Item: Soil Erosion Caused by Snow Avalanches: Preliminary Results of Two Case Studies in the Aosta Valley (NW-Italy)
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Title: Soil Erosion Caused by Snow Avalanches: Preliminary Results of Two Case Studies in the Aosta Valley (NW-Italy)
Proceedings: Proceedings of the 2006 International Snow Science Workshop, Telluride, Colorado
Authors:
- M. Freppaz
- S. Lunardi [ Di.Va.P.R.A. – Laboratorio Neve e Suoli Alpini, Università di Torino, Italy ]
- M. Maggioni [ Di.Va.P.R.A. – Laboratorio Neve e Suoli Alpini, Università di Torino, Italy ]
- F. Valfrè [ Di.Va.P.R.A. – Laboratorio Neve e Suoli Alpini, Università di Torino, Italy ]
- T. Bizzocchi [ Di.Va.P.R.A. – Laboratorio Neve e Suoli Alpini, Università di Torino, Italy ]
- E. Zanini [ Di.Va.P.R.A. – Laboratorio Neve e Suoli Alpini, Università di Torino, Italy ]
Date: 2006
Abstract: Snow avalanches exert considerable erosive forces on soils, which may be torn open and scraped away, especially in the transition zone, as a result of the ground shear stress. Soil material mixes up with the avalanche body and is normally deposited at the bottom of the valley, originating specific forms of erosion and accumulative topography. The quantity of soil material eroded and accumulated depends on avalanche characteristics (e.g. dimension, full depth dry or wet avalanches) and on morphological features (e.g. channelled or unconfined avalanches, slope angle), but also on soil properties and vegetation cover. The monitoring of two channelled avalanche cones in the Aosta Valley (NW-Italy) was realized in order to assess the erosive impact of avalanches on soil. Sediment concentration estimates and measurements of the avalanche deposit volumes were used to calculate the total sediment load. The sediments collected were separated into the fine earth (<2mm) and large (>2mm) organic and mineral fractions. Preliminary results obtained from the winter season 2003-2004 showed that the amount of upwards eroded material deposited on the pre-existent soil at the foot of the avalanche paths was constituted mainly by the fine earth fraction. The organic carbon and total nitrogen content in the fine earth fraction was respectively equal to 8-9% and 0.39-0.42%. The total sediment load was estimated equal to 31 and 25 t/ha, with the greatest value recorded in the smallest avalanche cone. The considerable avalanche sediment deposits together with the great amount of water released during the snowmelt may influence the soil development in the deposition zone, contributing to determine specific pedo-environmental conditions.
Object ID: issw-2006-880-886.pdf
Language of Article: English
Presenter(s): Unknown
Keywords: soil properties, avalanche deposits, alps, organic carbon, total nitrogen
Page Number(s): 880-886
Subjects: snow avalanche aosta valley snow metamorphism
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