Evaluation and Modeling Wind drift and Evaporation Losses of the Center Pivot Irrigation System in Moghan Region

Evaluation of irrigation systems consists of analyzing the measurable performance of the system in operation conditions, is a management tool that allows the system users to make the best use of the irrigation systems. Since various regions in Iran have arid and semi-arid climates, obtaining the actual wind drift and evaporation losses and also making optimized use of water towards sustainable water resources management has a great importance. Since estimation of evaporation and wind losses that has been presented in different climatic conditions has different results, and it is not possible to present a reference model, so the purpose of this study is to investigate the effective climatic parameters on evaporation and wind losses of the Center Pivot system and to present an optimal model using multivariate regression in the study area.

This research has been carried out in the city of Pars-Abad in Ardabil province. The study was conducted in Part of the Moghan Agro-Industrial Complex, at wind speeds of 0-3 and 3-6 meters per second with three replications. Experiments were performed on two Center Pivot Irrigation System in sections 5 and 6 of Moghan Agro-Industrial Complex (1-4-6 and 1-8-6), which included two design treatments. The average altitude of this area is 32 meters above the sea.

Results indicated that the efficiencies of the system at wind speeds of 0-3, 3-6 meters per second were 89.47, 84.47 percent, respectively, and wind speed, temperature, relative humidity, nozzle diameter, and vapor pressure deficit (saturation deficit) were among the factors that influenced wind drift and evaporation losses. Base on the results, the wind factor had the most and vapor pressure deficit had the least effect on wind drift and evaporation losses. Also, the equation of wind drift and evaporation losses was also obtained with the atmospheric conditions of the region, which had the best fit with the measured values. Results shown that the difference between results of the model and observed data was not significant in 1% level of confidence. Moreover, the measured and the modeled percentages obtained for wind drift and evaporation losses varied from 7 to 18 and from 10 to 18 percent, respectively.

The results show a direct relationship between the evaporation and wind losses with wind speed in the region. So that at wind speeds of less than 3 m/s the parameters of Coefficient of Uniformity, Distribution Uniformity and potential and Application Efficiency of the low quarter are in the appropriate range, and at medium and high wind speeds, evaluation parameters are not in the desired range, it is indicating the importance of center pivot system design in windy regions.

This research has been carried out in the city of Pars-Abad in Ardabil province. The study was conducted in Part of the Moghan Agro-Industrial Complex Province at wind speeds of 0-3 and 3-6 meters per second with three replications. For the experiment, two rows of cans at an angle of 3 ͦ were positioned radially along the center of the centripivot system 10 m apart. The sprayer used in this study was F33AS 11/64˝ with 26 m of spraying diameter and operating pressure of the sprinklers varied from about 2 to 2.5 bars.

Results indicated that the efficiencies of the system at wind speeds of 0-3, 3-6 meters per second were 89.47, 84.47 percent, respectively, and wind speed, temperature, relative humidity, nozzle diameter, and vapor pressure deficit (saturation deficit) were among the factors that influenced wind drift and evaporation losses.