| Soil erosion is the main problem that restricts the sustainable development of ecological environment and ecological environment of Karst Mountainous area.Based on the monitoring data of runoff plots in the middle area of Guizhou,the spatial distribution characteristics of runoff frequency,runoff and erosion amount in the middle area of Guizhou were systematically analyzed by using the method of mathematical statistics and GIS,the rainfall patterns of erosive rainfall in central Guizhou were classified,and the response mechanisms of soil erosion to different rainfall,topography and vegetation coverage were studied.The soil erosion model was modified by monitoring data,and the soil erosion in the middle area of Guizhou was calculated and evaluated by GIS method.It can provide a theoretical basis for the mechanism of soil erosion and the model of soil erosion in karst area and a reference for the information and scientific management of regional soil and water conservation.The main findings are as follows:（1）Rainfall erosivity K,vegetation cover C and slope S were the main factors affecting runoff in central Guizhou.The main factors affecting sediment are runoff R,slope S and vegetation C.Influenced by topography and rainfall,runoff generation times and runoff have the same law in spatial distribution,Although the erosion amount has a high correlation with the runoff in the linear fitting,there is a definite difference in the spatial distribution of runoff due to the influence of surface vegetation coverage.（2）The central part of Guizhou receives frequent,heavy and long-lasting rainfall,mainly in the summer half year.Rainfall amount,rainfall duration and I30min are the key factors affecting runoff and erosion.According to the selected key factors,the erosive rainfall was divided into four rainfall types by k-means Clustering Method.The C rainfall type with small rainfall amount,short duration and high intensity was dominant in the middle area of Guizhou,accounting for 42.95%of the total rainfall.C rain type has more influence on soil erosion because of its short duration,high intensity,large runoff and large erosion.（3）The average annual runoff decreased with the increase of slope length,and the erosion decreased first and then increased with the increase of slope length.soil erosion was positively correlated with rainfall（P）and maximum rainfall intensity of 30 minutes(I30min)in different slope gradient and slope length plot.P and I30min of A and C rain patterns were larger,These two rain patterns had great influence on surface runoff process and erosion characteristics of runoff plots with different slope and slope length.（4）The runoff and erosion of distinctive vegetation types vary greatly,the soil erosion of cultivated land and economic economic fruit forest was the most serious under different rainfall types,and the runoff and sediment yield of mixed forest,broad-leaved forest and coniferous forest were relatively small.Runoff and erosion under different rainfall patterns decreased with the increase of vegetation coverage,which should reach at least 75%in order to control soil erosion.（5）In the middle part of Guizhou,the soil erosion is mainly micro-erosion,but the proportion of high-intensity soil erosion is still large,the soil erosion is serious,and the area of soil erosion above moderate erosion increases with the increase of soil erosion intensity.In central Guizhou,Qixingguan District,Dafang County,Zhijin County and Qianxi County have a large amount of soil erosion and a high degree of soil erosion.More attention should be paid to soil and water conservation in this area.The CSLE model modified by runoff plot monitoring data has high applicability and can provide reference for soil erosion calculation in a karst area. |
PDF Full Text Request