Quantitative Characterization of the Roughness of Four Artificially Prepared Gravel Surfaces

Two-dimensional second-order structure functions (2DSSFs) have been widely used to investigate the roughness characteristics of gravel surfaces. Because of the complex patterns of the 2DSSFs, the interpretation of the 2DSSFs results remains challenging, and the explanations are mostly qualitative. Recently, a novel quantitative method for the description of the roughness of gravel-beds was proposed by Qin et al. (J Hydraul Res 57:90–106, 2019), which determines the statistical significance of structure functions based on Monte Carlo simulations. This new method is evaluated by four artificially prepared gravel surfaces to test the capability of the method in quantitatively differentiating predefined gravel structures. The four surfaces were prepared according to dissimilar arrangements of gravels and tried to represent gravel structures of different scales. The results successfully differentiated the roughness characteristics of the four surfaces and demonstrated the promising capability of the new method.