Climate change alters precipitation regimes, affecting flood hazard and sustainable urban development. This study assesses flood exposure of planned development and emergency assembly areas in Bismil and Çınar, Diyarbakır, Turkey, for 2023–2048. Precipitation projections from HadGEM2-ES, MPI-ESM-MR, and GFDL-ESM2M in RCP4.5 and RCP8.5 were bias-corrected using Equidistant Quantile Mapping (EQM) to develop intensity–duration–frequency (IDF) curves. HEC-HMS generated 100-year design hydrographs, HEC-RAS 2D simulated flooding, and GIS-based overlay analyses quantified exposure. In Çınar, maximum water depths ranged from 2.64 to 4.22 m, and inundation areas from 0.300 to 0.383 km². In HadGEM2-ES RCP8.5, exposed planned development areas increased from a reference value of 0.117 to 0.128 km², while exposed emergency assembly areas increased from 0.033 to 0.035 km². In Bismil, maximum water depths ranged from 6.39 to 7.41 m, and inundation areas from 4.320 to 5.932 km²; no overlap occurred with the evaluated development or assembly areas under any scenario. However, this absence does not imply that other parts of Bismil face no flood hazard. These differences highlight the need for district-specific exposure assessments. The framework identifies exposed development and assembly areas, supporting climate-adaptive land-use planning and sustainable urban resilience.