Influenced by crops' physiological mechanism and the unsteady, non-linear stochastic variation of meteorological factors, referenceevapotranspiration is characterized by its stochasticism.
In most parts of the area, the referenceevapotranspiration of chimonophilous and thermophilic crops during their temperature-defined growth season decreased, and the aridity index increased.
全区大部分区域喜凉作物和喜温作物温度生长期内参考作物蒸散量呈下降趋势，干燥度呈增加趋势。
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This paper reviewed the methods for computing crop water requirements and emphasized the method based on reference crop evapotranspiration.