金沙江上游径流演变趋势及自然驱动力

Runoff Trend and Natural Driving Force in the Upper Jinsha River

摘要: 基于金沙江上游干流水文站1961~2015年月径流量与控制面积以上同步气温、降水资料，对年和各月的气温、降水和径流年际变化特征及相关性进行了分析。结果表明：金沙江上游气温呈显著上升趋势，自上而下气温上升幅度逐渐减弱。气温突变点大都位于2002~2005年之间，上游早于下游；年降水量均呈增加趋势，上段和下段增加趋势明显，中间不显著。上中段冬春季11~4月降水增加趋势大于夏秋季，春季3~5月降水量呈显著增加趋势。下段仅春季3~5月呈非显著性增加趋势，其它月份增加和减少趋势互现。降水突变点位于1997~1999年之间；年径流变化趋势均不明显，除上段冬春季11~4月径流显著增大，其余月份径流增大趋势不明显。中段存在冬春季11~4月的增大趋势大于夏秋的现象，但增大趋势不明显。下段除春季2~5月呈不明显增大趋势外，基余各月增大和减小趋势交替出现。径流突变位于2002~2003年之间；金沙江上游愈靠近长江源头降水与气温的关系越密切，其径流量增加系由于气温上升和降水的共同影响，下段主要受降水变化的影响，气温影响可忽略。

Abstract: Based on the runoff, air temperature and precipitation data from 1961 to 2015 at the major stations on the upper Jinsha River, the annual and monthly variation characteristics and correlations among temperature, precipitation and runoff were analyzed. The results show a temperature rising trend which is gradually weakening from upstream to downstream. Most of the sudden changes in temperature occurred between 2002 and 2005, and the changes upstream are earlier than those downstream. The annual precipitation shows an increasing trend which is obvious in the upper and lower river sections, and not significant in the middle. The precipitation increase in the upper and middle sections from November to April is greater than that in summer and autumn months, and is significantly increased from March to May. In the lower river section, the precipitation shows a trend of slight increase from March to May, and in the other months there exist no obvious trends of decrease or increase. The sudden change points of precipitation occurred between 1997 and 1999. The trend of change in annual runoff is not obvious. The runoff increases significantly in the upper section from November to April, but not obviously in the remaining months. In the middle section, the increase from November to April is greater than that in summer and autumn, but the increase is not obvious. The runoff in the middle section shows trend of insignificant increase from February to May, and increases or decreases alternately in the other months. The sudden change points of runoff were between 2002~2003. On the upper Jinsha River, the closer the area to the source of the Yangtze River, the closer the relationship between precipitation and temperature. The increase of runoff is caused jointly by rising temperature and the precipitation, and is mainly affected by the change of precipitation in the lower section.