1979—2017年雅鲁藏布江流域雪深时空分布特征及其影响因素分析

积雪是水文过程的重要环节，基于1979—2017年中国雪深长时间序列数据集、中国区域地面气象要素数据集提供的降水和气温数据，结合DEM数字高程模型等，运用Mann-Kendall检验法、Sen氏坡度法、Pearson相关分析法，分析了雅鲁藏布江流域雪深时空变化分布特征，并对雪深与气象因子（气温、降水）和地形因子（高程、坡度、坡向）的相关性进行了分析。结果表明：1979—2017年雅江流域多年平均雪深为1.95 cm，且以0.02 cm·a^-1的速率呈现显著减少趋势；雪深空间分布特征差异性明显，呈现“二高二低”相间分布的特征，高值区为流域西部边缘和东部的山地区域，低值区为中游河谷、流域出口低谷区；气象因子对雪深的变化起决定性作用，其中年平均气温与雪深的相关系数数值为-0.63，二者相关性显著；雪深呈现出随着高程的增加而增加的变化趋势，但最大雪深并非出现在最高海拔处；雪深随坡度的变化呈现“减少—增加—减少”三段式分布规律，且东坡和南坡的雪深厚度高于西坡和北坡的雪深厚度。

Spatiotemporal distribution of snow cover depth and its driving factors in the Yarlung Zangbo River basin,1979—2017

Snow cover is an important part of the hydrological process. Based on long-term snow cover depth data set of China， as well as the regional surface meteorological element data from the China Meteorological Data Set （1979—2017）， combined with DEM digital elevation model， the spatiotemporal distribution of snow cover depth in the Yarlung Zangbo River basin from 1979 to 2017， as well as the correlation between snow cover depth and meteorological factors （temperature， precipitation）， and the correlation between snow cover depth and terrain factors （elevation， slope and aspect） are analyzed by using Mann-Kendall trend test， Sen’s slope estimator and Pearson correlation analysis method. The results show： （1） from 1979 to 2017， the annual average snow cover depth in the Yarlung Zangbo River basin was 1.95 cm， with a decreasing rate of 0.02 cm·a^-1； （2） the spatial difference of snow cover depth was obvious， showing a characteristic of "two peaks and two valleys"； the large value area located in the western edge and the eastern mountainous area of the basin， and the small value appeared in the middle valley and the outlet valley； （3） meteorological factor played a decisive role to the variation of snow cover depth； the correlation coefficient between annual average temperature and snow cover depth was -0.63， quite significantly； （4） the snow cover depth increased with elevation， but the maximum snow cover depth did not appeared at the highest elevation； （5） with slope changing， the snow cover depth presented a three-step distribution， i.e.， “decrease-increase-decrease”， and the snow cover depth on the east slopes and the south slopes were greater than that on the west slopes and the north slopes.