祁连山北坡河川径流变化的分析及趋势预测

本文结合大气环流及山区内,外气温和降水的年际变化,分析了径流变化与气候变化的关系。分析指出:山区东段河流的枯水年段与欧亚地区中高纬度纬向环流的加强有一定关系;山区对流性降水对本区河流年径流的变化有不可忽视的影响。用时间序列分析方法模拟了年径流的变化规律,并预测未来5—10年径流的变化趋势。

Analysis and Prediction of the Variation Trend of theAnnual Runoff on the Northern Slopeof Qilian Mountain

The variation of annual runoff is analysed in combination with the study on atmospheric circulation and climatic change. It is clear that 1) in the east section of Qilian Mountain the annual runoff is mainly affected by the monsoon circulation and thermal low pressure on the Qing-Zang Plateau, while in the west section by westerlies to a certain degree. The difference in dominant synoptic regime results in non-synchronization in the multiyear variation of the runoff in rivers between the east and west sections of the mountains; 2) the occurence of the year with low water in east section of Qilian Mountain is usually connected with the strengthening of zonal circulation and the weakening of meridional circulation at the high-mid latitudes in Eurasia; 3) the variations in high and low water of rivers in this region can be interpreted by the convectional precipitation resulted from the thermodynamic action in the mountains during the summer, in combination with circulation patterns) 4) the reduction in runoff during the 1960's and 1970's mainly resulted from climate changes, but there were a few rivers affected by human economic activities to a certain degree. The variation of annual runoff of the rivers in this region was modelled by means of time series analysis. From the short series obtained it is found that the period of optimal fit is 91-95 years for the rivers in the east section of Qilian Mountain. On the basis of the calculations and the possible future changes in climate and circulation it is predicted that the runoff will tend to increase in the east section of Qilian Mountain, but that in west section to decrease in the future 5-10 years,