Disaster Risk Assessment

Disaster Risk Assessment

What is disaster risk?
It is the possibility, or chance, of harmful consequences, or expected loss (of lives, people injured, property, livelihoods, economic activity disrupted or environment damaged) resulting from interactions between natural or human induced hazards and vulnerable conditions.

As required by the Disaster Management Amendment Act (Act No. 16 of 2015) and the National Disaster Management Framework, a disaster risk assessment must be done.  This assessment will inform the disaster management plan.  Not only for this but it MUST inform other planning mechanisms such as the IDP and SDF.

Conducting a disaster risk assessment

This blog will provide an introduction into conducting disaster risk assessments by and/or for municipalities and will focus on vulnerability.  Various methodologies exist to conduct disaster risk assessment but the one we use is based on the Community Capitals Framework which uses 7 capitals:

  • Human;

  • Social;
  • Cultural;
  • Financial;
  • Infrastructure;
  • Environmental and
  • Political.

To calculate disaster risk these 7 capitals will be used in the following formula:


R         =          Disaster risk

H         =          Probability of a hazard with a certain magnitude

CH          =          Capacity of factors that impact on the magnitude of the hazard

Vhuman   =          Human vulnerability

Vsoc      =          Social vulnerability

Vcul       =          Cultural vulnerability

Vfin       =          Financial vulnerability

Vinfra     =          Infrastructural vulnerability

Venviro   =          Environmental vulnerability

Vpol       =          Political vulnerability

Chuman  =          Capacity to mitigate and limit Human vulnerability

Csoc      =          Capacity to mitigate and limit Social vulnerability

Ccul      =          Capacity to mitigate and limit Cultural vulnerability

Cfin       =          Capacity to mitigate and limit Capacity to deal with economic vulnerability

Cinfra     =          Capacity to mitigate and limit Infrastructural vulnerability

Cenviro   =          Capacity to mitigate and limit environmental vulnerability

Cpol      =          Capacity to mitigate and limit Political vulnerability


In short, the capitals can be described as follows:

  • Human Capital

Human capital includes the managerial capacity and the peoples ability to withstand shocks/disasters or to adapt in time.

  • Social Capital

Social capital is the quantity and quality of social resources available (e.g., networks, membership in groups (formal/informal), social relationships, and access to wider institutions in society) from which people draw.

  • Cultural

Cultural capital considers ethnicity, generation differences, traditional beliefs and norms, stories and folklore, spirituality, habits and heritage.

  • Financial

Financial resources include among others savings, income, investments or businesses, and credit that people use to support their livelihoods.

  •   Infrastructure

Buildings and infrastructure in a community include schools, roads, water, electricity and sewer systems and access roads.  including telecommunications, industrial parks, main streets, water and sewer systems, roads, etc.

  • Environmental

The presence and status of soil, land, water, natural beauty, lakes, rivers and streams, forests, wildlife, soil, etc., in the local landscape.

  • Political

Political capital as the access to power relationships, and the capacity to influence the political system and governmental processes at local and higher levels.

Capital Indicators

To use these capitals in disaster risk assessment it must be included in a model to produce disaster risk values or score.  Important also is to map the vulnerability scores.  GIS is therefore very important for in the assessment of disaster risk.

Various research studies developed indicators for disaster-related risk assessment of which Jordaan’s work is influential in this regard in South Africa.  He developed indicators for drought risk assessment.  Some of these indicators will be used in the assessment of disaster risk.  The usability of indicators for this assessment will depend on the availability of data including spatial data for the use of GIS.

Human Capital

Vulnerability for Human Capital is a function of highest education levels, age and health. Coping is a function of perseverance and experience.

Social Capital

Vulnerability for Social Capital is a function of formal networks, informal support structures and safety and security nets.  Coping is a function of the availability of support structures and information.

Cultural Capital

Vulnerability for Cultural Capital is a function of  dependency, gender equality and beliefs and cultural beliefs.  Coping is a function of innovation and experience.

Financial Capital

Vulnerability for Financial Capital is a function of  unemployment and income rate.  Coping is a function of the availability of financial safety nets.

Infrastructure Capital

Vulnerability for Infrastructure Capital is a function of  access to basic services and amenities.  Coping is a function of innovation.

Environmental Capital

Vulnerability for Environmental Capital is a function of  land degradation.  Coping is a function of the soil quality.

Political Capital

Vulnerability for Political Capital is a function of availability of disaster management plans and government efficiency.

Disaster Risk Tool

The above described indicators are consolidated into a disaster risk assessment tool to calculate risk for an area.  Spatial feature that will be used to map the disaster risk is municipal wards.  In the tool, each ward will be assessed for its vulnerability and coping capacity (Figure below).

The end result is a ranking of wards in regards with their risk values.

Below is an example of municipal wards and the values above were linked to boundary of these wards.

A heat map was creating showing the area with the highest disaster risk.

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