Institute of Technology
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The Institute of Technology focuses on education, research, and innovation
in engineering, technology, and applied sciences to support sustainable development.
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Item DAM BREACH MODELING and INUDATION MAPPING A CASE STUDY OF JEMA DAM, ABAY BASIN, ETHIOPIA(Hawassa University, 2018-08-13) AMDEMARIAM SHIFERIE MULUPreparing dam safety plans and hazard management strategies are unquestionably vital, since lots of human lives have been lost and tremendous amount of economic crisis have been recorded from dam failure events throughout the world in history. Setting out risk management, emergency action plans or evacuation planning system to protect both lives and materials during sudden dam failure phenomena and resulting flood waves is highly essential. This thesis analyzed the probable failure of a dam under a set of pre defined scenarios, within the framework of a case study, the case subject being the Jema dam located at Amhara Region of Ethiopia. A probable maximum flood of Gilgel Abay river (tributary of Jema River) has been computed using Hershfield’s technique .Breach parameters prediction, peak outflow hydrograph were determined by HEC-RAS model based on available technical and geometric data. Different maps such as flood areal extent map, flood depth map and velocity map have been produced by HEC-GeoRAS. The worst scenario was found to be scenario three (when Jema dam failed by overtopping with PMF of Gilgel Abay River). Probable maximum flood of Gilgel Abay river by Hershfield’s technique was found to be 1726.28 m3 /s. The maximum breach discharge resulted from HEC-RAS model was 79,886.37m3/sec and the maximum area inundated by this flood in downstream was found to be 41.6km2 . The areal maps show that the part of command area at right side and farm in left side, Bikolo Abay Town and settlement villages to be prone to flooding. The depth and velocity of flood also depict that the downstream rural village near the river bank are under extreme hazard category and the maps reveals that Jema dam is categorized under high hazed damItem DAM BREACH ANALYSIS AND FLOOD INUNDATION MAPPING FOR GIDABO DAM(Hawassa University, 2019-03-15) FIRAOL BEFEKADU GELETAThis study presented the dam breach analysis and flood inundation mapping for Gidabo rock-fill embankment dam found in Southern part of Ethiopia. The geometrical data used for this study was extracted from the recently released ALOS PLASAR digital elevation model by Alaska Satellite Facility, which is having the spatial resolution of 12.5 by 12.5 meters. One dimensional unsteady flow simulation within HEC-RAS model was used to simulate dam breaching for both overtopping and piping failure scenarios. Dam breach parameters estimation was done for different empirical equations. Froehlich (2008) and Von Thun & Gillete methods was preferred since the results obtained for these methods are more approaches to the envelope curve developed for the historical dam failures for overtopping and piping failures, respectively. RAS mapper and ArcGIS tools was used to present the maps of spatial distribution of flood extent, flood depth and flood velocity, flood inundation, flood hazard maps of the study area. The breach parameters estimated for both overtopping and piping failure scenarios was provided the reasonable values. The maximum breach discharge simulated for overtopping and piping failure was obtained as 15,945.18 m3 /s and 14,904.18 m3 /s, respectively. Since the failure were tested for hydrologic failure and for normal water level condition, the magnitude of flood and the spatial distributions are obviously different. Developed inundation maps from this study could be possibly help as guidance for dam owners to develop the emergency action plan and for future expansion of irrigation project infrastructures, and other developmental activities around the downstream of the dam