Determination of flood risk in Sakarya sub-basin using remotely sensed data and GIS

Between 1970-2005, 936 floods occurred, 17664393 ha agricultural land was damaged, and 604 people lost their lives, in Turkey. The floods have been mostly recorded in the Sakarya basin, selected as study area. In order to analyze all kinds of changes in the study area, SPOT XS (20 m) and SPOT PAN (10 m) satellite sensor images within the years of 1999 and 2006 were used. Land-use/cover of the region was evaluated from satellite images. Obtained classification results were verified by the field study. Topography and the drainage qualities of the land were analyzed by DTM, produced from topographic maps of scale 1:25 000. In addition, meteorological data were collected and included as inputs to the system. The parameters of the basin were modeled with the Hydrologic Engineering Centers River Analysis System (HEC-RAS) software. At the end of the modeling, areas under flood risk in the study area and land-use/cover were calculated to be 39.5 km². When the results were examined, 6.2 km² of the risky areas were evaluated as residential, and the rest as agricultural areas.