Regime of Reservoir: Experience in Modeling Riverbed Processes with a Movable Bed

Abstract

The paper presents the results of the interrelated calculation of the unsteady uneven movement of the river flow and the re-formation of the bottom of the largest flowing Kuibyshev reservoir in Eurasia in different phases of water content. These calculations are based on the hydrodynamic model “Wave” and algorithms for calculating solid runoff (analytical formula for sediment flow rate), changes in the transport potential of the flow and, as a result of the latter, changes in the bottom marks. In this case, the dynamics of the bottom marks is taken into account in subsequent calculations and is one of the arguments of the model. Based on the model calculations, the spatial distribution of bottom sediments in the water area of the reservoir was investigated and maps of accumulation and erosion of the bed in different phases of water content were constructed. It is shown that for the entire calculation period, an uneven redistribution of sediments in the reservoir is observed: erosion occurs in the upper part, and accumulation occurs in the middle and lower parts. In general, for the Kuibyshev reservoir, the contribution to siltation only by river sediment is insignificant. On average, over the 150-day modeling period for the entire reservoir water area, sediment accumulation is 0.5 mm/period. The weak dynamics of currents in the vast water area of the reservoir reaches does not contribute to active channel transformations. The most intensive processes of bottom transformation occur in places of narrowing of the water area, where the contribution of the non-stationary regime to the formation of the bottom relief during the rise and fall of the flood is best expressed. More full-flowing years will also lead to a more intensive redistribution of solid runoff and bottom sediments coming from the upper strata.