الفهرس 
The specifications that are needed to be determined
DATA PREPROCESSINGOnly 14 pages are availabe for public view
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Abstract
Dams provide many benefits to humanity such as water supply, hydropower, and flood protection. However, historical and recent dam failures worldwide produced many catastrophic and destructive disasters; in the forms of loss of lives and widespread damages. Despite the great advancements in design methodologies, failures of dams and water retaining structures continue to occur. Dam failures occur due to many reasons, the main modes of failure are overtopping due to insufficient spillway capacity or insufficient free board, foundation defects, piping and seepage. Regardless of the reason, almost all failures begin with a breach formation that progressively enlarges until complete failure occurs. Breach is defined as the opening formed in the dam body that leads eventually to dam failure and this phenomenon causes the stored water behind the dam to propagate towards downstream regions. Break parameters prediction, the understanding of dam break mechanics, and predicting the propagation of unsteady outflow downstream constitute essential factors in the dam break analysis to eventually determine the volume of damage.
Hydrodynamic modeling of dam failures on major rivers is a more complicated problem due to the difficulties encountered in representing such long rivers using appropriate spatial and temporal resolutions. In addition, specifying the huge input data pertaining to river bathymetry/topography and producing the output flood inundation maps are main challenges in such modeling. These factors and challenges constitute the scope of the proposed research.
Achieving this objective, a separate flood routing model, based on level pool hydrologic routing, was developed on Microsoft Excel in order to simulate the dam break routing the flood hydrograph coming from the upper Blue Nile catchments and the reservoir storage through break. The routing model assumed that GERD reservoir failure could occur with maximum reservoir storage and during the summer peak flow from the Blue Nile. The results showed that the outflow will reach a peak value of nearly 400,000 m3/sec.
The hydraulic routing of the resulting flood wave through the river downstream of the GERD was investigated using Hydrologic Engineering Center’s River Analysis System (HEC-RAS) model that was used to model breach formation and to solve the unsteady flow equations of flood wave propagation. Geographic Information System (GIS) was implemented for pre-processing of the input data required for hydrodynamic modeling and for producing the flood inundation maps using the hydrodynamic model results. The resulted flood wave from the breaching had a catastrophic effect on the downstream Nile reach with a flood extent over few kilometers on both sides of the main channel until reaching Lake Nasser. The peak of break hydrograph will reach AHDR after almost one month (which constitutes the warning time for Egypt to respond at AHDR) with a peak discharge of 50,000 m3/sec.
Another hydrologic routing model, based on level pool routing, was then developed to rout the arriving flood hydrograph into AHDR. The model is developed on Microsoft Excel and takes its input from the output of the hydrodynamic model (i.e., the hydrograph resulting at the downstream end of the hydrodynamic model). The level pool routing model was applied assuming different outflow alternatives from AHD;
1. Normal Summer peak release of 250M m3/day.
2. Future planned maximum release of 350M m3/day.
3. Maximum turbines capacity of 950.4M m3/day.
The flood wave impact on AHDR were simulated against different AHDR levels at the beginning of simulation study period, which was assumed equal to the time when breaching occurs. The minimum AHDR level that should be maintained if the GERD failure occurred to avoid any damage to the downstream Main Nile reach.