Influence of particle shape on surface roughness: Dissimilar morphological structures formed by man-made and natural gravels

Static armored gravel surfaces composed of man-made and natural gravels have been analyzed using precise digital elevation models. The scaling behavior and spatial arrangement of the gravel surfaces were evaluated and discussed with respect to the successive formation of stable armor layers. The key results relate to structure functions and imbrication analysis of these surfaces: (1) man-made gravel surfaces show a similar scaling behavior and spatial correlation pattern to natural gravel surfaces; (2) man-made gravel surfaces have larger Hurst exponents than natural gravel surfaces; and (3) man-made gravels are poorly imbricated in comparison with natural gravels. Our results suggest that different morphological structures between man-made and natural gravels were attributed to shape features of individual grains.