Abstract:  

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.