Calculation of Total Erosion in the Lower Reaches of Mezhdurechensk Reservoir Using Empirical Morphometric Dependencies

“Tashkent institute of irrigation and agricultural mechanization engineers" National research university, Tashkent, Uzbekistan

^* Corresponding author: Kan_E1969@email.ru

Abstract

The research aims are to develop a methodology and the choice of initial formulas for calculating channel deformations in the lower reaches of waterworks on rivers composed of easily eroded soils (like the Amu Darya river). To calculate the total erosion below the Mezhdurechensk reservoir, both theoretical equations of channel deformation (Saint-Venant equations) and empirical dependences of the transporting capacity of the flow (turbidity) and morphometric dependences of the connection of the width of the deformable channel from the average depth obtained for the lower reaches of the Takhiatash hydrounit, the stem of which is located slightly above the Mezhdurechensk hydrounit, were used. A hydrological series of years was formulated for the calculation (considering the actual frequency of low-water, medium-water, and high-water years). The results of calculating the total erosion of the bottom in the first ten years of the simulated hydrological series of years, provided that the width of the channel in the lower reaches is constant, is expected to be 0.17-0.41 m (with full flow clarification) and 0.16-0.38 m (with partial flow clarification ε = 0.8). The change in the cross-sectional area of the riverbed will be 304(292)m². Provided that the width narrows to a stable width B_stable =kh^a : Δz = 0.41 m (with the concentration of the flow at a narrower width, the decrease will be correspondingly large). The proposed methodology can be applied to calculate the total erosion on rivers composed of easily eroded soils and having average slopes of the longitudinal profile of the river within 0.0001 (similar to the Amu Darya River).