Experimental study on hydraulic characteristic of submergence degree to flow under vegetation coverage
摘要
In order to explore the inherent law of slope flow structures under vegetation, we systematically researched, by testing via artificial vegetation simulation, the influence of submergence on the kinetic characteristics of slope flow in conditions where the vegetation is submerged or unsubmerged. According to the research:given the same gradient, both the average flow velocity and Reynolds number have a positive correlation with the degree of submergence; under flexible vegetation, slope flow changes from slow to rapid as the degree of submergence increases, the overall resistance coefficient drops with the increase of submergence degree; while under rigid vegetation, slope flow always remains slow, the overall resistance coefficient varies in a curve like single hump, the degree of submergence is 0.9 when the resistance coefficient peaks. The influence of submergence on the relative friction velocity is opposite to that on the resistance coefficient, the coefficient of determination of an empirical equation for calculating the resistance can be more than 0.97 based on the degree of submergence; the influence of submergence degree on hydrodynamic parameters is dependent on the slope gradient, so for conservation of soil and water on slopes, appropriate vegetation heights should be determined according to the slope and water depth of hilly regions.