Analysis and application of two complementary numerical models for predicting flood waves generated by failures or dysfunctions occuring on a complex of dams

A complete risk analysis related to a complex of dams may involve the assessment of a
large number of different scenarios of failures and dysfunctions. However, a high
computation time would be needed to perform a two-dimensional analysis of the flows
generated by all possible scenarios. For this reason, the present paper expounds two
complementary flow models, developed to be exploited within a rational methodology for
analysing the flows induced by various incidents on a complex of dams and reservoirs.
The first model is the two-dimensional flow solver WOLF 2D, while the second one is a
simplified lumped model, requiring very low computation time. An original analytical study
is presented to demonstrate the conditions of applicability of the lumped model. This study
leads to the practical conclusion that the evaluation of two non-dimensional parameters
enables to assess a priori the validity of the simplified approach for any specific application.
The paper also describes the combined application of both models to a practical case study
involving a complex of five dams. In a first step the lumped model has been validated by
comparisons with the results provided by the two-dimensional model WOLF 2D. Secondly
the simplified model has been successfully applied, at a very low CPU cost, to simulate flows
induced by various dysfunctions and to conduct sensitivity analysis.
In conclusion, based on both theoretical developments and numerical studies, the paper
provides new advances of practical relevance for dam break risk analysis.