Landslide risk management in

Norway

Bjørn Kalsnes, NGIF. Nadim (NGI), R. Hermanns (NGU), H.O. Hygen (met.no), G. Petkovic(NPRA), B.K. Dolva (NPRA), H. Berg (NVE), D.O. Høgvold (DSB)

JTC1-TR3, Napoli, 17 November 2015

Outline

A few words about Norway

Types of landslides in Norway

Climatic and demograhic changes

Landslide risk management

Research

Natural legislation and policy

Crisis preparedness

Norway

•Area: 300.000km2

•Population: 5.2 mill.

•N-S: ca. 2000km

•West coast and north, highmountains, deepvalleys, fjords, etc.

•NB! Large rural areas. Few citiesand many single dwellings.

Some facts - geohazards

• Last 150 years: >2000 deaths from geohazards in Norway

• Snow avalanches (1550 deaths), rock-, clay-and debris slides (450 deaths)

• Most slides have a meteorological trigger

• Extreme precipitation events, snowmelt

• 3-4 large catastrophes (>20 fatalities) per 100 years

• Frequency, intensity and location of slides may change in a future climate

Landslide hazard in Europe

SafeLand, Jaedicke et al., 2013

Landslide hazard and risk in Norway

-Snow avalanches-Rock slope failures-Water-triggered landslides-Quick clay slidesDeaths Landslide types

Distribution of deaths due to slides

1900-2010

0 50 100 150

2000

1990

1980

1970

1960

1950

1940

1930

1920

1910

1900

Antall drepte i skred per tiår 1900-2010

Snøskred

Steinskred

Løsmasseskred

Undervannsskred

Isnedfall

0 50 100 150 200

Akershus

Vestfold

Hedmark

Ø stfold

Aust-Agder

Oslo

Buskerud

Rogaland

Nord-Trøndelag

Vest-Agder

Telemark

Sør-Trøndelag

Oppland

Finnmark

Hordaland

Møre og Romsdal

Troms

Nordland

Sogn og Fjordane

Antall drepte i skred per fylke 1900-2010

Snøskred

Steinskred

Løsmasseskred

Undervannsskred

Isnedfall

Landslide types

Snow avalanche (not discussed more)

Rock slides/falls

Water-triggered slides (Debris flows/slides)

Quick clay slides

Rock slides 175 fatalities in 3 large accidents, 1905, 1934, 1936.

Fatalities causedby the tsunamis, not the rockslideitself.

Many large unstable rock slopes in Norway, only few aremonitored.

• Troms: 117 unstable slopes• Sogn & Fjordane: 23 unstable

slopes• Møre & Romsdal: 22 unstable

slopes

• Much of the country still not mapped.

• Many unstable slopes are periodically monitored, but only few are continuously monitored.

• NGU and ‘Åknes-TafjordBeredskap’ (NVE) play important roles in mapping and monitoring

Unstable rock slopes in Norway

Fallnesfjellet, Skibotn.I. Henderson, NGU

Kassen ved Bandak. R. Hermanns, NGU

Section for rock slides, NVE

Åknes, Volume ca. 50 mill m3

Movement 2-15cm/year

Cont. monitored

mountains 2015

Storfjorden (Å knes) • Narrow fjord with steep hillsides

• Maximum depth more than 700 m

• Fjord heads in the inner part of the

fjord are the most critical locations

– Largest amplification

– Most people live here

• In summer thousands of tourists

• Arrival times after slide release

– Hellesylt, 4-5 min

– Geiranger, 10 min

– Tafjord, 12 min

New movie:

‘Bølgen’ (The

Wave), released

September 2015.

The “Veslemannen”

Event, fall 2014

Volume:

120 000 – 180 000 m3

‘Mannen’

Veslemannen

From L.H.Blikra, NVE

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0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

27/10/14 0:0027/10/14 12:0028/10/14 0:0028/10/14 12:0029/10/14 0:0029/10/14 12:0030/10/14 0:00

Press conference 15:00, 28 October

Inverse velocity – timing of landslide

From L.H.Blikra, NVE

October 29: Less precipitation than forecast, colder weather with snow. Reduced velocity.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

27/10/14 0:0027/10/14 12:0028/10/14 0:0028/10/14 12:0029/10/14 0:0029/10/14 12:0030/10/14 0:00 From L.H.Blikra, NVE

Water-triggered slides

Ca. 125 fatalities in debris flows / slides last 150 years

Debris slide, City of Bergen 2005• Landslide caused by heavy

rain (and human activity).

• 4 Fatalities

• After 2005, City of Bergen hired 3-4 geologists.

• Started program of regional suceptibility mapping.

• Followed up with detailedmapping of all ”hot” areas.

• Based on the mapping, starts program of mitigation to secure dangerous areas.

Notodden station, July 2011, excess surface water due

to blocked drainage

Quick clay slides

•Large populationslive in quick clayareas

•Last 100 yearsmainly released by human activity

•River and streamerosion is alsoimportant

•Rare, large eventswith potentiallylarge consequences.

•150 fatalities last 150 years

Rissa slide 1978

Expected change next 100 years:

Continued increase, and increase in number and intensity of ”extremeevents”

NB! Large regional variation and uncertainties.

Climate changes

Annual precipitation

Annual precipitation in Norway, 1900-2013 (% of ”normal” (1961-1990))

Klima 2100

Report launched in September 2015.Describes past climate, and prospectscoming climate changes, and effects.Updated down-scaling ofIPCC AR5 report.

Demograhic changes (SafeLand)

Landslide risk management

Mapping

Building codes

Detailed hazard and risk analyses for building purposes

Risk mitigation measures

Managing risk: Mapping of hazards

Different levels and scales

• National level; Susceptibility maps (1:50 000). Do not include probability. Covers wholecountry.

• Municipality level: Overall land use planning (1:5000 – 1:20 000). Includes probabilityaccording to P & B act.

• Detailed land use planning: 1:5000. Includesprobability according to P & B act.

• Individual buildings: 1:1000. Includesprobability according to P & B act.

What are the hazard maps used for?

Identify the extent of slide and avalanche problems for a municipality

Plan new areas for buildings and other infrastructure─ Ensure safe localisation

In critical situations (e.g. in periods of extremeprecipitation)

─ Safe areas

─ Which houses are safe?

─ To where, locally, can people be evacuated.

Prioritizing of mitigation measures─ Risk assessment

─ Which houses need mitigation first?

Mitigation strategies for geohazards;

Risk reducing measures.

1. Good land use planning!

2. Proper and enforced building codes and good construction practice.

3. Construction of physical mitigation measures, such as dams, and barriers, catching nets, terrain modifications, etc.

4. Establishment of early warning systems

5. Establishment and maintenance of network of escape routes, safe places, etc.

6. Ensure public awareness and a community preparedness; build up competence regionally and locally.

7. Build up and maintain a functioning society; health, education, communication, transport, rescue and relief, etc., etc.

Physical mitigation measuresPurpose:

• To prevent slide release

• Stop landslides or lead them into areas where they do less or no damage

• Design and construct buildings to withstand slide forces.

• Move buildings (planned or existing) to safer places.

Mitigation measures; sometimes massive!

Preventing rock fall or rock slide

release

Dams for rockfall and debris slides

Catching dam

“Plough dam”

Dam with energy absorbing material for rock fall.

Levees for snow avalanches and debris slides

Received snow avalanches 6 times last winter.

Debris flow protection along creeks and ravines

With sedimentation basins

Quick clay mitigation; engineering solutions (support constructions and geometry changes)

Anchored retaining wall

Quick clay

Bedrock

Relief - counterfill

Quick clay

These are measures which the municipality may enforce to allow building. The stability must be improved, and the engineer defines the best measure.

Monitoring systems, Å kneset:

Surface movements(InSAR, tensiometers, Radar)Deformations in boreholesPore pressure / water tableSeismic activity, Weather station,

Total stations. Lasers, etc.

Early warning centre: in operation 24 / 7

Alarm tresholds criteriabased on:

• Total displacements

• Velocity in defined time periods

• Acceleration

• Treshold values need to be defined and updated

• Sirens in all the villages located in the tsunami hazard zone

• Phone messages

• Evacuation procedures and routes

• The police is responsible for the evacuation

A Norwegian Centre of Excellence established in 2003 by the Reseach Council of Norway

10 years duration

Budget : ~ NOK 20 – 25 mill. / year(including in-kind contribution of partners,

Contribution from Research Council of Norway = NOK 12 mill. / year)

RESEARCH ACTIVITIES –

INTERNATIONAL CENTRE for GEOHAZARDS

Research activities (Norway)Project Duration Coordinator Partners Funding/Budget Research topic

Climate and

Transport

2007-

2013

The Norwegian

Public Roads

Administration

(NPRA)

NPRA and more than 10

Norwegian institutions.

NPRA Effect of climate

change on the road and

rail network.

GeoExtreme 2005-

2008

ICG/NGU/

NGI

Bjerknes Centre,

Norwegian Meteorological

Institute (met.no), Centre for

International and

Environmental Research

(CICERO)

NRC/1 mill EUR Relationships between

climate scenarios and landslides in

Norway, assessment of social-

economic consequences of future

landslide.

InfraRisk 2010-

2013

ICG/NGI Met.no, CICERO, The Institute of

Transport Economics (TØ I), National

Emergency Planning College (NUSB),

The Norwegian Rail Administration

(JBV), NPRA

NRC/1 mill. EUR Impact of extreme

weather events on

Norwegian infrastructure.

Natural

hazards – infra-

structure for

floods and slides

(NIFS)

2012-

2015

NPRA NVE, JBV NIFS/5.5 mill EUR Reduce vulnerability

and prevent accidents

and injuries caused by

landslides, avalanches

and floods.

Klima2050 2015-

2022

SINTEF SINTEF, NTNU, NGI,

MetNo, BI + state and private

partners

NRC/25 mill EUR Climate related risks

on buildings and

infrastuctures

Research activities (EU)

Project Duration Coordinator Partners Funding/Budget Research topic

SafeLand 2009-

2012

ICG/NGI 27 European

organisations (universities,

national geological surveys,

private institutions)

EC FP7/

8.8 mill EUR

Landslide risk

assessment and

management in Europe a

changing climate and

demographic perspective.

Matrix 2010-

2013

GFZ

(Germany)

NGI, and 11 other

European organisations

EC FP7/4 mill EUR Multihazard risk

assessment.

Intact 2014-

2017

TNO

(Netherlands)

NGI, and 11 other

European organisations

EC FP7/3.5 mill

EUR

Natural hazards and

critical infrastructure.

RCN: Center for Research Based Innovation:

‘Klima 2050’

• Risk reduction throughclimate adaptation of buildings and infrastructure

• 5 scientific partners, 15 industrypartners. Lead by SINTEF

• 8 years; 2015-2023• Total budget NOK 221 mill.

WP3 on landslides –

Knowledge gaps to be filled by Klima 2050Consistent and verifiable procedures for mapping landslide risk at local or regional scale

Accurate methods for the vulnerability assessment of critical infrastructure (incl. multi- and cascading hazards)

Reliable local/regional early warning systems

Reliable geomechanical models

Environmentally friendly methods for slope stabilization

Cost-effective and sustainable methods for protection works

Relevant procedures for managing landslide risk at various levels (national, county, municipality)

Regulation and policy issues - actors

The Norwegian Water Resources and Energy Directorate(NVE)

The Norwegian Directorate of Civil Protection (DSB)

Municipalities, counties

Road and railway authorities (SVV, JBV)

Private consultants

Regulation and policy issues - activities

Legal framework

Mapping

Land use planning

Protection measures

Warnings

National legislation concerning natural hazards in Norway

Planning- and building act─ § 25: Coverage:

─ Building areas

─ Agricultural areas

─ Public traffic areas

─ Hazard areas: …areas that because of potential for

avalanches, slides or flooding, or other specific danger,

are not allowed to be developed, or can only be

developed under special conditions concerning safety

─ §68: Building ground. Environmental conditions

─ An area can only be built upon if there is sufficient

safety against danger or considerable disadvantage

because of natural- or environmental conditions.The

municipality may forbid building, or put forward special

requirements for the use of areas mentioned above.

Definition of acceptablehazard for buildingswith different functions

Based on probability

For new buildings, after1985. Most buildingsare older!

The Plan and Building Act

Slide

Annualprobability

(Return period)

10-3

(1/1000)

2 x 10-4

(1/5000)

10-2 (1/100)

Landslide

Organization and responsibilityThe municipality:Responsible for ensuring that all necessary investigations have been carried out prior to any building or other development. Responsible for reinforcement of the Planning and Building Act.

The County administration:Can stop building projects, even if approved by the municipality.

The government: Directorate for Water and Energy (Ministry of Energy):Responsibility for making plans and priorities for hazard and risk mapping, establishment of mitigation measures, landslide and avalanche warning, etc. Provides funding for mapping and mitigation.

Directorate for Civil Protection and Emergency Planning:Responsible for preparedness and safety at all levels. Natural hazards recently included. Excercises.

Crisis preparednes – four principles (DSB)

Subsidiarity: Lowest possible organisation level, i.e. municipality.

Similarity: Organisation as during normal circumstances.

Responsibility: Organisation responsible under normal circumstances also responsible during a crisis.

Cooperation: Authorities, agencies and other stakeholders must seek cooperation with each other.

Crisis preparedness

Emergency preparedness

Regional warnings (run by NVE)

Early warning large rockslides (run by NVE)

Test scenarios (quick clay slides, large rock slides)

Summary and conclusions

• Norway has frequent problems related to natural hazards, causing economic loss and loss of lives.

• National legislations provide the necessary instruments to prevent much damage. The problem is that they are not always followed.

• The planning and building act, if used properly, is efficient, but many houses were already built in hazardous terrain before the law appeared.

• Hazard (and risk) mapping is an important tool in all municipalities, and are important for land use planning, preparedness for acute situations, design of infrastructure, etc.

• Physical mitigation measures are important but not always sufficiently prioritized. They are expensive, and unfortunately it is often easier to get funds for mitigation after an accident has happened!

• Large tsunamigenic rock slides are the biggest potential catastrophes in Norway. Mitigation measures for these are mostly monitoring and early warning.

• Public awareness and a community preparedness, as well as competence at all levels (individual, local, regional, national) are perhaps the most important and effective measures!

Thank you for your

attention!