Abstract

The main information concerning the river bed process and the hydraulic parameters of the river flows are obtained for the long-term interaction of the flows and the river bed when the river flow parameters and the bed forms achieved the moment of their dynamic balance, i.e. the stable state.

A short-time change in the hydraulic regime of the water flow, for example the increase of the water rate for several hours may bring to the formation of a new bed form. These processes are not studied yet, as we did not have to create such conditions. Only recently the necessity of the regime was caused by the environmental problems as well as by the problems of the use of the water resources within the urban territories.

The riverbed forms and the flows are a self-regulated system. The change of the water rate during the flood or at the hydraulic bed flush, changes the bottom forms gradually and brings to new forms. As a result, the hydraulic resistance, the flow depth and the velocity change.

So we need to study the transformation of the bed forms and of the hydraulic parameters of the river flow with the time. These studies were carried out for different physical-and-mechanical parameters of the grounds and a wide range of the parameters of river flows. These experiments were performed with the use of natural grounds at the Hydraulic Laboratory of MSUCE.

We paid a special attention to the influence of the additional mass of the liquid upon the motion of hard parts in the bottom area of the flow.

On the basis of theoretical and experimental studies and other experimental data we obtained the relationship between the bed forms parameters and the integral parameters of the flow for progressing bottom forms:

Using the emergency principle, formulated by N.S. Znamenskaya for the initial stage of the interaction between the flows and the bed forms, we suggest new dependences for calculating the parameters of the river flow and the bed forms. Also we offer a physical model of the change of the bed forms and of the river flows at the initial stage of the interaction between the flows and the bed forms. On the basis of this model we developed the algorithm of the calculation of hydraulic characteristics of the flow and the riverbed with changing bed forms.

Keywords: River bottom drifts, physical model, computation methodology, hydraulic characteristics of the flow and of the river bed, terrain formation