Arsema Bridge was constructed on Jemo River, Jemo River is tributary of Little Akaki River which isrnthe sub catchment of Akaki basin and study area has an inclusive area of 73.3 Square Kilometer,rnArsema Bridge built as River crossing structure to connect the ring road from German round aboutrnto Lebu Mebrate Haile under Addis Ababa city Administration.rnIt had been built just before 15 years ago and currently the Bridge faces a serious problem of sedimentrnaggradations both at the left and right side of the abutment, and trash accumulation on the entrance ofrnthe Bridge. Due to this; overtopping of the Bridge and flooding of residential house were observedrnfrequently. rnHEC- HMS modeling was used to determine peak discharge of 2, 5, 10, 25, 50 and 100 year returnrnperiods and then 67, 97.6, 117, 136.1, 154.5 and 174.9 mrn/sec results were found, subsequence HECRASrnModelingrnwas usedrntorndeterminernwaterrnsurfacernprofilernlevel,rnperformance ofrnexistingrnbridgernwhenrnrndifferencernrnreturn period peak discharge pass through it and sediment transport at the bridge locationrnbased on the current river sectional profiles however the bridge accommodate only up to 10 year returnrnflow.rnThen Q50 was used to analysis before and after bridge constructed, then after the water surface elevationrnis 2214.36m and 2214.57m amsl respectively however existing bridge high chord is 2213.684m amslrni.e. 0.676m and 0.886m difference before and after the bridge constructed, this show us the existingrnbridge is submerged as per previously estimated flood. rnAfter detail analysis of the result and discussion I recommend the appropriate remedial measure forrnsedimentation aggradations and trash accumulation as well as flooding of the residential house, HECRASrnwasrnusedrnwithrncombinationrnofrnHEC-rnRASrnMapping:rntornredesignrnofrnBridgernwithrnTrashrnTraprnrnScreenrnandrnFloodrnHazardrnmap,rnthernresultrnshowrnusrnroadrnsurfacernfinishingrnlevelrnhasrntornincreasernatrnleastrnrn0.766rnmrnhighrnatrnthernbridgernandrnrefillrnbothrnleftrnandrnrightrnsidernofrnthernbridgernuprntorn150rnmrnlengthrnasrnperrnrnroadrnprofile;rntornaccommodaternthernredesignedrnbridgernhighrnchordrnofrn2214.45mrnamsl,rnresidentialrnhousernrnupstreamrntornbridgernhasrntornconsiderrnfloodrnprotectionrnorrnguidernwallrnuprntorn2.0mrnhighrndependingrnonrntheirrnrnOGLrnagainstrnthernfloodrnhazardrnmap,rnrelocaternofrnallrnutilitiesrnlinernwhichrnarernpassrnthroughrnbridgernandrnrnperiodrnclearing ofrntrashrntraprnscreen isrnhighlyrnrecommendedrnasrnmainrnmitigationrnmeasure.