Hydrodynamic model and flood risk map creation of inceağri stream basin in Gazipaşa district

In this thesis study, the flood risk of the İnceağrı Stream Basin, located in the Gazipaşa district of Antalya province, was analyzed using hydrodynamic modeling methods. The basin's steep topography, pressure from unplanned urbanization, and intense, sudden rainfall triggered by climate change increase the flood hazard in the region. The primary objective of this study is to model potential flood scenarios for various return periods to determine flood inundation areas and depths, thereby creating a scientific basis for effective disaster management and spatial planning. Within the scope of the methodology, a hydrodynamic model of the basin was established using the MIKE Zero software package. The main inputs for the model consisted of a high-resolution Digital Elevation Model (DEM) obtained from the General Command of Mapping and rainfall data acquired from the General Directorate of Meteorology. As a result of the frequency analysis performed on the rainfall data, flood hydrographs for 2, 5, 10, 25, 50, 100, 200, and 500-year return periods were generated. These hydrographs were used as boundary conditions in the model to perform flood simulations for each scenario. The study produced detailed flood hazard maps for all return periods. The findings indicate that while low-return-period floods primarily affect agricultural lands surrounding the stream bed, floods with a return period of 100 years and over pose a serious threat to residential areas, critical infrastructure, and cultural heritage sites such as the Ancient City of Selinus. These maps serve as a strategic decision support tool for developing structural (stream rehabilitation, bridge improvements) and non-structural (early warning systems, zoning plans) measures to enhance the resilience of the Gazipaşa district against future floods.