Risk Analysis of Geological Hazards and Disaster Management

Risk Analysis of Geological Hazards and Disaster Management

Dr Claudio J Ferreira

The University of Sheffield

2008 2

ContentsRisk definition

Hazard

Vulnerability

Damage

Risk Mapping

Analytical or Synthetic approaches

Examples

GIS role

Disaster Management

2008 3

Risk definition

R = H x V x D, where

R=RiskH=HazardV=VulnerabilityD=Damage

Process

Element at risk

What is the difference between risk and hazard?

2008 4

Hazard definition

Hazard is the probability of occurrence, within a specific period of time in a given susceptible area, of a potentially damaging phenomenon. Hazard appraisal is obtained by the following equation:

Hazard = extension (area) x frequency (time) x magnitude (strength) of the events

2008 5

Susceptibility

Phenomenon

Event

Accident

Disaster

any event, circumstance, or experience that is observable

an important happening but without social losses

a happening that results in injury, loss, damage

any happening that causes great harm or damage

predisposition of a place to occurrence of certain phenomenon

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Disaster any happening that causes great harm or damage

For example, at least one of the following criteria must be fulfilled to be considered a disaster at UN/ISDR secretariat:

* 10 or more people reported killed

* 100 people reported affected

* Declaration of a state of emergency

* Call for international assistance

http://www.unisdr.org/disaster-statistics/introduction.htm

2008 7

Disaster ClassificationDisasters

BiologicalGeologicalHydrometeorological

NaturalTechnological

Floods

Landslides, Mudflows, Avalaches, Tidal Waves

Windstorms

Typhoons, Cyclones, Hurricanes, Storms (Winter, Tropical), Tornadoes

Droughts

Extreme temperatures, wildfires

Earthquakes Epidemic

Volcanic Eruptions

Tsunamis

Insect Infestation

Chemical spills, explosion, radiation, transport accidents

Centre for Research on the Epidemiology of Disasters (CRED) School of Public Health, Catholic University of Louvain Brussels, Belgium http://www.cred.be - Annual Disaster Statistical Review: Numbers and Trends 2006

http://www.cred.be/

2008

Disasters

Physic Biological

Hydro-logical

Geolo-gical

Atmos-pheric

Fauna Flora

ExogenousEndoge-nous

Natural SocialTechno-logical

Disaster Classification

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Risk Analysis is always:probabilityforecastpredictionprognosiscalculationestimative

Phenomenon, event, accident, disaster, catastrophe are always what had already happened, took place, occurred

Disaster Management

Response, resilience, capacity, recovery: Decisions and actions taken after a disaster

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EXAMPLES OF HAZARDS AND DISASTERS

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Malawi, East Africa

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2008 13

2008 14Debris flow

2008 15

2008 16Deep Soil Planar Landslide, Brazil

2008 17Shallow Soil Planar Landslide, Brazil

2008 18Ilhabela, São Paulo State, Brazil, Rock Boulder Slide

2008 19South Yorkshire, Peak District, UK, Slow Deep-Seated Slide

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Vulnerability definition

Vulnerability is the condition determined by physical, social, economic, and environmental factors or processes, which increase the susceptibility of a community to the impact of hazards.

Element at risk: people, facilities, buildings, cars, environment, properties, economical processes

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Vulnerability is an intrinsic characteristic of the element at risk, but hazard dependent as well.

2008 25Diadema, São Paulo State, Brazil

2008 27Sheffield, North Yorkshire, UK

2008 28

What is more vulnerable?

Oak

Reeds

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2008 30

Damage definition

Damage is a valuation of the element at risk. It may be estimated in the form of loss of life and injuries and/or loss of land and properties.

Dwellings = number of people

Roads = extension (meters)

2008 31Campos do Jordão, São Paulo State, Brazil

Number of the houses

2008 33J. Remondo et al. / Geomorphology 94 (2008) 496–507

2008 34

RISK MAPPING1) To determine the study area and scale

2) To define the unity of analyses

3) To specify the attributes that qualify the process (hazard) and the element at risk (vulnerability and damage)

4) The GIS (Geographical Information System) role

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1:50,000 SCALE LANDSAT SATELLITE IMAGE, 30m resolution: a town, a region

Ubatuba, São Paulo State, Brazil

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1:10,000 SCALEIKONOS SATELLITE IMAGE1m resolution:a district, a neighbourhood


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1:3,000 SCALE AERIAL PHOTO IMAGE, 1m resolution: a hill, a quarter, an area


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RISK MAPPING1) To determine the study area and scale

2) To define the unity of analyses

3) To specify the attributes that qualify the process (hazard) and the element at risk (vulnerability and damage)

4) The GIS (Geographical Information System) role

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Parametric or Analytical

Geomorphology

Vegetation

Pedology

Geology

Two types of approaches

Physiographical or Synthetic

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Concept: Earth surface is the result of a vertical overlay of different components or “information layers”

Thematic maps

Assessment of individual layers (maps)


Concept: Earth surface is a mosaic formed by horizontal joining of homogeneous units, described by their attributes

Hierarchical subdivision of the territory

Assessment of Integrated units

2008 41

TURRINI, M C; VISINTAINER, P. 1998. Proposal of a method to define areas of landslide hazard and application to an area of the Dolomites, Italy. Enginneering Geology, 50:255- 265.

G e o l o g i c a l – t e c h n i c a l m a p

G e o l o g i c a l – s t r u c t u r a l m a pC o n t o u r l i n e t o p o g r a p h i c m a p

L a n d u s e a n d l a n d c o v e r m a p

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Characteristics:Necessity to produce many thematic layers

(geological map, geomorphological map, soil map, land-use map, and so on);

Analysis units are “ephemeral” ones (if another map would be done with different layers the limits of the units would be others)

Analysis units are “artificial” ones (resulted of intersection of many layers); they are not terrain recognisable units;

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Physiographic or Synthetic

XDAB

CDXD

In a given area

Identification of terrain zones with similar physiographical aspects

Physiographical Compartmentalisation

Geoenvironmental Characterization

Thematic Cartography

XDAB

CDXD

Characterization of the attributes of the defined units

Classification and assessment to produce the intended map

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Natural Units (a homogeneous mapping unit on the basis of geomorphological origin, physiography, lithology, morphometry, and soil geography)

terrain mapping units (TMU)

basic compartmentalisation unit (BCU)

homogeneous unit (HU)

Administrative Units (city, watershed, town, district, etc)

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Physiographical or Sinthetic

Characteristics:Analysis units are observably ones (resulted of image

interpretation and field observations); they are terrain recognisable units;

Analysis units are “permanent” ones (the same units can be used to produce different thematic maps)

Necessity to produce only the data required for the intended map;

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Example: Risk map for people related to landslide, Ubatuba, Brazil, 1:10,000 scale

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Landslide hazard map Ubatuba, Brazil, 1:10,000

Attributes:declivity,slope shape,drainage density,geological structures,soil,climatic aspects,land-use

No hazard

Low

Mode-rate

High

Very High

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Homogenous units land-use

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Vulnerability map Ubatuba, Brazil, 1:10,000

Attributes:planned or not planned urban occupation,consolidate or not consolidate urban occupation,building pattern (high or poor),sewage sanitation, water supply. waste collection, type of roads,people education and income (census data)

Very LowLowModerateHighVery High

2008 51

Damage map Ubatuba, Brazil, 1:10,000

Attributes:number of people

Very LowLow

Moderate

High

Very High

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RISK MAP FOR PEOPLE RELATED TO LANDSLIDE

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Example: Risk map for people related to landslide, Diadema, Brazil, 1:3,000 scale

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Urbanization and Increasing Hazards

Metropolitan Region of Sao Paulo

50km

Diadema city

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Population density of Diadema city: 12,063.8 people per km2

2008 56

UNPLANNED LAND OCCUPATION/ INATTENTION TO ENVIRONMENTAL MANAGEMENT

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STEPS OF THE WORK

1-Inventory of landsliding and flooding events

2- GIS processing of high resolution

imagery

3- Field work

4- GIS procedures and data interpretation

Target areas

Basis for field work,

quantification of dwellings and GIS

analysis

Hazard assessment, land use characterization, interviewing of residents, risk classification

Data interpretation

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METHODOLOGY

General criteria for risk classification

R1 Low

R2 Moderate

R3 High

R4 Very High

Geological and geotechnical factors

Evidences of land instabilities

Previous records of

events

Do not predisposing

Highly predisposing

Moderately predisposing

Highly predisposing

No evidences

Significant

Little

Large number

Absent

Frequent

Scattered

Frequent

Risk classes

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Geological, geotechnical and land use predisposing factors regarding risk assesment

High steepness of the hill slope

Vertical cut slope

Unsubstancial construction

Unconsolidated Tertiary Sediment

Distance from the river channel

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Evidences of land instability regarding risk assessment

Undercutting Riverbank disruption

Mass movementWeathered rock or soil displacement or erosion

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Evidences of land instability regarding risk assessment

Increasing hazard rating

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GIS interface

R1

R2

R3

R4

2008 63

GIS role

Data representation:maps, profiles

Spatial analyses of geographical data:geostatistics

Digital terrain models

Data bank

Experts systems

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DISASTER MANAGEMENT

http://www.pdc.org/emi

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Preparedness:Activities and measures taken in advance to ensure effective response to the impact of hazards, including the issuance of timely and effective early warnings and the temporary evacuation of people and property from threatened locations

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OBSERVATION Monitoring and forecasting

ATTENTION Field inspection

ALERT Restricted people remotion

MAXIMAL ALERT Extensive people remotion

Awareness:The provision of timely and effective information, through identified institutions, that allows individuals exposed to a hazard to take action to avoid or reduce their risk and prepare for effective response.

Early warning systems include a chain of concerns, namely: understanding and mapping the hazard; monitoring and forecasting impending events; processing and disseminating understandable warnings to political authorities and the population, and undertaking appropriate and timely actions in response to the warnings.

Leavel of warning Actions

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Relief / response The provision of assistance or intervention during or immediately after a disaster to meet the life preservation and basic subsistence needs of those people affected. It can be of an immediate, short-term, or protracted duration.

Recovery Decisions and actions taken after a disaster with a view to restoring or improving the pre-disaster living conditions of the stricken community, while encouraging and facilitating necessary adjustments to reduce disaster risk.

2008 68

Unnatural Disaster Growing Impacts

Random urban growth

Natural resources and environmental deterioration

Obsolete construction codes

Reactive and centralist disaster attention paradigms still prevail

Hazards increasingly strength and frequency

Vulnerable constructions and productive activities

Weak risk management institutions

Inadequate capacity for risk management

Population incapable of assessing its vulnerability and confronting emergencies

Inadequate management of natural resources

Inadequate territorial management

Decision makers lack awareness and willingness

Obsolete risk management legislation

Underestimation of hazards

Inadequate development model

Based in Sergio Mora 2006

Many Thanks,

Dr Claudio J FerreiraResearcher - Environmental and Applied Geology Section - Geological Institute, Sao Paulo, Brazil

Current address:

Department of Structural and Civil Engineering - The University of Sheffield - Post-Doctoral ProgrammeSir Frederick Mappin BuildingMappin Street, Sheffield, S1 3JD, UKPhones: 0114 222 5056 (office)[email protected]

Risk Analysis of Geological Hazards and Disaster Management

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