Analyzing the Day and Night Time Wind Characteristics and Their Effects on the Performance of Sprinkler Irrigation Systems

In this study in order to investigate the effects of wind speed in the day and night time on the performance of five impact sprinklers in the growth season, the wind speed values were forecasted for three years ahead in Tabriz region using time series models and ARIMA(2,0,0)(0,1,1)24 was detected as the appropriate model for both day and night time wind speed series. In the next step the water distribution patterns of three experimental sprinklers of IRRILINE IR30, VYR 35 and RAINBIRD 40B were overlapped in various shapes and spacing and water application uniformities were evaluated for each case and three different classes of wind speed (0-2, 2-4 and > 4 ms-1) during growth season. Additionally, to simulate distribution patterns and coefficients of uniformity of two more sprinklers of MEGA RC 130H and VYR 70, Ador-Sprinkler software was applied in the different wind speeds and sprinklers spacing. The results showed that the difference between day and night time wind speeds is relatively significant in the spring months, while that is almost negligible in the summer. Generally, in the growth season, night time irrigation improves application uniformity up to 3.46% for experimental sprinklers in comparison with day time irrigation. For simulated sprinklers this value was calculated 2.84%, averagely. Regarding to the obtained results it can be stated that night time irrigation practice in the spring and summer months is recommended due to lower wind drift values and lower evaporation losses, respectively.