## 3 Results
### Interannual Variability--2018 Monthly Analysis  
The analysis of the 2018 monthly NDWI images showed that interannual variability can have an impact on the extent of the resurfaced sites. In the Haditha and Mosul Dam reservoirs, 2018 was a year of particularly low water levels, and both reservoirs showed a comparable behaviour in the timing of their retractions (Figure 26a,b). During this year, months of high-water level were associated with the beginning of Summer, during May and June, while the minimum levels were registered in October and November for that year. The Hamrin Dam lake followed a similar trend, even if the period of lower water level began slightly earlier, during September (Figure 26c). Figure 25: Images of the area around Tell Baradan at different stages: (**a**) 1967 (CORONA image, August 1967); (**b**) HR Image from Bing Maps (likely 2011); (**c**) Planetscope Image (October 2018) ©TPMO (2020); (**d**) chart with emerged surface across time for Tell Baradan. Individual pixel values showed a large number of sites likely out of the water (i.e., with negative pixel values) for all the three reservoirs. During October and November, the Haditha Dam registered 26 and 25 emerged sites, respectively, also counting 13 which showed a negative pixel value for the entire year. In the Mosul Dam lake, 19 sites of the 48 analysed were out of the water for both the same months, including four sites with a negative pixel value for the entire year. Unfortunately, December was a particularly cloudy month in the Mosul Dam region, which prevented the extraction of any pixel values for this month. In the Hamrin Dam region, the earlier water reduction resulted in September and October as the months that registered a great number of sites resurfaced, 17 and 20, respectively, including eight sites that could be considered as out of the water for the entire year. In terms of spatial distribution, the visible pattern is similar to that of the long-term analysis, with sites at the edges of the reservoirs being more prone to emerge. However, given the particularly low water level in the Haditha and Mosul Dam during this year, even sites closer to the central part of the reservoirs emerged at least once (Figures 27 and 28). A similar pattern is evident for the Hamrin Dam, which showed a spatial distribution of emerged sites close to that of some previous years of low water level, such as 2015 and 2010 (Figure 29). Figure 26: Number of emerged sites and approximate lake surface area during 2018 for: (**a**) Haditha Dam; (**b**) Mosul Dam; (**c**) Hamrin Dam. Figure 27: Spatial distribution of always submerged, emerged, and never affected archaeological sites in the Haditha Dam in 2018. Figure 28: Spatial distribution of always submerged, emerged, and never affected archaeological sites in the Mosul Dam in 2018. The results from the point pixel analysis can be integrated with the analysis of the resurfaced extent: a pattern of decreasing and increasing emerged area was indeed registered for many sites in all three dams from May to December 2018 (Tables 2-4). In the Haditha Dam reservoir, while many sites were almost completely out of the water during the entire year, it is possible to appreciate the progressive emerging and submerging of a site such as Glai'a. This site was mostly submerged during summer, but approximately 80% of it resurfaced during October-November (Figure 30j,k). A comparable behaviour has been registered for Khirbet Kharasan in the Mosul Dam lake (>80% of site emerged) (Figure 31). In the Hamrin Dam sites such as Tell Yelkhi, Tell Khesaran and Tell Kharbud, all followed a similar trend, with more than 85% of their extent emerged during September-November (Figure 32). Planetscope images, acquired for specific sites for each month in 2018, confirmed the results of the analysis; the progressive emergence of the sites was clearly visible on the high-resolution images. Figure 29: Spatial distribution of always submerged, emerged, and never affected archaeological sites in the Hamrin Dam in 2018.