HR: 0800h
AN: H31B-02    [Abstracts]
TI: Geomorphic Effect of Wood in Southern Andes Streams: Evidences From Three Mountain Basins
AU: * Andreoli, A
EM: andrea.andreoli@unipd.it
AF: Dept. Land and Agroforest Environments, University of Padova, Viale Università 16, Legnaro (PD), Italy
AU: Comiti, F
EM: francesco.comiti@unipd.it
AF: Dept. Land and Agroforest Environments, University of Padova, Viale Università 16, Legnaro (PD), Italy
AU: Mao, L
EM: luca.mao@unipd.it
AF: Dept. Land and Agroforest Environments, University of Padova, Viale Università 16, Legnaro (PD), Italy
AU: Lenzi, M A
EM: marioaristide.lenzi@unipd.it
AF: Dept. Land and Agroforest Environments, University of Padova, Viale Università 16, Legnaro (PD), Italy
AU: Urciolo, A
EM: urciolo@tdfuego.com
AF: Subsecretaría de Recursos Naturales de Tierra del Fuego (SRNTF), San Martín 1401, Ushuaia, 9410, Argentina
AU: Iroumé, A
EM: airoume@uach.cl
AF: Instituto de Manejo Forestal, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
AU: Opazo, L
EM: luisopazo@uach.cl
AF: Instituto de Manejo Forestal, Universidad Austral de Chile, Casilla 567, Valdivia, Chile
AB: This study analyses large wood (LW) storage and the associated effects on channel morphology and flow hydraulics in three third-order mountain basins (drainage area 9-12 km²) covered in old-growth nothofagus forests, ranging from the temperate warm Chilean Andean Cordillera to the subantarctic Tierra del Fuego (Argentina). Amount, characteristics and dimensions of large wood (>10 cm large, > 1 m long) were recorded, as well as their effects on stream morphology, hydraulics and on sediment storage. Also, wood transport over a 1 year time period was assessed. Results show that major differences in LW abundance exist even between adjacent basins, due to the basins' disturbance history (fire). Massive LW volumes (i.e. > 1,000 m³ha^-1) can be reached in basins disturbed by fires followed by mass movements and debris flows. However, wood mobility at bankfull conditions appears quite scarce (<4% of the logs moved), with travel distances inversely related to the piece length/channel width ratio. Potential energy dissipation due to wood dams is about a quarter of the total elevation drop in two streams, with a the gross sediment volume stored behind wood dams of around 1,000 m³km^-1, which appears to be of the same order of the annual sediment yield. Finally, the presence of wood dams may increase flow resistance up to one order of magnitude.
DE: 1800 HYDROLOGY
DE: 1825 Geomorphology: fluvial (1625)
DE: 1862 Sediment transport (4558)
DE: 9360 South America
SC: Hydrology [H]
MN: 2007 Joint Assembly