Articles | Volume 15, issue 12
Nat. Hazards Earth Syst. Sci., 15, 2617–2630, 2015
Nat. Hazards Earth Syst. Sci., 15, 2617–2630, 2015

Research article 09 Dec 2015

Research article | 09 Dec 2015

3-D numerical approach to simulate the overtopping volume caused by an impulse wave comparable to avalanche impact in a reservoir

R. Gabl, J. Seibl, B. Gems, and M. Aufleger R. Gabl et al.
  • Unit of Hydraulic Engineering, University of Innsbruck, Technikerstr. 13, 6020 Innsbruck, Austria

Abstract. The impact of an avalanche in a reservoir induces impulse waves, which pose a threat to population and infrastructure. For a good approximation of the generated wave height and length as well as the resulting overtopping volume over structures and dams, formulas, which are based on different simplifying assumptions, can be used. Further project-specific investigations by means of a scale model test or numerical simulations are advisable for complex reservoirs as well as the inclusion of hydraulic structures such as spillways.

This paper presents a new approach for a 3-D numerical simulation of the avalanche impact in a reservoir. In this model concept the energy and mass of the avalanche are represented by accelerated water on the actual hill slope. Instead of snow, only water and air are used to simulate the moving avalanche with the software FLOW-3D. A significant advantage of this assumption is the self-adaptation of the model avalanche onto the terrain. In order to reach good comparability of the results with existing research at ETH Zürich, a simplified reservoir geometry is investigated. Thus, a reference case has been analysed including a variation of three geometry parameters (still water depth in the reservoir, freeboard of the dam and reservoir width). There was a good agreement of the overtopping volume at the dam between the presented 3-D numerical approach and the literature equations. Nevertheless, an extended parameter variation as well as a comparison with natural data should be considered as further research topics.

Short summary
The paper focuses on a new and practical way to model an avalanche for a 3D-numerical simulation with the software FLOW-3D. The main goal is to simulate the induced impulse wave in a reservoir in order to quantify the amount of overtopping water. A generalised geometry is used to validate the concept with the help of existing simplified formulas for this paper.
Final-revised paper