A 3D numerical simulation-based methodology for assessment of landslide-generated impulse waves: a case study of the Ter
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Murat Karahan I Hakan Ersoy I Aykut Akgun
A 3D numerical simulation-based methodology for assessment of landslide-generated impulse waves: a case study of the Tersun Dam reservoir (NE Turkey)
Abstract This paper focuses on the evaluation of temporal and spatial propagations of impulse waves using 3D numerical simulation-based models for a potential landslide area in the Tersun Dam reservoir, Northeast Turkey. The topographical model was created using Stereo Lithography files, and a drift-flux model was used to simulate the landslides. The wave generation was simulated using the Reynolds-averaged Navier–Stokes equations. The Drift-Flux approach was selected, and a renormalization group-based k-ε turbulence model was used to create a fluid– solid coupled model. The results show that a 16.5-m impulse wave is created as a result of sliding material hitting the water at a velocity of 16.4 m/s. The wave will reach the opposite shore in 27.4 s, and the run-up height will reach up to 48.8 m. As the wave, with an average velocity of 11.6 m/s in the reservoir, propagates toward the dam body, its height will decrease, and a 3.7-m-high wave will hit the dam in 155 s. A validation analysis performed using empirical equations and laboratory model tests indicates small differences in the results. The main reason for these differences is that the evaluation of wave properties is independent of the type of mass movement in empirical methods. A proper stability analysis is required to have a better estimation of the volume and the velocity of the sliding mass. Keywords Landslide . Impulse wave . Dam reservoir . 3D simulation . Numerical model Introduction Water waves are most commonly caused by wind and friction between the wind and the water surface. However, huge waves can occur in a water body as a result of landslides, rockfalls, glaciers, and snow avalanches. When granular or solid materials slide into a water body, such as a reservoir, lake, or the sea, the momentum of the mass is transferred to the mass of the water, which creates waves with large amplitudes. This phenomenon is known as an impulse wave in a reservoir and lake (Kamphuis and Bowering 1970) or as a landslide tsunami in the ocean and sea (Hermanns et al. 2013). This type of wave is classified as a gravity wave and can cause extreme situations, such as overtopping and breaking of dams as well as flooding. Because of these catastrophic consequences, landslide-generated impulse waves in dam reservoirs can be very dangerous and destructive for the dwellings located on the shore downstream or upstream as well as the dam body itself. The most devastating example of this case is the tsunami event that occurred in Lituya Bay, Alaska, in 1958. This tsunami event, which is the largest recorded tsunami in the world, resulted in a run-up height of 524 m (Zweifel 2004; Fritz et al. 2009). Another notable example is the Vajont dam disaster that occurred in Northern Italy in 1963. The impulse waves in the reservoir overtopped the dam by more than 70 m and resulted in about 200
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