JUSTIFICATION OF HYDRAULIC CALCULATION METHODS FOR IRRIGATION CANALS

Abstract

Purpose: justification of the applicability of various methods of hydraulic calculations of irrigation canals of land reclamation systems. It is recommended to use five types of hydraulic tasks allowing determining the following main parameters of irrigation canals for each type: conveying capacity (first type), canal slope (second type), roughness coefficient (third type), water flow depth (fourth type), cross-section dimensions of the irrigation canal (fifth type). Materials and methods. The well-known classical methods and dependences of N. N. Pavlovsky, B. A. Bakhmetev, R. R. Chugaev, A. A. Agroskin, Shezi and other scientists were taken as a basis during the research. Results. Methods for determining the main hydraulic characteristics of irrigation canals, including: canal discharge and slope and roughness coefficient are considered. These methods allow making calculations by the selection and graphical methods. The fifth type of problems is a series of independent solutions, where the effective width also calculated graphically is used. An analysis of the calculation results shows that for problems of the first type, the Chezy coefficients and hydraulic discharge decrease with an increase in the channel roughness coefficient values. Based on the calculated data obtained, canal discharge change chart depending on the roughness coefficient of the channel was constructed. Conclusions. The conditions for application of various methods of hydraulic calculation of irrigation canals were determined based on the results of the research. The values of the roughness coefficients of irrigation canals in impervious lining – concrete monolithic and reinforced concrete from prefabricated slabs are given. Summary calculation results for six different examples are presented.

Keywords

• irrigation canal
• canal hydraulics
• hydraulic roughness
• hydraulic exponent
• conveying capacity