Observation and estimation of the evapotranspiration of alpine meadow in the upper reaches of the Aksu River,Xinjiang
Observation and estimation of the evapotranspiration of alpine meadow in the upper reaches of the Aksu River,Xinjiang
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发表时间：
2015
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通讯作者：
Guo Shuha
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作者：
Guo Shuha
蒸散量（ET）在水平衡中起着重要作用。然而，高寒山区草甸面积较大，但通过野外观测获得长期的蒸散发存在很大困难，导致人们对高寒草甸的蒸散发缺乏了解。阿克苏河上游高寒草甸的蒸散发采用称重式微蒸散仪的方法获取。测量结果显示，高寒草甸总蒸散量为511. 3 mm，日均蒸散量为1. 4 mm·d- 1。ET值随季节变化显着。冷冻期、生育前期、生育期、生育末期ET值分别为53. 9,41. 0,363。分别为 8 和 52. 6 mm，所占比例为 10. 5%，8. 0%,71。分别为年ET值的2%和10. 3%。本文还讨论了最小二乘支持向量机(LS-SVM)在高寒草甸实际蒸散估计中的适用性。结果表明,LS-SVM能够较好地估计实际蒸散量,且精度较高,对于高寒山区实际蒸散量的估计将是一种良好且有用的方法。
Evapotranspiration( ET) plays an important role in water balance. However,there is a great difficulty to get long-term records of ET by field observations in high-cold mountainous regions,resulting in lack of understanding the ET of alpine meadow,in spite of the meadowcovering a large of area in high-cold mountains.Weighing microlysimeter method had been used to gain the ET of alpine meadowin the upper reaches of the Aksu River. Measurement revealed that the total ET of the alpine meadowwas 511. 3 mm,and the daily average was 1. 4 mm ·d- 1. The value of ET varies significantly with season. The values of ET in freezing stage,early growing stage,growing stage,last growing stage were 53. 9,41. 0,363. 8 and 52. 6 mm,respectively,and their proportions occupy 10. 5%,8. 0%,71. 2% and 10. 3% of the annual ET values respectively. In this paper,it is also discussed that the applicability of the least squares support vector machine( LS-SVM) in estimation of the actual ET in alpine meadow. The results showed that LS-SVMcan better estimate actual ET with high accuracy,which will be a good and useful method for estimating actual ET in the high-cold mountainous regions.