Simulation of landslide-induced impulse waves in dam lakes using physical and 3 dimensional mathematical simulations: The case of Hardisağır landslide

Within the scope of the project, impulse waves that will occur as a result of the possible movement of the Hardısağır landslide in the Kurtün Dam Lake area were evaluated with 3D numerical simulations, and the effect of the floor topography, which changes depending on the sediment accumulation, on the propagation and physical properties of the impulse waves was modeled. Within the scope of the project, 3D analyzes were carried out using data from boreholes drilled by the State Water Works 22 Regional Directorate, the measurements made in the field and the data obtained from the laboratory experiments. A solid model representing the current land topography was created by using point clouds produced from orthophotos obtained from the General Command of Mapping and drone measurements in the field to be used in 3D analysis, and the current reservoir floor topography was produced by bathymetric measurements made on the lake using Multibeam Echosounder. The volume of the landslide mass that will flow into the lake area as a result of a possible movement has been calculated by three-dimensional limit equilibrium analysis, and the analysis of the impulse wave that will occur was carried out using numerical models based on 3D simulations. In the impulse wave analysis, in both cases, all boundary conditions were kept constant and only the floor topography was changed, and the maximum water level was accepted as 645 m in the analysis. As a result of the 3-dimensional limit equilibrium analysis, it was calculated that 875.240 m3 of material would flow into the reservoir as a result of a possible mass movement. As a result of bathymetric measurements made to obtain information about the current topography of the lake floor, it was determined that sediment accumulated between 3.05 and 23.23 m in different areas in the reservoir. In the 3-dimensional analyzes made using the solid model established for the floor topography of the dam in the first period when the dam started to hold water, the maximum wave height in the impact zone was calculated as 30 m, run-up on the opposite shore was calculated as 75 and 193 m for vertical and horizontal distances, respectively, and the wave height reaching the dam body was calculated as 2.5 m. In the analyzes made on the model established for the current floor topography, the maximum wave height in the impact zone was calculated as 35 m, the run-up on the opposite shore was calculated as 97 and 218 m for vertical and horizontal distances, respectively, and the wave height reaching the dam body was 4.5 m. The results showed that the sediment accumulated over the years changed the bottom topography, which in turn increased the height of the waves caused by landslides. This situation clearly reveals that the analyzes to be made by considering the floor topography of the dam lake in the first period in the impulse wave analyzes can be misleading, and the analyzes should be repeated at certain times considering the sediment that will accumulate over time.