Resilient redevelopment of the banks of the
Bastan river

Assignment

. Vulnerability diagnosis (torrential floods, runoff, earthquakes)

. Redevelopment design

. Architects residence with ARM and Civic Wise associations

​Context​

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• The commune of Luz-Saint-Sauveur is located in the hollow of a valley whose highest point, at the level of Luz-Ardiden ski station, is at an altitude of 2500m.

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• The municipality is exposed to several types of flood risks (rising groundwater, submersible zones by overflowing streams and runoff) as well as seismic risk, avalanche, landslide, blocks falling and liquefaction.

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• Indeed, because of its geography, the commune suffers the steep slopes witch induce large flow corridors, defined by the ridge lines. The Bastan, the Yse and the Gave de Gavarnie Rivers allow to absorb a part of these flows but the complete management of the flood risk is complex. These three torrents are conducive to overflows when several factors are encountered. During the flood of 2013 for instance, the municipality had undergone heavy rainfall in early spring as well as significant snow melt following the first heat after a snowy winter.

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• Since then, the municipality has set up a Communal Safeguard Plan, which is currently being updated.

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• romote the integration of major risks in architecture to professionals and other publics to ensure a networking between specialized architects-students and professionals

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Concept

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• The objective of the project was to integrate the management of these risks with strong urban intentions to reveal the identity of the districts and to revitalize an attractive center between Luz-Saint-Sauveur and Esquièze, the neighboring municipality, on the north bank of the Bastan River.

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• A network of places has been developed around a requalification of each use, soil treatments and network of vehicles and pedestrians. Indeed, a new access near the current road crossing allows users to live, buy and work in Luz-Saint-Sauveur, rather than just crossing this village whose assets are hardly visible from the main roads.

• Two guiding threads have been developed to provide a common language, necessary for the discovery of the territory: the reuse of the materials available in the torrents bed after the floods in gabions and the introduction of water in urbanized areas, as a factor of conviviality and also to mark the floor risk in the daily life of the inhabitants.

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• After making a careful diagnosis of the structural condition of the buildings on several blocks, different grades of priority have been defined for the reinforcement and in agreement with the major urban intentions.

• Upstream, predictable volumes and speeds of water in case of high flood have been channeled through the development of a succession of infrastructures. In the village center and along the banks in its proximity, landscaping has been designed both for the security of habitats and the heritage and to invite to the discovery of the territory and to reveal the existing potentials of the municipality.

• One of the aims of the association of the Major Risks Architects is to sensitize institutional actors on the need to integrate architectural and preventive aspects in any type of spatial planning in risk zones.

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• During a week-long residence as assistants of the steering committee for the Bastan River banks redevelopment, we communicated about risks prevention by going to meet the inhabitants during several collective events (market, sheep festival) and by elaborating a questionnaire published on the website and the Facebook page of the town hall, aiming to sensitize and to get the population involved in the project, from planning to design an the construction site.

• Coming from these actions, we prepared a document that provides methodological support for the drafting of the design brief, with the objective to integrate the concept of flood risk into all the project phases.

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• The principle of a collaborative approach has been proposed. Indeed, it seems essential to us that the inhabitants are in the center of any urban project.

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• It is also the opportunity for the architect to introduce the concept of prevention and risk culture into the project. By participating in such a project, the citizen would take responsibility and learn naturally about the actions that can save him in case of disaster and about the technics that would enable him to improve his environment.

• In order to ensure continuity between Architecture&Marjor Risks training and the future professional missions of the association members, the final restitution of the work realized during that residence was the opportunity to introduce a long-term partnership for internships with the landscape agency which follow the project.