The Research On The Effect Of Terrace On The Quantitative Evaluation Of Soil Erosion

Soil erosion is a worldwide environmental problem. Loess Plateau has a worse situation. Large area of terrace were built to prevent the erosion take a turn for the worse. Terrace diminished the slope of the original ground and the slope length, made the Micro-landform changed. So terrace has an effect on soil erosion. In the Soil Loss Equation, terrace was taken as a measure of conservation of water and soil. In the thesis, the effect of terrace on LS factor was studied first and the effect of terrace on the quantitative evaluation of soil erosion is analyzed further. This thesis chose Zhifanggou Basin and Yangou Basin as experimental sample plot and used DEM of 5m, WorldView3 of 0.3m and Landsat8 images of 30m, rainfall data, soil data and landuse as data resource. By building the terrace DEM, the thesis analyze the effect of terrace on LS factor. Under the condition of rainfall, soil and vegetation remaining unchanged, the thesis calculated the amount of soil erosion using CSLE in two situation:taking terrace as engineering measures factor and LS factor. After comparing and analyzing the results, it showed:(1) On the basin scale, the average amount of soil erosion when taking terrace as LS factor is more less than that when taking terrace as engineering measures factor. Compared with slope terrace, gradient terrace had better function on soil loss. (2) Terrace made the area of moderate and mild level of soil erosion decrease so terrace had a good effect on soil erosion. (3) The proportion of terrace has different level of effect on the amount of soil erosion. Larger proportion the basin had, less amount of soil erosion it would be. The research had a lot of meaning to improve the measure of evaluating soil erosion and evaluate the effect of measure of conservation of water and soil on modern micro geomorphology and modern surface. The research was also meaningful for evaluating the effectiveness of engineering measures.