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ŠUMARSKI LIST 5-6/2020 str. 62     <-- 62 -->        PDF

To minimize construction costs and maximize ground stability, it was decided to locate lookout towers on ground with less than 5% slope. In this stage, the slope map developed previously was used to create a spatial layer of forested lands meeting the less than 5% slope criteria. Then, the ridgelines in the study area were determined since the ridges are considered as the best locations for the fire lookout towers in order to maximize visibility range (Harvey, 2015). Based on the DTM of the study area, ridgelines were determined using the “Flow Direction” and “Flow Accumulation” functions under the “Hydrology” tool in ArcGIS 10.4 (i.e. Flow Accumulation = 0). Then, the “Raster Calculator” function within the “Spatial Analyst” tools was used to generate a raster data layer consisting of suitable lookout tower locations based on the specified factors. This raster data layer was converted to a point type vector layer where each point represented an alternative new lookout tower location. The elevations of alternative towers were determined by extracting elevation information from the DTM. To increase the visibility from the towers, their heights were set to 15 m while visibility range was estimated as 25 km based on the field observations in the study area. The values of the other fields in the attribute table of tower layer were the same as the values of current lookout towers in Table 3 (Figure 3). Finally, the least number of fire lookout out towers covering the largest percentages of the study area were selected by running the “Observer Points” method in the Model Builder tool of ArcGIS 10.4. The forest lands that are visible and nonvisible from the selected new towers were identified and visible forest lands in the study area were classified according to the number of selected new towers that were in sight.
GIS Database – Baza podataka GIS-a
The land use type database of the Köyceğiz FED indicated that there were five land use types including forest land, agriculture, water, settlement, and sand dunes (Table 4). The largest land use type was forest land (83.65%), followed by agricultural areas (8.70%), and water bodies (5.04%) (Figure 3). Forest land DTM data was extracted from the DTM of Köyceğiz FED by using the boundary of the forest land