Fen River watershed was located in the middle reaches of the Yellow River. The variation of runoff volume and sediment load in this area especially the upper watershed had an indicating significance to the change of water-sand regime of the Yellow River. The Lancun station was the most important hydrological monitoring station on the upper Fen River. Based on runoff

suspended sediment load data observed at Lancun station in rainy season from 1954 to 2013

the characteristics and driving factors of suspended sediment load variation were analyzed by using linear trend analysis. The results showed that the declined trend of sediment and runoff were obvious in recent 60 years. But the changes of them not synchronous which the former’s trend was stronger than the latter’s. The precipitation showed no trending variation. However

the precipitation and runoff (P＜0.01)

precipitation and sediment load (P＜0.01) showed a significant linear correlation. Floods had a decreased tendency

and this trend was the most evident in the beginning of the 21st century. Using the analysis of double-mass curve

the effect of driving factors on the variation in suspended sediment load had been studied. The double-mass curve showed three breaks (1959

1981 and 2002) which divided the evolution process of suspended sediment load into four typical periods. The suspended sediment load was mainly affected by rainfall and runoff. Then it decreased significantly after 1959 which might be explained by Fen River reservoir construction. During the period from 1981 to 2002

the runoff and suspended sediment load decreased again. It could be related to the rainless

large-scale mining

urban construction

soil and water conservation measures. The runoff and sediment yield decreased significantly since 2002. In addition to the above reasons

reduction in precipitation especially storm and the second Fen River reservoir trapping sediment were the major cause for sediment reduction in the upper Fen River．