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ŠUMARSKI LIST 5-6/2020 str. 64     <-- 64 -->        PDF

road (17.14%). The total area of the buffer polygon (i.e. 100 meters from roadway) generated along the road network was found to be 36188 hectares.
The “Raster Calculator” function was used to generate raster data layer that satisfied other factors (i.e. elevation, ground slope, and ridgelines) within the border of buffer polygon. It was found that there were 144 alternative lookout towers to be evaluated in the visibility analysis (Figure 9). The results indicated that largest percentages of the forest land could be visible by observing the area from10 fire lookout towers in which five of them were placed on the identical location to the current lookout towers in the study area. These results do validate the existing tower siting process, and also provide support for our GIS-based approach to siting observation towers.
The results indicated that total visible forest lands were increased to 81.47% by proposing five new fire lookout towers in the study area. Thus, the area visible from the lookout towers increased about 4.35%. Although this may seem like a modest gain in some regards, if such an increase helps to control a single fire, the level of effort in this process has likely been time well spent. The forest lands that are within sight of the lookout towers are shown in Figure 10. In a similar study conducted by Kucuk et al. (2017), a visibility analysis of lookout towers in Turkey was conducted and it was reported that visible areas from lookout towers would be increased from 73% to 81% if additional lookout towers were located in the area.
The forest land visible by a single tower was 30.36%, while areas visible by two, three, four, and five towers were 28.78%, 19.89%, 2.22%, and 0.22%, respectively. The forest lands visible from various number of fire lookout towers were indicated in Figure 11. It was suggested that forest lands should be observed by at least two fire lookout towers (Çanakçıoğlu, 1993). The forest lands visible by at least two lookout towers was 41.80% considering the current lookout towers, while visible area increased to 51.12% after evaluating the lookout towers suggested by the suitability analysis.