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Sediment-related Disasters:

Mechanism, Prediction and Assessment6. November 2012 – Taichung, Taiwan

Thomas Glade

Landslide-triggering rainfall thresholds –a review of concepts and some examples

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Rational

• Landslides are occurring due to many factors.• Observations: Triggering conditions are manifold.

• Critical conditions need to be investigated for

– Research: Fundamental understanding of the slope system

– Application: Integration in landslide early warning systems.

• Differentiation:

– Local single landslides (often grade of activity)

– Regional landslide distributions (often linked with weather

forecasts)

Basic assumption:

Landslide frequency related to trigger frequency

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Different landslide-triggers

• Meteorological conditions – Extreme rainfall

– Prolonged rainfall

– Snow melt

• Earthquakes• Human related triggers

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Correlation with tr iggers

A. Threshold defined as a lower bound

to landslide-triggering conditions (”+”

symbols)

B. Threshold defined as an upper bound

to conditions that did not trigger anylandslides (”-” symbols). Very useful

for an initial calibration of thresholds

in newly instrumented regions.

C. Threshold defined as a boundary

between triggering and non-

triggering conditions.• This is the preferred approach for

calibrating thresholds for use in EWS.

• The challenge in optimising the threshold

model is to minimize the number of falsealarms (”-” symbols above the threshold)

and missed events (”+” symbols below the

threshold).

D. Thresholds defined as lower and

upper boundaries enclosing aprobability range of triggering conditions

A B C D

Modified from:

Cepeda J. & G. Devoli (2008): Rainfall thresholds for landslide triggeringfollowing volcanic ash eruptions and earthquakes.- Geophysical Research

Abstracts 10, EGU2008-A-03879.

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Different factors

Range of stability

Stable Marginallystable

Preparatory

factors

Aktivelyinstable

Triggering

factors

Controlling

factors

Disposition factors

Glade T & Crozier MJ (2005) The nature of landslide hazard impact.- In: Glade T, Anderson MG & Crozier MJ (Hrsg) Landslide hazard and risk. Wiley,

Chichester 43-74. NACH: Crozier MJ (1989): Landslides: Causes, consequences and environment. Routledge, 252 S.

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The threshold “ concept”

DefinitionIn general: Once a given border/value/range is exceeded,

the system will change.

Landslide related: Once a given magnitude of precipitation

is exceeded, landslides will occur with a given probability.

Three main types of rainfall thresholds

• Precipitation of a specific rainfall event• Precipitation including antecedent conditions (e.g.

rainfall, soil moisture)

• Other types of meteorological conditions (e.g. snow melt)

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Types of rainfall-thresholds

Typical landslide-triggering rainfall thresholds

• Event rainfall

• Intensity - Duration (ID)

• Rainfall event - Duration (ED)

• Rainfall event - Intensity (EI)

• Rainfall event – Antecedent Rainfall Conditions (ARI)

• Rainfall event – Soil Water Status Model (SWSM)

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Event rainfall thresholds 1/2

Note: Nomenclature is not consistent in the literature, and different definitions have been used for the

same or similar variables.

Refer to Appendix 1 for complete Table.

Variable Description Units First introduced

D Rainfall duration. The duration of the rainfall event or

rainfall period.

h, or days Caine (1980)

DC Duration of the critical rainfall event. h Aleotti (2004)

E(h),(d) Cumulative event rainfall. The total rainfall measured from

the beginning of the rainfall event to the time of failure.

Also known as storm rainfall. “h” indicates the considered

period in hours; “d” indicates the considered period indays.

mm Innes (1983)

EMAP Normalized cumulative event rainfall. Cumulative event

rainfall divided by MAP (EMAP=E/MAP). Also known as

normalized storm rainfall.

- Guidicini and

Iwasa (1977)

… … … …

Guzzetti F., Peruccacci S., Rossi M. & C.P. Stark (2007): Rainfall thresholds for the initiation of landslides in central and southern Europe.- Meteorol. Atmos.

Phys. 98: 242.

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Event rainfall thresholds 2/2


Phys. 98: 248.

# Extent AreaLandslide

typeThreshold Notes

72 L Hokkaido area, Japan A R >200 mm

73 R Los Angeles area, California A R >235 mm

74 L Hong Kong S A15d >50 mm and R>50 mm Minor events

A15d >200 mm and R>100 mm Severe events A15d >350 mm and R>100 mm Very severe events

75 R

Contra Costa County,

California Sh E>177.8 mm Abundant landslides

… … … … … …

Note: Extent: R - regional threshold; L - local threshold.

Area: The area where the threshold was defined.

Landslide type: A - all types; D - debris flow; S - soil slip; Sh - shallow landslide.


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Intensity - duration (ID) thresholds

Note: Extent: G, global threshold; R, regional threshold; L, local threshold.

Area: the area where the threshold was defined.

Landslide type: A, all types; D, debris flow; S, soil slip; Sh,shallow landslide, L, lahar.

Rainfall intensity in mm=hr, rainfall duration in hours.

Complete Table: Please refer to Appendix 3.

# Extent Area Landslide

type

Equation Range Notes

1 G World Sh, D I = 14.82 x D-0.39 0.167

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Legend: Very thick line: Global threshold;

Thick line: Regional threshold;

Thin line: Local threshold.


Phys. 98: 243.

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Rainfall event - Duration (ED) thresholds

Note: Extent: G - global threshold; R - regional threshold, L - local threshold.

Area: The area where the threshold was defined.

Landslide type: A - all types; D - debris flow; Sh - shallow landslide.Cumulative event rainfall in mm, rainfall duration in hours.


# Extent Area Landslidetype


90 G World Sh, D E = 14.82 x D0.61 0.167

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Rainfall event - Duration (ED) thresholds


Phys. 98: 250.

Legend: Very thick line: Global threshold;

Thick line: Regional threshold;

Thin line: Local threshold.

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Rainfall event - Intensity (EI) thresholds

Note: Extent: G - global threshold; R - regional threshold; L - local threshold. Area: The area where the threshold was defined.

Landslide type: A - all types; D - debris flow; S - soil slip; Sl - slide; E - earth flow; M - mud flow;

Sh - shallow landslide; L - lahar.

Refer to Appendix 6 for comprehensive table.

# Extent Area Landslide

type


105 R Chiba and Kanagawa

prefectures, central Japan

Sh Imax = 390 x E-0.38 0

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Intensity, duration and

antecedent rain

Generalization of I-D model

where:

I, D and β as in ID model

An: antecedent n-day precipitation (mm)

α 1 and α 2: constants of the model

• the term in brackets account for the effects of antecedent precipitation

• the model requires a calibration of the value of ”n”,

and the constants α1, α2 and β

Cepeda, J.; Nadim, F.; Høeg, K. & A. Elverhøi.(2009):A new function for estimating local rainfall thresholds for landslide triggering.- Geophysical Research

Abstracts,11, EGU2009-12290,

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Rainfall thresholds for

different landslide types

D: 1 to 9 hours I = 4.297 D-0.275 D: 3 to 17 hours I = 181,2 A23d

-0.6788 D-1.5163

• for debris flows, a traditional ID threshold is sufficient+ triggering rainfall 1 to 9 hrs

+ no need of antecedent rain

• for slides, an improved performance is achieved with the IAD model+ triggering rainfall 3 to 17 hrs

+ need of antecedent rain of 50 days.

Cepeda J.M., Malet J.P. & A. Remaître (2011): Empirical estimates of precipitation conditions for landslide triggering in France and Norway.- Geophysical

Research Abstracts 13, EGU2011-10550

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Basic disposition

0

8

DispositionVariable disposition

0

6

Forces

on the

slope

system

Triggering events

Based on Kienholz et al. (1998)

Time

Disposition

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Bilder

ParameterDaily

rainfall

Antecedent

daily rainfall

Index soil-

water status

Climate

- Percipitation

- Antecedent rainfall

- Pot. Evapotranspiration

Soil characteristics

( Depth, soil moisture, porosity, textur )

Modell requirements

Glade T (2000): Modelling landslide triggering rainfall thresholds at a range of complexities.- Landslides in Reserach, Theory and Practice, Proceedings of the8th International Symposium on Landslides, 26-30 June 2000, Cardiff, UK, Thomas Telford, 2, 633-640.

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Daily Rainfall Model

Glade T (1998) Establishing the frequency and magnitude of landslide-triggering rainstorm events in New Zealand.- Environmental Geology 35(2-3): 160-174.

1862-1995

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Antecedent Daily Rainfall Model

Wellington

Pa0 = P1 + 2k P2 + ...+ n

k Pn

Glade T, Crozier MJ & Smith P (2000) Applying probability determination to refine landslide-triggering rainfall thresholds using an empirical "Antecedent DailyRainfall Model".- Pure and Applied Geophysics 157(6-8): 1059-1079.

1862-1995

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Hawke’s Bay

Pa0 = P1 + 2k P2 + ...+ n

k Pn


1870-1995

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Pa0 = P1 + 2k P2 + ...+ n

k Pn


1862-1995

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Soil Water Status Index model

1931-1995

Glade T (2000): Modelling landslide-triggering rainfalls in different regions in New Zealand - the soil water status model.- Zeitschrift für Geomorphologie 122: 63-

84.

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Threshold based landslide forecast

Observations 1950-1979

Crozier MJ (1999) Prediction of rainfall-triggered landslides: A test of the antecedent water status model. Earth Surface Processes and Landforms 24:825-833

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Non-linearity – delayed response

Following Dearing J (2004), in: Goudie A.S. [Ed.]: Encyclopedia of Geomorphology, p. 721

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Forces and Response

Dearing, J.A., Battarbee, R.W., Dikau, R.,

Larocque, I. & F. Oldfield (2006):

Human-environment interactions: learning

from the past. Regional Environmental

Change, 6: 1-16.

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Following Graf (1988) and Brunsden and Thornes (1979)

Hufschmidt G., Crozier M.J. & T. Glade (2005): Evolution of natural risk: research framework and perspectives.- Natural Hazards and Earth System Sciences 5(3):

375-387.

Lagged responses ….

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Earth System Science …… ??

Hugget (2003), p.42

Trad Geoscience Approach:

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Trad. Geoscience Approach:

Environment Society

A geosystem within globalenvironmental change

(Slaymaker 2000, nach

NASA 1988) – IGBP 1991

Slaymaker O (2000): Global Environmental Change: The Global Agenda. - In: Slaymaker O (Hrsg.): Geomorphology, Human Activity and Global Environmental Change,

Wiley: 3-20.

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Old wine in new bottles?

Weichhart P (2005): Auf der Suche nach der dritten Säule. Gibt es Wege von der Rhetorik zur Pragmatik?- In: Müller-Mahn D & U Wardenga (Hrsg.): Möglichkeiten und

Grenzen integrativer Forschungsansätze in Physischer Geographie und Humangeographie.- Leibniz-Institut für Länderkunde, Leipzig Heft 2, 109-136.

BASED ON

Weichhart P (2003): Physische Geographie und Humangeographie - eine schwierige Beziehung: Skeptische Anmerkungen zu einer Grundfrage der Geographie und zum

Münchener Projekt einer „Integrativen Umweltwissenschaft".- In: Heinritz G (Hrsg.): „Intcgrative Ansätze in der Geographie - Vorbild oder Trugbild?". Münchner

Symposium zur Zukunft der Geographie, 28. April 2003. Eine Dokumentation. Münchener Geographische Hefte 85. Passau, S. 17 - 34.

The „Three Pillar-Model“ (Weichhart 2005, based on Weichhart 2003, S. 25)

Society-Environment

Interaction

SocietyPhysical

Environment

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Summary

• The threshold approach is useful and practical.• Long landslide and triggering records are required.

• Various threshold models exist.

• Limitations are evident:

– Different landslide types

– Transferability of models

– Single failures – widespread occurrence

– Trigger information (e.g. 24h = 12am-12am, or 9am-9am, or …?)

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Some perspectives

• The threshold approach assumes stationarity of both thetrigger and the responding system.

• Instead we are living in a complex system defined by

– Non-linearity

– Chaotic behaviour – Self-organization

– Emergence

• Spatial distributions: Landslides & Precipitation.

• Human interference modifies the trigger impact andlandslide response.

• Thresholds for coupled social – landslide systems are

required.

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Selected references

Cepeda J.M., Malet J.P. & A. Remaître (2011): Empirical estimates of precipitation conditions for landslide triggering in France and Norway.-

Geophysical Research Abstracts 13, EGU2011-10550

Cepeda, J.; Nadim, F.; Høeg, K. & A. Elverhøi.(2009):A new function for estimating local rainfall thresholds for landslide triggering.- GeophysicalResearch Abstracts, 11, EGU2009-12290,

Crosta G.B. & P. Frattini (2003): Distributed physically-based rainfall thresholds for landslide triggering. Geophysical Research Abstracts, 5:

11896.

Crozier M.J. (1999): Prediction of rainfall-triggered landslides: A test of the antecedent water status model. Earth Surface Processes and

Landforms, 24(9): 825-833.

Crozier M.J. & T. Glade (1999): Frequency and magnitude of landsliding: fundamental research issues.- Zeitschrift für Geomorphologie 115,

141-155.

De Vita P. & P. Reichenbach, with contributions by J.C. Bathurst, M. Borga, G. Crosta, M. Crozier, T. Glade, F. Guzzetti. A. Hansen, J.Wasowski (1998): Rainfall-triggered landslides: a reference list.- Environmental Geology 35(2-3): 219-233.

Glade T. (1998): Establishing the frequency and magnitude of landslide-triggering rainstorm events in New Zealand.- Environmental Geology

35(2-3), 160-174.

Glade T. (2000): Modelling landslide-triggering rainfalls in different regions in New Zealand - the soil water status model.- Zeitschrift für

Geomorphologie 122, 63-84.

Glade T., Crozier M.J. & P. Smith (2000): Applying probability determination to refine landslide-triggering rainfall thresholds using an empirical

"Antecedent Daily Rainfall Model".- Pure & Applied Geophysics 157, 1059-1079.

Guzzetti F., Peruccacci S., Rossi M. & C.P. Stark (2007): Rainfall thresholds for the initiation of landslides in central and southern Europe.-

Meteorol. Atmos. Phys. 98: 239-267.

Guzzetti F., Peruccacci S., Rossi M. & C.P. Stark (2008): The rainfall intensity–duration control of shallow landslides and debris flows: an

update.- Landslides 5: 3-17.

Hufschmidt G., Crozier M.J. & T. Glade (2005): Evolution of natural risk: research framework and perspectives.- Natural Hazards and Earth

System Sciences 5(3): 375-387.

Reichenbach P., Cardinali M., De Vita P- & F. Guzzetti (1998): Regional hydrological thresholds for landslides and floods in the Tiber River Basin

(central Italy).- Environmental Geology 35 (2-3): 146-159.

Wieczorek G. & T. Glade (2005): Climatic factors influencing triggering of debris flows.- In: Jakob M. & Hungr O. (Eds): Debris flow hazards and

related phenomena.- Springer, Heidelberg 325-362.

A t

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A great resource …http://rainfallthresholds.irpi.cnr.it/

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Paekakadiki, New Zealand © Graeme Hancox

Thank you for your attention!

[email protected]

http://geomorph.univie.ac.at/

http://homepage.univie.ac.at/thomas.glade/

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Appendix I

Guzzetti F., S.Peruccacci, M. Rossi and C.P.

Stark (2007): Rainfall thresholds for the initiation

of landsldies in central and southern Europe.-

Meteorol. Atmos. Phys. 98: 242.

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Appendix II

Guzzetti F., S.Peruccacci, M. Rossi and C.P.

Stark (2007): Rainfall thresholds for the initiation

of landsldies in central and southern Europe.-

Meteorol. Atmos. Phys. 98: 248.

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Appendix III

Guzzetti F., S.Peruccacci, M. Rossi and

C.P. Stark (2007): Rainfall thresholds for

the initiation of landslides in central and

southern Europe.- Meteorol. Atmos. Phys.

98: 244f.

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Appendix IV

Guzzetti F., S.Peruccacci, M.

Rossi and C.P. Stark (2007):

Rainfall thresholds for the

initiation of landsldies in central

and southern Europe.- Meteorol.

Atmos. Phys. 98: 246.

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Appendix V







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Appendix VI







Documents

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