| In the karst area due to the ecological environment and the comprehensive impact of human activities,making the karst area of serious soil erosion,rocky desertification is developing rapidly.It is helpful for us to understand and master the law of soil erosion on the slopes of karst stone teeth,and to provide theoretical support for soil and water conservation management in karst area.Based on the observed data of runoff and sediment production in the runoff plot of Tianshengqiao Village in Shilin,this paper studied the process,characteristics and influencing factors of runoff and sediment yield in Karst limb exposed slope under natural rainfall conditions.show:The results show that the stone teeth exposed slope runoff process is different from other slope,stone teeth decreases the surface to allow the infiltration area,restricting the rainfall infiltration,and the stone teeth surface runoff flow of soil layer,soil saturated saturation promote surface runoff process.The runoff yield and flow rate of the three plots showed A,B and C in the sample plots,which indicated that the higher the level of outcropping,the faster the flow rate and the greater the flow rate.At the same time,a large number of stone teeth exist barrier diffusion of surface runoff,the runoff collected in the stone between the teeth,the increase of runoff scouring,thereby increasing the amount of soil erosion;so the plots of three sediment samples showed A>B>C sample plots,thus there are stone teeth the distribution of the bare slopes are more susceptible to erosion.According to the rainfall intensity,the degree of tooth exposure and vegetation coverage,the calculation equation of soil erosion modulus of karst stone slope is determined as follows:Y=0.028X11.276×X2-1921E-8×X3-0.562?The difference of soil mechanical composition between three plots was small.With the deepening of soil erosion,the content of clay in soil less than 0.001mm increased gradually.The water physical characteristics of sample plots C are better than those of sample plots A and B.With the increase of soil erosion degree,the total porosity and capillary porosity decrease gradually.The large aggregates of A and B in the sample plots are easy to disperse after encountering water,and the soil is obviously Sandy and vulnerable to erosion.Of the 10 selected soil anti erodibility evaluation index by principal component analysis,found that,0.25mm aggregates,structure damage rate,clay particle content,<0.05mm Viscose powder content,<0.01mm physical clay content of 4 indicators can be used to evaluate soil erosion resistance index optimization.According to the weight of three main components,can be deduced from the study area soil erosion comprehensive index model for F=0.370F1+0.358F2+0.272F3;three comprehensive soil sample corrosion value from small to large order sample plots of C>B>A sample.The runoff and sediment variation in precipitation and the trend is basically the same,positive correlation between the increase with the increase of rainfall,runoff and rainfall runoff between the functional relation of power exists obviously,and the best fitting relationship between sediment and rainfall is logarithmic;runoff depth and sediment volume with 30 minute period of maximum rainfall intensity(I30)the relationship between the most closely;there are two times the relationship between runoff and sediment flow;The annual rainfall and annual soil erosion amount is basically the same trend.The soil erosion plots and A plots B and annual rainfall was significant at 0.05 level,and the amount of soil erosion plots C and annual rainfall is not significant;three soil erosion plots and erosion of rainfall are reached a significant level,the correlation coefficients were 0.912,0.905,0.785;between soil erosion and rainfall erosivity plots,A plots and B plots C correlation coefficient is very high,respectively 0.974,0.976,0.887,at the level of 0.01 were significantly related.This shows that erosive rainfall and rainfall erosivity are the main factors affecting soil erosion in the study area. |
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