INVESTIGATING THE EFFECTS OF VARIOUS DENSITIES OF PREDICTED URBAN EXTENTS ON FLOOD HAZARD IN AYAMAMA WATERSHED, ISTANBUL

This study predicted the urban extent of Ayamama Watershed by the SLEUTH model and investigated its effect on flood hazard in the watershed by considering various densities of development. MIKE 21 FM was employed to generate flood inundation maps; the HEC-1 hydrological model was employed to develop the corresponding flood hydrographs. The result of the study showed that, with the opening of Esenler Military Zone for development, the flood inundation extent under 85% density of development was found to be significantly larger than the flood inundation extent determined by taking into consideration the current urban extent in the watershed. As opposed to this, the flood inundation extents under 50% density of development and the current urban extent in the watershed were not found to be considerably different. Thus, if further urbanization is allowed in the watershed, limiting the density of development under 50% is recommended.