Landslide generated waves in dam reservoirs - Experimental investigation on a physical hydraulic model

Abstract

The impulse waves generated by landslides that occur in an artificial basin may have disastrous impacts on the surrounding environment. For Alpine lakes, impulse waves are particularly significant, because of steep shores, narrow reservoirs geometry, possible large slide masses, and high impact velocities. Catastrophic events, as the well-known Vajont disaster occurred in Italy in 1963 which led to the loss of more than 2000 human lives, promoted the study of the physical process and the possible consequences of this phenomenon. The present analysis is based on an experimental research performed on a 1:190 physical scale model in laboratory, which allows to simulate the entire phenomenon, from the landslide movement to the dam overtopping. The main objective of this study is to gain more knowledge about the landslide generated impulse waves in reservoirs by trying to find a general modelling that, despite the phenomenon complexity, could help in the prediction of potential disaster effects. With this aim, experiments have been conducted by modifying the landslide location, the altitude of fall, its shape and volume, and by investigating two different dam freeboards. The research is initially focused on the simple observation of generated impulse waves amplitude and propagation in the basin, water height on the dam crest and total overtopping water volume. Subsequently, it proceeds with a dimensional analysis, based on the identified phenomenon governing parameters. In this way, we can demonstrate not only the influence of the slide volume and the basin water level on the total overtopping volume, but also the existing relation between the water outflow and the slide shape and velocity at the instant of impact with water.