High-efficiency Sediment Transport Requirements for operation of the Xiaolangdi Reservoir in the Lower Yellow River

Sediment accumulation is severe in the Lower Yellow River. Improving sediment transport efficiency is an important way to save water resources. In this study, we analyzed the sediment transport efficiency at different sediment concentrations and discharge levels using data from 306 non-overbank floods in the lower reaches of the Yellow River from 1960 to 2016. When the sediment concentrations were below 20 kg/m(3), 60 kg/m(3), and greater than 100 kg/m(3), the clear water volumes for transporting sediment were above 50 m(3)/t, approximately 16 m(3)/t, and less than 10 m(3)/t, respectively. Given current scheduling, the Xiaolangdi Reservoir can lower its water level and increase non-overbank large water flows with an outflow discharge of > 3,000 m(3)/s when the incoming water flow has a sediment concentration of > 60 kg/m(3). Mathematical modeling indicates that, for an incoming sediment load of 600 million tons in the Middle Yellow River, the average sediment-transport water volume at the downstream Huayuankou station decreased by 27%, Optimized scheduling at the Xiaolangdi Reservoir could reduce the sedimentation in the downstream channel by 1.1 billion tons more than current scheduling, and extend the reservoir's sediment-trapping period by 10 years. These findings can be applied widely in sandy rivers.