Non-capacity transport of non-uniform bed load sediment in alluvial rivers

Zhixian Cao*, Peng Hu, Gareth Pender, Huaihan Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Rivers often witness non-uniform bed load sediment transport. For a long time, non-uniform bed load transport has been assumed to be at capacity regime determined exclusively by local flow. Yet whether the capacity assumption for non-uniform bed load transport is justified remains poorly understood. Here, the relative time scale of non-uniform bed load transport is evaluated and non-capacity and capacity models are compared for both aggradation and degradation cases with observed data. As characterized by its relative time scale, the adaptation of non-uniform bed load to capacity regime should be fulfilled quickly. However, changes in the flow and sediment inputs from upstream or tributaries hinder the adaptation. Also, the adaptation to capacity regime is size dependent, the finer the sediment size the slower the adaptation is, and vice versa. It is shown that the capacity model may entail considerable errors compared to the non-capacity model. For modelling of non-uniform bed load, noncapacity modelling is recommended, in which the temporal and spatial scales required for adaptation are explicitly appreciated.

Original languageEnglish
Pages (from-to)377-396
Number of pages20
JournalJournal of Mountain Science
Issue number3
Early online date10 Feb 2016
Publication statusPublished - Mar 2016


  • Bed deformation
  • Capacity transport
  • Fluvial process
  • Non-uniform bed load
  • Sediment transport

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Geography, Planning and Development
  • Geology
  • Global and Planetary Change
  • Nature and Landscape Conservation


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