CHANNEL COMPONENT OF SEDIMENT YIELD: SPECIFIC FEATURES FOR THE LARGE RIVERS OF RUSSIA

Bank and riverbed erosion produce a significant part of the sediment flux, i.e. its channel component. The article deals with the quantitative assessment of the channel sediment input for more than 14 000 km of the lower reaches of the Ob, Yenisei, Lena, Kamchatka and the Selenga River net. The absolute volumes of sediments supplied by bank erosion are maximum for the lower and middle Lena River (up to 38,7 million tons per year per 100 km of the channel). They are significantly lower for the lower and middle Ob River (down to 19,9 million tons per year per 100 km of the channel), and an order of magnitude smaller (about 2 million tons per year) for the Yenisei River because of the limited conditions for the development of channel processes, and for the Selenga and Kamchatka rivers because of the smaller size of rivers. The volume of sediments of channel origin is two times smaller, than the sediment runoff, for the Yenisei River and exceeds the sediment runoff up to 9 times for other rivers. The maximum rates of bank erosion are common for meandering and branched channels with wide floodplains. Most of the bank erosion within the braided sections of channels is the deformation of islands.