# Detecting Change at Archaeological Sites in North Africa Using Open-Source Satellite Imagery
## 3 Results
### Aswan and Kom Ombo
#### 3.1.1 True Positives  
With a producer's accuracy of 78%, changes/threats were correctly identified by the algorithm at 45 sites. These were confirmed by manual examination of the imagery and during field visits. In particular, the algorithm results highlight the rapid pace of development of 'New Aswan'. Although the construction of the new settlement has been ongoing, since the start of the twenty-first century, the work continues to threaten the remaining archaeological sites in the area. Several sites were identified by the algorithm as undergoing changes caused by this big construction project. The script highlighted the sites of WK40 (scatter of lithic artefacts, now destroyed) and WK41 (rock art) where road construction, bulldozing, and dumping of spoil were taking place (see Figures 5-8). The sequence of satellite images from Google Earth shows in higher resolution how WK40 was damaged by these changes in 2018, and that WK41 is at urgent risk (Figure 8), and therefore, must be a priority for protection efforts. Figure 5: Changes at WK40 and WK41 visible in the Sentinel-2 composites. By 2019, the trackway had been extended and additional spoil had been dumped. Smaller-scale, localised, but equally damaging changes away from the 'New Aswan' project were also identified by the script and included construction and quarrying. At the lithtic scatter site of WK32 (Figure 9), the algorithm detected recent digging of pits, spoil heaps, and the construction of a small agricultural building. Another example of the local activity causing change can be seen at two sites in the Wadi el-Tawil. The algorithm found that WT1, a second millennium BC cemetery of Nubian nomads, is threatened by the expansion of a modern cemetery which comprises burials, planting, and a trackway (see Figures 10 and 11). Given the potential archaeological significance of this site, these rapid changes make it's recording an urgent priority before it is destroyed. Across the other side of the wadi at a rock art panel (WT7) the  
Figure 6: WK40.The blue region represents the detected changed area within the buffered zone. The direction of the photograph is arrowed. The photograph (January 2020) shows the track and piles of spoil at WK40. The construction of the track destroyed the site. ‘New Aswan’ is in the background. Google image 2020 imported as an xyz tile to QGIS. algorithm identified that a large pit was excavated, with spoil heaps surrounding it. This may have been dug for clay extraction. Examination of daily 3 m resolution imagery from PlanetScope satellites allows the specific periods in which the change occurred to be narrowed down (in this case between December 2018 and January 2020, Figure 11). Because these kinds of changes are not part of a larger-scale, planned construction project like 'New Aswan', they are harder to predict. In such cases, the value of using automated remote sensing processes is clear. Figure 7: A new track and piles of spoil close to a rocky outcrop where WK41 is located. The direction of the photograph arrowed. Google image 2020 imported as an xyz tile to QGIS. Photograph January 2020. Figure 8: Modern activities underway between 2018–2020, and ongoing, has destroyed site WK40 and are threatening the survival of site WK41. Images from Google Earth. Some agricultural differences were detected, for example, caused by changes in planting within already-existing fields (see WK31, 35, 36, 37, 38, Figure 12). Comparing matching time periods from different years reduces the influence of routine seasonality in cultivation on the algorithm, although this should be integrated into the script by examining the standard deviation over a longer period. Sometimes it was found that the fields had been laid out and plughed prior to 2018, but were planted during the analysis period (as Figure 12 shows). The process of constructing and finally cultivating a new field took a long time in the Aswan area, and a similar pattern was observed in Jufra.