Channel morphodynamics of the Selenga River

The article presents the experimental data of the channel morphodynamics of the Selenga River and the Chikoy River mouth over a 100-year period within the 23.5 km long stretch from the Termyn-Tatur channel to Gustovskii Island. We analyzed changes in the planned pattern of the channel and systemized channel processes for three time sections – 1914, 1987 and 2019 on the stretch from the Termyn-Tatur channel to the Gustovskii Island. The main changes over more than a century have manifested themselves in the form of changes in the elements, types and shapes of bends, dynamics of the width and number of arms, as well as in degradation processes and appearance of new arms, redistribution of the main flow from one arm to another. The most stable areas turned out to be areas of relatively rectilinear channel of undivided and divided types located near the valley side, which was a limiting factor in the development of horizontal deformation. We determined the time of the most significant channel deformations-from 1914 to 1987. This is explained by the number of high-water periods in this period, the total duration of which was 43 years and possibly by the intensification of anthropogenic impact and the associated increase in suspended sediment discharge. The longest period of decrease in the manifestations of channel deformations occurred from 1987 to 2019, and it coincides with a prolonged dry period that began in 1995.