16 Nov 2021

16 Nov 2021

Review status: this preprint is currently under review for the journal NHESS.

Modelling the control of groundwater on landslides triggering: the respective role of atmosphere and rainfall during typhoons

Lucas Pelascini1, Philippe Steer1, Maxime Mouyen2, and Laurent Longuevergne1 Lucas Pelascini et al.
  • 1Univ Rennes, CNRS, Géosciences Rennes - UMR 6118, 35000, Rennes, France
  • 2Department of Space, Earth and Environment, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden

Abstract. Landslides are often triggered by catastrophic events, among which earthquakes and rainfall are the most depicted. However, very few studies have focused on the effect of atmospheric pressure on slope stability, even though weather events such as typhoons are associated with significant atmospheric pressure changes. Indeed, both atmospheric pressure changes and rainfall-induced groundwater level change can generate pore pressure changes with similar amplitude. In this paper, we assess the respective impacts of atmospheric effects and rainfall over the stability of a hillslope. An analytical model of transient groundwater dynamics is developed to compute slope stability for finite hillslopes. Slope stability is evaluated through a safety factor based on the Mohr-Coulomb failure criterion. Both rainfall infiltration and atmospheric pressure variations, which impact slope stability by modifying the pore pressure of the media, are described by diffusion equations. The models have then been forced by weather data from different typhoons that were recorded over Taiwan. While rainfall infiltration can induce pore pressure change up to hundred kPa, its effects is delayed in time due to diffusion. To the contrary, atmospheric pressure change induces pore pressure changes not exceeding a few kPa, but its effect is instantaneous. Moreover, the effect of rainfall infiltration on slope stability decreases towards the toe of the hillslope and is cancelled where the water table reaches the surface, leaving atmospheric pressure change as the main driver of slope instability. This study allows for a better insight of slope stability through pore pressure analysis, and shows that atmospheric effects shouldn’t always be neglected.

Lucas Pelascini et al.

Status: open (until 29 Dec 2021)

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Lucas Pelascini et al.

Model code and software

AtmoRainEffects Lucas Pelascini

Lucas Pelascini et al.


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Short summary
Landslides represents a major natural hazard, and are often triggered by typhoons. We present a new 2D model computing the respective role of rainfall infiltration, atmospheric depression and groundwater on slope stability during typhoons. The results show rainfall is the largest factor of destabilisation. However, if the slope is fully saturated, near the toe of the slope or during the wet season, rainfall infiltration is limited and atmospheric pressure change can become the dominant factor.