## 4 Discussion  
By including more than one case study, it was possible to see how the different dynamics of each lake affect archaeological sites. The Mosul and Haditha lakes are mostly similar in these terms, while the Hamrin lake is a peculiar case, much more unstable, and with its sites that are likely to emerge more often than in the former two areas. The results showed that the cyclical water retraction is indeed affecting a significant number of archaeological sites. This number might even be higher if we consider that older archaeological surveys suffered from visibility issues and methodological limits, and that this research had access only to a limited dataset (see Section 2.2). The analysis shows how the sites in each area can be divided into:  
* Sites that emerged cyclically from the waters;
* Sites that were never affected by the reservoir;
* Sites that were always submerged during the observed time span. Among the first category of sites, the one of interest for this research, the pixel analysis was able to identify those that were more likely to emerge more often. Usually, these sites are found at the edges of the reservoirs and are therefore impacted by any water level change; this is the case for sites such as Kifrin in the Haditha Dam, Khirbet Karhasan in the Mosul Dam, and Tell Zubeidi in the Hamrin Dam. On the other hand, drastic and substantial water level changes can directly affect inner sites, which can emerge, partially or entirely, from the waters even for a prolonged time. This is the case for sites such as Glai'a in the Haditha Dam, Jamrash and Kemune in the Mosul Dam, and Tell az Zawyeh in the Hamrin Dam. There are, however, some considerations to make about the results presented above, tied to the limits of a remote sensing approach. Firstly, even if an archaeological site is shown to be above the water level, the access to it might still be problematic, e.g., the environment might still present marshes, unstable sediment loads, or it might still be submerged. This is the case for sites such as Tell Yelkhi (Figure 32). The current state of an archaeological site after its emersion will also be tied to its characteristics before the formation of the lakes. For example, a site characterised by a surface scatter of archaeological material will have fewer chances to survive than a site with standing architectural elements (even if artefacts might be lost in this case as well). The dynamics of the receding waters also have an impact on the preservation of a site. In fact, frequent emersions and submersions might damage a site more than its long submersion, through processes of erosion, particularly dangerous for sites with subtle archaeological features [22] (p. 72). This effectively means that, even if a site emerges from the water, its archaeological features might not have survived. A visual inspection of the results is always advisable, because the pixel analysis might return negative values (i.e., land masses) for areas with high sediment loads. This is not a classification error, because the NDWI correctly identifies sediments as non-water pixels, but it is something to consider when planning a field inspection. This is evident for the Island of 'Ana, a multiperiod archaeological site in the Haditha Dam reservoir [82]. After a visual inspection of the year 2018 (Figure 33), the site showed a large meander bar (covering more than the extent of the original island) formed by the accumulation of sediments along the river, which was channelled to the north and east. Another limit of the single-pixel analysis is that it might return different values from the approach using polygons. In fact, the analysis of the site resurfaced extent is, of course, more accurate in determining which site is out of the water, because a single pixel might indicate a submerged site when only a small part of it has emerged.