Acta Geographica Sinica ›› 2021, Vol. 76 ›› Issue (1): 127-138.doi: 10.11821/dlxb202101010

• Water Cycle and Related Land Surface Processes • Previous Articles     Next Articles

Response of sediment delivery ratio to the incoming flow-sediment regime and channel geometry in the braided reach of the Lower Yellow River

CHENG Yifei(), XIA Junqiang(), ZHOU Meirong, WANG Yingzhen   

  1. State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
  • Received:2019-09-25 Revised:2020-11-05 Online:2021-01-25 Published:2021-03-25
  • Contact: XIA Junqiang;
  • Supported by:
    National Natural Science Foundation of China(51725902);National Natural Science Foundation of China(51579186);National Key R&D Program of China(2017YFC0405501)


One of the main tasks for the river regulation in the Lower Yellow River (LYR) is to improve sediment transport capacity of the braided reach, which is influenced by incoming flow and sediment regime as well as riverbed boundary condition. Variations in the reach-scale geomorphic coefficient and incoming flow-sediment regime (incoming sediment coefficient and fluvial erosion intensity) were investigated, using the hydrological data and cross-sectional profiles surveyed in the braided reach between Huayuankou and Gaocun over the period from 1971 to 2016. Empirical relationships were then established to quantitatively demonstrate the integrated effects of flow-sediment regime and the post-flood channel geometry in the previous year on the values of sediment delivery ratio (SDR) during flood seasons and flood events respectively in the study reach. Results indicate that: (1) the values of SDR of flood seasons and flood events increased with a smaller incoming sediment coefficient or a larger fluvial erosion intensity, and the incoming sediment coefficient was equal to 0.012 kg·s/m 6 when the value of flood-season SDR approached 1. The correlation coefficient is 0.76 for the relationship between flood-event SDR, incoming sediment coefficient, and the ratio of the water volume at the inlet section to the one at the outlet section in the study reach. (2) The SDR of the braided reach decreased with wider and shallower channel geometry, and it was less than 1 when the geomorphic coefficient was greater than 15 /m 0.5. (3) The determination coefficient is 0.82 for the empirical function established among flood-season SDR, incoming sediment coefficient and geomorphic coefficient, and the weight of the channel geometry is greater than the incoming sediment coefficient in the function of flood-event SDR. The established functions can reflect the sediment-transport characteristics of the braided reach, which is helpful to quantify the influence of channel geometry and flow-sediment regime on sediment transport capacity.

Key words: channel geometry, flow-sediment regime, sediment delivery ratio, flood season, flood event, braided reach, Lower Yellow River