祁连山讨赖河流域上游积雪时空分布及其变化研究

Spatiotemporal distribution of snow cover and its variation in the upper reaches of the Taolai River basin, Qilian Mountains

积雪是冰冻圈的重要组成部分,在水文循环和能量平衡中起着重要的作用。积雪时空分布及其变化分析是研究内陆河流域出山径流形成、分布及变异的前提。论文以祁连山讨赖河流域上游为研究区,采用降尺度方法获取高分辨率雪深数据,并基于Sen斜率法、敏感性分析和贡献率计算方法,分析2002—2018年间雪深时空变化,揭示积雪对地形及气候等因子的响应规律。结果表明:讨赖河流域上游雪深介于0~2.50 cm之间,变率介于-0.19~0.06 cm·a^(-1)之间,域内雪深减小面积占比68.30%。雪深随海拔的增大而增加,以海拔2 500 m为界发生增减变化,高海拔地区呈减小趋势;雪深随坡度增加则呈先增后减的趋势;各坡向雪深均呈减小态势,西北坡尤为显著。从敏感性均值来看,气温和辐射对雪深具负向抑减效应,降水则具正向促增效应。高海拔区域降水对积雪变化的贡献率相对较大;低海拔河谷地带气温对积雪变化的贡献更为显著。本研究为内陆河流域上游积雪动态研究提供了范例,对出山径流模拟、预测以及流域水资源管理具有一定参考价值。

Snow is an important part of the cryosphere and plays an important role in the hydrological cycle and energy balance. Study of the spatiotemporal characteristics of snow cover and its change is the prerequisite for analyzing the formation, distribution and variation of runoff from mountains in inland river basins. In this study, we selected the upper reaches of the Taolai River basin of Qilian Mountains as the study area, used downscaling methods to obtain high-resolution snow depth data, and adopted methods of spatial statistics, sensitivity analysis and contribution separations to quantify snow cover distribution and variation influenced by terrain and the regional climate during the time period from 2002 to 2018. Results showed that basin early average snow depth ranged from 0 cm to 2.5 cm, with variation from-0.19 cm·a^(-1)to 0.06 cm·a^(-1). The area of snow depth reduction during the study period accounted for 68.30% of the total area. It was found that the snow depth increase more with altitude and less with the increase of slope. Variation of snow depth increased below 2 500 m a. s. l.and decreased above 2 500 m a. s. l. As the slope increases, it first increases and then decreases;the snow depth of each aspect decreases, especially in the northwest orientation. The sensitivity of snow depth to air temperature and solar radiation were found negative in general, while that of the precipitation was found positive. The precipitation in high-altitude areas has a relatively large contribution to the snow depth variation, while in the valley areas, the contribution of temperature to snow cover is more significant. This work provides an example for the study of snow dynamics in the upper reaches of inland river watersheds, and benefits model simulation and prediction of mountain runoff and regional water management.