Adrian Fernandez Sanchez , Nestor Bernal López, Evelyng Peña Chávez, José Antonio Álvarez Aldegunde, Helio Vasco Nganhane

The dam breaching is one of the events with the most catastrophic consequences among the risks due to fluvial flooding, given the intensity, the great extension of the affectation and the speed of the event.

At present, various hydraulic modeling programs are capable of simulating the breach in the wall of a dam, as well as its possible subsequent flooding, granting speeds and drafts in the different study sections. The ability of hydraulic models like Hec-Ras to simulate the behavior of non-Newtonian flows in 2 dimensions improves the modeling carried out in the last decades.

The present work evaluates the flooding produced by a hypothetical phenomenon of breaching of the Chaglla dam, located in the department of Huánuco, Peru. This water reservoir constitutes the largest reservoir of fresh water and human origin in Peru with 308,500 m3 of water, supplying populations such as Tingo - María or Aucayacu. Through the application of a 2-dimensional hydraulic model and the Hec-Ras "Breaching" extension, it is intended to improve the knowledge of flooding due to the Chaglla dam breaching in the Huallaga river valley area, as well as to know the susceptibility to the danger due to the speeds and depths that the sheet of water could reach in this region.

The results show a catastrophic event that would cover a large part of the extension of the defined study area, with maximum depth of 40-20 meters and maximum speeds of 8-5 m/s. All of this could suppose the existence, for the most part, of a susceptibility to the danger of this event characterized as Very Serious. The population that would be in flood zones of any type would be 90,926 people.