Contribution of hyper-concentrated flows from deserts in the Loess Plateau to downstream channel siltation in the lower Yellow River

Hyper-concentrated flows(HCFs) in the Loess Plateau lead to severe channel siltation in the lower Yellow River, forming the world-famous “Aboveground River”. However, debate has long persisted over tthe relative role of desert-based HCFs versus loess-based ones in this siltation. In this study, the historical records of typical 69 HCFs in the middle-reach basin of the Yellow River and their related precipitation were used to establish the statistical relations between sediment supply from the desert-based HCFs or the loess-based HCFs and channel deposition/erosion in the lower Yellow River from 1960 to 1985. This time window was selected to rule out the period from 1986 to the present, in which the upstream large reservoirs’ operations have played an important role in regulating scour-and-fill of the downstream channel bed. Our results showed that if the HCFs’ suspended sediment concentrations are larger than 100 kg m− 3, both of the desert-based HCFs and the loess-based HCFs are combined together to contribute about 91.18% to the total sediment deposition amount of 65.7 × 108 t in the lower Yellow River during this period. Our results also indicated that the > 100 kg m− 3 desert-based HCFs contributed to about 65.20% of the total sediment deposition, and that only about 25.97% was contributed by the > 100 kg m− 3 loess-based HCFs. Because the desert-based HCFs can be a major source of sediment supply to develop the downstream channel siltation, its control should be a priority in protecting the Yellow River and ensuring its safety in the future.