| Overland flow is the main component of river flow,and also an important driving force for soil erosion and sediment transport.Therefore,it is of great significance to study the overland flow,whether to enrich and improve the hydraulic theory,or to solve the water and soil erosion and other engineering problems.150 virtual numerical simulations were performed on the basis of indoor artificial rainfall experiments over the soil tank,in order to study the resistance characteristic of sheet flow.The slope range was 5°?55°,and the rainfall intensity range was 30 mm/h?240 mm/h.Taking the Darcy-Weisbach resistance coefficient f as the object,the spatio-temporal distribution of the resistance coefficient was studied,the influence of rainfall intensity and slope on the resistance coefficient were analyzed.Finally,a resistance coefficient formula which considered the spatial position was regressed.The results show that:Under both certain rain intensity and certain slope,the resistance coefficient shows a decreasing trend,temporally and spatially towards the downstream;The resistance coefficient of overland flow is significantly affected by rain intensity.Under a certain slope,the greater the rain intensity,the smaller the resistance coefficient;Under a certain rain intensity,there is a positive correlation between the resistance coefficient and slope;The f-Re relation is negative.The thickness of the viscous bottom decreases with the increase of slope and rain intensity,and the total energy increases with the increase of rainfall intensity,which is the essential reason of the above-mentioned variation off.The innovation of this study are:1)Using the artificial rainfall physical model and distributed hydrological numerical model(InHM),resistance characteristics of overland flow under the super steep slope(up to 55°)was analyzed;2)The spatio-temporal distribution of f was studied in detail,quantitatively. |
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