Géomorphologie dynamique et aménagement des versants en moyenne Tarentaise : (Savoie, communes de Granier, Aime, Macôt-La Plagne et Champagny) : une contribution à l'étude de l'érosion naturelle et anthropique des Alpes
Institution:
Université Joseph Fourier (Grenoble)Disciplines:
Directors:
Abstract EN:
Several slopes of Tarentaise have a rapid erosion, by place this one is increased by man's activities. With a surface of 30 km2, oriented n-s, the study area, located in interior of alps, is made of quartzite, gypsum and glacial clay formations. Between 800 and 2000m, these rocks are destroyed by a growing weathering. The mountain climate of the study area has been measured by several thermographs and pluviographs (during 1984, 1985, 1986). Above 2000m, the periglacial processes dominate and induce rockfalls in quartzite cliffs and step in gypsum karstification. On this altitude, the building of the skiing resort of la Plagne has quickened erosion. Under 2000 m, the biostasy predominates but the concentration of waters causes gullying which the reafforestation and development of talwegs have attempted to stop, since the nineteenth century. These works done by r. T. M. Have slowed down the hemming on of the torrent reclaz of Champagny. Owing to many technics of measures, in situ, erosion is followed with accuracy. Models of morphodynamic evolution have been proposed. For 10 000 years, quartzite has eroded from 0. 01 to 0. 25 mm a year, gypsum from 0. 5 to 2 mm a year and clay slopes have been gullying 1 mm a year. Considered as revealing the dynamic of our environnement, erosion has been conceived as the result of inter-relations of morphdynamic parameters of the environnement and each time it is replaced within the context of geosystemic unities.
Abstract FR:
Grâce à plusieurs techniques de mesures, in situ, l'érosion est suivie avec précision. Des modèles d'évolution morphodynamique sont proposés. Depuis 10 000 ans, le quartzite s'érode de 0,01 a 0,25 mm an, le gypse de 0,5 a 2 mm an et les versants argileux ravines, de 1 mm an. Considérée comme révélatrice de la dynamique de l'environnement, l'érosion a été perçue comme la résultante des interrelations des paramètres morphodynamiques du milieu et chaque fois replacée dans le cadre d'unités géosystèmiques. L'intérêt, pour l'aménagement, d'une géomorphologie applicable est évoqué.