Research on the Evolution Characteristics and Driving Mechanism of Runoff in the Shiyang River Basin

Based on the hydrological and meteorological data of the Shiyang River Basin from 1956 to 2021, it analyzes the evolution characteristics of the basin's runoff under the combined influence of global warming and high-intensity human activities. The R/S method is used to analyze the changing trend and persistence of the long-term annual runoff. The research results show that over the past 66 years, the basin's temperature has risen significantly at a rate of 0.23 ℃ per decade, while the potential evaporation has decreased at a rate of 4.7 mm per year, presenting a "warming-drying-evaporation paradox" synergy. The runoff at the upstream outlet of the basin has undergone a phased evolution pattern of a decline period (1956-1968), a stable period (1969-2009), and a recovery period (2010-2021). Through key governance projects and ecological water conveyance, the water volume passing through the Caiqi section in the downstream increased to 4.01×10⁸ m³ in 2019, achieving a "U-shaped" recovery. Therefore, the runoff change in the Shiyang River Basin is the result of the combined effect of natural and human factors.