Performance assessment of sprinkler irrigation systems : a new indicator for spray evaporation losses

Performance assessment is an increasingly relevant concept in present-day irrigation systems. To this end some indicators have been proposed for comparing actual performance with established design criteria. Concerning sprinkler irrigation, evaluation of the jet losses due to environmental conditions can be considered an important indicator of system performance. The issue requires a full analytical description of spray flow and waste and entails both experimental and theoretical studies. In the former, it appears to be difficult to identify, and so to measure, the contribution of each parameter to the final result; in the latter, the non-linear relationships among the variables make it difficult to obtain an exhaustive analytical picture of the process. Numerous experimental and theoretical studies have been conducted recently in an attempt to gain a deeper insight into the phenomenon but much work still remains to be done. A mathematical model for irrigation sprinkler droplet ballistics, based on a simplified dynamic approach to the phenomenon, has been presented. The results compare very favourably with the kinematic results obtained by other authors using more complicated procedures. Moreover, field trials showed the model to reliably estimate spray evaporation losses caused by environmental conditions. Further analytic and experimental work is needed to gain a better understanding of the problem. Copyright