Yilma, Sileshi (PhD)Seife, Tadesse2019-12-092023-11-112019-12-092023-11-112019-07http://etd.aau.edu.et/handle/12345678/20333An investigation on Tana Beles diversion head-work is carried out for this research work and attempt is made to understand the failure problems encountered. This serve for different purposes such as for construction of new diversion structure (either as replacement for existing structures, or as an entirely new structure), rehabilitation of existing structures (from minor repairs to complete re-engineering either to maintain existing function, or to meet new requirements). Hydrology and hydraulic analysis, structural analysis and evaluation of the foundation condition of the weir has been made to investigate the causes for the failure of the weir. The hydrology analyses is made by Hec-hms and the result shows that the peak flood used for the design of the weir is smaller than the result obtained in this investigation, but the water way of the weir built can accommodate the estimated peak flood. Models used for the hydrology analysis include Global Mapper, Arc-GIS, Hec-Geohms and Hec-hms. On the other side, hydraulic design is evaluated and the evaluation exposes the absence of concrete floor, absence of energy dissipater and protection works on the hydraulic design of the weir and clogging of under sluice as a cause for the failure of the weir. The structural analysis involves checking stability analysis of the weir against overturning, sliding and shear. Surveying data upstream and downstream of the weir is collected and foundation condition were investigated by comparing the collected surveying data with the design bed level.in addition to this the applied foundation treatment is evaluated by comparing it with standards and found that the main structure was built on weak foundation which activates the weir failure. This investigation shows that the main cause of Tana Beles weir failure is due to the weak foundation condition of the weir and absence of the necessary concrete floor and energy dissipater on its design. Finally, the remedial design for the weir is recommended.en-USAnalysisConcrete FloorDiversionDownstreamEnergy DissipaterGatesHead workRegulatorScourSeepageSiltStability,Thesis