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ŠUMARSKI LIST 7-8/2022 str. 63     <-- 63 -->        PDF

Model database – Baza podataka modela
Before running SPreAD-GIS, the required GIS datasets for the model were obtained and some parameters were determined by field measurements. The database included location of the noise sources, the characteristics of the noise sources, model coverage area (extent), land cover map, Digital Elevation Model (DEM), climate parameters, and the ambient noise conditions in the working environment. The GIS datasets were generated in raster format with 30 m resolution, as required in the model.
Location of the noise sources – Položaj izvora buke
The noise source file was developed in the SPreAD-GIS database to represent the locations where the noises are propagated within the study area. Noise measurements were made during the tree cutting operation using a chainsaw in an alder stand in Section 52. The total area of ​​the stand where the measurements were made was 29.41 (about 30 ha) hectares. During the field studies, it was determined that the average length of the alder trees in the area was approximately 25 meters. Considering that the chainsaw operators must work at a safe distance of two tree-lengths during production, the Section 52 was divided into 120 grids with an edge of 50 m. The center point of 120 grids was recorded in the SPreAD-GIS database as locations of the noise source (Figure 2). Since three chainsaw operators work at the same time, noise propagation calculations were made for a total of 40 combinations in the SPreAD-GIS, taking into account three neighboring grids at each time.
Characteristics of the noise sources and model extent – Karakteristike izvora buke i opseg modela
SPreAD-GIS allows the user to select from the noise level data of the engines of different machines loaded in the database (Martin et al. 2005). In this study, the weighted noise level values ​​originating from the chainsaw for 500, 1000 and 2000 Hz from 1/3 octave frequency bands were taken into consideration. Another feature of the noise source that needs to be defined is the distance to the noise source. Since the noise meter was placed 30 cm from the operator’s ears, 0.30 m was used as the noise source distance. The model extent in SPreAD-GIS represents the spatial scope determined for noise propagation analysis. As the model extent gets larger, the processing time increases in SPreAD-GIS (Reed et al. 2009). In this study, a rectangular shape model extent (4509 m x 14588 m) that covers the Karacabey Flooded Forest was used in order to evaluate the noise propagation beyond Section 52.
Land cover type map and DEM – Karta zemljišnog pokrova i DEM
In this study, stand type map of the current forest management plan of Karacabey FMD was used to generate land cover data layer. Each land cover type that falls within the model extent was reclassified into one of the seven land cover types defined in the SPreAD-GIS environment (Table 1). Then, DEM was developed by using the digital contour map of Karacabey FMD.
Climate parameters – Klimatski parametri
In modeling the noise propagation using SPreAD-GIS, it is necessary to obtain and enter the climatic parameters for the day and season on which the field measurements are performed. These climate parameters include temperature (°C), relative humidity (%), prevailing wind direction (°), wind speed (km/hour), and seasonal conditions. The model also includes a list to defined seasonal conditions, from which the user can select the seasonal condition that best represents the situation at the time of measurement. Seasonal conditions in the list include “a clear, calm summer day”, “a clear, calm winter day”, “a clear, windy summer day”, “a clear, windy winter day”, “cloudy and calm”, and “cloudy and windy”. In this study, the average temperature, relative humidity, wind direction, and wind speed data were collected during the operation by using portable meteorology station. Seasonal conditions were determined and recorded at the time of measurement in the field.
Ambient noise conditions – Uvjeti ambijentalne buke
In the last stage, the ambient noise conditions in the harvesting area were defined and then the areas where the noise originating from the chainsaw can be heard at different frequencies were determined in the model. The ambient noise level values ​​for 500, 1000 and 2000 Hz from 1/3 octave frequency bands were measured as in noise source