Author(s): Rui M. L. Ferreira; J. G. B. Leal; A. H. Cardoso
Keywords: Mathematical modeling; Morphologic impacts; Dam-break flow; Ha! Ha! River
Abstract: Severe rainstorms scourged the Saguenay region (south Quebec, Canada) between the 18th and the 21st of July 1996. As a result, a retention dyke in Lake Ha! Ha! failed. The dam-break wave, superimposed to the natural flood, provoked massive geomorphic impacts in the downstream valley. The objective of this work is to discuss the mutual influence of the mophodyndamic and hydrodynamic aspects of the flood. In particular, it is discussed how the morphologic evolution of the river determines the disappearance of supercritical flow reaches and hydraulic jumps. The discussion is based on a one-dimensional simulation of the hydro- and morphodynamic aspects of the flood. Although the qualitative results are satisfactory, it is clear that erosion is not as well reproduced as deposition. The model is able to find non- oscillatory solutions even when subjected to important lateral sediment input. Artificial viscosity is at the root of this robust behavior. One of the most accomplished characteristics of the model is its ability to deal with different flow regimes within the computational domain. In addition, it is shown that the model withstands the elimination of flow structures such as hydraulic jumps, as a result of profound morphologic changes, without disturbing the solution. The model for the elimination of supercritical reaches is presented and discussed.