中尺度土壤预测制图中地形变量提取的适宜分辨率探讨

地形变量是土壤预测制图中重要的预测变量之一,为了满足中尺度土壤预测制图的精度要求,又能够减少数据的冗余,需要选择合适分辨率范围的地形变量。基于ASTER GDEM数据,对不同地形起伏状况的3个样区,通过重采样得到30 m、60 m、90 m、120 m、150 m共5组不同分辨率的DEM数据,分别选取土壤预测制图中常用的高程、坡度、平面曲率和剖面曲率4组地形变量,通过地形信息熵、局部方差均值以及比例尺和空间分辨率的关系,选取巢湖流域用于土壤预测制图的地形变量提取的适宜分辨率范围。研究表明:对于特定比例尺的土壤预测制图,地形变量的提取需要综合考虑两个因素:一是土壤预测制图的比例尺,二是地形变量提取的分辨率。中尺度土壤预测制图地形变量提取的适宜分辨率为30m,既能保留有实际意义的地形信息,又能满足土壤预测制图的精度要求。

Discussion on Appropriate Resolution of Terrain Factors Extraction in Meso-scale Soil Prediction Mapping

GTopographic variables is one of the important predictors for digital soil mapping.To satisfy the accuracy requirement of soil prediction and mapping at the medium scale and reduce data redundancy,it is necessary that selecting the appropriate resolution range of topographic variables.In this paper,based on the GDEM ASTER data,we selected 3 case study areas with different relief,and obtained 5 groups of DEM data with different resolutions of 30 m,60 m,90 m,120 m,150 m by re-sampling.The elevation,slope,plan curvature and profile curvature of soil prediction were extracted respectively.The suitable resolution range of the topographic factors in Chaohu River Basin was selected by the terrain information entropy,the local variance and the relationship between scale and spatial resolution.The results showed that two factors should be taken into account in the extraction of topographic variables for the specific scale soil mapping:the first was the scale of soil mapping,and the second was the resolution of the topographic variables.The appropriate resolution of terrain factors extraction in meso-scale soil prediction mapping was 30 m,which could not only meet the requirements of the mapping accuracy,but also retain the valuable terrain information.