高寒草甸蒸散量及作物系数的研究

Study on Evapotranspiration and Crop Coefficient of the Alpine Meadows in the Haibei Area

利用FAO Penman-Monteith计算法(FAO P-M法)、Penman修正公式法(P法)、Irmark-Allen拟合公式法(I-A法)分别计算了海北高寒草甸参考作物蒸散量,并以FAO P-M法计算结果为标准,与其它两种方法的结果进行比较。结果表明,海北高寒草甸地区年参考作物蒸散量为812.0mm,其中植物生长季的5-9月为500.9mm。FAO P-M法计算参考作物蒸散量较为合理,造成其他两种方法计算结果偏差的原因主要是辐射项的选取及土壤热通量的影响。利用实测土壤含水量资料和水量平衡方法计算的植物生长期的5-9月植被实际蒸散量为425.5mm,与FAO P-M法得到的参考作物蒸散量相比计算作物系数,得到植物生长初期、中期和末期的作物系数分别为0.51、0.96和0.87。

The reference evapotranspiration of the Alpine Meadows in the Haibei area was estimated by using the FAO P-M equation, Penman equation and Irmark-Allen equation. Calculations from the first method was considered as the standard to compare with those from other two methods. Results showed that the reference evapotranspiration was about 812.0mm in the Haibei alpine meadow, while it was 500.9mm in plant growing season from May to September. The comparison also suggested that the calculated reference evapotranspiration by FAO P-M was more reasonable, for there might be deviations by using the other 2 methods due to the influence of radiation and soil heat flux. Furthermore, the actual evapotranspiration was calculated by water balance, which was 425.5mm in plant growing season. Crop coefficient was the ratio between the actual and the reference evapotranspiration （ by FAO P-M method） , which was 0.51 , 0.96 and 0. 87 in the beginning, middle and end of the growing season, respectively.