Transcript LandSlides - European Soil Portal

Identifying Risk Areas for Landslides
Florence Carre (JRC, Subgroup leader),
D. Seebach, N. Filippi, M. Pizziolo, G.
Bertolini, A. Poschinger, J. FortunyGuasch, M. Gemmer
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
LANDSLIDE
Movement of a mass of rock, debris, earth down a slope (Cruden & Varnes,
1996)
LANDSLIDE CLASSIFICATION
TYPE OF MATERIAL
TYPES OF MOVEMENT
Soils
Bedrock
Coarse
Grained Soil
Fine Grained
Soil
Falls
Rock fall
Debris fall
Earth fall
Topples
Rock topple
Debris topple
Earth topple
Rock slide
Debris slide
Earth slide
Lateral spreads
Rock
spread
Debris spread
Earth spread
Flows
Rock flow
Debris flow
Earth flow
Slides
Rotational
Translational
Complex: Combination of two or more types of movement
(Cruden & Varnes, 1996)
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
MAIN CAUSES
Snow melt and heavy rainfall events  water saturation
DRIVING FACTORS RELATED TO VULNERABILITY OF SOIL
• Geology/bedrock material
• Slope
• Land cover
• Soil permeability
TRIGGERING MECHANISMS
• Rapid snowmelt
• Intense rainfall
• Water level change
• Human activities
• Changes in landuse/land cover
• Earthquakes / volcanic eruption
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
MAIN SOIL VARIABLES AFFECTED BY LANDSLIDES
Affected soil physical properties:
- structure;
- bulk density;
- water permeability;

Loss of soil functions and increase of soil vulnerability to other threats
- erosion
- soil organic matter decline
- compaction (but also as a driving factor)
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
Tier I
Source: EPSON
(European Spatial
Planning Observation
Network) project
http://www.gtk.fi/projects/
espon/Landslides.htm
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
Tier II approach
Usually 3 scale maps (Van Westen, 1993)
• Synoptic or territorial scale maps (> 1:50,000):
inventories maps used by planning agencies to direct
allocation of funds, develop emergency preparedness plans
and similar tasks
• Medium scale maps (> 1:20,000 to 1: 1:50,000):
used for preliminary or regional landslide hazard
assessments and feasibility studies followed by more
detailed work
• Detailed scale maps (> 1:5,000 to 1: 1:500):
Prepared as part of a landslide hazard assessment of a
specific site and should be accurate enough to guide layout
of individual structures or specific operations or to plan
mitigation
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
Common criteria (1)
Common criteria to delineate landslide risks
- Spatial probability of occurrence of landslides (like density of
landslide/km²)
- For tier I approach, landslides have to be defined in a common
way by all the MS in order to compare the density
- For tier II approach, the 3 scale maps can be produced
according to the purpose
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
Common criteria (2)
Common criteria
Data source/type of
information
Data Quality /Resolution
Tier 1
Tier 2
occurrence/density
of existing
landslides
statistics
NUTS III
larger-scale
regional/local
assessments
bedrock
nature of material + presence
of fissures and pores
Sensitive bedrocks can be
Gault Clay and Flish
Map of Geology
1:1,000,000
higher resolution maps
soil properties
texture, structure,
permeability
not required for in
Tier 1
classification/grouping
according to?
slope
classes: 0-10°; 10°-30°; >30°
250m
same or higher
land cover/land use
infrastructure; cultivation
density/pressure, mining
Non relevant for
Tier 1
100m
climate
likelihood of heavy rainfall
events
daily events (e.g. <
10, 10-70, >70
mm/day)
same or higher
threshold?
threshold?
seismic risk
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005
Conclusions
 Intensify collaboration with EuroGeoSurveys (EGS)
 Elaborate on qualitative approach, since no
operational approach has been presented
Today’s problems
• Improvements in harmonisation are necessary because:
- inventories do not follow any commonly agreed
standards or methodologies until now
- authorities in charge of inventories are either local,
regional or national and can be civil engineers, soil
scientists or geologists
• Only landslides related to civil damages are listed, others can
exist and not be listed (above all in unpopulated areas)
Soil Information Working Group (SIWG)
ESBN Plenary, London, 2005