This session aims to discuss innovative hydrological research applied to
landslide studies to improve our understanding of the spatio-temporal
patterns of slope movement mechanisms.

Water infiltration and the resultant transient changes in the
hydrological systems are the most common triggers of landslides. Because
of the large variability in the quantity of water stored in the soils,
the buffering capacity of the vadose zone, and the comparatively few
return periods of critical rainy episodes, the behaviour of many
unstable slopes is mainly controlled by hydrological processes.
There are different types of hydrological triggering mechanisms
dependent on the state of the system which defines the thresholds for
first-time failure and landslide reactivation. These hydrological
mechanisms, like pore water increase or matric suction decrease, are
reasonably well incorporated in geomechanical models. However, the
incorporation of hydrological process knowledge in slope failure
analysis still lags behind, whereas the importance of it has been
recognized already long time ago by the landslide community. The
research frontiers are connected with the complexity of real landslides,
the difficulty to monitor groundwater levels or soil moisture contents
in unstable terrain, and the difficulty to understand the water pathways
within fine grained or clayey soils which are the characteristic
substratum in which landslides occur and where preferential flow is
often observed.
We invite research ranging from unsaturated zone, hillslope processes
and regional hydrology which can be applied to landslide research in a
broad sense: ranging from soil slips to large scale slope deformation.
The session will give time to both laboratory and field observations, as
well as to advanced hydrological modelling. We especially invite
innovative studies dealing with spatial heterogeneity of water flows in
the subsurface, water tracing and travel time distribution. Lastly, we
invite pioneering research which includes the hydrological processes
knowledge in the geotechnical analysis and modelling that sets the next
step to improve landslide hazard analysis.