The present work shows how sediment composition can be used to constrain bed load sediment budgets in mountain catchments. A database of high-resolution petrographic and dense-mineral analyses of detritus carried by the Dora Baltea River and its tributaries allowed us to partition bed-load sediment budgets, obtained from data available from a public authority, between two different sets of sediment sources (major tributaries and major geological units). Relative and absolute budgets of sediment bed-load thus obtained are more robust than those derived from traditional empirical methods alone. Total detrital flux in the Dora Baltea drainage basin is 1,000,000 ton/year (bed-load 590,000 ton/year, suspended load 410,000 ton/year), with denudation rates of 0.12 mm/year (data from Italian public authority-Progetto di piano stralcio per l'assetto idrogeologico (PAI). Parma, Supplemento Straordinario della Gazzetta Ufficiale 166). More than 75% of the Dora Baltea total bed-load (453,000 9000 ton/year) is derived from tributaries (Dora di Ferret, Dora di Veny, Savara, Grand Eyvia, Buthier, Lys) sourced from the highest granitoid peaks (>4000 m a.s.l.: M. Bianco, M. Rosa, M. Cervino, Gran Paradiso massifs), which drain 36% of the whole catchment. The M. Bianco Massif, with its granitoid lithology, extreme relief and heavily glaciated drainage basins, occupies only 3% of total basin area, but it produces 294,000 +/- 6000 tons of arkosic sands per year, which represents 50% of total Dora Baltea bed-load. The Dora di Veny (2% of total Dora Baltea mountain catchment) exhibits the highest denudation rate of the whole Dora Baltea mountain basin (0.73 mm/year). The values calculated in this study compare well with measured modem river loads of pardy glaciated m:id-latitude mountain regions. (C) 2004 Elsevier B.V. All rights reserved.
|Citazione:||Vezzoli, G. (2004). Erosion in the Western Alps (Dora Baltea basin): 2. Quantifying sediment yield. SEDIMENTARY GEOLOGY, 171(01-apr), 247-259.|
|Tipo:||Articolo in rivista - Articolo scientifico|
|Carattere della pubblicazione:||Scientifica|
|Titolo:||Erosion in the Western Alps (Dora Baltea basin): 2. Quantifying sediment yield|
|Autori interni:||VEZZOLI, GIOVANNI|
|Data di pubblicazione:||15-ott-2004|
|Appare nelle tipologie:||01 - Articolo su rivista|