Soil erosion assessment using geomorphological remote sensing techniques: an example from southern Italy
Soil erosion assessment using geomorphological remote sensing techniques: an example from southern Italy
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利用地貌遥感技术进行土壤侵蚀评估：以意大利南部为例
DOI：
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发表时间：
2010
期刊：
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通讯作者：
P. Magliulo
中科院分区：
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作者：
Sergio Lo Curzio;P. Magliulo
本研究的目的是通过整合Landsat ETM 7+遥感数据和实地调查地貌数据，在流域尺度上评估土壤侵蚀的分布并绘制地貌影响图，以识别新形成的侵蚀地表（NeFEL）。该研究在位于意大利南部的228·6 km2宽的区域内进行。首先从岩性、土壤学、土地利用和地形地貌的角度对研究区域进行了表征，并制作了专题地图。然后，使用RSI ENVI 4.0软件对大地测量卫星ETM 7+卫星图像进行了地理参考处理。处理包括对比度拉伸、主成分分析（PCA）、去相关拉伸和RGB假彩色合成。进行了实地调查，以确定图像上发现的特征。与会者特别注意了NeFEL，因为它们是利用全球定位系统定位的。然后，我们在Landsat ETM 7+图像上划定感兴趣区域（ROI），即代表“地面实况”的多边形，将NeFEL与图像中出现的其他特征区分开来。一个简单的统计分析进行的数字（DN）值的像素封闭在感兴趣的NeFELs，目的是确定这样的陆面的光谱响应模式。然后使用最大似然分类算法在整个图像中对NeFEL进行分类。在实地检查了分类过程的结果。最后，通过将检测到的地表转换为矢量格式并将其导入ESRI ArcViewGIS 9.0软件进行空间分析。这些程序的应用以及实地调查的结果突出表明，分类图像中的一些“物体”，即使显示出与NeFEL相同的光谱响应，也不是遭受严重土壤侵蚀的地表，从而证实了对自动生成的数据进行实地检查的战略重要性。在制作NeFEL地图的过程中，这是研究的最终结果，这些“物体”通过地理信息系统（GIS）环境中简单的、地貌上一致的交叉程序被消除。NeFEL的总表面积为22.9 km2，占总表面积的10%。空间分析表明，NeFEL的最高频率发生在朝南和朝西南的斜坡上，切割在粘土质泥灰岩沉积物上，其上存在细结构和富含碳酸盐的始成土，并显示12°至20°的坡度值。两个不同时期的卫星图像的比较突出了NeFEL是最明显的夏耕作业后立即和不那么明显，他们之前，这表明这些做法可能在诱导侵蚀过程中发挥了重要作用。版权所有© 2009约翰威利父子有限公司。
The aim of this study is to assess of the distribution and map the geomorphological effects of soil erosion at the basin scale identifying newly‐formed erosional landsurfaces (NeFELs), by means of an integration of Landsat ETM 7+ remotely sensed data and field‐surveyed geomorphological data. The study was performed on a 228·6 km2‐wide area, located in southern Italy. The study area was first characterized from a lithological, pedological, land‐use and morpho‐topographic point of view and thematic maps were created. Then, the georeferenced Landsat ETM 7+ satellite imagery was processed using the RSI ENVI 4.0 software. The processing consisted of contrast stretching, principal component analysis (PCA), decorrelation stretching and RGB false colour compositing. A field survey was conducted to characterize the features detected on the imagery. Particular attention was given to the NeFELs, which were located using a global positioning system (GPS). We then delimited the Regions of Interest (ROI) on the Landsat ETM 7+ imagery, i.e. polygons representing the ‘ground‐truth’, discriminating the NeFELs from the other features occurring in the imagery. A simple statistical analysis was conducted on the digital number (DN) values of the pixels enclosed in the ROI of the NeFELs, with the aim to determine the spectral response pattern of such landsurfaces. The NeFELs were then classified in the entire image using a maximum likelihood classification algorithm. The results of the classification process were checked in the field. Finally, a spatial analysis was performed by converting the detected landsurfaces into vectorial format and importing them into the ESRI ArcViewGIS 9.0 software. Application of these procedures, together with the results of the field survey, highlighted that some ‘objects’ in the classified imagery, even if displaying the same spectral response of NeFELs, were not landsurfaces subject to intense soil erosion, thus confirming the strategic importance of the field‐checking for the automatically produced data. During the production of the map of the NeFELs, which is the final result of the study, these ‘objects’ were eliminated by means of simple, geomorphologically‐coherent intersection procedures in a geographic information system (GIS) environment. The overall surface of the NeFELs had an area of 22·9 km2, which was 10% of the total. The spatial analysis showed that the highest frequency of the NeFELs occurred on both south‐facing and southwest‐facing slopes, cut on clayey‐marly deposits, on which fine‐textured and carbonate‐rich Inceptisols were present and displaying slope angle values ranging from 12° to 20°. The comparison of two satellite imageries of different periods highlighted that the NeFELs were most clearly evident immediately after summer tillage operations and not so evident before them, suggesting that these practices could have played an important role in inducing the erosional processes. Copyright © 2009 John Wiley & Sons, Ltd.