Modelling of the landslide-induced impulse waves in the Artvin Dam reservoir by empirical approach and 3D numerical simulation

Due to the burgeoning energy demand in Turkey, there has been a significant increase in the number of dams and hydroelectric power plants constructed; >250 dams have been built in the past 10 years. Consequently, various engineering problems were encountered due to landslides near reservoirs, both during and after the construction. Generally, two-dimensional (2D) and three-dimensional (3D) empirical equations have been used to calculate the physical properties and propagation of the landslide-induced impulse waves; however, 3D numerical simulation-based methodologies are rarely used, although they can model the complex geometry of dam reservoirs better, using detailed topographic data. In this study, therefore, 3D numerical analysis is carried out for a potential generation of impulse waves, using the data of paleo-landslide at the Artvin Dam reservoir (NE Turkey), and the results are compared with the calculated results by empirical equations. A finite element method-based shear strength reduction analysis (FEM-SSR) was performed to analyse the slope stability. After the establishment of the correct propagation model, the equations were utilised with different input parameters and 3D numerical analysis-based simulations to evaluate the characteristics of the impulse waves. In the numerical model created using the FLOW-3D software, the ‘drift-flux model’ was used to simulate the probable landslides. The Reynolds-averaged Navier–Stokes equations were used in a free-surface modelling technique together with the volume of fluid (VOF) model for simulating the wave generation. The renormalised group model (RNG) for viscous flow and k-ε turbulence model for fluid–fluid coupled condition, were used as the boundary conditions. The results indicated that the values obtained from the proposed empirical equations and 3D numerical analysis were not similar. Thus, if the reservoir geometry is very complex and the wave propagation distance is more than a few kilometers (as in this study), highly detailed engineering geological studies should be performed to accurately define the boundary conditions, and three-dimensional numerical analyses should be performed to construct the impulse wave model.