LANDSLIDE HYDROLOGY: FROM HYDROLOGY TO PORE
WATER PRESSURE AND LANDSLIDE INITIATION
Thom A. Bogaard
Delft University of Technology,
of Water Management, Delft, The Netherlands
management of landslide risk and, more generally, natural risks is an
essentially interdisciplinary task, as the contribution of many knowledge
fields is required. In fact, a modern approach to landslide risk management
involves the deployment of a layered strategy, including not only structural
measures such as building defense structures or slope stabilization works, but
also non-structural measures which require setting up on-site monitoring
networks, remote sensing monitoring schemes, fast and reliable transmission of
data and its quality control, development of models and decision support tools
to assess the risk in real-time.
landslides is an interdisciplinary topic that requires knowledge from
geomechanics, geomorphology, hydraulics and hydrology fields, to name a few.
More specifically, the representation of hydrological processes in the models
used for assessing the stability of slopes is often incomplete. Landslide
hydrology, however, is not simply putting together hydrological calculations
(modeling) with the knowledge coming from the above mentioned disciplines. In
fact, the main challenge is embedding our increased understanding of
hydrological processes in hillslopes and catchments in a physically correct but
also parsimonious manner for landslide hazard assessment. The focus hereto,
should be on inclusion of the non-linear behavior of hydrological response on
precipitation due to complex water storage in soil layers as well as in the
entire catchment. This boils down to an issue in matching processes occurring
at very different time and space scales. Special attention should be given to
the boundary conditions around the domain considered for slope stability
small scale hydrological processes (e.g., infiltration and snowmelt) directly
affect the stress state of soil (at pore scale), leading to landslide trigger.
The catchment scale processes create the preconditions for the trigger to take
place, so they are landslide causes but in our modelling domain often only
visible as boundary condition. Uniquely and interestingly, the hillslope scale
hydrological processes, developing in the same domain considered for slope
stability assessment, make causes and triggers meet. Therefore, past and
current research on landslide hydrology can be usefully regarded into this cause/large
scale and trigger/small scale concept.
The lecture will address the
work done in the field of landslide hydrology and shed light to important
knowledge gaps that urgently need to be addressed in order to arrive at
improved landslide mitigation and early warning systems.