2DH numerical simulation of breach evolution in an earth dam

Flow- induced erosion of earth dams and leeves may induce important morphological changes in rivers and represent a danger for human activities. In the present paper the evolution of a breach in an earth-dam is simulated by means of a two-dimensional depth-averaged numerical model with fully coupled modeling of hydrodinamic and morphological evolution. The simulation of the whole process requires several specific aspects to be taken into account, from both the conceptual and teh numerical point of view. The strong unstaediness of the evolution claims for a dynamical description of the interaction between flow and sediments, since they may be conveyed under non-equilibrium conditions. To this aim, a two-phase dynamical approach is used, based on the encouraging results achieved by an earlier version of the proposed model and concerning the overtopping of a earth-dam in a 1-D depth-averaged framework. From the numerical standpoint, both quiescient-like flow condition over complex topography in the reservoir upstream the dam and the high-slope flow on the downstream side of the dam, along with the evolution of the notch cross-section during the widening phase and the propagation of wet/dry interfaces have to be addressed. To this aim, a recent divergence formulation of teh source terms is adopted for numerical solution of the model equations. A sample application on a laboratory test-case is discussed: comparison of model results against experimental data is carried out in order to enlighten the potentialities and the weaknesses of the proposed model.