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Mountainous regions of the world are the source of water for large amount of population living downstream. This is also the case for Pamir Mountains in Tajikistan which produces majority of the water for the several countries in the region. Despite increasing impacts of climate change, last several decades, there have been critical decrease of number of monitoring networks in mountainous areas of Central Asia bringing high uncertainty to water resources management and planning. In this study we investigate the possibility to combine the remote sensing data, ground observations and a modelling approach to estimate discharge of Gunt River in the Eastern Pamir, Tajikistan. The Gunt River watershed is of great importance for the region, as about 60 settlements are concentrated along the entire length of the river, including the administrative city of Khorog. Two hydropower stations were built in the lower reaches of the river to provide electricity for the local communities. These headwater glacier-fed basins of Central Asia are particularly vulnerable; as climate change threatens water supply from glacier systems and increases evaporative losses, while demand to irrigation water and electricity is rising. This uncertainty in water supply can result, to a deterioration in the development of the economy and the quality of life in the region. Therefore, for sustainable electricity production and economic development in the region, a better understanding of water availability in the river, is required. The aim of the study is to assess the characteristics of the flow regime of the Gunt River. We used "Hydrograph" hydrological model to simulate daily discharge of the Gunt River. The model algorithms combine physically based and conceptual approaches to describe snow and glacier melting and runoff generation processes. "Hydrograph" model has also successfully used to simulate river flow in Varzob River with similar climatic conditions in Tajikistan. Parametrization of the model including the assessment of precipitation distribution in the high mountainous areas is based on the data from the research watershed of the Varzob River with long term historical data availability. The verification and evaluation of the model was conducted based on the historical data (1970-1980) using data from the Dzhavshangoz and Khorog meteorological stations. The model performance and simulations for the recent period (2000-2020) were also evaluated by using the remote sensing data. The results have shown satisfactory quality with difference between the observed and simulated runoff does not exceed 2%. In general, the results of the paper confirm the possibility of using the deterministic model "Hydrograph" to simulate the daily water runoff in the river which is critical for hydropower and irrigation purposes. However, the lack of accurate information on distribution of precipitation in the catchment, significantly reduces the model results accuracy. The study was carried out with the support of St. Petersburg State University (project 75295879).

Significant changes are observed in the water exchange system of the North-Eastern Eurasia which still is the remote and poorly studied region of the cryosphere. Aufeis which are well recognized from the space may serve as the indicators of such changes. Aufeis are the ice sheets formed in permafrost environment due to the layer-by-layer freezing of discharged underground or surface water, their size may reach tenths of square kilometers. The primary goal of this study is to assess the changes in the dynamics of the characteristics (area and volume) of the giant Anmangynda aufeis based on historical and modern observational data. It is located in the zone of mountainous continuous permafrost of the Magadan region of Russia and was extensively studied in 1962-1992.We combined and analyzed the data of historical materials (1962-1992) with recent data from Landsat and Sentinel images (2000-2020) and our own ground-based observations on the perennial and annual dynamics of aufeis area (2020-2021). Aufeis volume was measured in 1962-1992 and in 2020-2021, but for the period of 2000-2019 the values were estimated based on the regional formula developed by [Sokolov, Sarkysyan, 1981].Maximum area of aufeis reached 6.6 km2 (about 1.6% of the basin area) in 1967. According to the data of 1969 its volume may grow up to 15.7 million m3. The greatest amplitude of fluctuations in the size of the aufeis (up to 30% of the average long-term value) was observed in the period up to 1976, then it did not exceed 10-15%. The smallest sizes of aufeis were 4.1 km2 and 5.3 million m3 in 1974, 4.3 km2 and 6.4 million m3 in 1990. Thus, over the thirty-year period of observations, the volume of aufeis has halved.In the recent period, according to satellite data, these values reached the maximum of 5.8 km2 and 12.4 million m3 (2002). The lowest values were 2 times lower than the historical ones (1.9 km2 and 3.6 million m3, 2014). Now, to study the dynamics of aufeis area and volume, the authors have been using UAV shooting. The thickness of the ice is determined by measuring the height of the surface at different periods of the aufeis development. In 2021, the maximum ice thickness reached 4.4 m, and the historical maximum was 8 m.The intra-annual dynamics of aufeis has also changed. Now the aufeis gets melted completely by August-September, and in the earlier periods the part of the ice sheet (about 4% of its maximum area) remained and was included in the formation of aufeis for the next year.According to natural and climatic conditions, the river basin in which the Anmangynda aufeis is formed is representative for the mountainous landscapes of the North-Eastern Eurasia. Comprehensive interdisciplinary observations at this site are important to characterize the impact of climate change on natural processes in this region.The study was carried out with the support of RFBR (19-55-80028, 20-05-00666), Russian Geographical Society (project 07/2021-I (continue)) and St. Petersburg State University (project 75295776).

The Putorana Plateau is located in the North-West of the Central Siberian Plateau in the Krasnoyarsk Territory in permafrost zone. Some mountain peaks reach a height of 1400 - 1700 m. The plateau is composed of stepped canyons formed by the outpouring of a huge mass of red-hot basalts. The Putorana Plateau is the territory that is still unexplored in hydrological terms. Climate change contributes to an increase in the thickness of seasonal thawing, therefore, the conditions of runoff formation change.The purpose of the work is to study the factors of runoff formation, including the research of geocryological conditions based on short-term expedition data of the State Hydrological Institute (St. Petersburg, Russia) collected in small catchments in 1988-1990.The object of study is the catchment of the stream Dupkun (an area of 2.75 sq. km), which is located in the basin of the Kureyka river basin, the right tributary of Yenisei River in the southwestern part of the Putorana Plateau. The maximum height of the catchment is 1228 m, and the hydrological gauge is located at an altitude of 923 m. The average slope of the catchment area is 12°. The landscape is a moss-grass mountain tundra, and perennial snowfields are also formed.The expedition studies in the period from July 19 to September 4, 1990 included the collection of hydrometeorological information, the determination of soil characteristics (moisture content, temperature, structure at different depths and landscapes), and the study of snow cover. The route studies were conducted to determine the characteristics of landscapes, vegetation and soils in the basins of the rivers Kureyka and Khantayka.The data of the expedition studies were processed, digitized and systematized. Based on the collected material, the water balance of the stream Dupkun was calculated. The presence of perennial snowfields has a significant impact on the formation of runoff. At the beginning of observations, the area of snowfields was 15 %, the average snow height was 2.6 m, and the average density was 0.7 g / cm3. At the end of observations, snowfields occupied 8% of the catchment area. For 20 days, the snowmelt depth was 38 mm, the precipitation reached 140 mm, and the runoff was 167 mm. The runoff coefficient is 0.89. During the entire observation period, the runoff reached 355 mm.These observations are considerable value due to the lack of knowledge of the geocryological, landscape and hydrological conditions of the Putorana Plateau. Since there are practically no hydrological stations in this region that study the processes of flow formation, the collected data become even more unique. Extremely scarce data allowed to conduct the assessment and verification of the parameters of the hydrological model "Hydrograph". The developed set of the model parameters was used to simulate the river flow of tundra landscapes of the Putorana Plateau and assess its contribution to the formation of the water balance of the territory in the current climate.The study was supported by the RFBR (project No. 19-55-80028).

Crimean water resources are unevenly distributed and mainly generated at the slopes of the Crimean Mountains affecting water supply of population and industry of the peninsula. The study of water resources has been limited for the last 30 years due to political situation and little quantitative information is available about climate change impact on hydrological regime of Crimean rivers. The aim of the study was the assessment of current flow characteristics for three rivers originating from the Crimean Mountains (the Derekoyka River at Yalta; 49.7 km2, the Demerdjy River at Alyshta, 53 km2; the Kokkozka River at Golybinka, 83.6 km2) and their comparison to the historical period (1960-1990) data. The study area is characterized by a Mediterranean climate and has a pronounced high-altitude zoning. Main vegetation type is the oak forests and shrubs. The highest elevation of the slopes reaches 1500 m.Due to the lack of hydrological data for the last 30 years, the assessment of current flow characteristics was conducted based on hydrological modelling and observed meteorological data. The hydrological model Hydrograph was used in the study. The model was successfully used for the simulations of streamflow in similar climate for the basins of the Black Sea coast of Russia (Makarieva et al., 2018; 2019). The model was parametrized based on the data on typical landscapes of the studied area. The verification of streamflow and water balance simulation results was conducted for the historical period (1960-1990). The model was used to produce streamflow hydrographs for the period of 1991-2018 based on meteorological data. The changes of hydrological regime of Crimean rivers was assessed in comparison with historical period. The results of the study will be presented.