Influence Assessment of Xiaolangdi Reservoir on Hydrological Regime of Downstream Channel

In order to evaluate the influence of Xiaolangdi Reservoir operation on the silt and ecological environment in the downstream of the Yellow River,based on the daily average runoff of Huayuankou station in the downstream of the Yellow River in 1960-2010,the method of range of variability approach(RVA) is adopted to assess the change degree of hydrological condition before and after construction of reservoir and evaluate the change of river silt and ecological environment.Compared with no construction of reservoir,the results show that Xiaolangdi Reservoir operation make hydrological situation in the downstream river change greatly;the overall degree of hydrologic alteration is about 71.6%.As for the serious deteriorated ecological environment in the lower reaches of the Yellow River,the current operation mode of Xiaolangdi Reservoir can improve the sedimentation in the downstream of the Yellow River greatly,and it appears the favorable trend on the influence of ecological environment.