Experimental study on hydrodynamic characteristics of overland flow under different resistance conditions

ObjectiveThe hydraulic characteristics of overland flow are important for clarifying soil erosion and sediment yield mechanism. In this experiment, the overland flow resistance and related hydrodynamic characteristics of the slope under different resistance conditions were studied. Investigating the hydraulic characteristics of overland flow under different morphological conditions is to provide theoretical support for guiding the rational allocation of soil and water conservation slope measures.

MethodThe study used a self-made bed to flush the sink, selecting different coverage （0%, 10%, 15%, 20%）gravel and grass bed surface, and performing indoor fixed bed scouring test under the condition of different flow rate (15–120 L/(min·m)) and different slope (3°–15°)

ResultThe results showed that: (1) the flow velocity on different slopes increased with the increase of flow rate and slope, and the flow velocity of the grass surface was larger than the flow velocity of the gravel bed under the same coverage, up to 2.2 times. (2) The Froude number (Fr) of different underlying surfaces increased with the increase of slope, and the Darcy-weisbach drag coefficient increased with the increase of coverage. Under the same coverage, the gravel bed surface was larger than the grass bed surface, the highest was 10.9 times of the grass. (3) The flow resistance of different underlying surface slopes was linearly positively correlated with the flow rate. Under the same coverage, the slope flow of the gravel bed surface was larger than that of the grass bed, and the highest was 2.2 times of the grass bed surface. (4) Slope and coverage had significant effects on overland flow resistance. The overland flow resistance increased with the increase of slope, and increased with the increase of coverage, and had a good linear correlation.

ConclusionThrough the study of the slope flow resistance under different conditions, it can provide a basis for the establishment of hillside hydrological models and erosion physical models based on runoff dynamics processes. And it provides theoretical support for guiding the rational allocation of soil and water conservation slope measures.