金沙江流域水沙变化及其驱动机制

为了探究金沙江流域控制水文站屏山站水沙序列的趋势及突变特性，量化不同驱动因素对水沙变化的贡献。基于金沙江流域1954—2016年径流和输沙数据，从长时期及场次事件两个角度揭示了水沙关系的动态变化特征。结果表明：(1) 63年间，径流量年均变化速率为-1.16×10⁸m³/a;输沙量年均变化速率为-2.0×10⁶t/a; 1998年长江流域发生特大洪水，水沙序列在该年发生突变；(2)水沙关系的特征参数a值在1998年前后由上升改为下降趋势，退耕等坡面水保措施在1998年后发挥了重要作用；b值始终下降，河道影响因素始终发挥减沙作用；在场次降雨尺度上，流域径流-悬移质泥沙环路(C-Q环路)以顺时针形环路为主，表明坡面泥沙物源充足，是影响流域产沙的重要因素；(3)流域内降水、温度及NDVI与径流和输沙之间有明显的相关性，人类活动与降水因素对径流量的贡献比为-1∶2,而输沙量主要受人类活动影响，对应的贡献比为-6∶1。综上，金沙江流域63年间的径流输沙受多种因素综合影响，径流量的变化主要由于降水的变化，输沙量受人类活动影响更大。

Runoff and Sediment Discharge Variations and Corresponding Driving Mechanism in Jinsha River Basin

The relationship between runoff and sediment discharge in Jinsha River basin has undergone remarkable variations over recent years, which played significantly role in regional ecological sustainable development and the control of water and sediment in the upper reaches of the Yangtze River. To investigate the trend and abrupt characteristics of runoff and sediment discharge sequences at the controlled hydrological station-Pingshan Station, and to quantify the contribution rates of different driving factors on runoff and sediment discharge, this study carried out statistical analyses on the records of runoff and sediment discharge during 1954 and 2016, and presented the dynamic variations of runoff and sediment discharge relatioinships from perspectives of long-term observations and shor-term events. The results showed that:(1)during the 63 years, the average annual change rate of runoff was -116 million m³, the average annual change rate of sediment discharge was -0.02 billion tons; a catastrophic flood occurred in the Yangtze River Basin in 1998, and the turning point of runoff and sediment sequence occurred in that year;(2)the featured parameter a value of the runoff-sediment discharge relationship changed from increasing trend to decreasing trend in the abrupt year 1998, which was potentially due to the Returning Rarmland to Forest Project after 1998; the featrued b value presented decreasing trends for both time stages, exhibiting the import role of river channels played on sediment reduction; on the rainfall event scale, the runoff-suspended sediment loop(C-Q loop)presented mainly clockwise type, indicating sufficient sediment source from the slope;(3)precipitation, temperature and NDVI showed obvious correlationship with runoff and sediment discharge sequences; precipitation played dominate role in runoff, and the contribution ratio of human activities and precipitation on runoff is -1:2, while the contribution ratio on sediment discharge is -6:1. In summary, the runoff and sediment transport of the Jinsha River Basin in 63 years were comprehensively affected by a variety of factors. The change of runoff was mainly due to the change of precipitation, and the sediment transport was more affected by human activities.