Transformation of River Channels in the Process of their Self-Development and Influence of Natural and Anthropogenic Changes in the Factors of Channel Processes

Abstract

Abstract—In article analyze the main ways of river channels transformation, their morphodynamic type, its complication or transition from one structural level of channel processes to a higher one, in the course of self-development of channel forms. On meandering rivers meanders in the process of development turn into large meanders with rectilinear “inserts” between adjacent forms, into loop-like meanders, which are a combination of the original in the near-top part and segmental ones on their wings. Other way – into chest meanders when the river approaches the bedrock bank (forced bend), elongation of the lower wing along it and the formation of an adapted bend when the channel deviates towards the floodplain. On rectilinear “inserts” between adjacent large bends and on their upper wings, single branches are formed. In the near-apex parts of steep bends with a violation of the condition of flow around the banks (r 2.5br), islands form in local channel extensions due to erosion of the convex bank or due to the rejection of part of the bend spur. For branched channels, under certain conditions, transformation in the process of self-development of single and conjugated branches into unilateral or alternating and intra-valley restructuring of the channel network due to erosion of floodplain isthmuses between branches and floodplain channels is characteristic. These reshaping, leading to the morphodynamic transformation of the channels, are superimposed by natural and anthropogenic changes in water content and sediment runoff and technogenic impacts on the channels, during which the channels are fixed and stabilized in an optimal position for the economic development of rivers. Accounting for the self-development of river channels is necessary in the operation of rivers and the use of water resources, in paleoconditional and paleohydrological analysis, and also in the development of forecasts for channel reformations.