Validation of Dripline Emitter Characteristics and Pump Performance Curve for Network Analysis

Abstract

In this paper, simple methods for validating the emitter characteristics of driplines and pump performance curves for dripline network design and simulation are presented. Pressure compensating driplines were tested and used to aid grass establishment to control erosion on the steep slopes of a newly constructed flood levee. The dripline networks consisted of several bays that had different lengths and numbers of lateral rows as dictated by fence lines of property boundaries and access road ramps. Single emitters as well as thousands in dripline networks were tested. The average emitter discharge was observed as able to exceed the supplier’s value (2.1 l/h) by as much as 10%. Moreover, the emitter discharge value tended to be higher between the opening threshold pressure head of the pressure compensating emitters of 4 and 10 m compared with those for pressure heads higher than 10 m. The emitter insertion head loss coefficient exhibited considerable variability (0.117–0.753), although the average value of 0.336 was close to the supplier’s value of 0.36. The supplier’s pump performance curve overestimated the pressure head by 11 m for a flowrate of 50 l/min, but the overestimation decreased to 6 m at the higher flowrate of 300 l/min. A comparison of observed and simulated pressures at strategic locations within the dripline networks were used to identify the emitter characteristics without the need for flow measurements. Simulation results were used to determine excessive bay inlet pressures and the corresponding ball valve opening fractions to drop the inlet pressure to an acceptable limit for each bay.