考虑坡度变换的中低分辨率地形湿度指数提取

基于中低分辨率的DEM提取地形湿度指数,对于区域土壤侵蚀因子和区域土壤侵蚀模型等研究有着重要的意义.但随着DEM分辨率的降低,坡度趋于平缓,单元栅格高程信息的改变也会影响单元汇流面积的计算,基于中低分辨率提取地形湿度指数必须考虑这两方面的影响.以1:5万数字地形图分别构TIN得到分辨率为10,20,40和60 m的DEM,进行频率和累计频率统计,以10 m分辨率DEM为参考对其它分辨率DEM做坡度变换,提出根据高分辨率DEM若干栅格的单元汇流面积的均值作为低分辨率DEM的单元汇流面积,根据这两方面对地形湿度指数进行了改正.

Extraction of the Topographic Wetness Index Based on Slope Transformation of Coarser Resolution Slope

Extracting the to pographic moisture index from medium and low resolution DEM has an important significance to the research o n regional soil erosion factors and mo dels. How ever, as the resolution becomes lower, slope tends to become gentle and unit grid elevation information changes will also affect the calculation of unit catchment area.So,extracting the to pographic wetness index at medium-low resolution must take into account the impact of these two aspects.The 10,20,40,and 60m resolution DEM s are separately interpolated from digital topographic map on 1:50 000 scale and then statistics frequency and cumulative frequency are analyzed. Slope transformation is made based on the 10 m resolution DEM . T he average of catchments area of hig h-resolution DEM raster is taken as the unit catchment area of the medium-low resolution DEM. Finally, the topographic moisture index is corrected according to the above mentioned two aspects.