ИСТИНА

The isotopic composition of snow is widely used for tracing processes on the catchment scale. However, the variability of the isotope signal in space and the influence of topographic and land cover factors remain poorly understood. In this work, we focused on assessing the influence of topographic factors on the variability of the bulk snowpack isotopic composition (δ18O and δ2H) in the Kasmala River catchment in the south of Western Siberia. Isotopic composition measurements were established at eight transects during the peak snow accumulation period in 2017-2019. Relationships between topographic predictors and isotopic composition were studied using multiple regression and ANOVA. We found no significant variability in mean isotopic composition values over the years. However, the variation increased in low-snow years and decreased in high snow years. The influence of snow depth was the most critical factor. Increased snow depth contributed to the depleting of the snow isotope composition. In addition, we did not find a significant effect of canopy interception on the isotopic enrichment of snow (snow in the forest was lighter by 0.2 and 4 ‰ for δ18O and δ2H). We suppose that this effect occurred due to the low energy inputs for sublimation in cold regions.