云蒙湖流域土地利用变化对土壤侵蚀的影响

Effects of Structural Changes Land Use on Soil Erosion in the Yunmeng Lake Watershed

在RS与GIS支持下,选用RUSLE模型估算土壤侵蚀量,利用转移矩阵分析土地利用及土壤侵蚀变化特征,引入土壤侵蚀强度指数分析土壤侵蚀效应,在此基础上,对88子流域进行回归分析,建立土地利用结构与土壤侵蚀定量关系。结果表明:1986～2010期间,研究区土地利用类型以耕地为主且呈减少趋势由63%减少到59%,土地利用类型变化主要由耕地和草地向其他地类转出为主;土壤侵蚀状况有所好转,侵蚀类型以微度为主,所占比例由60.7%上升到61.7%,强度以上所占比例由16.9%降到16.6%,土壤侵蚀等级变化显著,中度、强度和极强度变化率为50.54%、50.8%和47.34%,主要由较高强度和邻近较低强度转入为主;土壤侵蚀强度随土地利用类型变化而变化,当发生不合理变化由林地→耕地时,侵蚀强度指数由154.3增到259.3,结构合理化由耕地→林地时,侵蚀强度指数由233.2降到145.1;回归方程结果显著,检验误差为0.024%,有一定可靠性。因此,优化土地利用结构是控制土壤侵蚀的有效途径,通过建立土地利用结构与土壤侵蚀量的定量关系可为动态监测土壤侵蚀状况提供简单方法。

In order to investigate the influence of land use change on soil erosion over the Yunmeng Lake watershed, RS and GIS techniques were utilized and RUSLE model was selected to acquire soil erosion data. Transitional matrix was used to study the land use and the soil erosion level change. A soil erosion intensity index was introduced to quantify the relationship between land use change and soil erosion. On this basis, statistical regression method was used to study the soil erosion due to the changes of land use. The result showed that during the period of 1986 - 2010, farmland were the dominant land use type with reducing to 59% from 63%. Land use changes were mainly caused by converting farmland or grassland to other land use types. Soil erosion situation had improved with the proportion of minima zones rising from 60.7% to 61.7% and the total proportion of strong, extremely strong and severe erosion zones decreasing from 16.9% to 16.6%. Great changes happened for soil erosion with the change rate of moderate, strong and extremely strong as 50.54%, 50.8% and 47.34% respectively. Soil erosion was mainly converted from the adjacent degrees. Soil erosion was affected by the different land uses. The transition of foresdand to farmland and grassland were the primary causes for aggravating soil erosion. On the contrary, the transition of farmland to other land use types had alleviated the soil erosion. Moreover, a new dynamic assessment method for watershed soil erosion was proposed on the base of regression analysis and would propose more easy way for dynamic monitoring the soil erosion in the Yunmeng Lake watershed.