近50年金沙江各区段年径流量变化及分析

为深入探究不同自然地理条件下金沙江流域的径流特性，将屏山站以上区域分为6个区段，采用线性倾向估计、Spearman秩次相关检验、Mann Kendall检验、有序聚类分析、秩和检验等方法，分析了1960~2015年各区段径流序列，并结合流域的水文要素和人类活动情况讨论了影响径流量变化的因素。结果表明: 近50 a仅直门达以上区段和华弹-屏山区段径流变化在全时段有显著趋势，分别是上升和下降；但在近20 a中下游的石鼓-攀枝花、攀枝花-华弹、华弹-屏山区段均呈现明显的下降趋势。90年代后多个区段经历了突变。分析表明降水是近50 a来径流变化的主要驱动因素；其中石鼓站以上区段和雅砻江流域受降水影响最大。没有充足证据表明持续上升的气温对各区段径流量造成足够的影响。进入21世纪后，以水土保持措施为代表的人类活动是下游攀枝花-华弹、华弹-屏山区段径流减少的重要因素，但主导因素仍为降水。此外，雅砻江流域和华弹-屏山区段内大型水库投运前的初期蓄水对当年径流量有显著影响；蓄水后的水库蒸发及引水工程的损失对径流影响则相对较小。

Analysis on the Sectional Annual Runoff Change of the Jinsha River Basin in the Recent 50 Years

For the sake of exploring the runoff characteristics of the Jinsha River Basin under different geographical conditions, the basin above Pingshan Station is divided into six sections. A variety of mathematical statistics methods, including linear propensity estimation, Spearman rank correlation test, Mann Kendall test, ordinal cluster analysis and rank sum test are adopted in this research to analyze the runoff series which cover a range from 1960 to 2015 in each section, and hydrologic factors as well as anthropogenic activities are studied to make interpretation on the drivers of changes. Results show that only the section above Zhimenda and Huatan Pingshan section are detected to have obvious trend in runoff change, more specifically the trends are increasing and decreasing respectively, while all the sections in the middle reach and mainstream of lower reach have gone through a descending trend in recent 20 years. It is also illustrated that many of the sections have break points after 1990s. Precipitation is recognized and verified as the most significant driver of runoff change, which is found to be rather dominant in sections above Shigu and section of Yalong River. No conclusive evidence can be found that temperature change exerts considerable effects on the runoff change. Besides, soil and water conservation, serving as a typical aspect of anthropogenic activities, turns out to play an important role in runoff reduction in Panzhihua Huatan and Huatan Pinshan sections in the new century, though the influence of precipitation still cannot be overwhelmed. Additionally, the impoundment of large reservoirs for the first time round can apparently bring down the runoff, with several peculiarities in the figures conforming well to the inference with respect to Yalong River section and Huatan Pingshan section. However, the added water losses resulted from either the expanded surface evaporation of reservoirs or the diversion projects are relatively marginal in comparison to the sectional runoff.