Author(s)

J. L. García, J. A. Cuchí & R. Gairín

Abstract

Canfranc-village is situated on the alluvial cone of a torrent called ‘Los Meses’. The village lies on the highway to France (N-330), along the right bank of the river Aragon, into which the torrent discharges. The progressive deforestation of the basin of this ravine for the purposes of agriculture, pastures and firewood, a circumstance common in many Pyrenean valleys, caused the torrent to become dangerous for the village during the 18th and 19th centuries. In fact, it was so dangerous that the local people were forced to work to build and fortify a defensive stone wall every time there was a flood. The wall once stood at a height of more than 5m, and a width of almost 4m. Finally, at the beginning of the 20th century, the Spanish engineers Ayerbe and Azpeitia took charge of the stream control works. The stream control works carried out were cause for admiration in the profession. There is indeed considerable bibliography preserved from that time in which the dangers of the torrent and the magnificent works that inactivated it are described. Nevertheless, inexplicably no administration has preserved any trace of the original document for those stream control works. The succession of check-dams, perfectly integrated into the profile of the bed and the landscape, not only causes a compensation slope, but makes each dike section get wider, and it also acts like an area of lamination on the avenue. Because of that, and because of the large size of the materials and the soil and moss that grow on them, the values of the solid flows do not seem very credible. It is very unlikely that these materials will move, but even if they did, it would be less probable that they could be found in the outlet of the basin. Numerous structures, as well as profuse vegetation, would stop them. It is easy to observe that in some check-dams the flow digresses over deposited materials, like in a small alluvial cone. Keywords: torrential hydraulics, debris flow, restoration works.

Keywords

torrential hydraulics, debris flow, restoration works.