Gis based sensitivity analysis of the Çifthisar Basin and its vicinity (Adıyaman) in terms of mass movements

Mass movements are one of the natural phenomena that are effective in the change and shaping of the earth. Sensitivity to mass movements is the determination of the potential of mass movements based on the assertion that "areas exposed to mass movements today may also be exposed to mass movements in the future". Sensitivity maps are prepared by considering that the current preparatory and triggering factors that are effective on the occurrence of mass movements may also be effective in the future. Sensitivity analyses constitute the first step in areal-based mass movement studies and play an active role in carrying out studies to determine the risk and hazard of mass movement occurrence. Cifthisar Basin and its surroundings, selected as the research area, are located in the Upper Euphrates Section of the Eastern Anatolia Region. Cifthisar Basin, which is administratively within the borders of Gerger district of Adıyaman province, is located to the east of Nemrut Mountain National Park. Gerger district centre is located in the northeast of the basin. It is aimed to determine the mass movements in and around the Cifthisar Basin and to determine the sensitivity of the area in terms of mass movements. In order to realise this aim, the method of weighted overlapping of parameter maps was used. Within the scope of the research, lithology, slope, aspect, palaeo-mass movements, proximity to the dam lake, vegetation cover, elevation were determined as preparatory parameters; proximity to fault lines and precipitation were determined as triggering parameters. As a result of the research, a mass movement sensitivity map of the site was created. According to this map, insensitive areas are calculated as 1.95 km2, very little sensitive areas as 173.93 km2, and sensitive areas as 249.54 km2. It was determined that mass movements did not occur in the insensitive area, 17% of the movements occurred in very little sensitive areas and 83% in sensitive areas. It has been concluded that mass movements in the area occur in geological units overlying stratigraphically low permeability formations, on steep slopes intensely fragmented by the Adiyaman fault, on high slopes with high slopes compared to their surroundings, on the slopes undercut by the Euphrates River in the past, in areas where relative wave erosion is seen today on the edge of Atatürk Dam Lake and in areas where vegetation cover is absent or sparse. The susceptibility map produced in line with this study will lead the risk and hazard studies to be carried out in the area, especially the question "Where should risk and hazard studies be carried out?" will be answered. Keywords: Adıyaman, Gerger, Mass Movement Sensitivity Analysis, Weighted Overlay Method of Parameter Maps, Landslide