Flow Pattern and Hydraulic Parameter Characteristics of the Different Topographic Position in the Small Catchment

Flow pattern and hydraulic parameter characteristics of the different topographic position in the “slope-gully-basin” system under the rainfall intensities of 60, 90 and 120 mm/h using generalized small watershed model with the simulated rainfall experiment. The results show that the increase of the rainfall intensity will result in the increase of the Reynolds number. During the whole experiment, only when the rainfall intensity is 60 mm/h, the flow pattern of the hilly-slope is laminar flow. The flow patterns of the other geomorphic position are all turbulent flow. Moreover, the Reynolds number of slope flow is much less than that of channel flow. With the increase of rainfall intensity, flow patterns of the all different geomorphic position changed from the stratum flow into torrent flow. Furthermore, the Froude number increases first and then decreases with the increase of rainfall intensity. For the resistance coefficient of the overland flow, with the increase of rainfall intensity, the resistance coefficient of overland flow and channel flow decreases obviously. For the spatial distribution of resistance coefficient, the maximum occurs at the hilly-slope and the minimum at the channel.