NH3.12

Rainfall triggered landslides and debris flows and their effect on erosion and sediment yield in river catchments
Convener: Paolo Frattini  | Co-Convener: Giovanni Crosta 
Oral Programme
 / Tue, 04 May, 10:30–12:00  / Room 4
Poster Programme
 / Attendance Tue, 04 May, 17:30–19:00  / Halls X/Y
Rainfall is the most common triggering factor in slope stability. Both shallow and deep landslides and debris flows can be triggered by rainfall, with different frequency and under the effects of different types of storms. As a consequence, rainfall analysis is the most frequently adopted approach for forecasting the occurrence of such phenomena. According to the type of the involved slope instability phenomenon, different approaches have been presented, such as rainfall thresholds, hydrological models and coupled hydro-mechanical methods.
Rainfall-induced landslides and debris flows are a hazard in their own right but they are also a means of eroding soil and other material and redistributing it within a river catchment, including injecting it into the river channel. Debris flows may add to their load by scouring additional material along their track while, conversely, material deposited along the track may subsequently be washed into rivers by overland flow. The impact on catchment sediment yield depends on where the landslides and debris flows occur in the catchment, how big they are and whether they connect with the river network. Vegetation cover can also significantly modify both the occurrence of landslides and debris flows and the transfer of sediments. However, there is a lack of research quantifying the relevant processes and impacts and providing the understanding and data needed for the construction of mathematical models.
Contributions are therefore requested on the characteristics and impacts of rainfall triggered landslides and debris flows, including:
- empirical, semi-empirical and deterministic methods for modeling processes and the related hazards;
- case histories, making clear reference to landslide type, rainfall conditions, soil and rock characteristics, role of vegetation, wildfires and anthropogenic disturbance in controlling slope stability.
- the effect on sediment mobilization and transport, including flow characteristics (especially spatial and temporal occurrence and the relationship between magnitude and spatial and temporal frequency), runout distance, transporting capacity, deposition processes and the modifying effect of vegetation.
Field and modelling studies are welcome.
Public information: The presentation:
Rainfall thresholds for landslides forecasting based on a Bayesian methodology
Silvia Franceschini, Mario L.V. Martina, Sara Pignone, and Matteo Berti

will be substituted with:
Debris flow analysis with a one dimensional dynamic run-out model that incorporates entrained material
Byron Quan Luna, Alexandre Remaître, Theo van Asch, Jean-Philippe Malet, and Cees van Westen