**3. Methodology**

The data used was two layers of information. These are public and open and can be used to replicate this work in another work area. The analyzed area is the Galicia region, in Spain.

Firstly, land-use related to vegetation data were obtained. The European Space Agency (EEA) offers through the CORINE Land Cover (Coordination of Information-CLC) project a geodatabase using polygonal graphic features that evoke land uses throughout the European Union, for the years 1990, 2000, 2006, 2012 and 2018 [48].

The scale used is 1:100,000 in the Geodesic Reference System corresponding to the European Terrestrial Reference System 1989 (ETRS89) and the Mapping System is Universal Transverse Mercator (UTM), with the minimum cartographic unit (MCU) being equal to 25 hectares. The accuracy obtained has been increasing over the years, since in 1990 it was less than 50 meters, in 2000, 2006 and 2012 it was less than 25 meters, and finally, in 2018 it is less than 10 meters. Also, the information contained in these polygons is hierarchical in three levels of information (**Table 1**).

The second layer of information corresponds to the administrative delimitation of the Autonomous Community of Galicia. From the National Geographic Information Center in Spain (CNIG), as shown in **Figure 2**.



*\*For detailed information about the CLC Codes, the authors recommend the following source: www.eea.europa. eu/ publications/COR0-landcover, accessed on 30 November 2021.*

#### **Table 1.**

*CORINE Land Cover nomenclature (Source: [48]\* ).*

Subsequently, both layers of information were treated using ArcGIS 10.5 Geographic Information Systems (GIS) management software. Initially, all layers of information were transformed to the ETRS89-Azimuth Equiarea Coordinate Reference System of Lambert-2001, as this was adopted as official (ETRS-LAEA) [49]. Because ETRS-LAEA is based on the projection of equivalent areas in the territory. In this way, it serves as a reference for homogeneous units for all European countries. As a result, this coordinate system is used for the representation of analytical and statistical data.

Subsequently, the layer relating to the administrative divisions of the country, Spain has carried out a selection query through alphanumeric information and the Galicia region was selected. Subsequently, this single region was kept in a single layer of information. This layer of information was the limit of the scope of action of this work. The clip tool was then used, with Galicia's boundary as the reference layer. This procedure was used for each of the years studied (1990, 2000, 2006, 2012 and 2018). In this way, land uses were obtained, but only those that were included in the region. Subsequently, geometric measurement of the area of each of the polygons was performed in hectares. This resulted in the number of hectares of each polygon representative of land uses according to the CLC nomenclature.

*Analyzing the Evolution of Land-Use Changes Related to Vegetation, in the Galicia Region… DOI: http://dx.doi.org/10.5772/intechopen.106015*

#### **Figure 2.**

Once this information was obtained, the alphanumeric information recorded in each of the tables for the years analyzed was exported to a database that was managed by the Microsoft Access database management program belonging to Microsoft Office 365 software.

Selection queries were made to the database using Structured Query Language (SQL) to select according to the CLC nomenclature, and then another grouping query was added to the previous query, also using SQL. Finally, the hectares for each land use were obtained for the years 1990, 2000, 2006, 2012 and 2018.

However, to take into account not only numerical but also geographical results, thematic maps were also obtained for each of the years. In this way, it was possible to identify where the greatest variation in land uses related to vegetation occurred and where there was predominant land uses related to vegetation.

To an easy understanding of the used methodology and case study selection criteria, a scheme has been developed (**Figure 3**).

**Figure 3.**

*Summary scheme of the used methodology and case study selection criteria (Source: Authors).*

*Delimitation of the study area - Galicia region (Source: Authors by ESRI ArcGIS, 2020).*
