Study of hydrodynamic characteristics of rill and inter-rill flows on loess slopes
Through conducting rain simulation experiments under different rainfall intensities (1.5 mm/min,2.0 mm/min) and on different slopes (10°,15°,20°,25°),the runoff hydrodynamic characteristics during the process of rill erosion are discussed.The results show that:(1) The average velocity of rill flow is generally larger than the inter-rill flow velocity at the same water level,the velocity of rill flow changes with the morphology of rill.Where there is a measurement sill,the flow speed will be reduced.(2) The Reynolds number and Froude number change with the change of average flow velocity,changes on the different gradients are not obvious ; the Reynolds number and Froude number of rill flow are generally larger than the corresponding numbers of inter-rill flow.(3)The Darcy-Weisbach resistance coefficient and Manning roughness coefficient are influenced by the slope significantly,and there is a good linear relationship between them.The relationships between the drag coefficient of runoff and the Reynolds number are not significant,but there is a significant relationship between the drag coefficient of runoff and the Froude number.The drag coefficient of rill flow is generally less than the drag coefficient of inter-rill flow,the difference is more significant especially on large gradients.(4) The stream power and flow shear stress increase with the slope firstly and then decrease,the critical slope is between 20° and 25°.On the same slope,the difference of average runoff shear stress and stream power of rill flow and of inter-rill flow has no significant regularity.
国家科技期刊平台
NSTL
万方数据
维普
