Morphodynamics of floodplain-channel systems of Oka plateau (the Eastern Sayan)

The article analyzes the key features that determine the direction of fluvial processes and modern dynamics of floodplain-channel systems of the main rivers of Oka plateau (southeastern part of the Eastern Sayan), and also specify geomorphological and morphodynamic types of channels for them. We have assessed the role of natural factors influencing the direction of channel processes on the rivers of Oka plateau and their modern morphodynamics, such as quaternary glaciations, geological structure, sedimentary cover pattern, permafrost layers. An analysis of the dynamics of changes in the planned channel forms over a 30-year period for the Oka, Tissa and Dibi rivers carried out by overlaying topographic maps of 1985 and 1990 on modern satellite images made it possible to speak about the direction of one or another process, the leading role of erosion, accumulation, or their equilibrium ratio. The article discusses in detail some morphological characteristics of the valleys of the Oka, Tissa, and Dibi rivers (the width of the channel, the width of the floodplain, the slope of the longitudinal profile). It was established the regularities in distribution of the channels of morphodynamic types on the reaches of these rivers within the plateau. For Tissa and Dibi we have constructed longitudinal profiles specifying the geomorphological types of channels. The research has revealed that an equilibrium ratio of erosion and accumulation processes is observed in most reaches of the studied rivers; and there are no significant changes in the planned channel