Design of Trickle Irrigation Laterals Using Energy Drop Ratio Approach

Abstract

The pressurized pipes used in trickle irrigation include main lines, manifolds, and laterals with evenly spaced emitters. The problem addressed herein is the design of uniformly sloped laterals. This study is aimed to determine the pipe length that complies with the flow rate variation criterion. The design is based on the energy drop ratio approach. The present method provides the lateral length accounting for hydraulic parameters (nominal pressure head, flow rate variation, friction head loss gradient law, discharge versus pressure head relationship, pipe slope, inside diameter, and spacing between emitters). Subsequently, the pressure and discharge at the inlet tip are derived. Likewise, the method produces the locus of the outlet that delivers the mean discharge. Using these data, the pressure-head grade line and the flow rate distribution are established. The stepwise method was used as a reference to assess the accuracy of the present approach. The match between the two methods is deemed to be quite satisfactory for the span of pipe slopes considered. The present method is helpful for designers insofar as it provides accurate results without resorting to cumbersome calculations or tedious processing.