## 2 Materials and Methods
### Study Area  
The investigated region (Figure 2) is a polygon designated for gold mining activities, covering an area of 459.33 km\({}^{2}\), with a 6 km buffer zone from the Serrita-Cedro Project, which is part of the National Program for the Study of Mining Districts, conducted by the National Department of Mineral Production (DNPM), in the semi-arid region of the Brazilian state of Pernambuco.  
This area, in its first phase (1994-1995), focused on the investigation of gold mineralization, encompassing an area of 580 km\({}^{2}\)[46]. Over the years, the area has been subject to exploration, with increased investment since 2020 by the mining company Trilha Gold Capital (TGC). According to the Brazilian Mining Institute (IBRAM), all studies conducted in the Serrita Project follow the standards of the Australian Joint Ore Reserves Committee (JORC) code, along with environmental regulations and laws from the relevant authorities, ensuring maximum credibility and accuracy in the research activities in the area [47].  
However, gold mining is often accompanied by soil and vegetation destruction, landscape fragmentation, and biodiversity loss, as well as the disruption of ecosystem services flows [48]. Additionally, it stands as a significant driver of deforestation, unique in the severity of its impacts, leaving behind a highly altered landscape [36].  
The climate of the region is semi-arid and hot, classified as Bshw according to Koppen ([[https://www.glob2o.org/koppen/](https://www.glob2o.org/koppen/)]([https://www.glob2o.org/koppen/](https://www.glob2o.org/koppen/)), accessed on 1 April 2024), with a distinct rainy season (from February to May) and dry periods (from June to January). The vegetation cover consists of xerophytic Caatinga, characterized by heterogeneous vegetation, whose vegetative  
Figure 1: Workflow of the methodology employed in this study. The diagram illustrates the sequential steps, including data acquisition, data processing, and results and analysis, leading to the final results. Key processes such as “Satellite and hydrological data”, “Land cover mapping with kNN”, “Identification of land use and land cover changes”, and “Mapping accuracy analysis with kNN” are highlighted to emphasize the core components of the approach.  
vigor is sensitive to precipitation [45]. The terrain is hilly, with elevations averaging around 480 m above sea level.  
Gold mining in the semi-arid region of Pernambuco, Brazil, is predominantly conducted by corporate companies, such as the Serrita-Cedro Project, managed by Trilha Gold Capital. Despite these regulations, mining activities continue to be associated with environmental degradation, such as deforestation and significant land use changes. The mining sector faces the challenge of aligning its production processes with environmental and social sustainability requirements. As noted by IBRAM [47], incorporating responsible practices is increasingly essential for maintaining competitiveness in the market, given the growing environmental and social demands from investors and consumers.  
In this context, the use of satellite images combined with machine learning models presents a valuable tool for better understanding landscape changes in areas associated with gold mining practices [13].