Landslide mobility with erosion: Proof-of-concept and application - Part II: Experimental Verification

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Erosion can act to significantly increase the destructive power of landslides by massively amplifying their volume, mobility, and impact force. The threat posed by an erosive-landslide is directly linked to its mobility. However, no clear-cut mechanical condition has been presented so-far for when, how, and how much energy landslides gain or lose by erosion. Recently, we pioneered a mechanical model for the energy-budget of erosive-landslides that controls the enhanced or reduced mobility (Pudasaini & Krautblatter, 2021). With a fundamentally new understanding, we proved that the increased inertia is related to an entrainment-velocity. This ascertains the true inertia of erosive landslides, making a breakthrough in correctly determining landslide mobility. Outstandingly, we showed that the erosion-velocity regulates the energy-budget and decides whether the landslide mobility will be enhanced or reduced. This depends on the newly developed energy-generator, which provides the first-ever mechanical quantification of erosional energy and a precise description of mobility. This addresses the long-standing question of why many erosive landslides generate higher mobility, while others reduce mobility. We demonstrated that erosion and entrainment are fundamentally different processes. Landslides gain energy and enhance mobility if the erosion-velocity is greater than the entrainment-velocity. The energy-velocity delineates three excess energy- regimes: positive, negative, and zero. We rigorously proved that the existing, very influential mass flow models with erosion are physically and mathematically wrong (Pudasaini & Krautblatter, 2021). We presented a set of dynamical equations that correctly includes erosion-induced net momentum production. However, these seminal theoretical principles must be verified with laboratory experiments to gain further confidence, and be validated with field events, and potentially be used for predictive purposes. Here, we aim to achieve the proof-of-concept to realize the new physical principles presented in Pudasaini & Krautblatter (2021) on the mechanics of landslide mobility with erosion. We pioneer inventive experimental facilities and examine novel approaches in order to explore, verify, and demonstrate the practical usefulness of novel concepts to simulate erosive landslide events. This offers a first-ever complete and scientifically sound description of the complex entrainment phenomena and their impact on mobility of multi-phase erosive landslides, serving a very useful and unique tool for landslide practitioners in predicting and mitigating natural hazards.