The Third Test of Water and Sediment Regulation Conducted on the Yellow River

The third test of water and sediment regulation of Yellow River is conducted in period from June 19 to July 13, 2004. The test has created artificial density current in Xiaolangdi Reservoir area, regulated sedimentation behavior which is unfavorable to tail reach of reservoir, increased sediment discharging capacity and decreased siltation of reservoir through utilizing reservoir storage before flood season, fully having aid of natural power and reservoirs joint operation of Wanjiazhai, Sanmenxia and Xiaolangdi located on main stream of Yellow River and assisting with measures of artificial sediment disturbance. At same time, it has conducted sediment disturbance at the secondary suspended of lower reaches and natural channel-control section where sedimentation is most serious, reducing sedimentation in lower channel and increased flood capability of main channel in lower river by utilizing surplus capability of sediment carrying of water flowing into lower channel. It has achieved expected effects as follows: 132.9 million m~3 sediment deposited in Xiaolangdi Reservoir area has been washed out and all 38.5 million m~3 sediment deposited above longitudinal profile of designed sedimentation balance washed away, rationally regulating sedimentation behavior of tail reach of reservoir; 1.641 3 million m~3 sediment at natural channel-control section of downstream disturbed and 510～640 m~3/s bankfull discharge at disturbed section increased and; each section above Lijin on lower reaches scoured and all together 64.22 million tons of sediment in Xiaolangdi-Lijin reach washed out.