Tarbiat Modares University Journal of Agricultural Science and Technology 1680-7073 14 7 2012 12 01 Factor H for the Calculation of Head Loss and Sizing of Dual-diameter Laterals 1555 1565 15189 EN S. H. Sadeghi Department of Water Engineering, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran. S. F. Mousavi Department of Water Engineering, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Islamic Republic of Iran. S. H. R. Sadeghi College of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor 46417-76489, Islamic Republic of Iran. 0000-0002-5419-8062 M. Abdolali Department of Statistics, College of Mathematical Sciences, Isfahan University of Technology, Isfahan Journal Article Factor is introduced for direct head loss calculation and sizing in dual-diameter laterals of sprinkler and trickle irrigation systems when the Hazen-Williams equation is to be applied. Application of this factor prevents trial and error and uses fewer head-loss equations in calculating the total friction loss and designing dual-diameter laterals. The proposed factor is a function of total number of outlets on the lateral, number of outlets on the smaller-diameter section of the pipe and ratio of smaller diameter to the larger diameter pipe. By solving two practical examples, the advantage of this factor over other approaches was shown. It was also demonstrated that design of lateral sizing by the given equations is simpler, easier and more accurate than the previous methods. https://jast.modares.ac.ir/article_15189_a72805672a5c12f86c22eb67eb8bf7b8.pdf