The method (Nadim et al., 2006) is used to identify the global distribution of landslide hazard and risk. It uses existing global databases freely available online and it classifies areas accordingly with the level of hazard. The elements exposed are overlapped with hazard maps in a GIS environment to build risk maps (i.e, hotspots). A quantification of the elements exposed is also quantified.

To identify the global landslide hazard and risk "hotspots", Nadim et al. (2006) adopted a simplified first-pass analysis method. The scale of the analysis is a grid of roughly 1km x 1km pixels where landslide hazard, defined as the annual probability of occurrence of a potentially destructive landslide event, is estimated by an appropriate combination of the triggering factors (mainly extreme precipitation) and susceptibility factors (slope, lithology, and soil moisture). The weights of different triggering and susceptibility factors are calibrated to the information available in landslide inventories and physical processes (Figure 1).

Figure 1

Figure 1: Schematic approach for landslide hazard and risk evaluation (Nadim et al. 2006).

 
The landslide hazard indices were estimated using the following equations:

Hr = (Sr × S1 × Sv) × Tp

where Hr is landslide hazard index for rainfall-induced landslides, Sr is the slope factor within a selected grid, Sl is lithological (or geological) conditions factor, Sv is the vegetation cover factor Tp is the precipitation factor.

Landslide hazard map red

 
Upcoming improvements/future services

The GIS-based tool can identify possible landslide triggering areas. A combined use of the current method with simple runout analysis would help to identify risk areas and to quantify population, structures and infrastructures exposed. A quantitative risk assessment with damage estimation will be also implemented in the GIS tool.
 

WCS and WMS services for rainfall-induced landslide susceptibility and population exposure maps

Link to WCS (Currently the WCS link is only available via QGS, we are working on making it available in ArcGIS)

Link to WMS

References

Farrokh Nadim, Christian Jaedicke, Helge Smebye, Bjørn Kalsnes (2006). Assessment of global landslide hazard hotspots. International Centre for Geohazards (ICG) / Norwegian Geotechnical Institute (NGI), Oslo, Norway. IPL Project C102