Effects of path tortuosity on rill erosion

The rill path tortuosity represents the degree of the thalweg deviation from a straight alignment. The available literature regarding the effects of path tortuosity on rill flow resistance is limited. In this investigation, four rills characterized by different tortuosity values (1.02, 1.08, 1.16, e 1.28), were incised in a sloping (15%) plot filled with a clay soil. For each rill, measurements of flow velocity and water depth were carried out, and the 3D models for the initial and final (after the experimental run) conditions were generated by the Structure from Motion technique. The DEMs were also obtained from the 3D models. The developed analysis was aimed to assess the reliability of a theoretical flow resistance law for estimating the Darcy‐Weisbach friction factor f and the three additive components of the friction factor due to bed roughness, sediment transport, and localized energy losses occurring in the curves. Finally, the DEM of difference (DoD) was used to quantify the total eroded rill volumes and qualitatively evaluate the f components due to bed roughness and sediment transport.