A model of hydrological and mechanical feedbacks of preferential fissure flow in a slow-moving landslide
- 1Department of Water Management, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, the Netherlands
- 2Institut de Physique du Globe de Strasbourg, UMR7516, CNRS, Université de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 5 rue Descartes, 67084 Strasbourg, France
- 3Department of Physical Geography, Utrecht University, UCEL, P.O. Box 80115, 3508 TC, Utrecht, the Netherlands
Abstract. The importance of hydrological processes for landslide activity is generally accepted. However, the relationship between precipitation, hydrological responses and movement is not straightforward. Groundwater recharge is mostly controlled by the hydrological material properties and the structure (e.g., layering, preferential flow paths such as fissures) of the unsaturated zone. In slow-moving landslides, differential displacements caused by the bedrock structure complicate the hydrological regime due to continuous opening and closing of the fissures, creating temporary preferential flow paths systems for infiltration and groundwater drainage. The consecutive opening and closing of fissure aperture control the formation of a critical pore water pressure by creating dynamic preferential flow paths for infiltration and groundwater drainage. This interaction may explain the seasonal nature of the slow-moving landslide activity, including the often observed shifts and delays in hydrological responses when compared to timing, intensity and duration of precipitation.
The main objective of this study is to model the influence of fissures on the hydrological dynamics of slow-moving landslide and the dynamic feedbacks between fissures, hydrology and slope stability. For this we adapt the spatially distributed hydrological and slope stability model (STARWARS) to account for geotechnical and hydrological feedbacks, linking between hydrological response of the landside and the dynamics of the fissure network and applied the model to the hydrologically controlled Super-Sauze landslide (South French Alps).