Abstract: Climate change leads to the transformation of hydrological processes in the mountain permafrost regions, increasing the frequency and intensity of catastrophic floods. An example is the Magadan Oblast – an important region for the Russian economy, exposed to the risk of floods. The aim of the study was to calculate the maximum water discharge of three small rivers in the Magadan Oblast – the Krivulya, Ambardakh and Susuman rivers – using pluviograph data and the hydrological model Hydrograph. The model was verified on daily intervals for the periods 1966–1994 for the Krivulya stream and 1966-1987 for the Susuman and Ambardakh rivers. Modelling results have shown satisfactory correlation with the observed daily and mean annual values. The median values of the Nash-Sutcliffe coefficient varied from 0.52 to 0.62. The model parametrization for three main types of the landscapes was developed based on the data of the Kolyma Water-Balance station. The modeling was carried out for the historical floods of August 16, 1986 for the Susuman and Ambardakh rivers (maximum observed instant discharges were 393 m3/s and 74.7 m3/s, calculated 1-hourly discharge – 420 m3/s and 78.5 m3/s, respectively) and July 26, 1984 for the Krivulya Stream (observed instant discharge – 14.2 m3/s, calculated 1-hourly discharge – 16.5 m3/s). The relative error of simulated and observed maximum discharges did not exceed 20%. The results of the study confirm the possibility of applying deterministic hydrological modeling on an intra-day interval using pluviograph data. However, the main limitation for the mountain cryolithozone remains the lack of precipitation data. A promising solution may be the use of climate model data, which, in combination with runoff formation models, opens up new opportunities for assessing and predicting maximum runoff characteristics.

Keywords: floods, precipitation, pluviograph, mountainous territories, cryosphere, the Magadan Oblast, maximum runoff, Hydrograph model, hydrological modeling, model parametrization

Abstract: Aufeis are a key element in the chain of water exchange processes in the permafrost zone. The hydrological role of aufeis in the formation of river flow can be comparable to that of glaciers. Observations of aufeis during the construction of the Baikal-Amur Mainline showed that the share of aufeis runoff in the annual river flow can reach 35% for watersheds with an area of up to 500 km2. Despite the long history of studying aufeis and the results achieved, there are no methods for predicting the development of aufeis processes, as well as hydrological models that take into account the share of aufeis feeding in river runoff. This is due to the lack of observational data on the dynamics and development factors of aufeis. In the last century, long-term studies were carried out on some aufeis in Siberia and the Far East. One of these unique objects is the giant Anmangynda aufeis, which forms in the upper reaches of the Kolyma River basin. The aim of the research is to study the hydrological regime of the Anmangynda river basin and develop a method for accounting of aufeis runoff (module «Aufeis») in the distributed hydrological model «Hydrograph». The module “Aufeis” takes into account two factors of aufeis destruction – under the influence of solar radiation and thermal erosion destruction. The input data is the area of aufeis at the beginning of the warm season and daily meteorological data. The calculation parameters are the coefficients of ice melting and evaporation from ice, as well as the coefficient of the relative area of aufeis depending on the period of destruction, calculated for the modern climatic period. The result of the calculation is the aufeis runoff and the characteristics of aufeis for a given interval. Based on historical data and materials obtained during own field research, the module «Aufeis» was tested. The deviation of the calculated and observed values was 2—10% and 1—9% for the maximum values of the area and volume of the Anmangynda aufeis, respectively. Results of numerical calculations for the period 1967–2022 revealed the dynamics of the contribution of the Anmangynda aufeis to the river flow in different seasons. The expanded functionality of the Hydrograph model has improved the quality of modeling for rivers where aufeis form. For the river basin Anmangynda average Nash-Sutcliffe coefficient and annual runoff error were 0,57 and 13,0% compared to 0,41 and 18,0% when the module «Aufeis» was not used.

Keywords: Anmangynda river, permafrost, mathematical modeling, Hydrograph model, aufeis regulation, remote sensing, aufeis resources, aufeis, water balance, cryosphere

Abstract: The subject of the study is ice formations, which are formed as a result of the release of groundwater to the surface of ice sheets or soil. These formations cause significant damage in human economic activity. The work investigated natural ice located on fresh ice cover, as well as artificial ice formations on the ground. The glaciers located in the Transbaikal region near the city of Chita were investigated. The power of thermal radiation of these objects in the microwave range was determined at wavelengths of 2.3 cm and 0.88 cm. The power of thermal radiation in the microwave range was determined using radiometric receivers at wavelengths of 0.88 cm and 2.3 cm mounted on a car or on a fixed support. Cores of ice removed from the ice were studied to determine the layer-by-layer distribution of ice mineralization. A model of a plane-layered non-isothermal medium was used to calculate the thermal radiation of ice. The possibility of registering ice formations by radiothermal radiation of these objects in the microwave range is shown. If there is a layer of water on the ice, the radio brightness temperature will be significantly lower than the object on the surface of which there is no water mass. By the value of the radio brightness temperature in the microwave range for several ranges, as a result of which it is possible to indirectly estimate the thickness of ice formations. At the same time, it is necessary to take into account the variations in the radiofrequency temperature of the medium depending on its thickness due to the interference of radiothermal radiation of a plane-layered medium.

Keywords: underground waters, ground, ice cover, radiometry, remote sensing, radiothermal radiation, microwave range, radiobrightness temperature, aufeis, Transbaikal region

Abstract: The subject of this research is the historical data on the origin, geographical distribution, seasonal and long-term variability of giant aufeis ice sills in the Russian Far East. Ice sills are the ice fields, the thickness and area of which reach up to 10-12 m and several tens of sq. km respectively. They are formed in severe climatic conditions as a result of layer-by-layer freezing of groundwater poured onto the surface. This is a distinct form of seasonal, and at times, long-term glaciation, which regulates the processes of water and energy exchange in low temperature cryolithozone, as well as determines the extent of permafrost intermittency and developmental challenges. Assessment is given on the role of aufeis ice sills in the formation of river and underground runoff, transformation of terrain, morphological structure of landscape, and development of dangerous cryogenic phenomena. This article is first to review the data on aufeis ice sills in the Russian Far East that have accumulated over the past two centuries. Three author highlights the three research periods: until 1900, since 1900 to 1950, after 1950. The latter period is the most effective, indicate the creation of the map and cadastre of giant aufeis, including more than 7,000 ice fields based on the data of aerial photography. The article establishes the key patterns of their distribution, factors and conditions of formation, relation to permafrost-hydrogeological structures, forms of terrain and climate; as well as determines the peculiarities of seasonal and long-term variability.

Keywords: aufeis regulation, river streamflow, underground waters, aufeis hazard, mapping of aufeis, distribution of aufeis, aufeis resources, aufeis, permafrost, ice cover

Abstract: This article provides a database of the local snow-measuring observations for three river basins in the south of Western Siberia, reviews the methodological peculiarities of the conduct of measurements, and compares the acquired data with the observations at weather stations and available satellite data (CGLS SWE). Observations were carried out in several stages over the period of ten years (2011-2021) in small river basins of Kuchuk, Kasmala, and Mayma Rivers, and reflect the transition from the West Siberian Plain to the Altai lowlands. Total of 25,000 measurements of the parameters of snow deposits (snow mass and snow storage) were made over the years. The database of snow measuring observations is accessible to public. The comparison with station and satellite data indicated significant variances, but also fairly good coherence in some reservoir basins. According to satellite data, the common to basins mean squared error of snow storages was 42.9 mm, which is slightly higher than the claimed by the product engineers (37.4 mm). The time-limited observation data on the permanent routes of weather stations demonstrated the mean squared error of snow storages of 43.5 mm. In winter period, the mean squared error of satellite data gradually increased to the period of maximum accumulation of snow in reservoir basins. Moreover, the errors of satellite data did not depend on the snowiness of the winter period; and most likely, are associated with the parameters of microstructure of the snow mass in separate seasons.

Keywords: Kasmala, Altai, database, snow density, snow surveys, snow depth, snow water equivalent, Mayma, Kuchuck, river basin

Abstract: The object of this research is the groundwaters and surface waters of the Sentsa River Basin. The area of explorations is situated in the Eastern Sayan hydrogeological folded region. Cold and thermal waters occur in the PR and PZ metamorphic and igneous rock. These waters are discharged through the spring series in the river valleys laid along fault zones. The main type of fieldwork was hydrogeological sampling. The analysis of the macrocomponent composition of waters was conducted in the «Geodynamics and Geochronology Center» (Institute of the Earth’s Crust SB RAS, Irkutsk), the trace element composition was determined by ICP MS on an Element-2, Finnigan MAT (Germany) at the Vinogradov Institute of Geochemistry SB RAS (Irkutsk). The scientific novelty consists in the fact that this article provides not only the characteristics of chemical composition of cold and thermal waters, but also the primary data on the distribution of microelements in the ground and surface waters of the Sentsa River Basin. Groundwater (thermal and cold) are revealed to have a bicarbonate Ca-Na composition, withal river and lake waters are generally bicarbonate Ca. Thermal waters (in the Khoyto-Gol River Basin) are largely enriched in Li, Be, B, Si, Mn, Ge, As, Br, Rb, Sr, Cs, Ba, W and depleted in Al, P, Cu, Zn, Ag relative to surface and rainwater. The REE distribution profile in groundwater and surface waters have peculiarities that are characterized by a positive europium anomaly and the prevalence of light REE over heavy ones.

Keywords: Khoyto-Gol spring, rare earth elements, trace elements, chemical composition, surface waters, thermal ground waters, cold ground waters, Manzaragshi spring, Sentsa River, Oka Plateau