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Characteristics, distribution and geomorphic role of large woody debris in a mountain stream of the Chilean Andes
Author(s) -
Andreoli Andrea,
Comiti Francesco,
Lenzi Mario Aristide
Publication year - 2007
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.1593
Subject(s) - debris , large woody debris , geology , floodplain , sediment , hydrology (agriculture) , channel (broadcasting) , landslide , sediment transport , structural basin , geomorphology , streams , debris flow , habitat , geography , oceanography , riparian zone , ecology , geotechnical engineering , computer network , cartography , engineering , computer science , electrical engineering , biology
The paper presents an analysis of amounts, characteristics and morphological impact of large woody debris (LWD) in the Tres Arroyos stream, draining an old‐growth forested basin (9·1 km 2 ) of the Chilean Southern Andes. Large woody debris has been surveyed along a 1·5 km long channel section with an average slope of 0·07 and a general step–pool/cascade morphology. Specific wood storage is very high (656–710 m 3 ha −1 ), comparable to that recorded in old‐growth forested basins in the Pacific Northwest. Half of the LWD elements were located on the active floodplain, and around two‐thirds of LWD elements were found in accumulations. Different types of log jam were observed, some heavily altering channel morphology (log‐steps and valley jams), while others just line the channel edges (bankfull bench jams). Log‐steps represent approximately 22% of all steps, whereas the elevation loss due to LWD (log‐steps and valley jams) results in 27% loss of the total stream potential energy. About 1600 m 3 of sediment is stored in the main channel behind LWD structures, corresponding to approximately 150% of the annual sediment yield. Copyright © 2007 John Wiley & Sons, Ltd.