Scouring Effect and Trend Predicting of Xiaolangdi Reservoir on Downstream River

The paper analyzed the scouring effect of Xiaolangdi Reservoir on downstream river and predicted its trend.The results show that since the operation of Xiaolangdi Reservoir,the erosion on the lower reaches of the Yellow River is obvious through water and sediment regulation.As of October 2010,the accumulative sediment erosion of the lower reaches of the Yellow River have reached 1.94 billion tons,the water level under the same flowrate of 2 000 m3/s discharge drops about 1.6 m,and the minimum discharge capacity of the main channel in downstream river increases to 4 000 m3/s from less than 1 800 m3/s in the very beginning of flood season in 2002.During the main sediment storage periods of Xiaolangdi Reservoir from 2008 to 2020,the downstream river remains basically no deposition.While after 2020,it backs fast to silting.Thus,around 2028 the deposition amount accounts to the former level before the building of the reservoir,with the discharge 4 000 m3/s will be difficult to maintain.The paper suggests Guxian Project should be built as early as possible and operated in about 2025.