Investigation of Irrigation Canal Seepage Losses through Use of Four Different Methods in Hetao Irrigation District, China

Canal seepage is an important cause of irrigation water losses. Specific seepage losses of Gongan lateral and Zuosi field canals, which are located in the Hetao Irrigation District of Inner Mongolia in China, are calculated in this study. Specifically, canal seepage losses are calculated by field experiments, empirical formulas, the Kostiakov formula, and numerical simulations. The ponding method is rarely utilized in large irrigation canals and canals with many branches or high slopes. The results of the field experiment are utilized to compare and analyze the calculation results of three other methods. When the empirical formulas are employed to calculate canal seepage losses, more related factors are considered; hence, more-accurate calculation results are obtained. The first empirical formula is mostly used for canals that do not adopt seepage control measures or apply simple forms for seepage control. The second empirical formula is suitable for the case wherein the entire flow section of a canal has been paved with a soil impermeable layer and canal seepage is in a free state. When the Kostiakov formula is employed to calculate canal seepage losses, the parameter values may differ significantly from the actual conditions. Thus, a large difference exists between the calculation results of the Kostiakov formula and those of the field experiment. The Kostiakov formula is widely utilized in the planning and design of canals, as well as being applied to seepage loss estimation during canal water conveyance and distribution under normal canal operating conditions. The numerical method is utilized to calculate canal seepage losses by simulating the actual situation in the site. Except for the result of seepage loss for the lined Gongan lateral canal, the simulation results of seepage losses for the unlined Gongan lateral and Zuosi field canals and the lined Zuosi field canal are relatively reasonable. If sufficient data of the study area can be obtained and finite-element software can meet the computing requirements, the numerical method can be applied to any channel.