Quantifying impact of different surface covers on sediment transport capacity: Insights from flume experiments

Abstract

Sediment transport capacity (Tc) serves as a crucial determinant in soil erosion models. While surface cover types are recognized as key factors influencing sediment transport capacity, their effects have not been systematically quantified. This study provides mechanistic insights into the pathways through which surface cover modulates sediment transport capacity and quantitatively establishes the combined effects of cover type and coverage. The flume experiments were conducted using four cover types (corn residue, rock fragment, sweet potato, and corn stem) with coverage ranging from 2.5 % to 70 %, under a fixed slope gradient (15°) and a constant flow discharge (1 × 10^–3 m³ s⁻¹). The results showed that sediment transport capacity was significantly correlated (p < 0.05) with flow velocity (v), flow depth (h), and coverage (C) across different cover types. A significant power function increase was observed between sediment transport capacity and flow velocity for all cover types (p < 0.01, R² > 0.93). When estimating sediment transport capacity using a single flow velocity, coverage effects can be disregarded, but the velocity exponent must be adjusted based on cover type. Surface cover type primarily influences sediment transport capacity by altering flow velocity and flow depth. Flow velocity, flow depth, and coverage can be jointly used to describe sediment transport capacity under different cover conditions, thereby quantifying the effects of cover type. The findings of this study elucidate the pathways through which surface cover types affect sediment transport capacity, providing insights into the hydrodynamic mechanisms underlying this influence.