High-efficiency sediment-transport requirements for operation of the Xiaolangdi Reservoir in the Lower Yellow River

Abstract

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/m3, 60 kg/m3, and greater than 100 kg/m3, the clear water volumes for transporting sediment were above 50 m3/t, approximately 16 m3/t, and less than 10 m3/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 m3/s when the incoming water flow has a sediment concentration of >60 kg/m3. 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 ten years. These findings can be applied widely in sandy rivers. HIGHLIGHTS The sediment-transport efficiency and associated sediment-transport clear water volume in the lower reaches of the Yellow River were modeled in this study.; The sediment-transport clear water volume of the river channel decreased with increasing sediment concentration.; Optimizing operation of Xiaolangdi Reservoir can improve the sediment-transport efficiency and reduce sedimentation in the Lower Yellow River.;

Keywords

• flood event
• lower yellow river
• river channel scouring
• river channel silting
• sediment transport efficiency
• xiaolangdi reservoir