Towards A GIS Methodology for Disaster Risk Assessments

L. L. LewisGISc Professional

(Production)

TOWARDS A GIS METHODOLOGY FOR DISASTER RISK ASSESSMENTS

© Western Cape Government 2013 |

Presentation Outline

2Towards a GIS Methodology for Disaster Risk Assessments

Introduction• Disaster Management Cycle• Scope • Definitions

Overview of Methodology

Results and Challenges

Conclusion


Introduction


“In dealing with extreme events, many of the critical

problems that arise are inherently spatial”

(Thomas J Cova, 1999)


Introduction

Legislative Context

Disaster Management Act (Act 57 of 2002)• Three spheres of government• Disaster Management Plans (S 39 and 53), the prerequisite of which is a

Disaster Risk Assessment. – Department of Local Government: Disaster Risk Reduction is mandated to

facilitate and coordinate the reduction of potential risks posed by hazards in the province.

Spatial Data Infrastructure (SDI) Act (Act 54 of 2003)• Aims to establish, via the Committee for Spatial Information (CSI), standards

and procedure to promote information sharing and minimise duplication of datasets. – Reliable, up-to-date spatial data describes the current, on the ground

situation that could influence decisions relating to emergency response e.g. access to roads.

– Incorrect or outdated information could therefore directly impact on the quality of decision-making and hence on the quality of the response to disaster situations

Towards a GIS Methodology for Disaster Risk Assessments 4


Benefit of GIS



Disaster Management Cycle

Adapted from Godschalk D R, 1991



Scope


Focus area: West Coast District MunicipalityDiscussion of GIS methodology in a disaster risk contextUse of available GIS data relevant to the disaster risk assessmentExcluding aggregated data

Aim: • Developing a GIS based methodology applicable to Disaster Risk Management• Focus on a multidisciplinary approach based on community participation and

scientific input from a broad range of experts and GIS• Increase efficiency and improve the quality of decision-making in all level of

disaster management activities.


Definitions

As per West Coast Disaster Risk Assessment:


Capacity: The combination of all strengths, attributes and resources available within a community, society or organisation that can be used to achieve agreed goals.

Disaster: A progressive or sudden, widespread or localised, natural or human-caused occurrence. A serious disruption of the functioning of a community or a society involving widespread human, material, economic or environmental losses and impacts, which exceeds the ability of the affected community or society to cope using its own resources.

Hazard: A dangerous phenomenon, substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of

livelihoods and services, social and economic disruption, or environmental damage.

Risk: The combination of the probability of an event and its negative consequences.

Vulnerability: The characteristics and circumstances of a community, system or asset that make it susceptible to the damaging effects of a hazard.

Overview of Methodology


United Nations International Strategy for Disaster Reduction

Calculating Risk

Hazard * Vulnerability

CapacityRISK =

Natural

Environmental degradation

Biological

Technological

Economic

Societal

Environmental

Technological

Access to facilities offering

shelter

Adequately trained personnel Equipment

Contingency / emergency response

plans

Hydro-meteorologic

al

Geological


Public Participation

Format of community based workshops:


One workshop per local municipality

Presentation regarding purpose and context

Identification of hazards, vulnerability and capacity

Mapping exercise

Risk prioritisation process


GIS

Data flow process:


Data collection (scientific data, workshops etc)

Spatialising non-spatial data (from reports and workshops)

Categorising data into hazards, vulnerability and capacity

Mapping data for the Risk Assessment document

Spatially calculating risk


Scientific GIS spatial assessment


Geodatabase 1

Hazard 1 Hazard 2 Hazard 3Vulnerabilit

y 1Vulnerabilit

y 2Vulnerabilit

y 3Capacity 1 Capacity 2 Capacity 3

Risk Prioritisation

Collective Hazards

Collective Vulnerabilitie

s

Collective Capacity× ÷

Raster Conversion

Hazard 1 Hazard 2 Hazard 3Vulnerabilit

y 1Vulnerabilit

y 2Vulnerabilit

y 3Capacity 1 Capacity 2 Capacity 3

Risk

Results & Challenges


Collective Hazard Map


R = H * V / C

Natural Hazards:• Geological Hazards• Hydro-meteorological HazardsEnvironmental DegradationTechnological Hazards


Collective Vulnerability Map


R = H * V / C

SocietalEnvironmentalTechnologicalEconomicCritical Facility


Determining Capacity


Accessibility

Network AnalysisCritical Facilities:• Schools - 5km• Health facilities - 5km• Police stations - 24km• Fire stations - 13 minutesAccess norms and standards & Population grid (CSIR)

Municipality Access No Access

Bergrivier 95.14 % 4.86 %

Cederberg 86.14 % 13.86 %

Matzikama 95.8 % 4.2 %

Saldanha Bay 98.96 % 1.04 %

Swartland 97.35 % 2.65 %

WEST COAST DM

95.86 % 4.14 %


Collective Capacity Map


R = H * V / C

Access to Critical (relief) FacilitiesCritical services able to respond


Overall Risk Map


R = H * V / C

Overall risk score spatially calculated


Public Participation & GIS Challenges


Subjective input• Lack of understanding of context• Localised focus

Lack of expert attendance at workshops• Little / no input from local experts• Little / no representation from municipal departments

e.g. planning, environmental management etc.

Opportunist participants• Looking for work opportunities• Platform to vent (service delivery) frustrations

Lack of understanding of the bigger picture

Refinement of methods

Lack of spatial data

Aggregated data

Silos

Conclusion


Conclusion


Inclusive approach

Ownership of the Risk Assessment

Mitigation strategies requires local buy-in

Potential of GIS

Improved decision-making

Thank you

Tel:Fax:

www.westerncape.gov.za

Contact Us

Lauren Lewis

Department of the Premier: Spatial Information

+27 (0)21 483 3943 +27 (0)86 519 4956

[email protected]

Towards A GIS Methodology for Disaster Risk Assessments

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