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Multi-scale erosion assessment: a case study of the Merawu sub-watershed

Oluwafemi, Akilapa Olawale (2012) Multi-scale erosion assessment: a case study of the Merawu sub-watershed.

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Abstract:Soil erosion is one of the most important environmental problems in Indonesia. To control soil erosion, assessing soil erosion at different scale is important. Satellite imagery data and Digital Elevation Models are being used increasingly to assess erosion at different scales, but the main restrictions for these assessments are availability and quality of data. Therefore, it is necessary to analyse a most reliable way of assessing soil erosion and different scales. This study aim was to assess various methods of land cover classification and DEM by aggregation to produce a reliable erosion assessment method. Land cover classification for this assessment was done by Pan sharpening 30m Landsat 7 EMT of 2010 .The bands 4,2,1 were pan sharpened using the panchromatic band 8 to give a representation of the 15m image for land cover classification . Two methods were adopted for creating land cover maps in different resolution, 1. The pan sharpened image was first aggregated to course resolutions of 30m and 90m using the nearest neighbour for aggregation and then the land cover classification of the aggregated images are obtained using the spectral angular mapper for supervised classification. The second method is by first carrying out land cover classification of the pan sharpened image by spectral angular mapper and the aggregating the 15m land cover map to courser resolutions of 30m and 90m. The comparism of the two methods show that the most of the land cover types are aggregated to the predominate cover which is dry cultivation. The DEM was aggregated from the 15m DEM obtained for 10m contour lines of the area, to 30m and 90m using two methods, aggregation by median and average .The two methods of aggregation showed that the slope variation reduces as the DEM becomes courser. The Soil erosion and sediment delivery ratio was assessed by using the Revised Morgan Morgan Finney. The result from the second method of land cover aggregation was used as land cover in the model and both methods of DEM aggregation were used and the soil loss results were compared to see the best aggregation method for soil erosion assessment. The result show that the soil loss in both methods show increase as resolution becomes courser and also discharge increases as resolution becomes courser .After comparism of result with field result it show that the median aggregation gives a better erosion and sediment transport result than the average aggregation. Keywords: Land cover aggregation, DEM aggregation, SAM classification, RMMF model
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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