Study On Hydraulic Properties Of Shallow Flow On Slope Surface

Shallow flow on slope surface is the main power of soil water erosion process, the base of researching more erosion process property is to make clear of hydraulic properties of shallow flow on slope surface. Shallow flow on slope surface is apparently different from general open channel. Compared with the latter one, the former one's base slope is steeper, relative water depth thinner, relative roughness bigger, and more difficult to observe, which increase the difficulty of researching on shallow flow on slope surface.On the basis of consulting a large number of materials, this essay presents the complete situation of hydraulic properties of shallow flow on slope surface. Present research on hydraulic properties of shallow flow on slope surface focuses mostly on two aspects of the flow pattern of shallow flow on slope surface and resistance property. When distinguish flow pattern of shallow flow on slope surface with Reynolds number, and Reynolds number is in the field of laminar flow, the relation between resistance coefficient and Reynolds number is not presented the specialty of laminar flow as the result of nikuradse andА.П.Зегжда's experiments. Therefore, this research tries to search after a new method of judging and reflecting flow pattern shallow flow on slope surface, in order to afford the academic gist for slope surface soil erosion research. Hydraulic properties of shallow flow on slope surface were researched in this article from the following two aspects:(1)Primary study on flow pattern determinant method of shallow flow on slope surface.In order to give a quantificational description of shallow flow on slope surface, and ravel the influence on slope surface boundary status for shallow flow hydraulic properties, , a series of experiments on shallow flow on slope surface were performed on organic glass slippery bed with four kinds of gradient(base slope is: i= 0.005,0.017, 0.025,0.05) and artificial rough bed (grain size of sediment is from 0.5 mm to 1 mm) with four kinds of gradient(base slope is: i=0.001,0.002,0.02,0.1 ) through the indoor fixed-bed resistance test.In order to search after the new flow pattern determinant method of shallow flow on slope surface, the essay coordinates and compares the research data by applying two different parameter hydraulics binary fluid Reynolds number and sediment transport mechanics flow around Reynolds number respectively. The result shows that flow around Reynolds number is intuitionistic and distinct for reflecting the flow pattern of fixed-bed shallow flow on slope surface.(2) Experiment study on overland flow hydromechanics of different roughnessA series of experiments on overland flow hydromechanics of different roughness were performed on organic glass slippery surface and artificial rough bed (grain size of sediment is from 0.5 mm to 1 mm, 1 mm to2 mm, 2 mm to 5 mm, 5 mm to 10 mm) with three kinds of gradient(gradient is: s=5°,10°,15°).Through the experiment study on overland flow hydromechanics of different roughness, the relationship for fixed-bed shallow flow hydro-dynamic parameters (Reynolds number, Froude number, resistance coefficient and flow velocity ) as a function of bed roughness, flow discharge and slope gradient was studied by means of the experiment on overland flow hydromechanics of different roughness, the preliminary result indicates that:A. Fixed-bed shallow flow Reynolds number and Froude number tends to increase if slope gradient increases in the same condition of bed surface and flow discharge.B. Overland flow Reynolds Number and Froude number tends to diminish, water flow velocity tends to diminish, and resistance coefficient tends to increases, if bed surface roughness increases in the same condition of lope gradient and flow discharge. It shows that consumed energy for working of water flow surmounting resistance tends to increase.