Numerical Simulation of Downstream Flooding due to a Flexible-Dam Collapse. The case of “La Esperanza” dam, Hidalgo-México: Implication on Hazard Assessment.

Abstract:

The risk of flooding of settlements located downstream of a dam is high due to the large number of people living on natural waterways. Risk assessment of flooding could help in projecting containment and protection in case of a dam-break. For projecting containment and protection works, the assessment should take into account velocities, densities and impact pressure of the water on the villages in risk. Therefore, it is appealing to conduct a series of numerical simulations of downstream flooding including velocity and pressure fields, and their temporal and spatial fluctuations. The present work focuses on the real case of “La Esperanza” dam, located in the state of Hidalgo (Mexico). The dam was built 70 years ago and currently two thirds of its capacity is covered with silt, which implies a very high horizontal thrust. The simulation of the flood due to failure of the dam was carried on using the DualSPHysics code, a new implementation of the mesh-free Lagrangian Smoothed Particle Hydrodynamic (SPH) method. For the boundary conditions, a Digital Elevation Model of the potentially affected area was built using satellite images, the actual bathymetry of the dam and cross sections of the channel. In order to evaluate the hazard posed to the villages located downstream of the dam, different collapse scenarios were simulated, with particular focus on the consequences of the temporal variation of rainfall. Preliminary results show acceleration and dynamic pressure values of water in especially selected areas that are subjected to high risk for the elevated number of inhabitant.