This study aims to model and develop flood analysis for the Wadi Adai area using the Hydrologic Engineering Centre – River Analysis System (HEC-RAS) simulation software. The study area has a catchment area of more than 390   and the length of the main streamline is about 13 km starting near Bajariyah till Qurum beach. Whereas the present study focuses on the length of about 6.5 km of the main channel for simulation. The objective of the study could be achieved by using the Digital Elevation Model (DEM) of the area to prepare the geometric data, cross sections, and bank lines as well as the physical parameters and boundary conditions. As this study focuses on the hydraulic simulation, the input of flood peaks for the same catchment area was obtained from a study made at the Wadi Adai downstream. Obtained flood peaks for return periods of 2, 5, 10, 25, 50, and 100 years were used as inputs to the steady flow analysis. Water surface elevation and velocity of the inundation were obtained from the simulation model displayed in RAS mapper. The calibration of the model was performed considering the observed data of the Guno cyclone at Bajariyah gauge station along with the cross section on the same location. The calibrated Manning's n value was used to run the simulation model. Moreover, the HEC-RAS model was validated by choosing different events from the observed and recorded data at Bajariyah station. In addition, the sensitivity of the model was carried out by using various values of calibrated parameter, in which the inundation depth gets affected. The result showed that the model was very useful to predict the flood for different return periods and good estimate for inundation depths. This study will be useful for the design and management of urban drainage system in Wadi Adai catchment.