顾及梯田的DEM地形特征研究

梯田地表作为一种特殊的经人工深度影响的地貌形态,目前已成为在山丘地区具有经济效益和生态效益的土地资源。但是在当前强化推进土地资源管理数字化,信息化的今天,对梯田的数字化表达以及分析还存在欠缺。本研究通过对数据的改造,构建出顾及梯田的DEM,并从原始DEM与梯田DEM的剖面结构特征、高程特征以及地形因子特征等方面进行了对比分析。结果表明:(1)基于真实田坎构建的梯田DEM,可较为准确且直观地反映梯田地形的特征。(2)与原始DEM相比,加入梯田信息后,梯田DEM高程剖面图总体呈阶梯式分布,转折部位明显,且基于梯田DEM提取的坡度、坡长、LS因子值明显减小,反映修建梯田后地形因子的变化,对进一步定量分析土壤侵蚀以及水土流失具有重大意义。

Study on Topographic Features of the Terraces DEM

As the special and artificial micro topography,terraces have already become land resources with economic and ecological benefits in the Loess Plateau.However,most existing DEMs hardly satisfy the realization of terrace terrain,and partial artificial landform information is lost.In this paper,we choose terraces in a basin in Ansai County as the case study area,the materials include DEM of Ansai (its scale is 1 ∶ 10 000,resolution is 5 m) and a remotely sensed image with a resolution of 2.5 m.Based on the improved rapid modeling method for terrace digital elevation model,we adopt the actual ridge-based method to construct the DEM with terraces information (T-DEM) by integrating with high resolution remote sensing image.Using Spatial Analyst Module of ArcGIS and LS-TOOL,topographic features and terrain factors (slope,slope length and LS factor) were extracted from Original DEM and T-DEM,respectively.The results show that:(1) T-DEM reflects terrace terrain accurately and intuitively;(2) in comparison with the Original DEM in sample region,profile features of elevation extracted by T-DEM distribute like a ladder were more consistent with the real topographic features;meanwhile,slope,slope length and LS factor extracted by T-DEM are smaller;more precisely,the average of slope decreased by almost a half and its range increased;the range of slope length reduced obviously and the average of slope decreased;LS is reduced by 90％.In conclusion,terraces play an important role in DEM-based terrain analysis.This research has the significant meaning for evaluating soil erosion.