Morphology Dynamics of Ice Cover in a River Bend Revealed by the UAV-GPR and Sentinel-2

Abstract

After the formation of the bend ice cover, the ice thickness of the bend is not uniformly distributed, and an open-water area is usually formed downstream of the bend. The spatial and temporal variation of the ice thickness in seven cross sections was determined via Unmanned Aerial Vehicle Ground Penetrating Radar (UAV-GPR) technology and traditional borehole measurements. The plane morphology change of the open water was observed by Sentinel-2. The results show that the average dielectric permittivity of GPR was 3.231, 3.249, and 3.317 on three surveys (5 January 2022, 16 February 2022, and 25 February 2022) of the Yellow River ice growing period, respectively. The average ice thickness of the three surveys was 0.402 m, 0.509 m, and 0.633 m, respectively. The ice thickness of the concave bank was larger than that of the convex bank. The plane morphology of the open water first shrinks rapidly longitudinally and then shrinks slowly transversely. The vertical boundary of the open water was composed of two arcs, in which the slope of Arc I (close to the water surface) was steeper than that of Arc II, and the hazardous distance of the open-water boundary was 10.3 m. The increased flow mostly affected the slope change of Arc I. Finally, we discuss the variation of hummocky ice and flat ice in GPR images and the physical factors affecting GPR detection accuracy, as well as the ice-thickness variation of concave and convex banks in relation to channel curvature.

A Survey Method for Drift Ice Characteristics of the Yellow River Based on Shore-Based Oblique Images

“…The study area is the Shisi bend (111°2′53″ E, 40°17′39″ N) in the Inner Mongolia reach of the Yellow River, wh over a river length of 820 km [45], as shown in Figure 1b. This bend (Figure 1c) is a ty funnel bend characterized by a wide entrance and a narrow exit [46]. The angle o bend is about 120°, the hydraulic slope is about 0.1%, the average altitude is 991.8 m river width is 250-600 m, and the average water depth is 8 m [46].…”

“…This bend (Figure 1c) is a ty funnel bend characterized by a wide entrance and a narrow exit [46]. The angle o bend is about 120°, the hydraulic slope is about 0.1%, the average altitude is 991.8 m river width is 250-600 m, and the average water depth is 8 m [46]. The 3100 m downst of this bend is the Toudaoguai hydrological station, which measured flow discharg air temperature.…”