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利用天山西部地区10个代表性水文、气象站1957~2006年20 cm口径蒸发皿观测的水面蒸发量资料,分析了天山西部地区水面蒸发量的变化趋势。结果表明,天山西部地区代表站水面蒸发量具有明显的地区分布特性,水面蒸发量随海拔高程的增高而减少;水面蒸发量的年内变化很不均匀,而年际变化比较稳定;从1987年开始天山西部地区代表站年水面蒸发量转入一个快速下降的阶段,20世纪90年代和21世纪初,平均年水面蒸发量较1957~2006年50年均值减少6%~7%,较1957~1986年30年均值减少10%~11%。在季节变化中以夏季水面蒸发量的减少趋势尤为显著;滑动t检验的结果证实,1987年是天山西部地区水面蒸发量由多向少发生突变的转折年;50年来,水面蒸发量总体上呈明显减少的趋势,年水面蒸发量的气候倾向率为-53.2 mm/10 a。这与黄河等流域近40、50年蒸发皿蒸发量呈明显下降趋势的结论基本一致;水面蒸发量与降水量呈负相关关系,可以初步认为降水及湿度的增加是天山西部地区水面蒸发量明显减少的主要间接因素之一。
Based on the data of water surface evaporation measured from 10 representative hydrographs and meteorological stations from 1957 to 2006 in the west of Tianshan, 20 cm caliber evaporating dish, the change trend of water surface evaporation in the western Tianshan area was analyzed. The results show that the surface evaporation of the representative stations in the western Tianshan has obvious regional distribution. The evaporation of the water surface decreases with the elevation of elevation. The variation of water surface evaporation is very uneven and the interannual variation is relatively stable. Since 1987 The evapotranspiration at the representative stations in the western Tianshan Mountains turned into a stage of rapid decline. In the 1990s and early 2000s, the average annual surface evaporation decreased by 6% -7% compared with the 50-year average from 1957 to 2006, 30-year average annual reduction of 10% to 11%. In the seasonal variation, the decreasing trend of summer surface water evaporation is especially significant. The result of the sliding t-test confirms that the year 1987 was the turning point of the water evaporation in the western Tianshan from the multi-directional to the small. In the past 50 years, Significantly reduce the tendency of the annual surface water evaporation climate tendency rate of -53.2 mm / 10 a. This is consistent with the conclusion that the evapotranspiration of the Yellow River and other watersheds showed a significant downward trend in the past 40 and 50 years. The evaporation of water surface and the precipitation have a negative correlation, and it can be preliminarily thought that the increase of precipitation and humidity is the obvious surface water evaporation in the western Tianshan Reduce one of the main indirect factors.