Manning roughness of sloping ground in the loess area of west Shanxi Province

As a predominant parameter of surface runoff, Manning roughness is quite important in simulating hydrology process and soil erosion.Using the method of field scouring flume, the experiment on the effects of the fresh grass yield, litter amount and the soil hardness on Manning roughness in different land types was carried out, and the relationship between Manning roughness and sediment concentration of surface runoff was also explored.Resultsshow that Manning roughness varies significantly among different land types.Manning roughness increases linearly with the increase of fresh grass yield and decreases exponentially as soil hardness increases.Under certain discharge, Manning roughness increases within a limit as litter amount increases.Sediment concentration of the surface runoff decreases as Manning roughness increases, and this can be described by logarithm function.