Wind Drift and Evaporation Losses Model in Spray Nozzles of Center Pivot Irrigation system

Wind drift and evaporation are the main sources of water losses in sprinkler irrigation systems. A proper understanding of factors affecting these losses and estimating their amounts can be useful for reducing water losses and improving irrigation efficiency. It seems necessary to develop a model to estimate these losses in order to increase application efficiency of widely used center pivot irrigation systems. In this research a 25×25 m2 network of catch cans at 1.25 m spacing was prepared in the field. Commonly used Nelson R3000, Senninger LDN and Nelson D3000 spray sprinklers with various nozzle sizes, pressures and elevations were installed at the center of the network. Experiments were conducted at the various weather conditions and the needed climatologic data were measured simultaneously. Water losses were computed in terms of volumetric difference between the emitted water from spray nozzles and the received water on the soil surface. Using statistical analyses several equations which enable to estimate wind drift and evaporation losses were derived. From conventional methods, Frost-Schowalen, Keller-Bliesner and Playan et al methods were considered and their accuracies were investigated in comparison with the experimental data. Results showed that the proposed new equations estimated water losses satisfactorily and they calculated wind drift and evaporation losses more accurately than the mentioned methods.