On a feedback of the share of avalanche alimentation with a glacier accumulation

Abstract

Releases of avalanches are an important factor of snow accumulation for many mountain glaciers. However, the quantitative estimate of the share of avalanche snow in the incoming part of the mass balance has not yet been standardized due to the lack of a universal methodological scheme for the calculation and collection of actual material. In rare cases, e.g. for the Djankuat Glacier in the Caucasus, this problem is partly solved. Here, the conceptual basis of the required calculations is created, and the input information has been supplied for many years by the route snow-measuring profling performed in the spring close to the date of the maximum of seasonal snow reserves and accompanied by direct feld mapping. Annually, avalanche deposits attributed to additional snow income from outside the glacier are recorded in all high-altitude morphological zones, with the exception of the lowest (< 2850 m) hypsometric belt, although in the half-century history of monitoring there were cases when snow avalanches reached it. Te volume of avalanche deposits was calculated for 15 years afer 1991/92, and each time it correlated with the gross snow accumulation of the corresponding balance year. Te contribution of snow avalanches to the income of substances on the glacier varies from 1.8 to 10.0% and averages 4.7%. Paradoxical (but only at frst glance) conclusion based on the analysis of data on volumes of avalanche and total accumulation is the feedback of these indicators (r= -0.58). It should be noted that the share of avalanche contribution to alimentation of the glacier has a more convincing feedback with accumulation and background snow content of winter (r= -0.72). Probably, the revealed tendency of increasing role of the additional avalanche alimentation in low-snow years (and vice versa) is not limited by the only reference object, and it is true for any glacier prone to the avalanche influence.