Determining sprinkler technical parameters with consideration for microclimate modification effects

Application intensity and time are two important parameters for the design and operation of sprinkler irrigation systems. The effects of microclimate modification from sprinkler water evaporation have not still been adequately considered in conventional methods of determining sprinkler technical parameters. This study proposed an approach to determine application intensity and time with consideration for microclimate modification effects of sprinkler irrigation using the extended CUPID model. In the model, application intensity and time parameters were determined using maximized sprinkler efficiency. Sprinkler efficiency was simulated under varying application intensities and times in summer corn seasons in Xinxiang City during 2001-2007 and in Daxing during 2005-2011. The optimal parameters for the two regions were then determined. The results indicated that sprinkler efficiency decreased with time during summer corn growth. The influence of sprinkler intensity on inter-annual variations of sprinkler efficiency differed with irrigation region. Furthermore, daytime sprinkler irrigation produced higher inter-annual variations than that nighttime sprinkler irrigation. While the optimal application intensity in Xinxiang was 10 mm·h^-1 for silt-loam soils, it was 15 mm·h^-1 in Daxing for sand-loam soils. For both Xinxiang and Daxing region, maximum sprinkler efficiency was obtained at 8:00 am.