Contour Slope Topography Analysis

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5.2 Topography Analysis

Topographic analysis is carried out after the watershed delineation, because this analysis will need the perimeter from the object area. The result of this analysis are contour and slope, these are necessary in land suitability analysis and soil erosion. Topographic analysis could helps understand the surface condition of Buper watershed.

5.2.1 Contour

The making of contour map requires DEM data as main input for Global Mapper 12, to produce contour vector on the study site. In Global Mapper, the perimeter area is made broader than the existing water boundary because this operation can not give watershed boundary from Arcview 3.3 application. Figure 5.5 Global Mapper 12 Operation for Contour The result of contour vector in Global Mapper 12 will be treated in Arcview 3.3 by giving existing watershed boundary and adding more information that required. In this process, the countour interval used is 10 meters. 44 Figure 5.6 ArcView 3.3 Operation for Contour Topographic of Buper watershed has highest elevation in north and going down to south. The north area has sheer topography with high elevation difference and maximal elevation of 1320 MSL, while in the south the topography is sliding down from the hills to valley where the waters met with lowest elevation of 220 MSL. 45 Figure 5.7 Contour of Buper Watershed 46

5.2.2 Slope

Contour map data base can be used to produce slope map and its data base to help the calculation and further analysis by using ArcView 3.3. Slope classification in this process is made according to slope classification for land use suitability analysis and soil erosion analysis. The result of ArcView 3.3 process informs that majority of Buper Watershed have slope 8-15 in area of 4,87 km 2 , and 0-8 in area of 3,72 km 2 , where most of them located in the downstream of Buper Watershed. Table 5-1 Slope Classification of Buper Watershed ID Gridcode Slope Area Hectares Km 2 66 1 0-8 372.123 3.72 5 3 15-25 351.963 3.52 3 4 25-40 48.325 0.48 1 2 8-15 486.701 4.87 2 5 40 0.203 0.00 The result from ArcView shows that maximum slope of Buper Watershed, reached more than 40, within a small area of approximately 0,203 Ha. The result of the slope analysis are required to make land suitability scoring and soil erosion analysis according to the slope classification. The result of ArcView 3.3 process to Buper Watershed slope can also be seen from Figure 5.8 : 47 Figure 5.8 Buper Watershed Slope

5.3 Landuse Change Analysis.