Calculation of bend-scale sediment balance in meandering rivers of Yellow River source based on UAV aerial survey

Erosion-deposition changes of meandering channels are a dynamic equilibrium process in the long-term time scale. The part of sediment load transport is roughly equal the difference between bank erosion in concave bank and point bar deposition in convex bank. In summer 2018, the Unmanned Aerial Vehicle (UAV) aerial survey was used to obtain high-resolution imagery data in four meandering rivers of Yellow River source(i.e., Maiqu, Haqu, Gequ, and Lanmucuo Rivers), and the high-resolution topographic dataset were produced by post-processing of the Structure-for-Motion technology. Channel topography of cross sections of single bend and subsequent bends are extracted using ArcGIS. The differences of the cross-sectional area between convex and concave bank zone are calculated in single section and adjacent sections of meandering channels. Results demonstrate that sediment loss amount generated by bank collapse on concave bank and sediment deposition amount on convex bank are imbalanced, i.e., a net loss of sediment amount existing. For a single bend, the sediment loss per unit channel length in Lanmucuoqu River is about 0.191 m³, and about 0.045 m³ on average in Maiqu, Haqu, and Gequ Rivers. Nonetheless, the sediment loss in the reach scale of meandering channel is non-uniformity that indirectly reflects the difference in lateral migration rates among different bends.