ICING MAPPING IN THE CHIKOY RIVER TRANSBOUNDARY BASIN

The basin of the transboundary Chikoy River is the largest in terms of area among the catchment areas of the main tributaries of the Selenga River. The Selenga basin as a whole is characterized by a wide distribution of icing. The paper presents the results of mapping icings and their distribution according to various physical and geographical characteristics. Based on the Landsat-8 satellite imagery for 2019, a cartographic database of icings was compiled for the first time for this territory. The database includes 6,319 objects on a total area of 140 km2. The largest icing is 671.13 thousand m2 in area. The mean value, median, and mode are 22.16, 12.86, and 10.24 thousand m2, respectively. Most of the icings are located at altitudes of 900–1,200 m and on the slopes of the eastern exposure. Icings were not found in the western part of the Chikoy River basin and in the near-top belt of the ridges. Fissure rocks are predominant in the study area, which indicates the leading role of groundwater in the formation of icing. The greatest icing coverage is found in areas with annual precipitation in the range of 350–460 mm and with an average annual temperature of –2.5 ... –3℃. In the landscape structure, icing is common in low- and mid-mountain taiga larch-dark coniferous landscapes. About 80% of the icings are located on the complexes of soddy podburs, podburs, soddy podzols, and other associated soils. The level of icing coverage was found to be not proportional to the natural resources of groundwater, which can be caused by both the imperfection of the original groundwater map and the uncharacteristic manifestation of icing in 2019. The resulting database will become the basis for retrospective and predictive assessments of the icing dynamics in the Chikoy and Selenga River basins.