Effect of developed rill formation accompanied with the variation of slope length on soil loss

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It is one of the factors for soil erosion that the washing out of soil particles from inclined bare fields is rill erosion. In the case of producing rill erosion, even if the intensity of rainfall and runoff ratio are the same, it is possible to produce a difference in total soil loss. It is inferred that complicated rill owing to rainfall in inclined bare fields influences the quantity of soil loss. The present stuby is aimed at grasping and classifying the form of developed rill by an indoor experiment in the changing length of slope (100cm, 150cm, 200cm) which considers the influence of the length of a alope in case of each form of developed rill. The indoor experiment proved that the rills are classified in types (I,Y,RY) by establishing a condition of the present study, the effects of the length of a slope involved in soil loss have a different tendency in each type.Results are as follows ;1) Soil loss and rill formations for surface water flow were surveyed using old and new type rainfall simulators.2) Rill formations occurred by surface water flow running dawn on the soil box under the dry density of the soil layler set constant condition were analyzed qualitatively and quantitatively.3) Basic relationship of rainfall, surface water flow and soil loss was clarified by collecting, arranging and analyzing the data of the experiment under same soil condition in the soil box.4) A Soil loss equation with regard to rainfall types was developed using results of experiment and observations of the rainfall simulator and the field test plots, and it was found that the equation showed good application to actual fields.