| Due to the slow rate of soil formation,the specific geological and hydrological backgrounds of water and soil space mismatch,and the reasons for the development of underground structures,the soil erosion in karst regions is more complex and special than in non-karst regions.Soil erosion in karst regions is often associated with topography and lithology.Rocky desertification,road construction,etc.have complex relationships.However,previous studies have neglected the influence of natural factors such as rocky desertification,lithology,and roads and other human activities on the soil erosion process.Therefore,the spatial-temporal evolution of soil erosion and the correlation of spatial factors in the karst area are very lacking.How to take effective methods and means to study the temporal and spatial distribution evolution of karst soil erosion and its relationship with spatial factors is still a problem to be solved urgently.International research in this area is still relatively rare,not only lacks data support,but also lacks experience and contributions in technical methods.In view of this,this paper uses the typical karst troughs in southern China as the research object,combining with the actual investigation of soil types and soil erosion test results,based on GIS technology and the modified general soil erosion model(RUSLE),selecting slopes,Factors such as lithology and rocky desertification were used as natural influencing factors to analyze the spatio-temporal characteristics of soil erosion in the study area and its evolutionary relationship with lithology and rocky desertification.Road factor was selected as an influencing factor for human activities and landscape ecology was used.The methods and techniques of the study explored the impact of road construction under karst landscape on the landscape pattern of soil erosion,and revealed the relationship between soil erosion and the main natural elements and human activities in this area.The main conclusions are as follows:During the study period,the evolution of soil erosion in the study area was generally in a trend of improvement.The ratio of the area occupied by slight and light erosion showed an increasing trend,while the proportion of erosion area above moderate degree showed a decreasing trend,from the erosion area.The signs of moderate erosion and above erosion and slight erosion have shown signs of evidence that the soil and water conservation measures in the study area have played an active role on a large scale.The effect is significant.(2)With the increase of slope,the soil erosion modulus in Yinjiang County also gradually increased,showing a clear positive correlation.In areas with a slope below 35°,on the one hand,surface runoff increases the erosion of the soil as slope increases.On the other hand,sloping farmland in karst mountainous regions is mainly distributed in areas with a slope below 35°,and human activities are intense.As a result,the amount of erosion increases with the increase of slope.When the slope reaches 35°,the erosion becomes a downward trend.The effect of the increase in slope weakens.The 15°-35° slope zone is the main eroded slope section of the study area.The eroded area accounted for 60.59% of the total eroded area.The contribution of the total eroded area was 40.44%.This slope range was subject to severe artificial reclamation and was prone to soil erosion.In the area,the 15°-35° slope zone should be an important area for strengthening soil erosion control measures in Yinjiang County.(3)The erosion rate of soil erosion in the carbonate area of the study area was larger than that of the non-carbonate area.The soil erosion of all the rock exposed areas showed a tendency of improvement as a whole,but the soil between different lithological distribution belts was different.Erosion dynamics vary widely.In the interbedded areas of continuous dolomite,limestone-clad clastic,limestone and clastic rock,the decrease in annual erosion rate gradually decreases as the content of carbonate rocks decreases.The higher the content of carbonate rocks,the slower the rate of soil formation and the shallower layer of soil,the smaller the annual erosion rate.(4)With the aggravation of rocky desertification grades,the decline rate of annual soil erosion rate is gradually reduced,showing that the higher the degree of rocky desertification,the lower the erosion modulus,and the smaller the annual erosion rate.As the non-rock desertification areas are mainly distributed in river valleys and low-altitude areas,there is a certain soil thickness,and the vegetation coverage is good,so the annual erosion rate in rocky desertification areas has a larger decline than the rocky desertification area.(5)The surface of the karst area is fragmented,and the presence of a large number of mountains increases the fragmentation of the landscape pattern of soil erosion.At the same time,landscape fragmentation is also an important cause of aggravating soil erosion.The change of soil erosion in the road buffer zone of Yinjiang County is controlled by the spatial distribution of soil erosion in the whole county.This paper removes the mountain in the road buffer zone,and the calculation results can better reflect the actual conditions in the karst area.The results show that before the mountain was removed There is an overestimation of the erosion of 3069.18 hm2 in the road buffer.In future studies,special terrain factors such as karst terrain should be taken into account.The research results of this paper can provide the basis for the macro decision-making of government decision makers and environmental managers,and provide method experience and data reference for international peers to study the soil erosion in karst geomorphological areas. |
PDF Full Text Request