A model to study the grain size components of the sediment deposited in aeolian–fluvial interplay erosion watershed

• The sources of sediments in aeolian–fluvial interplay erosion areas are investigated.
• Sediments deposited in the channel are analyzed based on the grain size distribution.
• The unimodal grain-size distribution of samples is described by Weibull distribution.
• The polymodal grain-size distributions of deposited sediments are well fitted.
• Erosion dynamics and material sources of deposited sediments are both identified.

Aeolian–fluvial interplay erosion areas with complex dynamics and physical sources are the main suppliers of coarse sediment in the Yellow River. Understanding the composition, distribution, and sources of deposited sediments in such areas is of great importance for the control of sediment transport in rivers. In this paper, a typical aeolian–fluvial interplay erosion watershed – the Dongliu Gully – was studied and the frequency distribution curves of sediments deposited in the stream channel were fitted using the Weibull function. Sources of deposited sediment in the stream channel were analyzed based on the law of the conservation of matter. Results showed that the hilly zone accounted for 78% of deposited sediments, which were dominated by material with a median grain size (d50) of 0.093 mm, and the desert zone accounted for 22% of deposited sediments, which were dominated by material with a d50 of 0.01 mm. Wind erosion dynamics accounted for 72% of deposited sediments, while water erosion dynamics accounted for only 28%. This research provides a theoretical basis for the control and management of rivers with high sediment content.