Direct scaling analysis of roughness bed formations in laboratory experiments

This study examines the scaling behavior and structural nature of bed roughness structures observed in controlled laboratory experiments conducted by Penna et al. (J Hydraul Res 59(3):420–436, 2021), utilizing the analytical framework of Taylor’s variate Power Law (TPL) as extended by Rizzello et al. (Phys Rev E 109(3):034306, 2024). The results reveal a marked contrast in the scaling regimes as a function of the reorganization of the bed surface induced by hydraulic forcing. Specifically, unworked bed surfaces, i.e., those not subjected to water flow, exhibit predominantly multi-scaling behavior, indicative of underlying multi-fractal organization. On the contrary, water-worked beds are characterized by a simpler, simple-scaling regime, consistent with mono-fractal surface structuring. This suggests that flow-induced reorganization acts as a homogenizing mechanism, suppressing heterogeneity and reducing the complexity of bed surface patterns, with important implications for sediment transport dynamics, hydraulic resistance, and morphodynamic modeling.