| Quantitative simulation of soil erosion continues to be applied and developed in soil and water conservation research.Different soil erosion models are continuously updated to promote the widespread use of quantitatively simulated soil erosion research in soil and water conservation and harnessing.As we all know,soil erosion is closely related to rainfall intensity,soil texture,vegetation coverage,topography,engineering measures and other aspects.However,whether the shape of vertical terrain has an impact on soil erosion intensity?Whether the relationship of them can be described quantificationally?This question need to be futher explored.The developmental stages of the Yanhe River Basin,the characteristics of spatial variability of soil erosion and the relationship between soil erosion intensity and the river longitudinal profile system Correlation of profile system have been analyzed in this study with several methods such as HI,the model of CSLE and the river longitudinal profile system.The results will be showed as followed.The overall development of Yanhe River basin structure is from northwest to southeast,and the bending of the main channel is larger.The branch ratios of adjacent rivers in the basin are both greater than 3,and their ranges are around 3 to 5 with a maximum of 5.33,which indicating that the development of the Yanhe River Basin is relatively mature and its basin morphology will not change much.In addition,the topographic factors such as slope gradient and topographic relief in the Yanhe River Basin are also explored in this study.The results show that the topographic variation of the Yanhe River Basin is large with large fluctuation in the upper,middle and lower reaches,especially in the Yanhe River Basin Of the upper reaches of the region,indicating that the new structure of the upper reaches of the cumulative lift greater.The study of Hypsometric Index(HI)shows that the upstream of Yanhe River basin are more likely to be in the transitional phase of over-developed in juvenile period and over-aged stage in young adulthood,the midstream are more likely to be in the transitional phase of stable adolescence and old,and the downstream is more likely combined with mature years(major)and minor part of elderly.Yanhe River Basin is divided into tributaries and the longitudinal profile,steepness index,concave curvature and crack point have been calculated and analyzed in this study.The results show that the meaning of the best function fitting indicates that the developmental stages of the most part of the Yanhe River Basin are located in the early stage of the maternal age,with the increase of river network density and river development coefficient,the widening of the river valley and the undercutting erosion of the river channel.Several tributaries of the developmental stage are at the elderly(old age).longitudinal section of the fitting parameters quantitative description of the development stage of the watershed and HI value of the similarity of the results.And these are similar points for the description of development stage between these two methods,longitudinal section of the fitting parameters quantitative description and HI.After the standardized steepness index and concave curvature analysis of Yanhe River Basin,it can be showed that the steep index range of this basin lies between 10 and 50,mostly between 20 and 30,and the concave curvature between 0.15 and 0.99 is mostly between 0.4 and 0.7,that is to say,mainly in the concave curvature.The Ksn values of the upper reaches of the Yanhe River are higher than those of the midstream of the Yanhe River,while there are obviously high and low value mixed distributions in downstream.The Ksn values of the Yanhe River are relatively low in the whole basin.There are obvious differences between the north and south of the Ksn distribution.The low-kurtosis tributaries are mainly distributed in the middle and lower reaches of the Yanhe River basin.The distribution of the cracks is more in the northern part of the downstream of the Yanhe River basin.According to the existed model of soil erosion with Chinese characteristics(CSLE),the simulation of soil erosion was carried out in Yanhe River Basin.The results show that the soil erosion intensity is dominated by micro-erosion,and the slight erosion and severe erosion in this area is accounting for a considerable proportion of the area.The proportion of greatest erosion is small.Relative exploration based on these indexes,soil erosion modulus and the longitudinal section of the river system and other indicators,formulas of soil erosion modulus and steep index,concave curvature values,y_a=-0.00004x_a+1.3181,y_b=-0.0015x_b+55.746,and the R~2 values are 0.4065 and 0.3112,respectively,indicates that the modulus of soil erosion in this study is related to the concave curvature and the steepness index.From the perspective of standard deviation of soil erosion modulus,the correlation between soil erosion modulus and camber index and steep index is explored.The linear regression analysis is y_c=-0.0005x_c+1.0675,y_d=-0.0015x_d+62.708,and the correlation coefficient(R~2)is 0.1884 and 0.4589 respectively. |
PDF Full Text Request