Analysis of tidal creek morphology in the Yellow River estuary based on high-resolution remote sensing imagery

In this paper, the distribution of tidal gully ecosystems in the Yellow River Estuary, from 2017 to 2023 was analyzed, and the distribution, change, stability and correlation between tidal gullies and salt marsh vegetation and ecological restoration projects were analyzed. (1) The total length of tidal ditch in 2021 is 793.64km, which is slightly higher than that of 701.33km in 2017, and the total length of tidal ditch in 2023 is 919.86km, which is a significant upward trend compared with 2021. (2) The overall curvature in 2017, 2021 and 2023 is 1.19, 1.18 and 1.16, respectively, and the overall curvature is slightly curved and the degree of bending gradually decreases. In 2017, 2021, and 2023, the tidal channel density was 1.91km•km^-2, 2.16km•km^-2, and 2.50km•km^-2, respectively. (3) From 2017 to 2023, the instability of tidal gullies increased, with 47% of the main tidal gullies belonging to stable tidal trenches, 49% belonging to unstable tidal trenches, and 4% of tidal gullies being severely unstable tidal trenches. (4) The density and length of the tidal channel had the same development trend with the area of Spartina alterniflora. From 2021 to 2023, the disappearance of 13 main tidal gullies, the severe instability of 2 main tidal gullies, and the disappearance of a large number of small tidal gullies in areas II and III may be related to anthropogenic restoration activities. The increase in the instability of some of the main tidal ditches in the northeast and southern ecological restoration areas of the Yellow River Estuary, and the increase in tidal gullies in areas II and III may be related to natural factors such as tides.