Rivers dynamically respond to changes in the discharge and sediment supply of catchments. Arnchange of land use and other natural factors in catchments result in changes on sediment supplyrnand discharge. And this process of change of river geomorphology seeking for its equilibriumrnmay affect people and property especially in urban areas located adjacent to rivers. ThernKombolcha town, situated on flat land plains in the middle course of the Borkena River isrnfacing a danger of flooding and destruction of properties due to the instability of the Borkenarnand Berberie River reaches crossing the town.rnTo prevent the loss of lands and properties resulting from the changes in the characteristics ofrnthose river reaches, stabilization measures must be employed. For proper design andrnimplementation of any stabilization measures, analysis on stability of these channel reachesrnmust be carried out. So this thesis deals with analysis of the stability of the channel reaches byrnevaluating their capacity and stability in response to discharge and sediments that are suppliedrnfrom the catchments.rnField investigation and surveying to collect data for channel cross sections, bed & bankrnmaterial, and the vegetation covers is carried out. Gradations of bed and bank materials arerndetermined in laboratory using sieve analysis. Design discharges of different return periods andrnquasi unsteady flow data are analyzed from measured maximum daily instantaneous dischargerndata. Using such flow and existing field data as input, HEC-RAS 4.0 beta version is used forrnsimulation of flow and mobile bed sediment transportrnBased on the model results which are analyzed using the Meyer Peter Muller and Yangâ€™srnsediment transport formula, deposition is observed in almost all of the stations of the BorkenarnRiver. And there is deposition at some of the down stream stations in the tributary reach andrndegradation in the rest. It is also analyzed that the material on the banks is less resistance to thernminimum shear induced by the flow, besides much of the stations in the tributary reach arerngeotechnically unstable. Over flooding still is the problem on upper and lower reaches ofrnBorkena which is resulted from the complex processes of aggradational problems. Andrnstabilization measures are proposed and should be implemented with further engineering,rneconomical and hydraulic analysis for effective and sustainable stabilization of the rivers.