Direct solutions for normal depths in curved irrigation canals

摘要

The normal depth is an important hydraulic element for canal design,operation and management. Curved irrigation canals including parabola, U-shapedand catenary canals have excellent hydraulic performance and strong ability ofanti-frost heave, while the normal depths in the governing equations of thecurrent common methods have no explicit analytical solution. They are onlyindirect methods by using trial procedures, numerical methods, and graphicaltools. This study presents new direct formulas for normal depth in curvedirrigation canals by applying for Marquardt method. The maximum relative errorof the proposed formulas is less than 1% within the practice range bycomparative analysis, and they are simple and convenient for manualcalculations. The results may provide the reliable theoretical basis and usefulreference for the design and operation management of irrigation canals.