Sediment Transport Dynamics Modeling of Overland Flow on Gentle Slopes Based on Flume Experiments

Soil erosion is a global environmental issue, and sediment transport capacity ( T c ) is critical for developing soil erosion models. This study conducted flume drainage experiments at six flow discharges (0.15, 0.25, 0.35, 0.45, 0.55, and 0.65 L s −1 ) and eight slope gradients (1.5, 3.0, 4.5, 6.0, 7.5, 9.0, 10.5, and 12.0°) to investigate how the T c of gentle slopes in the northeastern hilly region of China and water erosion factors are related and to establish a T c model of overland flow. The study demonstrated a power–law relationship between T c , flow discharge, and slope gradient, as evidenced by a high coefficient of determination ( R 2 ; 0.94) and Nash–Sutcliffe efficiency (NSE; 0.92) values. Additionally, there was a positive correlation between T c and average flow velocity, with R 2 and NSE values of 0.86 and 0.84, respectively. Among the hydrodynamic parameters tested, the average flow velocity was determined to be the most effective T c predictor, surpassing stream power ( R 2 > 0.7, NSE > 0.7), shear stress ( R 2 > 0.6, NSE > 0.6), and unit stream power ( R 2 < 0.5, NSE < 0.5). These findings lay the foundation for developing process‐based sediment transport models for gentle slopes in the northeastern hilly regions of China.