Chislennoe issledovanie vliyaniya raskhoda vody na urovennyy rezhim v ust'evoy oblasti Dona

Abstract

Purpose. The purpose of the paper is to determine the patterns of the level regime formation in the Don riverbed and the delta area of its valley at different volumes of the river flow discharge and water levels in the Taganrog Bay. Methods and Results. The mathematical model of the river Don flow in its delta area is described. The mainstream consisting of several reaches is considered at its running into the receiving reservoir – the Taganrog Bay. The model is described by the Saint-Venant system of equations which is solved by the finite-difference methods. The equations are approximated at the four-point template that leads to the system of linear equations with a five-diagonal matrix. Roughness coefficients were selected for different water flow discharges. The simulated values of the water flow discharge and the flow velocity are compared with the values observed at different water levels in the Taganrog Bay. The results of the numerical study of the water flow effect at the estuary top upon the water surface level in the riverbed were obtained at different water levels in the receiving reservoir. It is numerically defined that the flow discharge value exerts a significant effect on the surface level of the Don mainstream. However, the flow almost does not influence the water level in the river delta area. At the same time, the water level in the Taganrog Bay significantly affects the surface level in the delta reaches; and no its influence is observed in the top part of the riverbed. Conclusions. The computational experiments involving the mathematical model showed that in the mouth area above the first node of the Don delta, the level surface was significantly influenced by the flow discharge, whereas in its lower section – by the water level in the Taganrog Bay.