Influence Mechanism of Xiaolangdi Project Regulation on Erosion-deposition Variation of the Yellow River Estuary

Through comparative analysis of the erosion-deposition variation in the Yellow River estuary under the natural and flow/sediment regulation condition,the paper explored the influence mechanism of the Xiaolangdi project on the erosion-deposition variation.The results showed that there was a significant positive relationship between land-forming area and the flow and sediment in the Yellow River.The Xiaolangdi project regulation improved the flow and sediment condition in the Yellow River,which rapidly changed the Yellow River estuary state from erosion to deposition and the spit extended at the rate of 0.9km/a,resulting in a land-forming rate 1.34times from 2003to 2006which was higher than that under the natural flow/ sediment condition from 1977to 1989and an extending length per 0.1billion of spit 2.9times.The Xiaolangdi project should regulate the flow/sediment about 0.02t/m3 and the incoming sediment coefficient to 0.01～0.015(kg·s)/m6 in Lijin station,which was at least about 2×1010 m3 of flow,(3～4)×108 t of transported sediment and 6.34～9.52kg/m3 of sediment concentration,to drive the Yellow River estuary development in the positive direction.