Daniel, Fikreselassie (PhD)Getanew, Sewnetu2020-11-252023-11-112020-11-252023-11-112020-07http://etd.aau.edu.et/handle/12345678/23563Channel dynamically changes in response for the variation of flow and sediment transport. Sediment variation is because of land use change, composition of channel bank and bed material while for variation of discharge is because of climate change, as a result channel become altered. This channel change cause to flooding, channel bed and bank instability consequently destruction of infrastructure constructed along a river, irrigation area, home and other property in adjoining area. Assessing channel stability and provide stabilization measure is critical to prevent such damage. The objective of this study is evaluating channel stability investigation and recommend appropriate mitigation measure of Mersa river, Awash basin Ethiopia. HEC-RAS5.0.7 model with BSTEM (its extension) was developed to evaluate Mersa river bed and bank stability, quantify in depth or mass sediment erosion amount and identify flood prone area. To achieve the objective both filed investigation such as river cross section data collected, soil sample taken and experimental tasks such as sieve analysis, triaxial compression test are carried out. HEC-RAS model simulation with Yang sediment transport formula is best fit for study reach as compare to Meyer Peter and Muller sediment transport method. For entire simulation period an average aggradation was 1.24m and 0.98m at upstream and downstream reach respectively, whereas average degradation on both upstream and downstream reach was 1.25m. The average sediment eroded generated from Mersa river was 22.47kt/yr. Both aggradation and degradation were observed on the study reach but Mersa river reach more affected by erosion than deposition. Mersa river bank stability and toe erosion assessed by BSTEM of HEC-RAS was safe and again bank toe neither aggrade nor degrade in response to the flow. Additionally, Water surface of Mersa river was computed using steady flow analysis shows that flood over top above the bank, adjacent area (Mersa town) were affected by flood and the reality also true. The reality shows people around that loss their farm land and different property due to flood. Finally, this investigation presented that channel bed was unstable while bank was stable. Different stabilization measures like Gabion bank, Check dam and drop structure were recommended to prevent flood prone area from flood and to control channel bed instability.en-USSieve AnalysisTriaxial compression testChannel bed and bank stabilityHEC-RAS modelBSTEMAggradation and DegradationStabilization measureThesis