Analiz izmeneniya koeffitsienta sherokhovatosti rusla maloi reki v zadannom stvore (na primere r. Chernoi) [Roughness coefficient meas-urements of the Chernaya River channel]

Abstract

The paper presents the determination of the roughness coefficient of the minor river channel, since one of the main design parameters depends on the minor stream, required for a substantiation of design decisions. In accordance with the regulatory documents of the Russian Federation, the roughness coefficient is taken according to the visual characteristics of the riverbed.The purpose of this work is to determine the relationship of the roughness coefficient and dimensionless complexes at different water depths (before and after entering the floodplain).All calculations are performed according to the results of studying the hydrological conditions of the Chernaya river. The roughness coefficient is determined by the numerical method.Analysis of the maximum depth allows to obtain its certain value. It is shown that the hydraulic radius increases at a higher depth. When the maximum depth is deeper, this dependence is nonmonotonic, and when water enters the floodplain, the hydraulic radius strongly differs from the average depth of the minor stream. It is found that before entering the floodplain, there is a significant stochastic relationship between the roughness coefficient, Reynolds number and the dimensionless complex. After entering the floodplain, there is a close stochastic relationship between roughness coefficient and the Froude number. When determining the minimum water levels, the exponent of Chezy's velocity factor in the Manning formula cannot be considered a constant value, because this can lead to a great error.