A predictive model for overland flow velocity on vegetated slopes considering various environmental factors

Accurately predicting the arithmetic mean velocity of overland flows on vegetated slopes is essential for developing hydraulic erosion models. However, there exists a significant challenge in predicting this velocity in various vegetation conditions. This study proposed a new predictive model based on the principle of resistance superposition, which accounted for a wide range of environmental factors—e.g., vegetation coverage, slope angle, and flow discharge. The model was validated against a comprehensive database with 4168 datasets established from published sources, showing 83.3% of the calculated R squared values in excess of 0.750. The model was also compared with the existing models, demonstrating superior applicability and reliability at various test conditions. After validation and comparison, parametric analysis was conducted to assess the effects of the environmental factors on the velocity. The results highlighted that the velocity decreased with increasing vegetation coverage until reaching a limit and the strong interactive effects of these environmental factors on the velocity. These findings provide valuable insights into how environmental factors influence flow velocity, offering a theoretical foundation for erosion control on vegetated slopes.