Flood occurs repeatedly in Ethiopia and cause tremendous losses in terms of propertyrnand life, particularly in the lowland areas. The majority of flood disastersâ€™ victims arernpoor people living in nearby stretch of floodplain. Therefore, the study was carried out tornperform floodplain analysis and risk assessment of Fogera and nearby areas.rnThis research involves the integration of HEC-Hydrologic Modeling System (HECHMS)rnand HEC-River Analysis System (HEC-RAS) with Geographic InformationrnSystems (GIS) to develop a regional model for floodplain determination andrnrepresentation.rnThe study describes the flood extent and depth in the area for different flow conditionsrnderived from the historical flow data of the Ribb River. The hydrologic model isrncalibrated using HEC-HMS for hourly time series data for return periods of 2, 10, 50 andrn100 years. The value derived by the hourly data of the HEC-HMS is compared withrndifferent frequency analysis methods. One dimensional hydraulic model HEC-RAS withrnHEC-GeoRAS interface in co-ordination with ArcGIS was applied for the analysis.rnTriangulated Irregular Network (TIN) was prepared from shape file generated from spotrnelevations of the floodplain through field survey data and the DEM of the study area inrnArcGIS. Required data sets as stream centerline, banks, flow paths and cross sectionsrnwere prepared in HEC-GeoRAS thus, creating import file and imported in HEC-RAS. InrnHEC-RAS, boundary condition for downstream were defined. Similarly, floodrndischarges for different return periods were also inputted and steady flow analysis wasrndone for the results.rnThe result of hydrologic model by HEC-HMS shows a flow value of 91.8m3/s, 202.4rnm3/s, 273.1m3/s, and 308.4m3/s for return periods of 2, 10, 50 and 100 respectively. Thernresult was compared with the frequency analysis using event flow values of the RibbrnRiver.rnAccording to the food map, the flooded area for the return periods 2, 10, 50 and 100rnyears are 12.63km2, 18.63km2, 21.31km2 and 22.5km2 respectively. The classification ofrnflood depth area showed most of the flooding area had water depth less than 1.5m. Onrnthe other hand 88% of agricultural land, 11.6% of agro-pastoral land and 1.36% River isrninundated by the flood.Key words: HEC-HMS, HEC-RAS, TIN, DEM, flood map