Variation in Runoff, Suspended Sediment Load, and Their Inter-Relationships in Response to Climate Change and Anthropogenic Activities Over the Last 60 Years: A Case Study of the Upper Fenhe River Basin, China

The variation of river runoff (Q) and suspended sediment load (S), in addition to their influential factors, is an important area of focus in hydrological sciences. Here, Mann&ndash:Kendall tests and double mass curve analyses were used with hydrometric data from four hydrological stations in the upper Fenhe River Basin in China to evaluate temporal trends in annual Q (Qa) and S (Sa) values between 1955 and 2015. Based on the observed inflection points, three distinct periods were identified, namely, 1955&ndash:early 1980s (period I), the early 1980s&ndash:1996 (period II), and 1996&ndash:2015 (period III). The Qa and Sa values for the four stations, except for Qa values for the Jingle station, significantly decreased over the study period, with average reduction rates of 0.68&ndash:1.07 mm∙km&minus:2∙a&minus:1 and 9.24&ndash:54.39 t∙km&minus:2∙a&minus:1, respectively. Decreased rainfall, implementation of soil and water conservation program, and reservoir construction were primarily responsible for decreased Qa and Sa values for the three stations during period II, while the first two factors led to variation in Qa and Sa for the Jingle station during the same period. During period III, the Qa, Sa, and Qa&ndash:Sa relationships for the four stations were intensively affected by increased anthropogenic activities, including water diversion, cross-basin water transfers, soil and water conservation measures, revegetation efforts, and sand excavation. Further, the Qa, Sa, and Qa&ndash:Sa relationships at the Lancun station were affected by the construction of the No. 2 Fenhe Reservoir. Effective water use and supply strategies should be implemented in the future for the upper Fenhe River Basin.