All over the world, there are many dams failure due to many different reasons. These reasons range from structural instability to some hydraulic conditions. The dam failure may occur due to overtopping, seepage or piping through the dam body or its foundation. There are some situations which may cause sudden failure to the dam like earthquakes, landslide or even possibility of terrorist attacks. Failure of dams can result in loss of life, property and environmental damage, and have economic repercussions. The Aswan High Dam, (AHD) plays an important role in the main system of Egyptian irrigation system, hydropower, flood control, drinking water. This importance is related to that, the population majority of Egypt is located downstream the dam site accompanied with the high portion of the national economic activities as agriculture and industries. The present paper assesses the risk of the Aswan High Dam breaching due to overtopping, numerically. All related data were collected and analysed. A suitable numerical dam breach model was chosen and selected to be implemented. Three scenarios were designed to represent minimum, normal and maximum flood flow to the lake at normal water level, respectively. Other three scenarios represent the same flood configuration flow to the lake at maximum water level conditions, respectively. The six scenarios were simulated using the dam breach model. The expected impacts of the Aswan High Dam failure, due to overtopping, were analysed. Outflow hydrographs due to the failure were obtained. The Nile River downstream Aswan High Dam until Delta Barrage was simulated using 1D 2D model. The obtained results from dam failure of the scenario of maximum inflow to normal Nasser Lake water level were applied to 1D2D model. A risk assessment to the dam breaching was achieved. Results of the calculated show the flood wave propagation in terms of inundations maps, flows, water levels, flood arrival time, and flow velocities along the water course from Aswan High Dam to delta Barrage. The results of this investigation could be further applied and could assist decision makers to set a plan to confront the risks of the Aswan High Dam failure