05 Landslide Risk Maps Planning

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Background of the problem

Some inactive landslides had been recently re-activated in a study area.

Answering these questions is the target of this contribution

Illustrated by using the Bonn Case Study, Germany and Fuzzy SetModel, a typical spatial prediction model.

Open Questions Of the remaining inactive landslides, which ones are likely be re-activated near

future?

In answering the question using spatial modeling, should we use the activelandslides only or both groups of active and inactive ones?

Why?

Chung C.-J.. & Glade T. (2004): Use of Active and Inactive Landslides for Spatial Landslide Hazard Modeling.-Presentation givenat the EGU conference in Nice, April 2004

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Bonn Case Study, Germany

23 active landslides1983 pixels

45 inactive landslides4064 pixels

23 active landslides arereactivated landslides

Bedrock geology

DEM consisting ofSlope angles,Elevations, andAspects angles

10m x 10m pixels

1,074,440 pixels instudy area (107 squarekm)



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Landslide distributions

23 active landslides scars,1983 pixels

45 inactive landslides scars, 4064pixels

Bedrock geology map

DEM consisting of

Slope angles,Elevations, andAspects angles

10m x 10m pixels

1328 pixels x 1298 lines

1,074,440 pixels in study area(107 square km)

Non-landslide area 1,068,393pixels


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Empirical distribution functions (histograms) of slope angles:1. 23 active landslides (1983 pixels) Red curve

2. 45 inactive landslides (4064 pixels) Blue curve

3. All 68 landslides (6047 pixels) Green curve

4. Remaining area (1,068,393 pixels) black curve

Emprical frequency distribution functions of slope angles

0.000

0.002

0.004

0.006

0.008

0 10 20 30 40

Slope angle in degree

Normalisedfrequency Inactive landslides

Acti ve l andslid es

All lan dsli des

Non-landslide area

Slope angles, a topographical characterization


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Empirical distribution functions (histograms) of elevation:1. 23 active landslides (1983 pixels) Red curve

2. 45 inactive landslides (4064 pixels) Blue curve

3. All 68 landslides (6047 pixels) Green curve

4. Remaining area (1,068,393 pixels) black curve

Emprical frequency distribution functions of elevations

0.000

0.001

0.002

0.003

0.004

0.005

0 50 100 150 200 250 300

Elevation in m

Norma

lise

dfrequency

Inactive landslides

Active l andsli des

All landsl ides

Non-landslide are a

Elevation, a topographical characterization

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Empirical distribution functions (histograms) of elevation:1. 23 active landslides (1983 pixels) Red bars

2. 45 inactive landslides (4064 pixels) Blue bars

3. All 68 landslides (6047 pixels) Green bars

4. Remaining area (1,068,393 pixels) black bars

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

1 3 5 7 911

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15

17

19

21

23

25

27

29

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Bedrock types

Norma

lize

dfrequency

Acti ve la nd sli de s

Inactive landslides

All la nd sli de s

Non-landslide are a

Bedrock Geology, a geological characterization


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75%

Top 1%2,5 - 5%10 - 15%

20 - 25%

50%

Prediction

23 active

107,444 km2

1,0% 1,07 km2

2,5% 6,80 km2ChungC-JF & Glade T (2004) Useof active andinactive landslides for spatial landslide hazardmodelling.- In: EGU, 26.-30 April 2004, Nizza, France

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75%

Top 1%2,5 - 5%10 - 15%

20 - 25%

50%

Prediction45 inactive

107,444 km2

1,0% 1,07 km2

2,5% 2,68 km2

Chung & Glade (2004)


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InactivelandslidesWITHOUT

expectedreactivation

InactivelandslideswithPARTIALLY

expectedreactivation

SCENARIO:Susceptibility map calculated withactive landslides and combined with locations of

currently inactive landslides

A

A

D C

B

B

D C

Top 1% area5.0-10.0%

20.0-25.0%

30.0-60.0%

Chung & Glade (2004)

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Resolution of data sets example DHM

1m 5m 10m

20m 50m 100m


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Of 45 inactive landslides, 37 expected to re-activate. Two (inpink circles) expected to partially re-activated, while only sixlandslides (in black circles) NOT expected to re-activate.

Active landslides help identifying which ones will re-activate.

Fuzzy sets are valuable tools however experiments with logisticdiscriminant analysis and likelihood ratio models providesimilar results

Concluding remarks


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Example of the Swabian Alb, Germany- a contrast: the geometrical approach


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Example of the Swabian Alb, Germany

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Example of the Swabian Alb, Germany

Preliminary results of the InterRISK project

Local and regional landslide risk analysis

Aims of the study

Geomorphological and soil mechanical investigation of asingle landslide

Measurement and modeling of recent kinematics Analysis of climatic thresholds

Natural hazard modeling

Risk analysis (R = H x E x V)

Coupling of local and regional results => upscaling

Validation of regional results using statistical methods andhistorical data

Integrative risk management


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Study areas

Regional: ca. 2000 km

Regional 2: ca. 400km

Local:

Mssingen schingen (1)

Lichtenstein -Unterhausen (2)

Irrenberg (3) (planned)

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Preliminary results: local scale Mssingen-schingen

rotational and translational slides

various ages and magnitudes


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Preliminary results: local scale Mssingen-schingen

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Investigation

Oes 1

Oes 3

Oes 2

Plateau schingen linear structures linear arranged small dolines => linear network of fissures?


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Scenarios of complex landslide evolution

1.5 Mio m

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Evolution of a complex landslide

17 Mio. m

5 Mio m


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21DOP, Source: Landesvermessungsamt Baden-Wrttemberg(www.lv-bw.de), AZ.: 2851.9-1/11

DEM, Source: Kreja, R., Uni Tbingen

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Common limitation of landslide hazard assessments

No information on potential landslide volume

One solution: Sloping Local Base Level (SLBL)

Assumptions

All undercut slopes are unstable on a longterm scale

These slopes can be detected from a DTM by the SLBL


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Sloping Local Base Level (SLBL)

Iterative routine Lowers each point of the DTM located above the average altitude

of two opposite points among its four direct neighbours untilconvergence is reached(Jaboyedoff et al. 2004, 2005)

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Study area schingen

0 400m

DOP, Source: Landesvermessungsamt Baden-Wrttemberg(www.lv-bw.de), AZ.: 2851.9-1/11


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Study area schingen

5m DEM

Source: Kreja, R.,Uni Tbingen

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SLBL profile spur

400

500

600

700

800

900

1000

0 200 400 600 800 1000 1200 1400

Length (m)

Height(m)

P1_slbl

P1_orig

Profile

Legend

landslide thickness (m)

>1 - 10

>10 - 20

>20 - 30

>30 - 40>40 - 50

>50 - 60

>60 - 70

>70 - 80

>80 - 100

Sliding of whole spur



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Profile

SLBL profile spur front

400

500

600

700

800

900

1000

0 200 400 600 800 1000 1200 1400

Length (m)

Height(m)

P1_slbl

P1_orig

Legend


>1 - 10

>10 - 20

>20 - 30

>30 - 40

>40 - 50

>50 - 60

>60 - 70

>70 - 80

>80 - 100

Sliding of spur front


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Profile

SLBL profile lowest landslide block

400

500

600

700

800

900

1000

0 200 400 600 800 1000 1200 1400

Length (m)

Height(m)

P2_slbl

P2_orig

Legend


>1 - 10

>10 - 20

>20 - 30

>30 - 40>40 - 50

>50 - 60

>60 - 70

>70 - 80

>80 - 100

Sliding of lowest landslide block



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17 Mio. m

5 Mio. m1.5 Mio. m

Volume estimation whole spur

spur frontlowest landslide block

Legend


>1 - 10

>10 - 20

>20 - 30

>30 - 40

>40 - 50

>50 - 60

>60 - 70

>70 - 80

>80 - 100


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Applied Methods for validation


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Validation of SLBL results

Sass, Bell & Glade (submitted)

2D-resistivity


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Spatial distribution of landslides trigger????

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Classification 1 Classification 2

Logistic RegressionGeomorphometry 50m (Height, slope, aspect)GeologySoilsLandslide locations (Uni Tbingen)


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SLBL at regional scale

36Land use data provided by Blchl & Braun, InterRISK Assess


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Spatial distribution of landslides Rainfall????

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Conclusion

First results of the SLBL are very promissing

The shear plane for different landslide scenarios can bemodelled in 3D

SLBL can reliably estimate potential landslide volume

SLBL can be applied at local and regional scale Integration of lanslide volume in local and regional landslide

hazard assessment will lead to significant improvements


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Use of landslide risk maps in landuse planningand restrictive zoning

PD Dr. Thomas [email protected]

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Risk assessment & management (1/3)

P robability oflandsliding

Triggeringfactors

Landslideinventory

P reparatoryfactors

Hazardassessment

Runoutbehavior

Land use

E lements atrisk

Vulnerabilityassessment

Riskassessment

Riskmanagement

C ost-benefitanalysis Dai et al. (2002)


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Lecture Overview

Risk management Risk management and spatial planning

Risk assessment

protection objects

Acceptable and tolerable risk

Risk treatment options

Strategies for risk reduction

Efficiency of mitigation measures

Contribution of spatial planning to risk managementstrategies

Natural hazards in land use plans

Some preliminary findings of ARMONIA on spatialplanning & risk

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.... Everything a question of management?

Risk-perception

Risk-management

Risk-evaluation

Cartoon: Sidney Harris

Weichselgartner J (2003): Risiken im Naturrisikomanagement: Herausforderungen einer politikrelevanten Naturgefahrenforschung.- 54. DeutscherGeographentag Bern, FS 11 'Katastrophenvorsorge als Thema der Hazard- und Risikoforschung'


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Definitions of risk management

Application of measures and methods to achieve thetargeted security and to adapt security planning tochanging circumstances. Risk managementcomprehends risk control and risk communication.

(BUWAL, 1999)

The process of weighting policy alternatives in thelight of the results of risk assessment and, if required,selecting and implementing appropriate control

options, including regulatory measures.(FAO, 1997)

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Risk management development

Risks used to be treated technically (Greiving, 2002)

Focusing on defence of risks

E.g. disaster management originated during the cold war(planning for nuclear war/bomb shelters) (Pearce, 2003)

Influence on probability of events influence on damage

potential Sustainable Development => greater focus on prevention

Shift of paradigm towards risk and disaster management

Spatial planning as an important actor

Partly due to technical and economical limitations ofdefence of risks (Greiving, 2002)


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Shift in management strategies

Salter, 1998 in Pierce, 2002

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Risk management & spatial planning


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Natural disasters are typical examples of people living inconflict with the environment

The vulnerability of populated areas to natural disaster ispartly a consequence of decades of spatial planningpolicies that have failed to take account of hazards andrisks in land use zoning and development decisions

Spatial planning as one important actor plays animportant role for the prevention of natural hazards by:

Selecting the areas most suitable for further urbandevelopment

Restricting future development in areas at risk(Greiving, 2005)

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There is a need to develop a more effective methodologyto incorporate:

Natural hazard assessment and disaster reduction intospatial planning

Knowledge, technology and actors in the field of risk

assessment and land use zoning(Greiving, 2005)


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What is safe?

Before risk is managed, risk needs to be assessed

Definition of protection objects

Definition of acceptable and tolerable risk

acceptable risk of a single individual

acceptable risk of the whole population

acceptable risk of objects

Giovanni Crosta

Residual Risk!!!!!

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Protectionobjectives &planning

Utilisation Hazard

Protectionobjectives

Lack ofprotection

Sufficientprotection

Protection ofactual state

Action planning

Actions technically,economically &

ecologicallyproportional ?

Implementation ofaction

& emergency plans

Yes

No

Correction ofgoal of

protection/utilisation

Adapted from KAWA, TBA &AGR, 1999


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Who defines acceptable risk level?

Differs from country to country, region to region,

Formation of opinion in socio-political discourse

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Risk treatment options

Accept the risk

Avoid the risk

Reduce the likelihood

Reduce the consequences

Monitoring and warning systems

Transfer the risk

Postpone the decision

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Strategies for risk reduction

1. Increasing of social acceptable threshold risk

2. Mitigation of risk through structural action to hazardreduction

3. Mitigation of risk through non structural action topotential damage reduction

The total risk evaluation, (in terms expected annualcost of damage), permits to choose through differentmitigations strategies with cost-benefit analysis. Byevery single cost of each action, a benefit in terms ofrisk reduction should be associated, expressed by thereduction of annual cost of landslide damage.ARMONIA Project report, 2005


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Increasing of social acceptable threshold risk (1/2)

It is very seldom that local governments attempt toeducate the public to the hazards that threaten them(Aguirre, 1994)

But: (Drabek, 1986)

Surveys indicate that the public would welcome suchefforts

Relationship between the degree to which communitiesaccept disaster management planning and to the degree to

which they experience disasters

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Increasing of social acceptable threshold risk (2/2)

Instruments for awareness campaigns:

use of mass media communication

diffusion of informative brochures that describe the kindof risk and the behavior to assume in case of alarm andemergency

assemblies and meetings with administrations andstakeholders

installation of hazard signage

stipulation of insurance for damage coverage

ARMONIA Project report, 2005


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Mitigation of risk through structural action to

hazard reduction Reduction of the triggering factors

Land use reclamations and hydrological and geologicalenvironmental restoration work

rationalisation of land use and agricultural activities

Direct intervention on active landslides in order toprevent remobilisation and control the evolution

Stabilisation works designed to reduce the mobilisation

forces (slope re-profiling, detachment of unstable blocks)or increase resistant forces (i.e. drainage, chemical andphysical treatment, concrete injection, walls, nails,anchors, bolts, piling)

=> Usually of high costsARMONIA Project report, 2005

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Mitigation of risk through non structural action topotential damage reduction

Reduction of the potential damage

Acting on elements at risk and vulnerability

Delocalisation of EE

Limitation of urban expansion

Land use definition of unstable areas

Implementation of technical measures or restrains

More flexible than structural measures

=> Usually lower costs ARMONIA Project report, 2005


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Efficiency of mitigation measures (1/2)

Usually done in cost-benefit analysis

Evaluation of protection objects and acceptable risk

Definition of maximal costs for risk reduction(depending on the element at risk)

(Hollenstein, Merz, Bhler, 2004)

benefit

tEfficiency

cos=

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Efficiency of mitigation measures (2/2)

Example (Adapted from BUWAL, 1999):

If a landslide hits a road it will cause 0.05 deaths/year

Through geotechnical measures the risk will be reduced to0.01 deaths/year

Cost for the measures: 5 million US$

Expected durability: 50 years

=> yearly cost of measures: 100.000 US$ (w/o discounting)

=> Risk reduction costs = Costs for measures/risk reduction

lifesavedperlifesaved

treductionrisk 000.500.2*)01.005.0(

000.100cos =

=

Proportional or not ?


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Non-landslide specific contribution of spatial

planning to risk management

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Possibilities topresent naturalhazards in landuse plans

EPSON Hazardsproject report, 2006


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LandslidesDamages following the event on 2-6 November 1994 in the Piemonte

Region, Northwest Italy

Photographs: Casale & Margottinieds., 1996

Photographs: Regione Piemonte, 1998

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Some preliminary findings of ARMONIA onspatial planning & risk

Spatial planning is not responsible for undertakingrisk assessment, but makes use of the results provided

by sectoral planning.

However, the relevance of risk assessment for spatial

planning has to be readjusted again: Spatial planningnormally needs only hazard information; risk andvulnerability are only important in a few extremesituations (e.g. where relocation of existingdevelopment is being considered).

Greiving, 2005


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Some preliminary findings of ARMONIA on

spatial planning & risk For risk management (non-structural mitigation

activities), only the vulnerability of the differentobjects to be protected is, in general, of relevance(e. g. the different type of land-uses or the differenttypes of buildings).

In contrast, structural mitigation and emergencyplanning need information about the existingvulnerability. This information has to be seen as a

basis for the analysis of costs and benefits of givenalternatives or evacuation plans.

Greiving, 2005

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In consequence, the further scientific work shouldconcentrate on the optimisation and harmonisation ofhazard assessment, which is principally needed forthe daily, routine practice of spatial planning.

For extreme situations of high hazard and likelihoodwhere the relation of existing population anddevelopment is being considered; further work shouldmake use of an existing multi-risk approach whichcan be adopted for spatial planning. Here, the need toagree on a common definition of vulnerability hasto be seen as crucial.

Greiving, 2005


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spatial planning & risk Spatial scales: Hazard information is needed on two

different scales: a regional and a local one. Inconsequence, there is only a need for two harmonisedlegends.

Multi-risk approach: There is no real need to createmulti-risk indicators or indices from a spatial

planning point of view. It is more important that allrelevant hazards are really considered in spatial

planning practice.

Multi-hazard approach: Most of the examples haveshown that relative hazard scales are a possibility tocreate integrated multi-hazard information.Greiving, 2005

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Information management: It is highly important thatexisting information is accessible and thatinformation flows are managed.

Indicators: the most important indicator for spatialplanning is the extent of the hazard; further, theoccurrence is important; for some planningdesignations, indicators about hazard intensities(water depth, water speed etc.) are important

Greiving, 2005


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spatial planning & risk Addressees: Sectoral planning has to be seen as the

direct addressee of the forthcoming Directive whereasspatial planning can be characterised as one of severalend-users which have to take into account the

provided hazard information.

Greiving, 2005

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Current European situation


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References

Aguirre B. 1994: Planning, Warning, Evacuation, and search and rescue:A review of the social science research literature. Texas A & MUniversity, 46 pp.

ARMONIA Project report 2005: Collection and evaluation of currentmethodologies for risk map production - Task 2.3: Collection andevaluation of current methodologies for landslides. 88pp.

Bundesamt fr Umwelt, Wald und Landschaft 1999:Risikoanalyse beigravitativen Naturgefahren - Fallbeispiele und Daten. In: Umwelt-Materialien Nr. 107/II Naturgefahren. Bern, 129 pp.

Dai, F.C., Lee, C.F. and Ngai, Y.Y. 2002:Landslide risk assessment andmanagement: an overview. Engineering Geology 64, 65-87.

Drabek, T. E. 1986:Human system responses to disaster: An inventory ofsociological findings.New York. 509 pp.

EPSON Hazards project report 2006: The Spatial Effects and Managementof Natural and Technological Hazards in Europe. 198 pp.

FAO 1997:Risk management and food safety. Report of a joint FAO/WHOConsultation. Rome, 32 pp.

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References

Greiving, S. 2002: Planung und Katastrophenvorsorge Verknpfung berVerfahren und organisatorische Regelungen. In: Deutsches Komitee frKatastrophenvorsorge e.V. (DKKV): Zweites Forum KatastrophenvorsorgeExtreme Naturereignisse Folgen, Vorsorge, Werkzeuge, 120-127.

Hollenstein K., Merz, H. & Bhler, B. 2004:Methoden des risikobasiertenPlanens und Handelns bei der Naturgefahrenabwehr. ETH Zrich. 47 pp.

Pearce, L. 2003:Disaster management and community planning, and

public participation: How to achieve sustainable hazard mitigation.Natural Hazards 28, 211-228.

Volkswirtschaftsdirektion Amt fr Wald, Bau-, Verkehrs- undEnergiedirektion Tiefbauamt, Justiz-, Gemeinde- und KirchendirektionAmt fr Gemeinden und Raumordnung 1999:Achtung, Naturgefahr! Verantwortung des Kantons und der Gemeinden im Umgang mit

Naturgefahren. Bern, 29 pp.

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