漓江流域水土流失特征及其侵蚀影响因子典型分析

Characteristics of soil and water loss in the Lijiang River Basin and soil erosion factors in typical karst small watersheds

选择漓江流域及其典型岩溶小流域为研究对象,通过遥感数据综合分析和地面路线验证调查与定点监测相结合的方法,对漓江流域岩溶区和非岩溶区的水土流失特征进行了研究,并重点分析岩溶区内典型小流域——寨底小流域侵蚀影响因子对水土流失的影响。研究结果表明:漓江流域水土流失以中度和轻度等级为主,约占流域面积的29.9%;流域内岩溶区与非岩溶区的水土流失表现出一定的差异性,岩溶区以中度、极强烈和轻度等级水土流失为主,水土流失面积约占岩溶面积的53%;非岩溶区中度和轻度等级水土流失分别占非岩溶区面积的12.4%和10.4%。高程、坡度、植被覆盖、土地利用等因子对岩溶小流域土壤侵蚀面积和侵蚀量比例的影响表现出明显的差异性和独特性,这四种影响因子中的高程(300,500]m,坡度[15°,25°]、植被覆盖度≤20%、土地利用为工矿用地等对岩溶小流域土壤侵蚀的影响最大,是寨底岩溶小流域水土流失治理中应重点考虑的因素。

The purpose of this study is to determine the characteristics of soil erosion in the Lijiang River Basin and the relationship between soil erosion and impact factors in the Zhaidi karst underground river watershed.The distribution feature of soil and water loss on a medium scale in the Lijiang River Basin and the influencing factors of soil erosion on a large scale are analyzed based on remote sensing interpretations and field investigations.Research reveals that the soil erosion in the basin is dominated by moderate and medium degrees,which account for 29.9%of the total drainage area.There are obvious differences in soil and water loss between karst area and non-karst areas in the basin,where soil and water losses in the karst area are moderate,extremely strong and medium,accounting for 53%of the entire karst area;while moderate and medium soil erosion in the non karst area accounts for 12.4%and 10.4%of the total non-karst area respectively.The Zhaidi karst underground river is located in the southeast of Guilin,Guangxi Zhuang Autonomous Region,which belongs to the Caotian river,a tributary of the Lijiang River.The relationships between the soil erosion amount,soil erosion area,influencing factors including elevation,slope,vegetation coverages and land utilization are also analyzed.The results show that the 300-500 m elevations,15-25 degree slopes,less than 20%vegetation coverage and industrial and mining lands pose the largest influences on soil erosion in the karst small watersheds.