Drip irrigation lateral design procedure based on emission uniformity and field microtopography

Field microtopography, hydraulic variation of the emitter, and manufacturing variation of emitters were analyzed to study their influence on the uniformity of drip irrigation system water application. The manufacturing coefficient in the emitter flow equation is taken as a random variable that represents the emitter manufacturing variation. Uneven field microtopography resulting in emitter pressure and flow variations is also considered as a random variable. Microtopography and the manufacturing coefficient that are assumed to follow a normal distribution were generated with a computer code. The rate of emitter discharge variation, the coefficient of discharge variation, and Christiansen's coefficient of uniformity were calculated for drip irrigation systems. Finally, the emitter uniformity equation was determined through the statistical analysis of 100 data sets, and a new design method for drip irrigation laterals is proposed. The results indicate that neglecting the microtopography leads to inappropriate design of lateral pipe diameter and length, especially when emitter operating pressures are low. Copyright © 2009 John Wiley & Sons, Ltd.