Analysis of dam breach events and the associated flooded area are helpful in the risk assessmentrnof dams. Because sudden failure of dam causes risk of flooding hazard to downstream area. Thernobjective of this study is to model the dam break and map flood inundation areas to be used forrnestimating the potential consequence of dam breach and emergency planning purpose.rnTo meet these objectives materials used are HEC-RAS model in conjunction withrnHECGEORAS an extension of ARCGIS for the case of Middle Awash Multipurpose Damrnwhich is located in Middle Awash sub-basin and DEM 30m of the area was used because of itsrnavailability for the extraction of river geometries in HECGEORAS then exported to HECRAS.rnIn HEC RAS dam feature is entered as inline structure, and breach parameters were estimatedrnusing the built-in parameter calculator in HEC-RAS and the PMF flow data is entered andrnunsteady flow simulation is run. The flood map is done with RASMAPPER in HECRAS andrnExported to ARCGIS for further work.rnAccordingly the Middle Awash dam has been checked for both overtopping and piping mode ofrnfailure in HECRAS. The out flow hydrograph result was different for each breach method andrnbreach parameters which in turn affects the inundation area and hazard. It is also different forrnboth mode of failure in HECRAS.rnThe Middle Awash Dam was checked for overtopping failure with the PMF inflow and forrnpiping starting elevation at the center of dam which occur due to internal erosion of damrnmaterial. The peak outflow hydrograph was routed down stream and flood inundation mappingrnwas produced. Failure with overtopping inundate 31000ha area and the failure of the dam withrnpiping inundate 30840 ha. The inundation extent, depth and hazard map of dam breach floodrnshows that the towns at downstream Melkasedi, MelkaWerer and the cultivated area,rninfrastructures, the animal and human life in the downstream can be affected with inundationrncaused due to flood from dam failure.rnThe flood inundation map helps in estimation of the severity and extent of dam break flood,rnwarning time, consequence classification for emergency action planning and to alert therngovernment body. Therefore, damages that could occur in the surrounding settlements,rnagricultural areas, on both lives and infrastructure can be minimized and even controlled