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蒸散发是水循环的关键环节,是水量平衡的重要组成部分.由于在高寒山区进行长期野外观测的难度较大,导致对区域实际蒸散发的认识不清,从而无法明确区域水资源分配与不同植被的生态水文功能.在天山山区,高寒草甸占其总面积近15%,其对降水的调节作用巨大,但目前高寒草甸的实际蒸散发量多用潜在蒸散发进行推算,缺少实际观测数据.2012年10月-2013年9月,利用3个小型蒸渗仪观测了阿克苏河上游科其喀尔冰川综合考察站附近山区的高寒草甸的实际蒸散量,并尝试利用最小二乘支持向量机(LS-SVM)估算实际蒸散发.结果表明:研究区高寒草甸全年内实测蒸散量511.3 mm,日均蒸散量为1.4 mm·d-1;在不同时期,蒸散量变化剧烈,冻结期、生长前期、生长期和生长后期的蒸散量分别为53.9、41.0、363.8和52.6 mm,分别占全年蒸散量的10.5%、8.0%、71.2%和10.3%.最小二乘支持向量机对实际蒸散发的估算精度较高,对观测资料相对缺乏的高寒山区来说,不失为一种较好的估算蒸散发方法.
Evapotranspiration is a key part of the water cycle and is an important part of the water balance.Due to the difficulty of long-term field observation in the alpine region, the understanding of the actual evapotranspiration in the region is unclear, which makes it impossible to identify the distribution of water resources in different regions In the Tianshan Mountains, the alpine meadow accounts for nearly 15% of the total area, which plays a huge role in the regulation of precipitation. However, the actual evapotranspiration in the alpine meadow is mostly estimated with potential evapotranspiration, which lacks the actual observation data. From October 2012 to September 2013, the actual evapotranspiration of alpine meadow in the mountainous area near the Kakar glacier comprehensive investigation station in the upstream of the Aksu River was observed by using three small-scale lysimeter. At the same time, (LS-SVM) was used to estimate the actual evapotranspiration.The results showed that the measured evapotranspiration was 511.3 mm and the average daily evapotranspiration was 1.4 mm · d-1 in the alpine meadow in the study area. The evapotranspiration varied sharply in different periods, The evapotranspiration in the early growing season, the growing season and the later growing stage were 53.9, 41.0, 363.8 and 52.6 mm respectively, accounting for 10.5%, 8.0%, 71.2% and 10.3% of the total annual evapotranspiration respectively. The least squares support vector machine High precision distributed estimation of alpine mountains for the relative lack of observational data, after all, a good method to estimate evapotranspiration.