wood near Arcaute as well as poplar groves and riverside copses. Lastly, a great deal of effort has been made in order to recover the woodland covering characteristic of the area and therefore a large part of the park (20% of its total surface area) has been reforested with species typical of oak woods.

The main installations for public use are located near the Arcaute lake, and consist of a sitting area, two observatories and a small information centre. Currently, there are 9 km of pathways with a number of wooden gangways placed over watercourses as well as footbridges over the streams that run through the area.

Future plans
Although it can be said today that the main structure of the park has been completed, there are still a number of actions that must be taken, some of which are crucial for the definitive consolidation of the park.

• The establishment of a hydrological protection perimeter around the wetlands in order to prevent the potential effects of the urban development around the Salburua park on the amount and quality of the water in the Betoño lake
• Ecological and landscape development of the areas where the park is to expand southwards
• Promotion of the ecological corridors between the wetlands and the natural areas nearby, especially the Vitoria Mountains range
• Construction at the northern end of the park of an Environmental Interpretation Centre, which has been given the name of “Ataria”, a multiuse building which is to house several different kinds of installations such as exhibition halls, an auditorium, a mirador and workshop-laboratory
• Actions to control access by the public and planting to shield the southern and western flanks of the Betoño lake, the intention of which is to reduce the possible impact on the wetlands due to the closeness of the new urban development states as well as their associated roadways