The study aims to reconstruct the Altai glaciers at the maximum of the LIA, to estimate the reduction of the Altai glaciers from the LIA maximum to the present, and to analyze glacier reduction rates on the example of the Tavan Bogd mountain range. Research was based on remote sensing and field data. The recent glaciation in the southern part of the Altai is estimated (1256 glaciers with the total area of 559.15 ± 31.13 km2), the area of the glaciers of the whole Altai mountains is estimated at 1096.55 km2. In the southern part of Altai, 2276 glaciers with a total area of 1348.43 ± 56.16 km2 were reconstructed, and the first estimate of the LIA glacial area for the entire Altai mountain system was given (2288.04 km2). Since the LIA, the glaciers decrease by 59% in the southern part of Altai and by 47.9% for the whole Altai. The average increase in ELA in the southern part of Altai was 106 m. The larger increase of ELA in the relatively humid areas was probably caused by a decrease in precipitation. Glaciers in the Tavan Bogd glacial center degraded with higher rates after 1968 relative to the interval between 1850–1968. One of the intervals of fast glacier shrinkage in 2000–2010 was caused by a dry and warm interval between 1989 and 2004. However, the fast decrease in glaciers in 2000–2010 was mainly caused by the shrinkage or disappearance of the smaller glaciers, and large valley glaciers started a fast retreat after 2010. The study results present the first evaluation of the glacier recession of the entire Altai after the LIA maximum.

The destruction of ground dams, of natural and artificial origin, is caused by certain critical conditions. The main reasons for this are the overflow of water over the crest of a dam, the filtration of water through its body, or mechanical destruction. The processes of destruction of ground dams of moraine lakes are very frequent phenomena for mountain regions and can often occur there. In addition, the outburst of ground dams can take place under the thickness of the cover and mountain glaciers that leads to the formation of the subglacial hydrographic drainage system. Because of the dam destruction, outburst floods, which are accompanied by significant destruction and even human losses, are formed. Considering that, it is extremely difficult and unsafe to investigate the outburst process directly at the time of its natural occurrence, the researchers turn to alternative methods, like physical modeling. In this paper, the results of physical modeling of the outburst of the moraine model reservoir are presented. The experiment was carried out near the coastline of the outburst glacier lake Bashkara (Central Caucasus, Elbrus Region, Russia). Therefore, the artificial dam, consisting of material of moraines surrounding the lake, was created. This leads to a possibility to recreate the experimental conditions closest to natural. During the research photography and video filming of the outburst of the model reservoir were carried out. The results of physical modeling are in complete agreement with previously published data of outburst of ground dams and do not contradict with the physical essence of the process.

There is a reduction in the area of glaciation of mountain massifs as a result of climate warming, which leads to the formation of lake-glacial complexes in areas of glaciation degradation. These complexes are dynamic systems that are rapidly changing over time, therefore, unstable and potentially outburst. Moraine and periglacial lakes outbursts are dangerous hydrological phenomena. As a result of outbursts catastrophic floods and mudflows can form, causing serious damage to the infrastructure of settlements located downstream and often leading to human toll. Therefore, the study of outburst-hazardous lakes is necessary and is an important applied problem associated with forecasting natural hazards. In this paper an the outburst hazard of little-studied moraine and periglacial lakes at the Mongun-Taiga mountain massif (Tyva Republic, Russian Federation) assessment was carried out using the scoring method, supplemented taking into account regional characteristics, using data from remote sensing of the Earth. The performed assessment according to satellite images showed that most of the massif's lakes have a high outburst hazard. Based on the assessment results a group of lakes was selected located in the right branch upstream of the river “Tolaity” for the purpose of a more detailed field survey (hydrological and geophysical studies were carried out). Field work carried out on the selected group of lakes allowed us to correct the performed assessment. In paper the applicability of the method based on comparing field data and data obtained from satellite images was estimated.

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