Experimental Investigation of Meander Morphodynamics and Sediment Transport Using the Natural River Model Method

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 φ=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.