An empirical equation for sediment transport capacity of overland flow: Integrating slope, discharge, and particle size

Abstract

Accurate estimation of sediment transport capacity is crucial for effective soil erosion modeling and management. While empirical methods offer a practical approach for calculating sediment transport capacity using limited data, existing equations often lack reliability and applicability across a broad range of scenarios. This study addresses this gap by developing an empirical equation based on extensive datasets encompassing a wide spectrum of hydraulic and physical conditions ranging from slopes (1%–45%), unit flow discharges (0–15 × 10⁻² m² s⁻¹), and median particle sizes from (0.021–10.5 mm). The proposed equation integrates slope, discharge, and particle size to predict sediment transport capacity, leveraging advanced machine learning techniques. It was rigorously tested against other empirical equations, demonstrating superior performance with a coefficient of determination (R²) of 0.99 and a Nash-Sutcliffe efficiency of 0.99. The equation's strong alignment with physical sediment transport principles, particularly its similarity to stream power equations, underscores its theoretical robustness and practical relevance. Findings indicate that sediment transport capacity increases with discharge and slope while decreasing with particle size. Notably, rainfall intensity and flow depth did not significantly impact sediment transport capacity, emphasizing the equation's focus on the most influential variables. This research presents a significant advancement in sediment transport modeling, providing a reliable and accurate tool for a wide range of conditions and contributing valuable insights for soil erosion and sediment management. Future work should involve further validation with additional datasets to enhance the equation's applicability and robustness.