黄土高原34年蒸发皿蒸发量的变化特征分析

Analysis on Variation Characteristics of Pan Evaporation in Recent 34 Years in the Loess Plateau

采用黄土高原地区及其周边1956～1989年期间85个气象站逐月的蒸发皿蒸发量观测资料,分析了黄土高原地区34年蒸发量的空间分布情况以及变化趋势。结果表明,34年来黄土高原地区蒸发皿蒸发量多年平均为1 358.0 mm,呈现十分显著的下降趋势,年蒸发量变化速率达-115.9 mm/10a,其绝对值远高于全国平均变化速率-30.7 mm/10a的绝对值;各季节蒸发量均呈现明显的下降趋势,夏季和春季蒸发量下降较多,分别达-52.2和-34.4 mm/10a。由此可知,黄土高原地区蒸发皿蒸发量变化剧烈,蒸发明显减小,初步分析其原因,认为与地区植被保护等水土保持措施取得较好成效有关。

Based on the monthly observational data of pan evaporation from 1956-1956 of 85 meteorological stations in the Loess Plateau Basin and its surrounding,the spatial distribution and variation trend was analyzed.The results showed that in recent 34 years,the average evaporation of the Loess Plateau Basin reached an annual 1358.0 mm,indicating significant dropdown trend and the variation rate of annual pan evaporation reached-115.9 mm/10 a.Its absolute value is much higher than the national average variation rate of absolute value-30.7 mm/10 a.And the seasonal evaporation were showed obvious downward trend especially in summer and spring,reach to-52.2 and-34.4 mm/10a.The pan evaporation changes in the Loess Plateau region is intense,evaporation decreased obviously.The causes were preliminary analyzed,it was thought that soil and water conservation measures of vegetation protection have a good effect on the pan evaporation.