Оценка гидравлической шероховатости русла магистрального канала

Abstract

The purpose of the study was to determine the roughness coefficient of the main channel bed BP-1 of the Sarpinskaya watering-irrigation system (SWIS) and to compare the data obtained with the normative values. The materials for performing the calculations were: an explanatory note to the project of the second stage of the construction of the SWIS, passports of the main and inter-farm channels of the system (2015), a technical report of the operating organization for 2021, data of full-scale measurements of the depths and velocities of the water flow in the considered alignment using the «speed-area» method, the results of full-scale surveys of the water supply network and HTS SWIS, as well as data from GIS maps and literary sources. The methodology for calculating the elements of the live section of the channels took into account the recommendations of SP 100.13330.2016. The calculation of the roughness coefficients of the channels was carried out using known dependencies, including the Chezy formula, the Manning equation, the dependencies of I.I. Agroskin and N.N. Pavlovsky. The elements of the living section are determined and the values of the roughness coeffi cient in the considered alignment of the main channel are obtained. At the same time, the calculated values of the roughness coefficient obtained have good convergence (the deviation of the results does not exceed –2.8%). However, the obtained values exceed the normative value of the roughness coefficient by 1.6-1.64 times, which is explained not only by the overgrowth of the channel bed with aquatic vegetation, but also by the peculiarity of the shape of the cross-section of this channel, which in the area under consideration has a signifi cant width along the bottom. The calculated values of the roughness coeffi cient obtained indicate the overgrowth of the main canal bed, which was confi rmed during field surveys of the water supply network of this canal in the spring of 2022. In view of this, it is necessary to carry out preventive measures in a timely manner aimed at reducing the additional hydraulic resistance caused by overgrowth of the riverbed with vegetation.