Rapid urbanization and increasing impervious surfaces at the urban areas leads to serious reduction in infiltration rate of the surface and this causes several environmental problems and critical challenges in stormwater management. This research work dedicated to develop a Rainfall-Runoff and inundation model for a highly urbanized area using EPA SWMM (Storm Water Management Model). For this purpose, Istanbul Technical University main campus selected to model development and simulations under a rain storm event with 25-year return period and duration of 2 hours. This model developed based on the GIS data and infrastructure map of the study area. The peak runoff value and its occurring time have calculated through the model. Also, the number and location of flooded nodes of the study area's drainage system at the peak runoff moment have determined in this study. According to the model results at the peak runoff moment there will be several flooded nodes in the study area. For reducing the number of flooded nodes and peak runoff value it is proposed to use LID (Low Impact Development) strategies at the university campus.