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Based on the analysis of Landsat satellite images over the period of 2013–2019, the number (6683) and total area (4529 km2) of giant aufeis fields (area ≥ 0.1 km2) were estimated for the territory of North-Eastern Eurasia. The contribution of aufeis runoff to river streamflow in different seasons was calculated for 58 hydrological gauges (area 523–526,000 km2). The contribution of aufeis and glaciers to water balance is compared. The aufeis resources vary from 0.4 to 4.25 km3 (or 3.7–11 mm) for individual basins of large rivers. They are at least 10.6 km3 in total or 5 mm of water depth on average for the study area. Aufeis annual runoff varies from 0.3 to 29 mm (0.1–22%, average 3.8%), with the share in winter runoff amount about 6–712% (average 112%) and the spring freshet 0.2–43% (average 7.1%). In general, the aufeis runoff exceeds the glacial runoff. The dynamics of aufeis formation are directly related to winter runoff, whose changes are observed in different parts of the cryosphere. The presented results are relevant for studying the impact of climate change on the hydrological cycle and its components in the permafrost regions of the Northern Hemisphere. [ABSTRACT FROM AUTHOR]

On the basis of corrected Landsat data for 2013–2017, a modern assessment of aufeis in the Indigirka River basin and its partial catchments with an area of 1830 to 305000 km2 was conducted. The potential contribution of the aufeis flow to the formation of the water balance of rivers during various phases of hydrological regime was calculated. During the phase of the maximum development, the aufeis area of partial catchments ranges from 0.30 to 1.49%, reaching 0.54% of the total area of the Indigirka River basin. The aufeis resources (water content in aufeis) of the Indigirka River basin are 10.0 mm of the runoff level or in total 3.5 km3. For individual rivers, the aufeis flow can reach 5–28 mm per year, which makes up 2.6 to 20.8% (an average is 8.1%) of river runoff. On average, water resources stored in aufeis make up 235% of the winter river flow (135% for the Indigirka River basin). The contribution of the aufeis flow during the spring flood can reach 39% and is 13.7% in the outlet of the Indigirka River basin. The ambiguous impact of climate change on aufeis (reducing their area and increasing their number) requires further detailed studies. [ABSTRACT FROM AUTHOR]

This study discusses the environmental consequences of a major landslide that occurred on the shore of the Bureya reservoir in December 2018, for the first time in the winter period; it was the largest such phenomenon in Russia over the last decade. Toxic organic substances present in water and aufeis in the landslide impact zone and after the collapse of the dam composed of rocks were analyzed. A comparative analysis of aromatic compounds contained in water in the vicinity of the landslide body prior to and after blasting operations and in the newly-built artificial canal was performed using gas chromatography. Predominant organic components present in the water included a number of toxic substances (e.g., methanol and methylated benzene derivatives); after the drainage of the water through the landslide body, concentrations of these substances increased. Many volatile organic substances have a natural origin and could be contained in the pore space of rocks. After the blasting operations, the content of hexane and isopropyl benzene in the water of the artificial canal increased. It has been established that rock grinding caused by the landslide and by the blasting operations significantly affected the composition of volatile organic substances. Rock watering, thawing, and freezing; decomposition of plant residues; and transformations of detonation products of explosives initiate various biogeochemical processes in the pore space; aromatic compounds formed as a result of such processes pose environmental risks to the reservoir ecosystem. [ABSTRACT FROM AUTHOR]

The analysis of ice jam formation processes of anthropogenic nature in the middle reach of the Lena River in 2001 and 2010 is carried out. Peculiarities of ice jam formation, springflood and inundation of villages in the Republic of Sakha (Yakut Republic) related to preventive actions are demonstrated. Intensity of variation of stages of spring ice jam flooding at the Lena River streamgage sites is considered. The degree of anthropogenic factor effect on ice jams through hydrological and hydromorphological processes is demonstrated. [ABSTRACT FROM AUTHOR]