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    Mapping and analysis of structural lineaments using SRTM radar data and Landsat-8 OLI image: an example from the Telouet–Tighza area, Marrakech High Atlas, Morocco
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    Abstract:
    This study provides the first evaluation of the potential of both the Landsat-8 Operational Land Imager (OLI) sensor images and the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) data for automated lineament extraction in the south side of the Marrakech High Atlas (Telouet–Tighza area). After image corrections, enhancement methods such as principal component analysis, band composite (BC), and directional filtering were adopted to create new images that provided high visibility of linear structures. The new Landsat BC image used in this study was selected based on the calculation of the optimum index factor and correlation index. In addition to the Landsat image, the SRTM DEM was used to detect structural lineaments in the area by generating shaded relief images. Multisource data, such as band ratio image, geological maps, and fieldwork, were used to eliminate the nongeological lineaments extracted. The results indicate that an automated method was applied successfully for lineament mapping in this area, by detailing the main tectonic faults. Moreover, new lineaments are identified and are validated by fieldwork. Structural lineaments extracted show compatibility in their direction, length, distribution, and density with the tectonic evolution of the study area. A total of 2945 lineaments were extracted with major ENE–WSW and predominant E–W directions. The new structural map shows more structural information compared with the geological map of this area and exemplifies the performance of Landsat-8 OLI bands and SRTM data in this kind of study.
    Keywords:
    Lineament
    Geologic map
    A new global elevation dataset known as G‐DEM, based on the ASTER satellite imagery, will be released in late 2008. G‐DEM will be the best freely available global digital elevation model (DEM) at a horizontal resolution of 1 arc second. We assess the quality of G‐DEM in comparison with 3‐arc‐second SRTM DEM, the best current global elevation dataset. Basic geomorphometric parameters (elevation, slope and curvature) were examined for a pre‐release version of G‐DEM and SRTM DEM for western Japan. G‐DEM has fewer missing cells than SRTM DEM, particularly in steep terrain. Also, G‐DEM gives smoother and more realistic representations of lowlands, valleys, steep slopes, and mountain ridges, whereas, SRTM DEM includes many local spikes and holes, and tends to overestimate valley‐floor elevation and underestimate ridge elevation. G‐DEM will be commonly used in geoscientific studies, because of its higher resolution, fewer missing data, and better topographic representation than SRTM DEM.
    Elevation (ballistics)
    Citations (150)
    This study provides the first evaluation of the potential of both the Landsat-8 Operational Land Imager (OLI) sensor images and the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) data for automated lineament extraction in the south side of the Marrakech High Atlas (Telouet–Tighza area). After image corrections, enhancement methods such as principal component analysis, band composite (BC), and directional filtering were adopted to create new images that provided high visibility of linear structures. The new Landsat BC image used in this study was selected based on the calculation of the optimum index factor and correlation index. In addition to the Landsat image, the SRTM DEM was used to detect structural lineaments in the area by generating shaded relief images. Multisource data, such as band ratio image, geological maps, and fieldwork, were used to eliminate the nongeological lineaments extracted. The results indicate that an automated method was applied successfully for lineament mapping in this area, by detailing the main tectonic faults. Moreover, new lineaments are identified and are validated by fieldwork. Structural lineaments extracted show compatibility in their direction, length, distribution, and density with the tectonic evolution of the study area. A total of 2945 lineaments were extracted with major ENE–WSW and predominant E–W directions. The new structural map shows more structural information compared with the geological map of this area and exemplifies the performance of Landsat-8 OLI bands and SRTM data in this kind of study.
    Lineament
    Geologic map
    Citations (4)
    Vertical accuracy of the processed Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM) was evaluated using spot height as well as reference DEM. Terrain dependency of error was also explored in relation to elevation, slope and aspect of the terrain. The positive mean error (6.77 ± 1.79 m) indicated that the SRTM DEM was slightly underestimating the elevation and this pattern gradually increases towards higher elevation. The observed root mean square error (RMSE) (27.58 ± 4.22 m) for the region do not fulfill the 16 m RMSE specification of the SRTM mission. High magnitude errors are typical to steep slope (due to overestimation) and in stream valley (due to underestimation). The magnitude of residuals for NW, W and SW facing slope was smaller as compared to their complementary angle. Results also indicated a S and NE components in SRTM DEM because of underestimation and overestimation of elevation, respectively.
    Elevation (ballistics)
    Citations (24)