Ribeira da Granja, daylighting streams in Portugal
6 de February de 2018

“Ribeira” is the name the Portuguese use to say “ribeirão”, as we know streams in Brazil. And one of them, Ribeira da Granja, in the city of Porto, became the landmark of the process of recovering rivers in Portugal.
From 2009 to 2013, the engineer Pedro Teiga gave support, as a consultant, for the renaturation of streams in Porto. First, an evaluation of these water lines was made in terms of cartography. It was necessary to know its size, and what would be the priority to be recovered.
Some were in very “bad health”, “true sewers,” in Teiga’s words. But others had great learning potential: they could teach politicians and technicians how valuable it would be to remove rivers from underground galleries, return them to the surface, and how they could become an ecological corridor within the city itself.
In the first phase, a pilot was made, with Ribeira da Granja as its backdrop. It was possible to use natural engineering techniques to stabilize the banks, using coconut fiber, plaiting and living walls, as well as strengthening gallery forests. This process also mobilized the local population, creating a community involvement with the recovering process.
Pedro Teiga’s team knocked door to door. He explained what would be done in relation to the river, and how the process would be carried out. “The people, with their backs to the river, started looking at it,” explains the engineer. Many people did not believe that the process could happen. Gradually, the resistance was overcome. And young people were the first to explore the new natural setting for leisure activities.
The first phase resulted in the removal of 300-meter pipe from the Ribeira da Granja. The process involved heavy machinery, with the actual destruction of concrete structures. The reconfiguration of the stream, with the recovery of the riparian forest, also led to the creation of a flood retention basin. There were homes that were flooded every two years on average and today, with the changes, they can stay up to ten years without suffering from the floods.
Floods are inevitable, even by the location of these constructions. But the frequency of them is decreasing. And when they happen, it happens slowly. The waters have recovered the space to spread, and run with less strength and speed.
The vegetation species were selected to be used in the recovering process. A multidisciplinary team took care of the confection, the design and the development and monitoring of the work. This is also a very important phase, which can last up to 10 years – this is the period that Teiga understands as most suitable for the evaluation of the process.
As a pilot, the process started in the Ribeira da Granja made the practice to bury the rivers and make them run through the pipes water under the bridge now. “Portugal is no longer ‘tubing’ rivers,” says Pedro Teiga.
The work has resulted in several benefits, not only in the quality of life, but also the community and social achievements that add to the simple restoration of the natural conditions of the river. Public managers realized that renaturation was not just boldness by Germans, Dutch or Scandinavians. It can, indeed, occur not only in a region lacking Port, but throughout the country. Who knows, an initiative like Ribeirão da Granja can happen in Brazil, triggering the same process with our managers and our community.

Leave a Reply