Flood susceptibility mapping using GIS and multicriteria decision analysis: Saricay-Çanakkale (Turkey)

Floods are natural disasters that are among the most damaging natural events for humans and the environment. Globally and in Turkey, a variety of engineering studies are performed to solve problems that may form before and after flood events. In this situation, the preparation of flood susceptibility maps is beneficial to observe areas with tendency to flood and to make plans in accordance with this. This study focuses on previous and current floods on the Saricay River passing through the settlement area of Çanakkale. Within this scope, multi-criteria decision analysis (MCDA) was used with the help geographical information systems (GIS) that was used to determine possible flood areas. In the first stage, the most important factors affecting flooding were determined. These include slope, aspect, elevation, geology, land use and proximity to the river. Subcriteria were developed to ensure more accurate evaluation of each criteria. For each criteria, an appropriate weight value was assigned, and for each subcriteria, an effect value was assigned. All criteria were included in the weighted overlay method, and sensitivity analysis was performed to create a flood susceptibility map for the study area. According to this map, the study area was divided into five classes from very low susceptibility to very high susceptibility. According to these results, 13.9% of the study area has high susceptibility, while 14.2% has very high susceptibility. Furthermore, paleoflood analysis studies of Saricay included identification of fluvial deposits using geological and geomorphological data and determination of soil profiles. Fluvial sediments were dated with the optically stimulated luminescence (OSL) method, and it was determined that the Saricay river changed its course about 30–40 thousand years before present. The ancient bed had NW-SE orientation, while the current bed flows in an E-W orientation within the city.