An Alternative Analytical Approach to Designing Paired Lateral Lines for Microirrigation on Slopes

Abstract

In localized irrigation systems, paired lateral lines are characterized by the dimensioning of two lateral lines installed in the opposite direction along the same manifold line. In this study, an alternative, simple, and easily adaptable analytical approach was developed for paired microirrigation lateral lines, which was designed for uniformly sloped ground (0<|slopes|/|total head loss|<1) based on the principle that the final pressures at the ends of the uphill and downhill lateral lines are equal. Analytical expressions for the number of emitters in a single lateral line and the best submain position were developed for single and mixed commercial diameter alternatives, using the energy gradient line method. A comparative test was carried out with three other models, on the principle that the minimum pressures or average pressures of the paired laterals are equal. The proposed procedure was found to better than the more complex numerical techniques, and it was possible to evaluate the laterals’ uphill and downhill performance based on the ratio of coefficients that describe the water distribution suitability, for six levels of variation in the emitter flow. The proposed methodology provided the best design for the paired lines, with the smallest difference in performance between the uphill and downhill laterals, as indicated by the ratio between the coefficients of uniformity of water distribution.