HESS Hydrology and Earth System Sciences HESS Hydrol. Earth Syst. Sci. 1607-7938 Copernicus Publications Göttingen, Germany 10.5194/hess-16-517-2012 Estimation of soil redistribution rates due to snow cover related processes in a mountainous area (Valle d'Aosta, NW Italy) Ceaglio E. 1 2 3 Meusburger K. 4 Freppaz M. 1 Zanini E. 1 Alewell C. 4 Dipartimento di Valorizzazione e Protezione delle Risorse Agroforestali – DIVAPRA, Chimica Agraria e Pedologia, LNSA and NatRisk, University of Torino – Via Leonardo Da Vinci 44, 10095 Grugliasco (TO), Italy Ufficio neve e valanghe, Direzione assetto idrogeologico dei bacini montani, Regione Autonoma Valle d'Aosta, Loc. Amérique 44, 11020 Quart (AO), Italy Fondazione Montagna Sicura – Montagne Sûre, Villa Cameron, Località Villard de la Palud 1, 11013 Courmayeur (AO), Italy Institute of Environmental Geosciences, University of Basel, Bernoullistr. 30, 4056 Basel, Switzerland 17 02 2012 16 2 517 528 Copyright: © 2012 E. Ceaglio et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://hess.copernicus.org/articles/16/517/2012/hess-16-517-2012.html The full text article is available as a PDF file from https://hess.copernicus.org/articles/16/517/2012/hess-16-517-2012.pdf

Mountain areas are widely affected by soil erosion, which is generally linked to runoff processes occurring in the growing season and snowmelt period. Also processes like snow gliding and full-depth snow avalanches may be important factors that can enhance soil erosion, however the role and importance of snow movements as agents of soil redistribution are not well understood yet. The aim of this study was to provide information on the relative importance of snow related processes in comparison to runoff processes. In the study area, which is an avalanche path characterized by intense snow movements, soil redistribution rates were quantified with two methods: (i) by field measurements of sediment yield in an avalanche deposition area during 2009 and 2010 winter seasons; (ii) by caesium-137 method, which supplies the cumulative net soil loss/gain since 1986, including all the soil erosion processes. The snow related soil accumulation estimated with data from the deposit area (27.5 Mg ha<sup>−1</sup> event<sup>−1</sup> and 161.0 Mg ha<sup>−1</sup> event<sup>−1</sup>) was not only higher than the yearly sediment amounts, reported in literature, due to runoff processes, but it was even more intense than the yearly total deposition rate assessed with <sup>137</sup>Cs (12.6 Mg ha<sup>−1</sup> yr<sup>−1</sup>). The snow related soil erosion rates estimated from the sediment yield at the avalanche deposit area (3.7 Mg ha<sup>−1</sup> and 20.8 Mg ha<sup>−1</sup>) were greater than the erosion rates reported in literature and related to runoff processes; they were comparable to the yearly total erosion rates assessed with the <sup>137</sup>Cs method (13.4 Mg ha<sup>−1</sup> yr<sup>−1</sup> and 8.8 Mg ha<sup>−1</sup> yr<sup>−1</sup>). The <sup>137</sup>Cs method also showed that, where the ground avalanche does not release, the erosion and deposition of soil particles from the upper part of the basin was considerable and likely related to snow gliding. Even though the comparison of both the approaches is linked to high methodological uncertainties, mainly due to the different spatial and temporal scales considered, we still can deduce, from the similarity of the erosion rates, that soil redistribution in this catchment is driven by snow movement, with a greater impact in comparison to the runoff processes occurring in the snow-free season. Nonetheless, the study highlights that soil erosion processes due to the snow movements should be considered in the assessment of soil vulnerability in mountain areas, as they significantly determine the pattern of soil redistribution.

 References Ackroyd, P.: Erosion by snow avalanche and implications for geomorphic stability, Torlesse Range, New Zealand, Arctic Alpine Res., 19, 65–70, 1987. Agnesod, G., Operti, C., Zappa C., and Capodaglio, P.: Distribuzione comparata di Cs137 in diverse matrici ambientali sul territorio della Valle d'Aosta. ARPA (Agenzia Regionale per la Protezione dell'Ambiente), "Atti del III Convegno nazionale Controllo ambientale degli agenti fisici: dal monitoraggio alle azioni di risanamento e bonifica", Biella, 7-8-9 giugno, 2006. Bell, L., Gardner, J., and DeScally, F.: An estimate of snow avalanche debris transport, Kaghan Valley, Himalaya, Pakistan, Arctic Alpine Res., 22, 317–321, 1990. Bonnett, P. J. P.: A review of the erosional behavior of radionuclides in selected drainage basins, Journal of Environmental Radioactivity, 11, 251–266, 1990. Boubakari, M. and Morgan, R. P. C.: Contour grass strips for soil erosion control on steep lands: a laboratory evaluation, Soil Use Manage, 15, 21–26, 1999. Bozhinskiy, A. N. and Losev, K. S.: The fundamentals of avalanche science, Mitteilungen des Eidgenössisches Institute für Schnee- und Lawinenforschung, 55, 280 pp., p.&nbsp;227 (Translation of "Osnovy Lavinovedeniya", Leningrad, Gidrometeoizdat, 1987 by C.&nbsp;Bartelt), 1998. Caine, N.: A model for alpine talus slope evolution by slush avalanching, J. Geol., 77, 92–100, 1969a. Confortola, G., Maggioni, M., Freppaz, M., and Bocchiola, D.: Modelling soil removal from snow avalanches: a case study in the Italian Alps, Cold Regions Sci. Technol., 70, 43–52, 2011. Descroix, L. and Mathys, N.: Processes, spatio-temporal factors and measurements of current erosion in the French Southern Alps: A review, Earth. Surf. Proc. Land., 28, 993–1011, 2003. European Avalanche Warning Services: <a href="http://avalanches.org/">http://avalanches.org/</a>, last access: 11 February 2012. Facchinelli, A., Magnini, M., Gallini, L., and Bonifacio, E.: <sup>137</sup>Cs contamination from Chernobyl of soils in Piemonte (North-West Italy): spatial distribution and deposition model, Water Air Soil Pollut., 134, 341–352, 2002. Felix, R. and Johannes, B.: Bodenerosionsuntersuchungen auf Testparzellen im Kalkhochgebirge, Mittlgn. Österreich, Geogr. Ges., 137, 76–92, 1995. Freppaz, M., Lunardi, S., Maggioni, M., Valfrè, F., Bizzocchi, T., and Zanini, E.: Soil erosion caused by snow avalanches: preliminary results of two case studies in the Aosta Valley (NW-Italy), Poster Session, ISSW 2006, Telluride, Colorado, October 2006, 880–886, 2006. Freppaz, M., Godone, D., Filippa, G., Maggioni, M., Lunardi, S., Williams, M. W., and Zanini, E.: Soil erosion caused by snow avalanches: a case study in the Aosta Valley (NW Italy), Arctic, AntArctic Alpine Res., 42, 412–421, 2010. Gabriels, D., Ghekiere, G., Schiettecatte, W., and Rottiers, I.: Assessment of USLE cover-management C-factors for 40 crop rotation systems on arable farms in the Kemmelbeek watershed, Belgium. Soil Till. Res., 74, 47–53, 2003. Gardner, J. S.: Observations on erosion by wet snow avalanches, Mount Rae area, Alberta, Canada, Arctic, AntArctic Alpine Res., 15, 271–274, 1983. Heckmann, T., Wichmann, V., and Becht, M.: Quantifying sediment transport by avalanches in the Bavarian Alps - First results, Zeitschriftfür Geomorphologie N.F., Suppl. 127, 137–152, 2002. Higgitt, D. L., Froehlich, W., and Walling, D. E.: Applications and limitations of Chernobyl radiocaesium measurements in a Carpathian erosion investigation, Poland, Land Degradation & Rehabilitation, 3, 15–26, 1992. Isselin-Nondedeu, F. and Bedecarrats, A.: Influence of alpine plants growing on steep slopes on sediment trapping and transport by runoff, Catena, 71, 330–339, 2007. Jomelli, V. and Bertran, P.: Wet snow avalanche deposits in the French Alps: structure and sedimentology, Geografiska Annaler, 83A(1/2), 15–28, 2001. Kohl, B., Brauner, H., and Markart, G.: Soil erosion due to avalanches: measurements on an avalanche cone, International Symposium on Snowmelt and Related Problems, 28–30 March 2001, Oslo, Norway, 38, 2001. Konz, N., Schaub, M., Prasuhn, V., Baenninger, D., and Alewell, C.: Caesium-137 based erosion-rate determination of a steep mountainous region, J. Plant Nutr. Soil Sci., 172, 615–622, 2009. Konz, N., Baenninger, D., Konz, M., Nearing, M., and Alewell, C.: Process identification of soil erosion in steep mountain regions, Hydrol. Earth Syst. Sci., 14, 675–686, <a href="http://dx.doi.org/10.5194/hess-14-675-2010">https://doi.org/10.5194/hess-14-675-2010</a>, 2010a. Konz, N., Prasuhn, V., and Alewell, C.: On the measurement of Alpine Soil Erosion, Catena, 91, 63–71, 2010b. Lana-Renault, N., Alvera, B., and García-Ruiz, J. M.: Runoff and Sediment Transport during the Snowmelt Period in a Mediterranean High-Mountain Catchment, Arctic, Antarctic Alpine Res., 43, 213–222, 2011. Leitinger, G., Höller, P., Tasser, E., Walde, J., and Tappeiner, U.: Development and validation of a spatial snow-glide model, Ecol. Modell., 211, 363–374, 2007. Leser, H., Meier-Zielinski, S., Prasuhn, V., and Seiberth, C.: Soil erosion in catchment areas of Northwestern Switzerland. Methodological conclusions from a 25-year research programme, Z. Geomorphol., 46, 35–60, 2002. Luckman, B. H.: The role of snow avalanches in the evolution of alpine talus slopes, Inst. Brit. Geogr., Spec. Pub., 3, 93–110, 1971. Luckman, B. H.: The geomorphic activity of snow avalanches, Geografiska Annaler, 59A, 31–48, 1977. Luckman, B. H.: Geomorphic work of snow avalanches in the Canadian Rocky Mountains, Arctic Alpine Res., 10, 261–276, 1978. Mabit, L. and Fulajtar, E.: The use of <sup>137</sup>Cs to assess soil erosion and sedimentation processes: advantages and limitations, Book of the Extended Synopses of the International Conference on Environmental Radioactivity: From Measurements and Assessments to Regulation, IAEA Publication, 338–339, IAEA-cn-145, 2007. Mabit, L., Benmansour, M., and Walling, D. E.: Comparative advantages and limitations of fallout radionuclides (<sup>137</sup>Cs, 210Pb and 7Be) to assess soil erosion and sedimentation, Journal of Environmental Radioactivity, 99, 1799–1807, 2008. Meusburger, K., Konz, N., Schaub, M., and Alewell, C.: Soil erosion modelled with USLE and PESERA using QuickBird derived vegetation parameters in an alpine catchment, International Journal of Applied Earth Observation and Geoinformation, 12, 208–215, 2010. Nearing, M. A., Govers, G., and Norton, L. D.: Variability in soil erosion data from replicated plots, Soil Sci. Soc. Am. J., 63, 1829–1835, 1999. Owens, P. N. and Walling, D.: Spatial Variability of Caesium-137 Inventories at reference Sites: an Example from Two Contrasting sites in England and Zimbabwe, Appl. Radiat. Isot., 47, 699–707, 1996. Prasuhn, V., Liniger, H., Hurni, H., and Friedli, S.: Map of soil erosion risk in Switzerland, Agrarforschung, 14, 120–127, 2007. Renaud, P., Pourcelot, L., Métivier, J.-M., and Morello, M.: Mapping of <sup>137</sup>Cs deposition over eastern France 16 years after the Chernobyl accident, Sci Total Environ., 309, 257–264, 2007. Ritchie, J. C. and McHenry, J. R.: Application of radioactive fallout caesium-137 for measuring soil-erosion and sediment accumulation rates and patterns – a review, J. Environ. Qual., 19, 215–233, 1990. Simonato, T., Bischetti, G. B., and Crosta, G. B.: Evaluating soil erosion with RUSLE and WEPP in an alpine environment (Dorena Valley – Central Alps, Italy), Sustain. Land Manage. – Environ. Prot., 35, 481–494, 2002. SMS: Atlante climatico della Valle d'Aosta. Società Meteorologica Subalpina, Torino, 239–241, 2003. Sutherland, R. A.: Examination of Caesium-137 areal activities in control (uneroded) locations, Soil Technol., 4, 33–50, 1991. Sutherland, R. A.: Caesium-137 soil sampling and inventory variability in reference locations: a literature survey, Hydrol. Process. J., 10, 43–53, 1996. Walling, D. E. and He, Q.: Improved models for estimating soil erosion rates from caesium-137 measurements, J. Environ. Qual., 28, 611–622, 1999. Walling, D. E. and Quine, T. A.: Calibration of caesium-137 measurements to provide quantitative erosion rate data, Land Degradation and Rehabilitation, 2, 161–175, 1990. Wischmeier, W. H. and Smith, D. D.: Predicting Rainfall Erosion Losses: A Guide to Conservation Planning. Agriculture Handbook No. 537. USDA/Science and Education Administration, US. Govt. Printing Office, Washington, DC, 58, 1978. Zapata, F. (Ed.): Handbook for the Assessment of Soil Erosion and Sedimentation using Environmental Radionuclides, Kluwer Ac. Publ., Dordrecht, The Netherlands, 219, 2002. Zhang, X. B., Higgitt, D. L., and Walling, D. E.: A preliminary assessment of the potential for using caesium-137 to estimate rates of soil erosion in the Loess Plateau of China, Hydrol. Sci. J., 35, 267–276, 1990.