| Hydraulic erosion is an erosion pattern in which soil erosion is very serious.Slope flow is the primary source of hydraulic erosion.Studying the hydrodynamic characteristics of overland flow and revealing the source and mechanism of soil erosion dynamics plays an important part in studying soil erosion dynamics.To study the hydrodynamic characteristics of overland flow under different width conditions.Further,to study the effects of different width conditions on the soil detachment capacity of the collapsed soil.This study through the artificial scouring in the laboratory.Set up two different underlying surfaces(Cr=0/Cr=3.51),three slope lengths(3,6,9m),three different flume width(10,20,30 cm)and five different discharge per unit width(0.02,0.04,0.06,0.08,0.1 m~2/min).The results as follows:(1)On a smooth bed surface,flow velocity,flow depth,Reynolds number and the kinetic parameters all increased with the increase of discharge per unit width.The resistance coefficient and Manning's roughness coefficient decreased with the increase of discharge per unit width;the trend of the Froude number was different on each slope.When the discharge per unit width was 0.02 m~2/min,the velocity,Froude number,resistance coefficient and Manning roughness coefficient,the unit stream power the cross-sectional unit energy,the stream power and the shear stress of the water flow were more affect by the width of the flume.When the discharge per unit width was 0.04 and 0.08 m~2/min,the flow depth and the Reynolds number was more affect by the width of the flume.The influence of the width of the flume on the hydrodynamic parameters was not obvious under other discharge conditions.The resistance coefficient and Manning's roughness coefficient was negatively related to the discharge per unit width(P<0.01).The discharge per unit width highly positively correlates with other hydraulic parameters and various erosion kinetic parameters.The length of slope positively correlates with flow depth,Reynolds number,stream power and the shear stress of the water flow.The length of slope significantly correlates with the Manning roughness coefficient(P<0.01).The width of the flume positively correlates with water depth,resistance coefficient,Manning roughness coefficient,stream power and the shear stress of the water flow(P<0.01),and positively correlates with Reynolds number(P<0.05).(2)On a rough bed surface,the flow rate,the depth of the flow,and the Reynolds number and the kinetic parameters increased with the increase of the discharge per unit width.The resistance coefficient as the discharge per unit width increased,it gradually decreased.The fluctuation trend of Froude number and Manning coefficient was different from other hydrodynamic parameters.When the discharge per unit width rate was 0.02m~2/min,flow velocity,the water depth and the Froude number,the resistance coefficient,Manning's roughness coefficient,the unit stream power and the cross-sectional unit energy were more affect by the width of the flume.When the discharge per unit width rate was 0.04 m~2/min,the unit stream power the cross-sectional unit energy was more affect by the width of the flume.When the discharge per unit width rate was 0.08 m~2/min,the water depth and Reynolds number were more affect by the width of the flume.The effect of the width of the flume on hydrodynamic parameters was not obvious under other flow conditions.There was a significant negative correlation between discharge per unit width and Manning's roughness coefficient(P<0.01).It had a very significant positive correlation with other hydrodynamic parameters and the kinetic parameters(P<0.01).Slope length significant negative correlates with Manning roughness coefficient and resistance coefficient(P<0.05).The width of the flume significantly correlates with the resistance coefficient and significantly positively correlates with the water depth and the shear stress of the water flow.(3)Under smooth bed conditions(Cr=0),soil detachment capacity was much larger than that under rough bed conditions(Cr=3.51).The degree of erosion and sedimentat ion on the smooth bed surface was more severe than that of the rough bed surface.The influence of different width of the flume on the soil detachment capacity of the rough bed surface was more obvious than that under the smooth bed surface.Different bed surfaces have significant differences in the soil detachment capacity at different the discharge per unit width.There was no significant difference in soil detachment capacity between the two different bed surfaces under different width of flumes.The underlying surface properties significantly affect the ability of the soil detachment capacity. |
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