T L Before b. After

18

IV. RESULTS AND DISCUSSION

IV.1. T

OPOGRAPHIC NORMALIZATION OF LANDSAT IMAGE The area study is a mountainous area which certain parts have a significant variation of topography. In turn, it affects the result of classification. Therefore, topographic correction has to be done, before conducting classification. Topographic slope, aspect, calculated incidence, and angle existence were merged with the multi- spectral Landsat response for TMETM bands. In order to fit a generalized photometric function, Minnaert method, a member of non-Lambertian model in which utilizing regression analysis, was applied Smith et al., 1980; Riano et al., 2003; Kato, 2003. Figures below show the results of the topographic normalization process. Figure 4.1. Results of topographic normalization LANDSAT Image Generally, the effect of topography was reduced. Previously, at the area which has a high slope and aspect in line with solar radiation is darker than others, even they has a same land cover type Figure 4.1. Minnaert method was able to correct such error, although it was overestimated for a small area which slopes more than 50  Figure 4.1.

IV.2. L

ANDSCAPE AND SOIL CLASSIFICATION Based on Landsystem Map Landsystem with Suitability and Environmental Hazard, 1989, there are three soil associations found on the site location. They have existed in three kinds of different land system Figure 4.2.

a. Before b. After

19 Figure 4.2. Landscape and soil classification Soils of the Dystrandepts-Hydrandepts association occur in largely inaccessible deep V-shaped drainages and narrow ridges on very steep westeast-facing slopes above an elevation of about 1,500 meter a.s.l above sea level, and serve primarily as a watershed Foote et al. 1972 Figure 4.3.. These are thin, well-drained, light soils derived from volcanic ash that are high in organic matter, can contain more water than other soil when saturated, and are strongly to extremely acid. Because of their characteristics, medium textured soils, such as the silt loam soils, this association have moderate K values, about 0.25 – 0.40. They are moderately susceptible to detachment and produce moderate runoff http:www.iwr.msu.edu. Their occurrence on steep slopes, potential friability at the surface, and fine silty texture, the soil erosion hazard by water is high for this association, especially in areas where vegetation has been depleted. However, in case a forest as cover vegetation, organic matter in their structure can reduces erodibility because it reduces the susceptibility of the soil to detachment, and it increases infiltration Armas, 2004. Association Dystrandepts-Hydrandepts Landsystem Type: TGM Association Vitrandepts-Eutropepts Landsystem Type: CGS Association Dystropepts-Tropudults Landsystem Type: BSM Ciliwung Hulu Cibeet Cigundul 20 Figure 4.3. Description for soil type in study area Vitrandepts-Eutropepts association is a porous soil, which developed from volcanic ash Hart et al, 2004. Depending on the above parent material and weathering force, those soil type characterized by low soil organic matter, even though they is developed by deposits material from upper area and leaching process not as intensive as upper area. So have low K value, about 0.05 – 0.10, because erodibility can reduced if soil structure in stable caused by organic matter bounding. Dystropepts-Tropudults association is a mature soil type, which weather process intensively and high in clay.

IV.3. L