Experimental Tests to Validate a Simple Procedure to Design Dual-Diameter Drip Laterals on Flat Fields

Multiple-diameter laterals reduce the total cost in microirrigation systems, however, the length of each sublateral should be determined carefully to assure appro-priate performance of emitter flow rates. The most accurate method is the numerical trial and error, which is time-consuming. A series of research efforts have been made to propose simple analytical design procedures. By using the power-law form of the Darcy-Weisbach formula, and equal emitters spacing for the sublaterals, Sadeghi et al. (Sadeghi et al. in J Irrig Drain E-ASCE 142:04,016,020, 2016) extended a previously introduced design solution for one-diameter laterals to tapered laterals. Recently, a simplified procedure to design dual-diameter drip laterals has been intro-duced, providing relative errors in pressure heads less than 0.5%, and allowing to set different Hazen-Williams coefficients, flow rates and emitter interspaces for each sublateral. Moreover, this analytical procedure easily detects the required commer-cial emitter characteristics. The objective of this paper is to experimentally test this solution for drip sublaterals with different lengths, flow rates and emitter interspaces. Drip laterals of a major manufacturer (IRRITEC S.p.A) with diameters of 16 and 20 mm and given emitter characteristics were used in the experiments.