The Yangtze Estuary is confronting unprecedented challenges due to intensifying human activities and a rising incidence of extreme weather events, which collectively threaten its essential functions in flood control, water supply, ecological sustainability, and navigation. In this study, the functions of the Yangtze Estuary under evolving hydrological and sediment conditions are comprehensively investigated and evaluated based on long-term measurement and statistical data. Using the comprehensive indicator evaluation method (CIEM) and the analytic hierarchy process (AHP), a River Functional Assessment Model for the Yangtze Estuary (RFAM-YE) is developed. The model incorporates four sub-models: flood control, water supply, ecological protection, and navigation demand. The southern branch of the Yangtze Estuary is selected as a case study for evaluation. The results show that in recent years, the flood control capacity, waterway stability, and ecological conditions in the southern branch have improved. However, the ongoing overall erosion trend poses a threat to water supply security and the integrity of biological habitats. The assessment results are generally consistent with actual engineering conditions, demonstrating the validity and applicability of the proposed model. Finally, recommendations for the protection and restoration of the Yangtze Estuary are proposed based on the evaluation. This study provides both theoretical and practical references for the management and conservation of the Yangtze Estuary.

Understanding the morphological evolution and sediment transport characteristics of meandering rivers is crucial for river regulation and management. This experimental study employs the natural river model method in a 50 m × 6 m laboratory flume, with four groups of experimental models designed to investigate morphodynamic evolution and sediment transport characteristics under controlled hydrodynamic conditions. The input parameters of the physical model cover discharge rates (10–40 L/s), suspended sediment concentrations (0.6–1.4 kg/m³), hydro-sediment cycle frequencies (2–6 cycles per test), bed sediment grain sizes (0.2 mm and 0.5 mm), and longitudinal channel slope (0.001). Using advanced measurement techniques including acoustic Doppler velocimetry and automated topographic mapping, we systematically examined channel response to these varying hydro-sediment conditions. Results demonstrate that sinuosity development is enhanced by shorter hydro-sediment cycles and elevated sediment concentrations (reaching $\phi =1.35$ in high-concentration scenarios), while excessive discharge suppresses meandering through overbank erosion and backwater effects. High-resolution velocity and sediment concentration measurements reveal a decoupling between flow and sediment transport pathways: as discharge increases, the main flow path shifts laterally toward the convex bank upstream of the apex but returns toward the concave bank downstream, while suspended sediment transport consistently deflects toward the convex bank with increased vertical dispersion. These findings provide fundamental insights into the fluid mechanical processes governing meander evolution, with significant implications for river engineering and morphodynamic modeling.