Flood risk analysis with geographic information system: A case study of Osmaneli̇/Bilecik

The concepts of climate change, wrong land use, and unplanned construction bring the risk of flood formation. As a result of floods, serious material and moral damages are experienced. These damages can be both economical and life-threatened results. A number of measures should be taken to prevent or minimize the occurrence of floods. In this thesis study, flood risk analysis was carried out on Osmaneli district on Bilecik province borders by using Geographical Information Systems (GIS). It was chosen Sakarya River, which is one of the important streams and its tributaries in the region, due to its influence in the selection of the Osmaneli district of Bilecik province for the application area. The weight values of the parameters causing the flood were calculated and the areas with the flood risk were determined by using the Analytical Hierarchy Method (AHM), one of the Multi-Criteria Decision Analysis (MCDA) methods. In order of importance, the parameters used in the determination of AHM and flood analysis are; precipitation, distance from the stream, slope, elevation, land use, aspect, geology, and temperature. The data set of ALOS PALSAR satellites was used to obtain Digital Elevation Model (DEM) data. ArcGIS program was used for mapping and overlapping analysis by using raster and vector data. As a result of the flood risk analysis; areas with very high risk in 11.94%, high risk in 35.98%, risky areas in 28.72%, low risk in 20.61%, and risk-free areas in 2.75% were determined. It has been observed that the risk of flood formation is high in areas close to river basins. Keywords: Analytical Hierarchy Method (AHM), Flood Risk Analysis, Geographic Information Systems (GIS), Multi-Criteria Decision Analysis (MCDA)