天山乌鲁木齐河源冰雪径流的极值分析

Analysis of the Extremum of Snow and Glacier Meltwater Runoff at the Headwaters of the rümqi River

利用乌鲁木齐河源区近20多年的水文气象实测资料, 研究了河源区冰川、季节积雪和夏季降水等形成径流极值(极大值和极小值)的时空变化特征, 并对其产生过程及其与气温、降水等气象要素的关系进行初步分析. 结果表明: 春季(5月)1号冰川水文点和空冰斗水文点极大值径流呈现出轻微增大的趋势, 总控水文点表现为减小的趋势; 夏季(6～8月)径流极大值变化显示, 空冰斗和总控水文点有增大趋势, 1号冰川水文点总体为轻微的减小趋势. 春季径流极值的主要影响因素是气温; 夏季极大值径流是气温和降水综合作用的结果, 而极小值径流主要源于大降水(雪)后的相对较低气温的影响.

The extremum of snow and ice meltwater runoff is analyzed in this paper, based on the observation (1980-2002) at the headwaters of the ürümqi River, Tianshan Mountains. It is revealed that there is a slight increase of the extremum at the Glacier No.1 and the Ice-Free Cirque Stations in spring, but a decrease of that in the total-Control Station; and there is an increase of the extremum at the Ice-Free Cirque and the Total- Control Stations in summer, but a decrease at the Glacier No.1 Station. Analysis of the extreme (maximum/minimum) runoff series and the correlative temperature shows temperature is the principal factor to the extremum in spring, both temperature and precipitation control the maximum runoff in summer, and relative low air temperature after a major precipitation results in the minimum runoff.