Geomorphological Mapping in the Upstreams of Muger River, Using Geospatial Tools

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2010-06

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Advancement of GIS and remote sensing, introducing new methodologies and techniques, has made mapping of large areas manageable with few people. Availability of free and commercial datasets, software and tools invites researchers to develop new approach to conduct scientific studies. Advanced Space-born Thermal Emission and Reflection Radiometer (ASTER) satellite imagery, with high spectral resolution, allows a number of band combinations and manipulations making the imagery suitable for geomorphological mapping. The study area located in the upstream of Muger River, tributary to the Blue Nile River, is known for its distinct geological setup and active river morphology. Sedimentary rock seccusions underlying thick tertiary volcanics is exposed to the surface due to the incision of the Muger River deep in to the highland plateaus. Physiographic zonings of the area made based on existing datasets helped to develop scientific approach for modification of lithological map and surface deposit mapping. Enhancements of ASTER satellite imagery sharpened the boundaries between neighboring lithologies. Surface deposits like Laterite, Colluvials, Residual Soil, Alluvial Soil and Limonite are mapped using a number of enhancements. Composite relief maps stacked from three relief maps of different illumination azimuth angle allowed mapping of linear features from a single view. Remnants of erosion and their elevation gave information about depth and volume of erosion. Active river morphology is detected from aerial photo of two different times. Generally, geomorphological map of the area is produced and techniques like pan-sharpening using aerial photograph for geomorphological studies are introduced. Key words: Geomorphological Mapping, Surface Deposits, Muger River, ASTER image, Aerial Photograph, River Morphology

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Geomorphological Mapping, Surface Deposits, Muger River, ASTER image, Aerial Photograph, River Morphology

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