Dam Engineering

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Browsing Dam Engineering by Subject "Land slide"

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    Overtopping of Dam by Landslide Wave Action a Case Study of Sego Dam
    (Addis Ababa University, 2024-02) Amdemariam Shiferie; Netsanet Nigatu (PhD)
    Since dam failure occurrences have resulted in numerous recorded human casualties and severe economic crises throughout history, it is without a doubt necessary to prepare safety plans and hazard management strategies. It is crucial to set up risk management, emergency action plans, or evacuation planning systems to safeguard people and property during abrupt dam failure phenomena brought on by landslide impulse wave causes. In the context of a case study, this thesis examined the landslide impulse wave in a dam under a number of pre-established scenarios. The case topic was the sego dam, which is situated in Ethiopia's Gamo zone SNNPRS. Landslide zonation map of the area around the reservoir rim has been prepared using ILWIS tool. Considering existing historical landslide spot, susceptibility map and geological structures three main landslide point has been identified for impulse wave analysis. Different maps such as historical inventory map, land use and land cover, soil, slope, aspect, lithological maps, distance from road and distance from rivers have been prepared using ArcGIS. Using the actual topographic map of the area, the geometry of the dam and from prominent literatures design inputs, the wave generation and propagation, wave run-up and overtopping has been estimated by excel spreadsheet templates. Three main landslide impact zones have been chosen after taking into account the landslide susceptibility map and discovered geological faults. In terms of overtopping volume and depth ,the impact of the event is minimal whenever the slide position is far from the dam (landslide three), and the worst-case scenario occurs when the landslide impact point is close to the dam (landslides one and two).In landslide one with bulk slide volume of 24,000m3 and drop height of 50m, the wave height ,period, amplitude, length and wave run-up height found to be 6.94m,18.04s,5.55m ,332.14m and 7.34m respectively and overtopping volume per unit length dam crest and across the dam axis length found to be 50.61m3/m, 13,564.3 m3 respectively. In land slide number two, which had a bulk slide volume of 27,000 m3 and a drop height of 35 m, the overtopping volume per unit length dam crest and across the whole axis was determined to be 1.8 m3/m, 482.4 m3 respectively, and the wave height, period, amplitude, length, and run-up height were all estimated to be 5.75 m, 18.53 s, 4.6 m, and 4.49 m, respectively. Finally, the wave height, period, amplitude, period, and wave run-up height for landslide three, which situated at the end of the reservoir and has a bulk slide volume of 115,200 m3 and a drop height of 25 m, were found to be 0.1 m, 6.93 s, 0.07 m, 155.5 m, and 0.11 m, respectively. In conclusion, because the dam's freeboard is 4 meters in the analysis, overtopping of the flood by landslides one and two has observed in the computation.