Bifurcated channels of large and the largest rivers: conditions of formation, water runoff distribution and morphodynamics

Bifurcated channels represent the highest structural level of channel branching in the large rivers and characterized by two equal channels that flow on the opposite sides of a very wide valley for tens and hundreds of kilometers. They form when the floodplain is 10 times wider than the channel, the entire floodplain is being inundated during flood stage, the branches are located near the sides of the valley, exposure of bedrock banks control discharge distribution between the channels. Their formation is usually accompanied by the development of numerous floodplain channels that provide hydraulic connection between the main branches. In some cases, bifurcated channels occur on small rivers. Typically bifurcated channels occur in the low reach close to the river mouth; or form as a result of stream capture by tributaries that share the same floodplain with the main river; or when river flowing out of the mountains to the plain, etc. There are differences in the development of branches of bifurcated channels, the distribution of morphodynamic types of channels; various riverbank erosion rates. These characteristics depend on the change in their water content, the morphodynamic type of the channel, the location in relation to the bedrock banks, as well as the effect of the distribution of discharge on sediment runoff and its longitudinal changes.

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