摘要
With digital elevation model （DEM）,sloping data were extracted automatically and soil erosion situation was also investigated. Compared with field survey and the related studies,the results showed that parallel range-gorge landform in Three Gorges reservoir area,the inter-bedded structures formed by Jurassic purple clay （page） rocks and human activities were the key controlling factors for small-scale sloping terrain.
利用数字高程模型(DEM)实现坡耕地数据的自动提取和侵蚀状况调查,并与实地勘察及相关研究结果进行对比,分析利用中低分辨率DEM提取坡耕地坡度信息误差的来源及其对水土流失调查结果的影响。结果表明:利用忠县1∶50000地形图生成分辨率为25m的DEM,基于该分辨率DEM自动提取的坡耕地信息在评价其水土流失现状时与实地勘察和相关研究结果存在一定差异,其主要原因为:①该地区地貌特殊,平行岭谷地貌和出露的侏罗纪紫色泥(页)岩与砂岩互层结构共同作用形成的地形较为复杂,造成该区土地利用多以小地块为主的镶嵌结构,而分辨率较低的DEM对地形起伏的描述误差较大;②人为修建的梯田(水田)、坎田以及垄沟整地措施对坡耕地微观地形改变的影响较大。因此,在坡耕地水土流失现状评价中,单从中低分辨率DEM获取坡度信息来判断水土流失程度,将会产生较大误差。DEM分辨率越高,对与坡度有关的地貌和水文参数的描述越精确,提取的坡度信息越准确。中低分辨率坡度可以通过变换,使其接近较高分辨率坡度对地形起伏的反映能力。此外,还应加强实地勘察力度,并与计算机自动提取技术相结合,才是正确评价坡耕地水土流失的方法。
基金
Supported by Chinese Academy of Sciences of Western Action Plan Project (KZCX2-XB2-07-01)
National Scientific and Technological Support Project (2008BAD98B04)~~
