## 3 Materials and Methods  
### Study Area Characteristics and the Datasets  
The study area is located in the upper basin of Ataturk Dam and includes Doganyol Town of Malatya, Gerger Town of Adiyaman and Cungus Town of Diyarbakir Province, Turkey. The size of the area is approximately 2718.7 km\({}^{2}\). The altitudes range between 525 and 2430 m. Figure 1 shows the location of the study area and the digital elevation model (DEM) cropped from EU-DEM v1.1, which was produced by upgrading EU-DEM v1.0. The EU-DEM v1.1 includes enhancements, which are the correction of geopositioning issues, reducing the artefacts and improving the vertical accuracy of EU-DEM using ice, clouds, and land elevation satellite (ICESat) mission data of National Aeronautics and Space Administration (NASA), U.S.A. as a reference [11]. EU-DEM v1.1 has a nominal resolution of 25 m with vertical accuracy of \(\pm 7\) m root mean square error (RMSE) [10]. EU-DEM v1.1 was preferred here since it has superior spatial resolution in comparison to the freely available shuttle radar topography mission (SRTM) 30\" DEM with 9.7 m RMSE [33]. There exist overall 27 tiles in the EU-DEM v1.1 dataset. Each tile has \(25\times 25\) m\({}^{2}\) cell size and covers 1000 km \(\times\) 1000 km area defined in the European Terrestrial Reference System 1989 Lambert Azimuthal Equal-Area Europe (ETRS--LAEA) projection with European Petroleum Survey Group (EPSG) Geodetic Parameter Dataset code as 3035. The tile with the ID of E60N20 covers the study area mapped here. This tile was clipped according to the study area extent and employed for further processing. The statistical descriptors of the DEM are provided in Table 1 together with the areal statistics of the landslide inventory, which was obtained from the MTA [5]. The inventory includes 132 landslide polygons in total. In the southeast of Turkey, between the Mediterranean Sea in the west and the Iran-Iraq border in the east, the geological structure is highly complex due to the closing of two oceanic branches (northern and southern branches of Neo-Tethys) during the Late Cretaceous [34]. As a result of this complexity, they form a nappe-stack, several kilometers-thick, between the Malatya-Keban Metamorphics of the Tauride-Anatolide terrane in the north and the Bitils-Puturge Metamorphics of the Arabian Plate in the South [35]. The region is also prone to seismic hazards, which often trigger the landslides [36]. The study area has twenty-seven lithological units in the area as shown in Table 2 and Figure 2. The identifier (ID) numbers shown in Table 2 were assigned to each unit within the study for computational reasons. The frequencies of occurrences in the whole area (F\({}_{\text{i}}\)) and in the landslide inventory areas (FL\({}_{\text{i}}\)) for each lithological unit are also provided as percentage values in Table 2. Among all lithological units in the study area, only seventeen of them appear in the landslide inventory. The nerritic limestone, pelagic limestone, radiolarite, chert and clastics were the most landslide-prone units in the study area. In Figure 3, the numbers of pixels in each lithological unit for the whole area (Figure 3a) and inside the landslide inventory (Figure 3b) are presented. As can be seen in Figure 3 and Table 2, although gneiss, schist type (ID = 11) was the mostly observed lithological unit in the area, nerritic limestone type (ID = 5) had the highest amount of landslide pixels followed by the pelagic limestone, clastics, radiolarite, chert, etc. (ID = 12). The metamorphic and magmatic units form the higher altitudes and they were not landslide-prone units. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Data** & **Mean** & **Std. Dev** & **Min** & **25\%** & **50\%** & **75\%** & **Max** \\ \hline DEM (m) & 1262.1 & 391.4 & 524.3 & 955.1 & 1255.8 & 1561.3 & 2431.6 \\ Landslide inventory (km\({}^{2}\)) & 0.51468 & 0.60711 & 0.01767 & 0.11635 & 0.23652 & 0.73473 & 3.43389 \\ \hline \end{tabular}
\end{table}