Numerical simulation of flood dynamics for scenarios of failure of a marginal dam in Nechi (Colombia)

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Nathaly Triviño Leon, Jorge Escobar-Vargas, Paula Villegas

Friday 3 july 2015

14:45 - 15:00h at Oceania Foyer (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Flooding along in rivers and coasts

Parallel session: 16L. Flood risk - Flooding

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This work presents the recent advances on the numerical simulation of flood dynamics in Nechi (Colombia) caused by the failure of a marginal dam located at the left side of the intersection between Cauca and Nechi rivers. Specifically, the flood scenario caused during La Niña (2010-2011) event is analyzed in space and time. A 2D numerical simulation, based on a shallow water approximation, is taken as a platform of analysis, where it is assumed that the dynamics of the flood occurs mainly in the horizontal direction, and a hydrostatic pressure gradient in the vertical direction. The model was built with the finite differences based ISIS2D computer software, which allows the evaluation of the free surface elevation and the velocity dynamics, so that risk of flooding of the area of interest can be determined. Field measurements of free surface elevation are taken from limnigraphic stations in Cauca River, and were imposed as boundary conditions for the numerical model at the points of the marginal dam failure. The behavior of the flooding within the one hour was analyzed for three cases of failure of the marginal dam. The obtained results show that the flood propagation, based on the velocity vector field and frees surface elevation, affect the urban area of the municipality just when there is failure of closest breaker to it. A discussion on the effect of the lack of information in that specific area is presented, as well as the strategies used to overcome that problem. Finally, future work needed to increase the level of detail of the model is presented.