Determination of flood risk maps by using GIS software

In this study, flood analysses near Derme Stream have been mode for the Drinking Water Supply Catchment Facility of Malatya Province. Within the scope of the study, flood levels have been provided with the help of Geographical Information System (GIS) software by using digitized maps and measurements taken in the field. Arc-GIS and NetCAD-GIS were used for GIS software, and HEC-RAS and HEC-GeoRAS softwares have been utilized for flood analysis. Digital Elevation Model (DEM) of Derme basin has been created and hydrological characteristics of Demre Streem has been provided by ArcGIS Hydrology module. 1/25000 scaled map of the basin has been digitized with NetCAD and sections have been designated on Derme Stream. With these sections, 3D model of the stream bed has been created in HEC-RAS and analysis have been made according to recurring flood flow values of Q10, Q25, Q50, Q100, Q500. Following this preliminary flood assessment, measurements have been taken in the stream bed with field measuring devices, and real size stream sections of the stream bed have been created by transferring these point measures to NetCAD. Flood risk maps have been created according to the water surface levels of the study area by using Arc-GIS HEC-Georas module. Proposals have been made by interpreting the obtained flood levels.