Slope and climate variability control of erosion in the Andes of central Chile

2013

Article référencé dans le Web of Science WOS:000314327200025

Carretier Sébastien, Regard V., Vassallo R., Aguilar G., Martinod J., Riquelme R., Pepin E., Charrier R., Hérail Gérard, Farias M., Guyot Jean-Loup, Vargas G., Lagane Christelle

Geology, 2013, 41 (2), p. 195-198 ISSN 0091-7613

Climate and topography control millennial-scale mountain erosion, but their relative impacts remain matters of debate. Conflicting results may be explained by the influence of the erosion threshold and daily variability of runoff on long-term erosion. However, there is a lack of data documenting these erosion factors. Here we report suspended-load measurements, derived decennial erosion rates, and Be-10-derived millennial erosion rates along an exceptional climatic gradient in the Andes of central Chile. Both erosion rates (decennial and millenial) follow the same latitudinal trend, and peak where the climate is temperate (mean runoff similar to 500 mm yr(-1)). Both decennial and millennial erosion rates increase nonlinearly with slope toward a threshold of similar to 0.55 m/m. The comparison of these erosion rates shows that the contribution of rare and strong erosive events to millennial erosion increases from 0% in the humid zone to more than 90% in the arid zone. Our data confirm the primary role of slope as erosion control even under contrasting climates and support the view that the influence of runoff variability on millennial erosion rates increases with aridity.

Sciences du milieu [021] ; Hydrologie [062] ; Géologie et formations superficielles [064]

CHILI ; ANDES

Fonds IRD [F B010058978]

fdi:010058978