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Sediment mobility and bedload transport conditions in an alpine stream
Author(s) -
Mao Luca,
Lenzi Mario Aristide
Publication year - 2006
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.6372
Subject(s) - bed load , sediment transport , hyperconcentrated flow , sediment , hydrology (agriculture) , shear stress , geology , streams , environmental science , geotechnical engineering , geomorphology , mechanics , physics , computer network , computer science
The mobility conditions of bedload transport in an alpine high‐gradient step–pool stream (Rio Cordon) are analysed. Since 1986, a device system at the downstream end section of the stream has been operating in order to monitor the water discharge, suspended sediment and bedload transport. Sediment distribution of bedload transported by various floods has been analysed, and equal‐mobility evidence is recognized only for the high‐magnitude flows ever recorded (RI > 50 years). The thresholds for size‐selective and equal‐mobility transport conditions are identified and quantified by using both data provided by the fractional transport rate and by length displacements of marked particles. Size‐selective bedload transport seems to dominate when the critical shear stress of the size fractions τ c i considered is exceeded, whereas the equal‐mobility condition is approached as levels of excess shear stress become higher (τ eq i = 1·45τ c i ). Copyright © 2006 John Wiley & Sons, Ltd.