Abstract
The interaction between turbulent flow and bedload transport generates diverse bedform morphologies, yet the structural characteristics of these bedforms and their relationship with turbulence remain insufficiently characterized. Understanding these dynamics carries significant theoretical and engineering implications for riverbed evolution and sediment deposition. Through a series of open-channel experiments under equilibrium sediment transport conditions, this study investigates the three-dimensional structural features of bedforms and their correlation with flow intensity. Utilizing Structure from Motion (SfM) photogrammetry, we achieved high-precision reconstruction of post-scour bedform topography. Bed elevation signals were processed using wavelet transform techniques to remove slope trends and noise, enabling accurate extraction of topographic data. Subsequent application of peak detection algorithms yielded key dune morphological parameters, including wavelength (L), height (H), steepness (δ), and lee-side angle (φ). The results demonstrate that within the investigated flow intensity range (Θ = 0.089–0.370), both L and H exhibit a non-monotonic trend characterized by initial decrease followed by increase. Probability density function analysis reveals that wavelength follows a gamma distribution, while height and steepness conform to Weibull distributions. A significant positive linear correlation exists between δ and φ, with 60% of the dunes classified as low-angle dunes (φ < 10°). This study establishes with enhanced precision the quantitative relationships between scaled dune parameters (L/h, H/h, δ) and relative flow intensity (Θ’), demonstrating that H/h exhibits greater sensitivity to Θ’ variations than L/h. Furthermore, our analysis enriches the characterization of three-dimensional bedform structural features and their interaction with turbulence under low Shields conditions, thereby providing valuable references for investigating sediment transport dynamics under sand wave condition.