This thesis analyzes the probable failure of a dam under a set of pre-definedrnscenarios, within the framework of a case study, the case subject being thernTendaho dam located at Afar Region of Ethiopia. The failure of the dam is notrnanalyzed neither structural nor hydraulic wise but, is assumed to be triggeredrnwhen certain critical WSELs are exceeded. Hence, the analyses focused on thernaftermath of the failure and strive to anticipate the level of inundation atrndownstream of the dam itself. Break parameters prediction, peak outflowrnprediction were shown as the essential for the dam break analysis andrneventually determined the loss of the life. Tendaho dam break was furtherrnmodeled and analyzed using USACE Hydrologic Engineering Centerâ€™s RiverrnAnalysis System (HEC-RAS Version 4.1) model based on available technicalrnand geometric data. Water surface elevations and discharges occurring atrndownstream of the Tendaho dam were predicted spatially and temporally underrnthe defined set of eleven scenarios. Eight of the scenarios were analyzed forrnovertopping failure of the dam. Two of the scenarios were analyzed for pipingrnfailure and the last scenario was analyzed to investigate the sensitivity ofrnManning roughness. Overtopping failure yielded more severe flow conditionsrnat downstream. The worst case scenario was found to be scenario W4 (when allrnthe three spillway gates are completely closed). Hence, indicative inundationrnmap and settlements under risk were identified. Total numbers of fatalities forrnprecise and vague understanding of warnings were found 1,012 and 2,972rnrespectively. The thesis study further addressed some available pre-eventrnmeasures that may be taken in advance.rnKeywords: Tendaho Dam, HEC-RAS, HEC-GeoRAS, Breach, Dam Failure,rnDam Break Analysis