1. Towards A GIS Methodology for Disaster Risk Assessments
L. L. Lewis
GISc Professional (Production)

2. Presentation Outline Introduction Disaster Management Cycle Scope
Definitions
Overview of Methodology
Results and Challenges
Conclusion
Towards a GIS Methodology for Disaster Risk Assessments

3. “In dealing with extreme events, many of the critical
Introduction
“In dealing with extreme events, many of the critical
problems that arise are inherently spatial”
(Thomas J Cova, 1999)
Towards a GIS Methodology for Disaster Risk Assessments

4. 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Incorrect or outdated information could therefore directly impact on the quality of decision-making and hence on the quality of the response to disaster situations
Disaster Management Act (Act 57 of 2002), the three spheres of government are required to prepare Disaster Management Plans (Sections 39 and 53 of the Act), the prerequisite of which is a Disaster Risk Assessment.
WCG’s 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 Act (SDI) (Act 54 of 2003)
The potential to enhance the decision-making process by increasing availability and access to spatial data.
Aims to establish, via the Committee for Spatial Information, standards and procedure to promote information sharing and minimise duplication of datasets.
Reliable, up-to-date spatial data is crucial in a disaster management context as it 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Incorrect or outdated information could therefore directly impact on the quality of decision-making and hence on the quality of the response to disaster situations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

5. Benefit of GIS
Towards a GIS Methodology for Disaster Risk Assessments

6. Disaster Management Cycle
Adapted from Godschalk D R, 1991
Towards a GIS Methodology for Disaster Risk Assessments

7. Scope Focus area: West Coast District Municipality
Discussion of GIS methodology in a disaster risk context
Use of available GIS data relevant to the disaster risk assessment
Excluding 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.
Towards a GIS Methodology for Disaster Risk Assessments

8. 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.
Hazards:
Can include latent conditions that may represent future threats
Can have different origins: natural (geological, hydro meteorological and biological) or induced by human processes (environmental degradation and technological hazards).
Hazards can be single, sequential or combined in their origin and effects.
Each hazard is characterised by its location, intensity, frequency and probability
Towards a GIS Methodology for Disaster Risk Assessments

9. Overview of Methodology

10. United Nations International Strategy for Disaster Reduction
Calculating Risk
Economic
Societal
Environmental
Technological
Natural
Environmental degradation
Biological
Technological
Hydro- meteorological
Geological
Hazard * Vulnerability
RISK =
Capacity
Access to facilities offering shelter
Adequately trained personnel
Equipment
Contingency / emergency response plans
Towards a GIS Methodology for Disaster Risk Assessments

11. 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
Towards a GIS Methodology for Disaster Risk Assessments

12. 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
Towards a GIS Methodology for Disaster Risk Assessments

13. Scientific GIS spatial assessment
Geodatabase 1
Hazard 1
Hazard 2
Hazard 3
Vulnerability 1
Vulnerability 2
Vulnerability 3
Capacity 1
Capacity 2
Capacity 3
Risk Prioritisation
Collective Hazards
Collective Vulnerabilities
Collective Capacity × ÷
Raster Conversion
Risk
All spatial data stored in geodatabase
Risk prioritisation – primarily based on the scientific norms and standards, however results from the public participation process is analysed and incorporated if the justification is merited.
Resulting spatial data is classified and mapped
Raster conversion
Adds some generalisation that may not be reflected in vector data e.g line data road network where both lanes aren’t reflected.
Not dependant on scale, but rather resolution
The inherent nature of raster maps, e.g. one attribute maps, is ideally suited for mathematical modeling and quantitative analysis
Each cell can be assigned an individual value i.e. risk score, thereby localising the analysis, unlike vectors where one polygon would have the same value throughout.
Raster datasets produced
Map algebra is applied to each category to produce one collective hazard, vulnerability and capacity map. Map algebra applied again according to the UNISDR formula
Risk map produced
Towards a GIS Methodology for Disaster Risk Assessments

14. Results & Challenges

15. Collective Hazard Map R = H * V / C Natural Hazards:
Geological Hazards
Hydro-meteorological Hazards
Environmental Degradation
Technological Hazards
Towards a GIS Methodology for Disaster Risk Assessments

16. Collective Vulnerability Map
R = H * V / C
Societal
Environmental
Technological
Economic
Critical Facility
Towards a GIS Methodology for Disaster Risk Assessments

17. Determining Capacity Accessibility Network Analysis
Critical Facilities:
Schools - 5km
Health facilities - 5km
Police stations - 24km
Fire stations minutes
Access 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 %
Towards a GIS Methodology for Disaster Risk Assessments

18. Collective Capacity Map
R = H * V / C
Access to Critical (relief) Facilities
Critical services able to respond
Towards a GIS Methodology for Disaster Risk Assessments

19. Overall Risk Map R = H * V / C Overall risk score spatially calculated
Towards a GIS Methodology for Disaster Risk Assessments

20. 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
Towards a GIS Methodology for Disaster Risk Assessments

21. Conclusion

22. Conclusion Inclusive approach Ownership of the Risk Assessment
Mitigation strategies requires local buy-in
Potential of GIS
Improved decision-making
the benefit of the inclusive approach was to engage role players and promote a sense of inclusion and ownership of the Risk Assessment as the successful implementation of mitigation strategies requires local buy-in.
Towards a GIS Methodology for Disaster Risk Assessments

24. Lauren Lewis Department of the Premier: Spatial Information
+27 (0)
+27 (0)