## 2 Materials and Methods
### Methodology and Sources of Land Use/Land Cover Data  
The Urban Atlas is an LULC map that provides high-resolution and detailed information about urban areas with the classification of satellite images and auxiliary data. The first Urban Atlas project was conducted in 2006, and was funded by the ERDF (European Regional Development Fund) and the European Commission (EC) as part of GMES (Global Monitoring for Environment and Security) [40; 41; 42]. The Urban Atlas project was conducted for approximately 300 European cities with a population of more than 100,000 in 2006. The Urban Atlas project was expanded for 2012 and 2018, and Urban Atlas maps were produced for more than 800 cities in the EU, EFTA, West Balkan countries, United Kingdom, and Turkey with a population of over 50,000. In addition, Urban Atlas maps were produced for the city and its surroundings according to the Functional Urban Area (FUA), which was defined in line with the approach developed by the DG Regional and Urban Policy (REGIO) of the European Commission. While there was no FUA from Turkey in the Urban Atlas for 2006, there were 76 FUAs in the Urban Atlas for the 2012 and 2018 Urban Atlas datasets [40, 41, 42]. The Urban Atlas shows LULC information, and it can give information about the direction of urban sprawl with high accuracy. The Urban Atlas aims to assist in the planning of cities according to the needs of the local population by evaluating the risk of economic, ecological, and social problems and taking into account the needs of living spaces (public transportation systems, infrastructure systems, etc.). Accordingly, it provides production of data that will enable the analysis of transportation, the environment, and land use [41]. In the Urban Atlas methodology, an LULC map is produced with 27 subclasses under 5 main classes (urban fabric, arable land, forest, wetland, and water). Within the scope of the Urban Atlas methodology, the minimum mapping unit for map production is 0.25 ha for urban fabric areas and 1 ha for other areas. The minimum accuracy of overall classification (for all classes) for the Urban Atlas is 80%, and the classification accuracy of the classes is stated to be 85% for urban classes and 85% for rural classes in the mapping guide. Google Earth, city maps, COTS (Commercial Off the Shelf) navigation data, cadastral and zoning maps, and higher-resolution satellite images are used as control points [35, 42]. High-resolution satellite images with a 2.5 m spatial resolution were used for the first Urban Atlas projects in 2006, and it was observed that with the update made, high-resolution satellite images with a 2 m to 4 m spatial resolution were used for the Urban Atlas projects in 2012 and 2018 [41]. The Urban Atlas for Gaziantep was not selected as an FUA and completed by the European Commission before 2012, but the surface classification processes for Gaziantep were produced with the Urban Atlas methodology for 2010 and 2015 with the object-based classification method. Cloud-free satellite images from the summer months were obtained to ensure similarity in cloud and environmental conditions to monitor LULC changes. The classification process was then carried out on these acquired satellite images. The satellite images were segmented according to the appropriate scale and shape parameters, and the objects' segments were classified according to their reflectance, shape, and index properties [2]. These datasets were produced through the object-based classification of Spot 5 and Spot 6 satellite images that were acquired on 5 June 2010 and 7 July 2015 with  
Figure 1: Location of Gaziantep and city center of Gaziantep. 2.5 m and 1.5 m spatial resolutions, respectively. In addition, a 1:1000-scale Gaziantep master zoning map (including industrial and residential areas) was used as auxiliary data for segmentation in classification and attribution in the data processing stages.