Icing/Aufeis processes are a typical feature of permafrost hydrology in mountainous regions. Regional databases of Aufeis have been compiled since the 2010. In this study, we attempted to create an initial Aufeis database for the Qinghai-Tibet Plateau (QTP) to evaluate the patterns of the icing processes in the arid and high mountain regions at low latitudes. In this article, the icings/Aufeis in the Kunlun Mountains on the northern edge of the QTP were investigated. A total of 65 Landsat 8 Operational Land Imager images for 2017–2020 of the key sites were acquired. Icings occur at elevations of 2500–5400 m a. s. l. More than 1600 Aufeis were identified with a total ice-surface area of 2670 km². About 88% of these areas are related to a gigantic Aufeis (tarin) field. Artesian aquifers related to the active faults play an important role in feeding the Aufeis in the Kunlun Mountains. About 120 Aufeis fed on glacier-melt have formed in the West Kunlun Mountains. Icing development was found to vary with the order of river channels and more than half of all of the identified Aufeis are located along first- and second-order river channels. The significance of Aufeis at the QTP related to as an indicator of climate change, and a volume of surface and ground waters conserved into Aufeis should take into consideration of river runoff estimation of the region.

Groundwater icings, typical features of permafrost hydrology, are indicative of hydrothermal interactions between surface and ground waters, and permafrost. Their main morphological parameters, i.e., icing area and volume, are generally estimated with low accuracy. Only scarce field observational data on icing volume and seasonal development exist to date. Our study evaluates and compares performance of several widely used techniques of icing morphometric estimation, based on field data, collected on a giant Icing #2 in the Samokit River basin, southern Yakutia. Groundwater icing area was estimated by: (a) staking, (b) unmanned aerial vehicle (UAV) surveys, and (c) satellite imagery analysis. Icing #2 area in late February was between 1.38·10⁶ m² and 1.68·10⁶ m², icing volume, between 1.73·10⁶ m³ and 4.20·10⁶ m³, depending on the technique used. Staking is the least accurate, but also the only direct technique, which is hence used as a baseline tool in our study. Staking-based assessment of icing morphometry is the most conservative, while UAV-based estimates of icing area are higher by 14% to 17%, and of icing volume, by 74% to 142%, compared to staking. The latter appears, in our case, to be the least accurate method, although a direct one. It requires a sufficient number of staking points and transects, which should be set up to represent all icing zones, i.e., channel branches and alluvial islands. Photogrammetry based on UAV surveys has numerous advantages, i.e., higher precision of a per pixel icing volume calculation, based on an ice-free valley bottom digital surface model (DSM), and potential reusability of a resulting DSM. However, positioning precision suffers from the overlay of multiple flyovers required because of battery replacements, and, in our case, an insufficient number of ground control points. Satellite imagery along with B.L. Sokolov’s empirical approach were used to estimate the annual maximum icing area and volume, and the empirical estimates tend to converge to satellite-based values. Finally, all thing being equal, UAV-based photogrammetry shows higher precision in estimating the icing morphometrical parameters.

Climate warming and anthropogenic impact causes transformation of geocryological conditions in the river basins of the North-East of Russia. Changes in the thickness of the active layer, configuration of taliks, types of landscapes and other factors lead to transformation of water exchange processes between surface and groundwater runoff. This is manifested in the seasonal redistribution of the components of the water balance, accelerated melting of aufeis, change in the ratio of waters of different genesis in the structure of river runoff. As a result, natural and anthropogenic risks that affect the safe and efficient development of infrastructure and socio-economic processes are increasing. At the same time the system of observations developed in the Soviet period has been practically destroyed in the region. This paper offers a vision of organizing complex multidisciplinary research to assess and project the changes in the conditions of underground and surface water interaction in natural and disturbed river basins of the cryolithozone of the North-East of Russia, including for solving applied problems, based on permafrost, hydrology. hydrogeology, landscape science and geophysics with applications of remote sensing and field research integrated through mathematical modeling methods. To achieve the goal, the identification of natural and disturbed landscapes using remote sensing data. and key areas for detailed research will be selected. Geophysical and drilling works will be carried out within the sites to establish permafrost-hydrogeological conditions, monitoring stations will be equipped to determine hydrogeological, hydrometeorological and geocryological characteristics, including sampling for isotopic and hydrogeochemical studies. As the main key sites, it is proposed to use the area of the Kolyma water-balance station and the site on Anmangynda aufeis, for which there are long-term observation series in the 20th century. Field data will become the basis for improving the mathematical model of runoff formation, considering the relationship between groundwater and river runoff in the conditions of permafrost. Mathematical modeling will make it possible to quantitatively analyze the water balance of rivers considering various factors and project water availability both for specific industrial facilities and for the region as a whole.

The objectives were (i) to evaluate the relationship between recent climate change and extreme hydrological events and (ii) to characterize the behavior of hydrological events along the Alazeya River. The warming rate of air temperature observed at the meteorological station in Chersky was 0.0472 °C·year⁻¹, and an extraordinary increase in air temperatures was observed in 2007. However, data from meteorological stations are somewhat limited in sparsely populated regions. Therefore, this study employed historical remote sensing data for supplementary information. The time-series analysis of the area-averaged Global Precipitation Climatology Project (GPCP) precipitation showed a positive trend because warming leads to an increase in the water vapor content in the atmosphere. In particular, heavy precipitation of 459 ± 113 mm was observed in 2006. On the other hand, the second-highest summer National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution radiometer (AVHRR) brightness temperature (BT) was observed in 2007 when the highest air temperature was observed in Chersky, and the anomaly from normal revealed that the summer AVHRR BTs showed mostly positive values. Conversely, riverbank, lakeshore and seashore areas were much cooler due to the formation, expansion and drainage of lakes and/or the increase in water level by heavy precipitation and melting of frozen ground. The large lake drainage resulted in a flood. Although the flooding was triggered by the thermal erosion along the riverbanks and lakeshores—itself induced by the heat wave in 2007—the increase in soil water content due to the heavy precipitation in 2006 appeared to contribute the magnitude of flood. The flood was characterized by the low streamflow velocity because the Kolyma Lowlands had a very gentle gradient. Therefore, the flood continued for a long time over large areas. Information based on remote sensing data gave basic insights for understanding the mechanism and behavior of climate-induced extreme hydrologic events.

Modern research on icing is focused on regional patterns of its distribution and compilation of its catalogs from different regions. This study discusses new approaches to mapping icings using NDSI based on Sentinel-2 and SAR images of Sentinel-1. Using the polarimetric decomposition of a backscatter signal and unsupervised classification, we identified the contours of the icings in May 2018–2022, and calculated their areal extent. We compared the areas of icing using both methods, and correlated the data. Only 10 % of all icings showed a difference of less than 10 % in the area values. It is located in river valleys where the boundaries of the icing field coincide with a flood plain, and their width is at least 100 m. The reflected backscatter signal at such objects is characterized by moderate or high entropy volumetric scattering. On the basis of the NDSI index, 237 icings were identified within the Chulman Plateau, with a total area of 134.44 m². We assessed the main natural controls in the development of the icing process. This is the initial stage of studying icings in the southern part of the permafrost region. Furthermore, we plan to classify icings according to their sources of nutrition and to detail the patterns of icing formation in this region. The research results will make it possible to predict the formation of icing during engineering construction and evaluate groundwater resources.