Methodology for Determining the Emitter Local Head Loss in Drip Irrigation Systems

Abstract

Precise estimation of local head loss (hl) remains a challenge for the hydraulic design of drip irrigation. This study develops a robust protocol for estimating the emitter hl based on the Borda-Carnot principle. The method requires cross-sectional flow area measurements with and without emitter obstruction and a contraction coefficient, which is determined by the empirical relationship of the obstruction ratio. For comparison purposes, cross-sectional flow areas were also measured with a profile projector, which resulted in absolute deviations lower than 2.6%. Observed and predicted single-emitter hl deviation values were consistent with previous studies; the three examined emitting pipe types had deviation values of −6.67%, 21.6%, and 1.07%. Thus, the proposed methodology for estimating the cross-sectional area can be applied without compromising hl estimates using a single flat inline emitter operated by the proposed semiempirical model.