Abstract

The results of complex hydraulic investigations of the Moskva river are discussed herein as applied to the problem of removing polluted bed loads by flushing the river channel during the floods. As a result, a universal velocity profile was obtained and it was found that the river bed functions as a rough channel. The analysis of vertical distribution of suspended sediments allowed to connect its characteristics with the ratio of friction velocity and of sediment particles fall velocity. The results of turbulence investigations and plan velocity distribution were used for analysing local deformations and for designing turbidity variations along the water course. The calculation results agree with the field data. Some engineering recommendations for better efficiency of removing polluted bed loads were made based on this research.

This investigation was carried on in accordance with а comprehensive programme of protecting the Moskva river basin against pollution.

The aim of the researches was to substantiate the conditions promoting an effective removal of polluted bed load by hydraulic means. This was done during the flood by opening the outlets of the dams of two hydro developments to create high flow velocities within the city territory, some part of the bed loads being eroded by the current and transported out of the city. Since the sediments thus removed are spread on vast areas downstream the pollution involved is intensely neutralized and is of no danger at all. The efficiency of such hydraulic channel flushing results in removal of great volumes of polluted soil at minimum amount of water used for this purpose, and it is governed by the erosive and transporting capacities of the river flow. The latter, in turn, depends both on kinetic characteristics and turbulence of the river flow and on physical and mechanical properties of the bed loads. The detailed investigation of these parameters is of primary importance for solving the problems of removing polluted bed loads by hydraulic means.

Keywords: Urbanization effects, river sediment, properties, critical velocity, river runoff for improvement of the river ecology