PhD project: Landslides triggered by hydro-meteorological processes

Landslides triggered by hydro-meteorological processes are expected to occur more frequently in the future, due to increased frequency of extreme precipitation associated with climate change. Landslides termed as debris flows are composed of coarse-grained soil and water, and are usually highly mobile (high velocities and long runout distances). In Norway, debris flows are typically triggered during local extreme rainfall events, and by groundwater and runoff exceeding normal conditions.

A debris flow usually starts with local erosion, which can make ravines and riverbanks unstable, triggering small local failures, and gradually increasing the flow density and give potential for further erosion. As the flow progresses, more material is entrained from the base and sides along the path, and the final volume can be several orders of magnitude higher than initial failure volumes. Due to high pore water pressures, the internal friction is low and debris flows can travel very long distances. The potential consequences of this type of landslide include damage to infrastructure like roads and railways, damage to buildings and casualties.

To reduce the consequences of precipitation-induced landslides, a better understanding of the physical mechanisms of debris flows is required. This PhD research work will focus on numerical modelling of debris flows for improving both the prediction of run-out distance and the evaluation of mitigation measures that aim to reduce consequences.

The specific objectives of Petter Fornes's PhD project are:

• To develop or adapt a numerical method for simulation of sub-aerial debris flow
• To improve the understanding of the physics that control debris flows
• To evaluate the effects of excess pore pressures on entrainment and runout
• To explore the coupling of numerical methods for fluids and particles for capturing a more realistic material behaviour
• To improve predictions of run-out distances based on site specific topology and soil characteristics using numerical methods
• To give recommendations for selection of input parameters and the initial condition to the numerical simulation
• To evaluate the performance of selected mitigation measures for reducing consequences based on numerical simulations

The supervisor team is Prof. Steinar Nordal (NTNU), Assoc. Prof. Hans Bihs (NTNU) and Dr. José Cepeda (NGI). Dr. Peter Gauer (NGI) and Dr. Harald Norem (NTNU) are scientific advisors of this PhD project.