Dams are built for different purposes, but failure of a dam could result in extreme disasters such as floods. The Grand Ethiopian Renaissance Dam (GERD) was mainly built for power generation, but concerns about its safety, location and site conditions have led the downstream countries to investigate the GERD’s stability. This paper aims to investigate the impact of the failure of the dam on the downstream countries using the Hydrologic Engineering Center River Analysis System (HEC-RAS). Outflow hydrographs and flood inundation maps were provided through a hypothetical dam break scenario. An unsteady flow hydrodynamic routing with a 2D model was used to simulate the failure of the dam. A sensitivity analysis study of the output’s findings against breach parameters was also performed. The breach outflow discharge increases as the breach dimension increases. However, the peak discharge decreases with increasing breach formation time. Moreover, to prepare emergency action plans, it is important to predict the inundation depth, levels, arrival of flood waves, flood coverage area and water velocity. Furthermore, the results showed that Khartoum would turn into lakes within about 10 days and flood water depth would exceed 11 m at some locations in residential areas. Moreover, the flood waves overtopped the Roseires, Sennar and Merowe dams by 11, 7 and 20 m, respectively. In addition, the level of Lake Nasser would reach 188 m above sea level and the Aswan High Dam might be in great danger.

Understanding and modeling a dam breaching process is an essential investigation, because it aims to minimize the flood’s hazards, and its impact on people and structures, using suitable mitigation plans. In the current study, three-dimensional numerical modeling is carried out using the FLOW-3D HYDRO program to investigate the impact of various factors, including the dam grain size materials, crest width, inflow discharge, and tail water depth on the dam breach process, particularly the peak outflow, and the erosion rate. The results show that changing the grain size of the dam material from fine sand to medium and coarse sand leads to an increase in the peak outflow discharge by 16.0% and the maximum erosion rate by 20.0%. Furthermore, increasing the dam crest width by 40% leads to a decrease in the peak outflow by 3.0% and the maximum erosion rates by 4.50%. Moreover, increasing the inflow discharge by 25.0% increases the peak outflow by 23.0% and the maximum erosion rates by 21.0%. Finally, increasing the tail water depth by 50.0% leads to decreasing the peak outflow by 4.50% and the maximum erosion rate by 43.0%. The study findings are considered of high importance for dam design and operation control. Moreover, the results can be applied for the optimum determination of the crest width and tail water depth that leads to improving the dam stability.

Recently, many countries have sought to obtain sustainable energy from different sources. This study’s primary objective is to determine ways to optimize the advantages of water structures, especially ski-jump spillways, within the hydropower sector. A ski-jump spillway is a type of energy dissipation structure that relies on projectile principles, causing scour holes in the downstream bed. To convert the flow energy into hydroelectric power, the wheel turbine is mounted in the spillway bucket. The turbine’s impact on total hydraulic energy reduction, power generation, and downstream scour was evaluated, alongside optimizing blade design (number and shape) for peak performance. To conduct this research, a numerical 3D model was created using FLOW-3D HYDRO. Adding turbines to the ski-jump spillway is a promising modification, increasing total hydraulic energy reduction by approximately 22.10% and decreasing the maximum scour depth under the investigated conditions. It was discovered that increasing the number of turbine blades from five to 10 results in a 2.77% increase in total hydraulic energy reduction under the investigated conditions. This study represents a starting point toward harvesting flow energy that would otherwise be dissipated, in contrast to most researchers in this field, who focus primarily on reducing hydraulic energy without recovering it.

Understanding and accurately predicting the outflow hydrograph from embankment dam breaches is essential for managing the associated flood hazard and improving emergency preparedness. This work simulates the breaching process using a high-resolution 3D computational fluid dynamics (CFD) model, a critical natural hazard for earth-fill dams under overtopping conditions. The model was validated against the experimental data, showing high accuracy in predicting breach development and failure timing. A parametric analysis was performed to assess the influence of the initial breach geometry on erosion dynamics. The results indicated a high sensitivity, while increasing the breach width by 5% led to an average 11% increase in the erosion rate, and decreasing the depth by 5% caused an average 16.5% rise. To enhance predictive capabilities for this hazard, a multilayer neural network (MLNN) was trained on the CFD-generated dataset. The network utilized breach geometry and time as inputs to forecast the peak outflow and erosion rate, achieving excellent accuracy (RMSE = 0.019, R² = 0.99). This integrated modeling strategy combines data-driven learning with physics-based simulation and demonstrates its effectiveness for laboratory-scale dam breach modeling. This approach is a step toward more efficient surrogate-based tools for flood risk analysis, though its extension to full-scale dams and varied material properties requires additional validation and scaling analyses beyond the scope of this work.