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3.3. Procedure of application
In this study, an estimation of land degradation in the study area was carried out based on the flowchart of the procedure to obtain the purpose of the
study.
Literature Review Problem identification
Research objective Data collection
Primary Data
Secondary data
Land use and
vegetative cover data
Soil profile description
Soil erodibility factor K
Land cover management
factor C Soil conservation
factor P Climate
data
Topographic map
Rainfall runoff erosivity R
Rainfall data
Contour line map
Elevation DEM
Slope length Slope steepness
factor LS
Preparation of map layers Calculate erosion potential
parameter
RUSLE erosion model
Land Degradation based on erosion
potential
Soil Survey
Data
1989,1993 Landsat TM+, 1998 and 2003
Landsat ETM+, Using Supervised and
Unsupervised Classification for testing land use and cover change
Statistical analysis of land use and cover
change Given weight based on
land used cover characteristic
Fig 3.2: The flow chart of the whole procedure of study
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3.4. Deriving Digital Elevation Model DEM
Digital Elevation Model DEM is an essential intermediate product that was derived in this study. DEM is used as main input in calculating slope length
and slope steepness for prediction of potential erosion risk. In this study, a Digital Elevation Model was derived from contour line map with original scale of
1:25.000 and contour interval 12.5 meter. The general process of deriving the DEM is presented in figure 3.3. The contour line map was digitized and stored
in format of ESRI PC ArcInfo® line coverage. Since the elevation interpolation algorithm requires point map as the input, the contour line map was converted into
grid which have same grid cell size with desired DEM grid cell and then
converted into point coverage. After the conversion was done, spline point
interpolation of ArcView® was carried out to produce elevation grid with resolution of 30 metres. Nevertheless, the grid size of 30 meter was chosen to
have more detailed result and to have the same grid cell size with other spatial data i.e. land cover type map.
Fig 3.3: The process of driving digital terrain model DEM from contour line map
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3.5. Classified the Digital Image
Kategori