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Wood storage in three mountain streams of the Southern Andes and its hydro‐morphological effects
Author(s) -
Comiti Francesco,
Andreoli Andrea,
Mao Luca,
Lenzi Mario Aristide
Publication year - 2008
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.1541
Subject(s) - streams , hydrology (agriculture) , structural basin , geology , sediment , debris flow , temperate climate , debris , environmental science , geomorphology , ecology , oceanography , computer network , geotechnical engineering , computer science , biology
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 km 2 ) covered in old‐growth Nothofagus forests, ranging from the temperate warm Chilean Andean Cordillera to the sub‐Antarctic Tierra del Fuego (Argentina). Amount, characteristics and dimensions of large wood (>10 cm diameter, >1 m long) were recorded, as well as their effects on stream morphology, hydraulics and sediment storage. Results show that major differences in LW abundance exist even between adjacent basins, as a result of different disturbance histories and basin dissection. Massive LW volumes (i.e. >1000 m 3 ha −1 ) can be reached in basins disturbed by fires followed by mass movements and debris flows. Potential energy dissipation resulting from wood dams is about a quarter of the total elevation drop in two streams, with a gross sediment volume stored behind wood dams of around 1000 m 3 km −1 , which appears to be of the same order as the annual sediment yield. Finally, the presence of wood dams may increase flow resistance by up to one order of magnitude. Copyright © 2007 John Wiley & Sons, Ltd.