Effects of water-sediment regulation by Xiaolangdi Reservoir on channel erosion in the Lower Yellow River

Since the Xiaolangdi Reservoir was impounded in 1999,the water-sediment regulation has being adopted as one of the main operation modes of the reservoir.From 2002 through 2007,0.3077×10~9t of sediment was eroded from the main channel in the Lower Yellow River by seven water-sediment regulations.Thus,the flood conveying capacity(bankfull discharge) of the river was also raised and the water level under the same discharge was dropped.All of these are of benefit to the reshaping of the withered Lower Yellow River.However,the effect of water-sediment regulation on the total erosion in the LYR was limited,but was over evaluated by some researchers.To properly evaluate the erosion efficiency by the water-sediment regulation of the Xiaolangdi Reservoir is of much significance for both the reservoir and the Lower Yellow River.