Impact of Surface Cover Types and Coverage on Hydraulic Parameters of Overland Flow

Abstract

Surface cover influences the hydraulic parameters of overland flow, subsequently affecting soil erosion. Therefore, exploring the flow dynamic mechanisms under different surface cover types is crucial. A series of flume experiments were conducted to investigate the impact of surface cover on the hydraulic parameters of overland flow. The specific experimental conditions were as follows: one slope gradient (15°) and one flow discharge (1.0 × 10⁻³ m³ s⁻¹), four cover types (corn residue, rock fragment, sweet potato, and corn stem), and seven coverage percentages ranging from 0% to 70%. The results indicated that the cover of non-submerged state was the most effective at reducing flow velocity, with cover of submerged state being the least effective. Under the four cover conditions, flow velocity, Froude number, flow depth, and shear stress exhibited significant power function relationships with coverage (R² > 0.91). The relationships between Reynolds number and stream power with coverage were not significant under corn residue and rock fragment cover (P > 0.05), but showed significant power function relationships under sweet potato cover (R² > 0.88). The cover type alters the form of the cover and the flow submergence degree, leading to the change of hydraulic radius, thereby influencing the hydraulic parameters of overland flow. The findings provide scientific evidence for understanding the flow dynamic mechanisms under surface cover and improving the predictive accuracy of soil erosion process models.