小流域土壤侵蚀预测预报基本生态单元生成和模型设计

Research on Basic Ecological Landform Unit and Model of Soil Erosion Estimation and Predict in Small Watershed

土壤侵蚀预测预报的目的是为治理水土流失、合理利用土地资源而服务的,所以说土壤侵蚀的预测预报单元应落实到一个具体的土地利用生态地形面上。以黄土高原风蚀水蚀交错带的六道沟为研究区,基于土壤侵蚀的发生学原理,首先将各主要发生因子的图件数字化,并通过GPS对数字化图进行校正;然后,对地形条件、物质组成、土壤相三图件进行制图综合,生成流域侵蚀地块图;在此基础上,迭置土地利用类型图,在GIS平台上,生成土壤侵蚀预测最小单元图——生态地形面图。在每类生态单元内,系统分析土壤侵蚀发生的各环境要素,并确定其权重,应用组合数学原理,建立适合于当地环境整治、水土流失治理的土壤侵蚀生态预测系统,为建立适合我国土壤侵蚀预测预报模型提供一些基础依据。

The northern region of loess plateau in China, where is cross water-wind erosion, is typical ecosystem environment fragile zone with serious soil erosion. The research on soil erosion prediction is very urgently. However, due to special geography of loess plateau, social and economic condition, the application of oversea prediction models is suffered to limit. We must develop a suite nation situation prediction model. For this, according to the purpose to predict soil erosion, we propose a soil erosion ecological prediction way. The Liudaogou small watershed, which is located in cross zone of water-wind erosion in the north of loess plateau in China, is taken as studying area. According to theprinciple of soil erosion, we select some main affecting factors as cartographic generalization objects. They respectively are landforms surface material composition, slope gradient and land utilization ways. On the based of cartographic generalization with GIS, according to combinatorics principles, the ecological landform unit is formed. In the Liudaogou small watershed, there are 83 kinds of ecological landform unit scattered in (284) plots. The soil erosion basically occurs on wasteland, slope land and sparse shrub land with the slope gradient of 15°~25°, and their areas sums up about 50% of whole watershed.