IRRIGATION UNIFORMITY WITH MEDIUM SIZE SPRINKLERS PART II:INFLUENCE OFWIND AND OTHER FACTORS ONWATER DISTRIBUTION

The adequate choice of sprinkler head as well as operating conditions in order to achieve high irrigationuniformity values is necessary for design purpose. Catch-can tests were performed to determine the spatial distribution ofwater applied with solid set sprinkler systems in open field conditions. Factors affecting water distribution were studied(i.e., direction and speed of wind, working pressure, design and number of nozzles, evaporation and drift losses, height ofsprinkler above the ground, etc.). Results show that wind speed has a clear negative effect on irrigation uniformity. Thelarger the spacing between sprinklers, the lower irrigation uniformity. Uniformity increases by using jet-straighteningvanes in the main nozzle, double nozzles under low wind speeds and single nozzles under high wind speeds, and bylocating the sprinkler at 2 m aboveground. In addition, several recommendations on design and management of sprinklerirrigation systems are inferred.