Use of prioritisation techniques

The choice of the prioritisation techniques that you may decide to use is yours - but it is suggested that two techniques are used to cross-check the validity of each other in your particular application.

Let us consider an example. The following information is the summary of the possible effects of hazards that exist in and near a fictitious country town.

HAZARDS AND COMMUNITY DESCRIPTION AND HAZARD EFFECTS SUMMARY FOR A FICTITIOUS TOWN

The town is near a river, with a forest bordering one side of the town. It consists of approximately 1200 people, who are evenly spread throughout the town, most families have vehicles, and there are no aged care homes, and one school. The people in the town all speak the same language, all have a similar cultural and ethnic background, and consider themselves self-sufficient in most major respects. The economy of the town is based on the provision of services to the surrounding rural community, and there are also a few light industries. There is a strong feeling of pride in the town, and there are a number of active community groups. The town is the seat of a local government area, but the services provided by the local government mostly relate to road maintenance, garbage collection and sewage disposal. The local government has not developed any emergency management strategies.


The river is known to flood on a regular basis, and major flooding has occurred approximately once every 40 years for the past century. Alterations to the environment upstream suggest that flooding may be more extreme in the future. Major floods have the potential to destroy the sewage treatment plant and contaminate water supplies, incapacitate all telephone and electricity services, destroy most bridges in the area and cover many roads, force the evacuation of about 15% of all homes and disrupt half of the light industries of the town. It is not thought likely that many residents would be killed by floods whilst in their homes or evacuating, but it is possible that people may be killed whilst using flooded roads. A major flood has not occurred for many years and most residents do not perceive flood as a grave hazard.


The forest adjacent to the town is fairly dense and subject to selective logging. There have been frequent bushfires in this forest and some have threatened houses on the forest side of the town. The vegetation in the fields surrounding the town is generally kept low by grazing animals, but there are periods in summer following heavy rains when considerable growth of grass occurs and then dries. There is an active fire brigade in the town, but they are infrequently called to fires. Telephone and electricity services may be disrupted by a severe fire, and it is possible that some houses (about 5% of total number) may be burnt. Deaths and injuries are only likely during evacuations or of firefighters.


The area is thought by geologists to be potentially subject to earthquakes, with a chance of exceeding Modified Mercalli VII intensity of 10% in a given 50 year period. The area has experienced one severe earthquake in known history, but this occurred prior to the construction of the town when the first settlers had only just arrived. Half of the town is built on alluvial soils which may be prone to liquefaction. Most buildings are of medium quality masonry and timber construction, therefore there is not likely to be much destruction of buildings, and thus a large number of deaths. It is likely that there would be some destruction of buildings in a severe earthquake, but the greatest risk is the destruction of all electricity, telephone, water reticulation and sewage services, the partial destruction of most bridges and many roads, and the long term disruption to the light industry. There is no local knowledge of any earthquake hazard.


The existence of the town is almost totally dependent on the success of the surrounding rural areas, the economic basis of which is the raising of livestock for internal consumption, but mainly for live export and export as meat products. Their is a rudimentary quarantine system in place for the entire country, but no planning for response to an exotic animal disease outbreak. An uncontrolled outbreak of an exotic animal disease would lead to the quarantining of the entire country, and an immediate cessation of all exports of animal products. This would cause an almost immediate cessation of most businesses in the town, with resultant widespread bankruptcy and unemployment. It is highly unlikely that the exotic animal disease would directly cause human deaths or injuries. Local farmers and veterinarians are aware of the possibility of exotic animal disease, but are unaware of the full possible effects of an uncontrolled outbreak.

 

Using the SMAUG technique

So, how would SMAUG rate the four hazards of flood, forest fire, earthquake and exotic animal disease for this town based on the information given above?

Table 8.4 summarises a possible prioritisation using SMAUG.

To summarise the SMAUG prioritisation, inspection of Table 8.4 suggests that the hazards should be ranked in the following order.

NB: When using SMAUG one needs to rate the relative Seriousness of all hazards first, then rate the relative Manageability of all hazards, then the relative

non-acceptability of all hazards and then so all for all of the criteria. Rate all hazards vertically under each criteria. Do not rate each hazard in turn on all criteria horizontally.

Using the FEMA model

How does this compare with the FEMA rating? Let us have a look.

In order to complete this FEMA rating, I have made quite a few assumptions about the frequency and consequences of an event, and in a real analysis these assumptions would have to be explicitly written down. According to the principles of the FEMA system, where a score in excess of 100 suggests that management of that hazard is required, the earthquake hazard would not be considered particularly serious by comparison to the other three.

How does the FEMA rating compare to the SMAUG rating?

What do you do if two prioritisation systems give you different rankings? Don't despair-the prioritisation systems use very different criteria, and it is expected that there would be some variation between their results. Experience has shown, however, that the various possible systems tend to produce results which are more similar than dissimilar.

Using Foster's index

Let us see what Foster's gives us.

And how does this compare to the other ratings?

Summing up

So it would seem that exotic animal disease is the greatest hazard for our small fictitious town, with flood coming a close second. In reality, most of the hazards for this town are relatively minor, as there is little expectation of loss of human life. But there are some significant economic effects due to the hazards in the area.

Would this be the same for all towns and villages? Perhaps not. The fictitious town and rural area described and the potential effects are based on towns that may be found in Western countries. If the fictitious town had been based on those that may be found in non-Western, developing countries, the effects to people and property may well be reversed, with a potential for more human deaths and injuries and less structural and property damage.

The results of your prioritisation can be used in emergency management planning. Those risks that consistently rank highly must be addressed in your planning. Those risks that rank low may be addressed at a later date or not at all.

A word of caution

One of the most deceiving aspects of risk prioritisation is the meaning of any numerical values attached to the risks that are developed by the various techniques. These numerical values have no meaning out of the precise context in which they were developed . This means that any number attached to a risk is only of use when it is compared to another number attached to another risk that has been developed by the same group of people, perhaps even in the same approximate time period. This is because different groups of people are using different assumptions when prioritising risks.

Can risk prioritisation be manipulated dishonestly to suit the political or other goals of some people? Yes! But the possibility of this is minimised by ensuring the planning group that performs the prioritisation represents a mix of interests and a good cross-section of the community, industry or activity. Also, by writing down all of the rationale behind each ranking, ie. documenting the process well, you can ensure that you produce a justifiable result, and not just a series of numbers in a table.

Evaluating Risk acceptability

The final stage in the evaluation of risks is the determination of whether risks are acceptable or not. The Emergency Risk Management Applications Guide provides some guidance on how you might determine the acceptability of risks.

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