How exposed root distribution patterns regulate overland flow hydrodynamics on slope segments: a simulated scouring study

The exposure of plant roots caused by soil erosion significantly alters surface microtopography and runoff pathways; however, the specific mechanisms by which it affects hydrodynamic processes remain not fully understood. This study investigated how slope segment, exposed root distribution pattern, and runoff discharge influence the hydraulic characteristics of overland flow by simulated scouring experiments. Results revealed that transverse and cross-slope root arrangements effectively reduced flow velocity and erosive energy, whereas parallel arrangement had a minimal effect. Significant differences in Reynolds number, Froude number, and friction coefficient were observed among different exposed root distribution methods and slope segments, with transverse slope arrangement demonstrating better overall regulation of flow patterns compared to the other two distributions. Notably, stream power and unit stream power were significantly higher under the parallel arrangement, and shear stress was significantly higher on the upper and middle slope segments. Overall, exposed roots significantly reduced the erosion potential of overland flow compared to bare slopes. These findings help clarify the potential hydraulic mechanisms by which exposed root distribution patterns may influence overland flow.