基于CSLE模型的贵州省水土流失规律分析

Analysis of the Characteristics of Soil and Water Loss in Guizhou Province Based on CSLE

应用第一次全国水利普查水土保持专项数据,分析了喀斯特地区实际土地利用单元地块空间统计特征及相应侵蚀规律。结果表明:喀斯特地区土地利用类型以林地、耕地为主,共占调查总面积的86.2%。由于地形破碎,地势陡峭,土地表现出破碎化特征,地块面积、坡长、坡度均值分别为3.45hm^2,45.3 m,21.7°。坡度对土壤侵蚀的影响大于坡长,陡坡耕作是导致耕地土壤侵蚀严重的主要原因,68.6%的耕地位于陡坡,其侵蚀量占总侵蚀量的65.6%。贵州省土壤侵蚀程度由西向东递减,以黔西南地区侵蚀最为严重。工程措施能够有效防治土壤侵蚀,减沙效益在75%以上,但随坡度增大而减小,林草地减沙效益优于工程措施。在区域水土保持规划时,应重点考虑土壤侵蚀强烈地区,减少陡坡耕作,推广还林还草。

To explore the characteristics of soil and water loss in the Karst region,we analyzed the spatial statistic features and soil erosion characteristics of blocks.According to the First National Water Census,field surveys were carried out using blocks as the minimum survey units.A block is an area in which land use,soil and water conservation measures and coverage are identical.Soil erosion modulus was calculated using the CSLE（Chinese Soil Loss Equation）model.The results showed that farmland and forest were dominated in the Karst region,accounting for 86.2% of the total area.Because of cracked terrain and steep slopes,the landscape showed fragmentation characteristics.The average area,slope length,slope gradient of blocks were 3.45hm^2,45.3 m,and 21.7°,respectively.Analysis of the erosion modulus showed that68.6% of farmland blocks had steep gradients and accounted for 65.6% of the total sediment yield.About50% of farmland suffered severe erosion.The effects of slope gradient on soil erosion were significantly greater than that of slope length.Engineering measures reduced soil erosion by 75%.With the increase of slope gradient,the efficiency of engineering measures in reducing soil erosion decreased and became smaller than that of the forest and grassland.The most serious soil erosion occurred in southwest of Guizhou Province,and the degree of soil erosion decreased from west to east.When planning for regional soil and water conservation,the most seriously eroded area should be given the primary consideration,and reducing cultivation on steep slopes and returning farmland to forest should become the first choice.