The Effect of Cover Rate and Disposition of Rock Fragments on Interrill Soil Erosion
Date Issued
2004
Date
2004
Author(s)
Chung, Yi-Chuan
DOI
zh-TW
Abstract
The primary purposes of this study are to investigate the effects of cover rate and disposition of rock fragments on interrill soil erosion, the relationships among them, and the causes of these effects.
In this study, the soil used for erosion tests was the lateritic soil from Lin-Kou. Soil samples were placed in erosion boxes and the slope steepness was controlled to be 20%. Natural pebbles were used as rock fragments to cover the soil surface. Different cover rates and disposition of the rock fragments were used along with two rainfall intensities of simulated rainfall. Following results were obtained from the erosion tests. Firstly, when the rock fragments were completely or partially exposed on the soil surface, they could protect the fine particles on the soil surface from raindrop impact, and accordingly, the erosion was less. As for the rock fragments completely embedded into the soil, they tended to cause lower soil permeabilities. Subsequently, the runoff and erosion increased. Secondly, under the conditions of three different disposition methods of rock fragments and of two different rainfall intensities, it was found that while the rock fragments were completely exposed to the soil surface, the runoff coefficient were the least, i.e., the infiltration rates were the highest and water retention ability were the best. Among all the conditions, with 30% cover rate and 40 mm/hr rainfall intensity, the runoff coefficient had a smallest value of 23.87%. Thirdly, while the cover rate of rock fragment was as high as 60%, it was found that soil with rock fragments completely and partially exposed to the soil surface were the best, in reducing the erosion rate. Soil with rock fragments completely embedded into the soil was worse than soil without any treatment. Fourthly, regarding the effects of disposition methods on reducing soil erosion, it was found that the erosion of soil with rock fragments completely exposed to the soil surface was the least, followed by rock fragments partially exposed to the soil surface. With the rock fragments completely embedded into the soil, erosion was greater than soil that without any treatment.
Overall, it was found that erosion rate, cover rate, disposition of the rock fragments and rainfall intensity were well related. A regression equation, with a coefficient of determination of 0.839, were developed to relate these parameters.
Subjects
放置方式
降雨強度
土壤沖蝕
覆輔v
石塊
紋溝間土壤沖蝕
rainfall intensity
cover rate
disposition
soil erosion
interrill soil erosion
rock fragment
Type
thesis
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