ANALYSIS AND GIS-BASED MODELING OF FREE AND OPEN DATA FOR TRACKING THE DYNAMICS OF THE URBAN ENVIRONMENT: CASE STUDY FOR SOFIA, BULGARIA

The Geographic Information Systems (GIS) are one of the main tools through which changes in the urban environment can be tracked. They can be used to analyze processes not only as territorial phenomena, but also to derive spatio-temporal models and trends. Free and open access data was used for the present study � from Copernicus, OpenStreetMap and the Urban Development Plan of Sofia Municipality were used as sources. Data layers for the terrain, land cover, buildings, street network and others were analyzed together. Data from the National Statistical Institute was also used to support the analysis of the dynamics of urban environment. Sofia is the capital of Bulgaria and for the last 15 years it has been the most dynamically changing city in the country. By using the data described above and the functionality of GIS, it is possible to automate the process of locating the areas with the most intensive changes. Two-dimensional and three-dimensional modeling was used to adequately demonstrate the temporal and spatial dynamics of the urban environment. The data is processed by regions and then combined for the whole territory of Sofia Municipality. Free opensource software QGIS is used for the analysis and deriving the models. Qgis2threejs was used in the three-dimensional representation and modeling of the data. The time interval for which data were taken is from 2006 to the present, which makes the study relevant. The results can be useful for decision making related to planning the development of the territory and even for improving the living environment.