Landscape variability of snowpack characteristics in the Anuy river basin (Russian Altai)

Introduction. Knowledge of the spatio - temporal variability of snow cover characteristics plays a key role in determining the timing and magnitude of spring meltwater runoff, water resource management, and flood preparedness and mitigation. The study of the material composition of snow cover is widely used to identify spatial pollution halos and quantify the actual supply of pollutants from various sources. The purpose of the study: assessment of spatial variability of the characteristics of snowpack, including the snow water equivalent and the chemical composition of snow in the representative for the northern macro - slope of the Russian Altai Anuy river basin. Materials and methods. Observations were carried out during field work during the period of maximum snow accumulation on February 20-26, 2024 at snow measuring sites. There are 35 snow measuring sites in the basin (735 depth measurements and 175 density measurements). The location of the sites was determined by their representativeness for the landscape structure of the basin. Snow water equivalent is computed from measurements of depth and density of the snowpack. The standard deviation and the coefficient of variation were calculated for the snow depth, density and snow water equivalent at each site. The data obtained during field work became the basis for extrapolating the values of snowpack to the landscapes of the basin. Snow sampling was carried out at six sites. Snow samples were taken from pits with horizontal dimensions of 30x30 cm for the entire thickness of the snow, excluding the lower five - centimeter layer. Analytical work was carried out at the laboratory of Institute for Water and Environmental Problems of the Siberian Branch of the Russian Academy of Sciences using standardized methods taking into account the requirements of GOST standards. The pH values, content of main ions (Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, SO42-), compounds of nutrients (NH4+, NO3-, NO2-, PO43-), and mineralization were determined in the samples. Results. It has been established that the average values of snow depth, density and snow water equivalent in the Anuy river basin at maximum snow accumulation in the winter of 2023/24 are 21 cm, 0.19 g/cm3, 41 mm, respectively. The variation in snow characteristics at the sites is as follows: snow depth from 5 to 59 cm, density from 0.14 to 0.31 g/cm3, snow water equivalent from 8 to 127 mm. Snow depth and snow water equivalent in the Anuy river basin are increase with rise above sea level as it happens in the mountains. Maximum s snow water equivalent in 2024 occurred on watersheds and in watershed parts of ridge slopes within the mountain - taiga sub - belt (average 96 mm). Snow water equivalent decrease significantly in the lower altitude zones: 52 mm in the sub - taiga, 29 mm in the mountain forest - steppe and 20 mm in the foothill forest - steppe. There are significant intra - landscape contrasts of snow water equivalent at all altitudinal levels in the basin. It was found that snow in the landscapes of the Anuy basin is characterized by a neutral reaction (from 6.3 to 7.1) and has low mineralization. This is largely determined by the zonal position of the basin. The dust load varies quite significantly: from 3.53 to 68.77 mg/(m2 day), but at all sites it corresponds to a low degree of pollution.