首页|The Patterns of Seasonality of the Suspended Sediment Load along the Braided Channel of the Lena River
The Patterns of Seasonality of the Suspended Sediment Load along the Braided Channel of the Lena River
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NSTL
Springer Nature
The features of the suspended sediment load along the 200-km braided channel of the Lena River from the city of Pokrovsk to the Aldan River mouth (upstream of the Aldan braiding) are described in detail (30-m resolution) based on water-sediment concentration modeling, using the collection of Landsat images for the period of 1992-2018. It is shown that large anabranching river reaches correspond to changes of the system of sediment transport and accumulation, manifesting themselves as the predominance of the occurrences of positive (increase) or negative (decrease) Delta S-0 values (where Delta S-0 stands for suspended sediment-concentration budget). The conditions of a longitudinal decrease in suspended-sediment concentration along the braided reach of the Lena River are characterized by high water discharges (>20 000 m(3)/s) and are associated with sediment accumulation in riffles and floodplain areas. It has been revealed that a significant role in the longitudinal decrease in water-sediment concentration is played by lateral floodplain branches, which accumulate a part of the incoming suspended sediments and exert a dilution effect on the sediment flow downstream of the confluence with the main channel. Cases of a longitudinal increase in the water-suspended sediment concentration are typical for lower water flow rates (<20 000 m(3)/s) and are related to increased bank thermal erosion in summer and erosion of riffles during a low-water period. A combination of the grid of suspended-sediment concentration, velocities, and channel depths with a 30 x 30-m resolution (more than 20 000 cells) for low-water conditions revealed a dependence of the local suspended-sediment concentration on the transporting capacity of the flow, which was determined for particular verticals. A correspondence between the regime of certain reaches in different phases of water regime is observed. It indicates the mutual influence of the directedness of mass exchange and channel morphology. The transformation of distribution systems of suspended sediments may be interpreted as one of the self-regulation mechanisms in the channel system. Complex systems of sediment flow distribution along the channel of a large river reflect the opposite directions of erosion-accumulation processes caused by bends in the longitudinal profile.
suspended-sediment concentrationsediment budgetremote sensing methodsbraided channelrunoff distribution in branchesTRANSPORT
NSTL
Springer Nature
