Research on dynamic change of soil erosion distribution and its controlling factors in yimeng mountainous area of china | 沂蒙山区土壤侵蚀空间分布及其影响因素动态变化

chinois. 【目的】研究土壤侵蚀强度空间格局与坡度、土壤、降雨、植被覆盖和土地利用等影响因子的动态变化关系,揭示沂蒙山区土壤侵蚀规律。【方法】以TM影像、地形图、土壤图和气象资料为源数据,综合运用GIS和RS技术,获取沂蒙山区坡度、土壤可蚀性K值数据以及1986年、1995年和2005年的年降雨侵蚀力、植被覆盖度、土地利用和土壤侵蚀强度数据;通过对研究区山地丘陵地带进行子流域划分,以子流域为单元,选取土壤侵蚀强度指数、平均坡度、土壤可蚀性指数、平均年降雨侵蚀力、平均植被覆盖度和土地利用结构指数,并采用统计分析方法,对土壤侵蚀强度空间格局与其主要影响因素的动态变化关系进行分析。【结果】随着植被覆盖度的增加以及土地利用结构向有利于控制土壤侵蚀的改善,1986年、1995年和2005年3个时期内山地丘陵地带上土壤侵蚀明显降低。土壤类型对3个时期土壤侵蚀强度空间格局的影响不显著;降雨侵蚀力在2005年成为影响侵蚀强度格局的主要因素之一,但影响程度较低,贡献率仅为5.35%;坡度因子是影响各时期侵蚀强度格局的最主要因素,但影响程度逐渐降低,其贡献率由1986年的93.33%下降到2005年的79.75%;植被覆盖因子在1986年影响侵蚀强度格局的贡献率为6.67%,之后则减弱;而土地利用结构对侵蚀格局的影响程度逐渐增强,贡献率已增至到2005年的14.90%。【结论】年降雨侵蚀力分布的空间差异增大后,降雨因子将成为显著影响土壤侵蚀空间格局的因素之一;受人类活动影响,当植被覆盖度达到一定程度后,土地利用结构逐渐成为影响侵蚀格局的重要因素,建议该地区今后的水土流失防治工作应优先考虑调整土地利用结构。

anglais. 【Objective】The aim of this study is to provide some references for the rule of soil erosion and the control of soil loss in Yimeng Mountainous area by analysing the dynamic change relationship of soil erosion intensity distribution relevant to slope gradient, soil types, rainfall, vegetation cover and land use.【Method】Supported by the technology of GIS＆RS, data of slope gradient, soil erodibility and data of annual rainfall erosivity, vegetation cover, land use and soil erosion intensity in different years (1986, 1995 and 2005) in the study area were acquired from Landsat TM image, relief map, soil map and meteorological information. Then, the hilly and mountain region of the study area was divided into 122 subbasins in which the soil erosion intensity index (SEI), average slope (AS), soil erodibility index (KI), average annual rainfall erosivity (AR), average vegetation fraction (AVF) and land use structure characteristic index (SI) were used to study the dynamic change relationship between soil erosion intensity distribution and the above factors at subbasin scale by the method of statistical analysis. 【Result】The investigation showed that with the increase of vegetation cover, the change of land use structure tended to be favorable for controlling soil erosion, the soil erosion intensity in the hilly and mountain region in the years of 1986, 1995 and 2005 presented a obvious decline. The effect of soil factors on the distribution of soil erosion intensity of the three years was not significant. The annual rainfall erosivity significantly influenced the distribution of erosion intensity in 2005 with a lower contribution rate (CR), which was 5.35%. Slope was the most critical factor affecting the distribution of erosion intensity, but the CR fell from 92.82% in 1986 to 84.23% in 2005. Vegetation cover only effected in 1986 with a CR of 7.18%, while the effect of land use which is closely related to human activities had been gradually enhanced, and the CR reached 15.77% in 2005. 【Conclusion】 When the space difference in distribution of annual rainfall erosivity increased, rainfall will be a factor which significantly influence the distribution of erosion intensity. Affected by human activity, land use exhibited its noteworthy factor on the erosion distribution after the restoration of vegetation. It is suggested that adjustment and optimization of land use structure should still be made in this area for the control of soil erosion.