Desert river channel deposition characteristics and their implications for lateral infusion of aeolian sand in the Ulan Buh desert reaches of the Yellow River

The river flowing across the desert are controlled by the aeolian–fluvial interaction, with frequently scouring and depositing, which threaten the river banks safety. The floodplains are the main sediment sink, where aeolian sands and fluvial sediments are interacted. Exploring the characteristics and mechanism of selective deposition in the floodplain can provide insight into the influence mechanism of aeolian–fluvial interaction on desert river geomorphological process. Based on the sediment drilling data, this paper discusses the process and law of the selective deposition in the floodplain through the multi-dimensional analysis of the sediment grain-size in this desert reach of the Yellow River. The results show that the sedimentary structure of the river floodplain and bar shows a coarse and fine binary sedimentary interbedded under the control of the two origin components of aeolian and fluvial sediments, without forming a typical binary sedimentary structure. The median grain-size of the finer sediment layers is about 0.06 mm, which is comparable to that of upstream fluvial sediments. In addition, the median size of coarse sediment layers is about 0.19mm, which is consistent with the aeolian sand of the left bank. Meanwhile, the farther away from the desert dunes, the closer to the main channel, the characteristics of the interbedded river floodplain sedimentation gradually weaken, and binary sedimentary structure of floodplain gradually strengthened, which indicate the weakening of the coupling interactions between aeolian process and fluvial process and the gradual redution in the lateral infusion of the aeolian sand into the Yellow River, and the river channel are gradually stabilizing.