Case study

Let us consider an example of the way in which a community interacts with its environment and hazards.

What happens when people move into a hilly, forested area with a medium to high annual rainfall, and they clear land for agriculture?

Before the forest is cleared, rainfall is absorbed and trapped by the live and dead vegetation, and by the accumulated humus, before it has a chance to run off to creeks and rivers. In a way, forests and many other natural ecosystems such as swamps act as sponges during heavy rain, in that they store a certain amount of water, some of which then evaporates or is slowly released over a prolonged period of time. Of course there is still the potential for flood, but it is only the very heavy rain events that will cause serious flooding.

When a forested area is cleared, the drainage characteristics are different. There is less vegetation and humus to collect and store water, and so the water runoff is greater. There is also a greater amount of erosion, and so the profile of river beds is altered by silt. So when heavy rainfall occurs, there is a greater likelihood of serious flooding. This serious flooding may lead, in turn, to further changes in the drainage system.

Figure 2.2
The evolution of natural hazards

(Ruchelman, L.I. (1988). Natural hazard mitigation and development: An exploration of the roles of the public and private sectors. In Managing disasters: Strategies and policy perspectives, Duke University Press: London , p. 61.)

Given that parts of this community will probably live on or own property on or near flood plains, and that their settlement may only have taken into account the flood characteristics that existed prior to forest clearing, there may be some problems.

Activity 2.1 1. Write down some of the harm caused to this hypothetical community due to forest clearing. See if you can come up with 3-4 points before reading on.     2. Do you know of any places near you that may have problems due to environmental change? How about in other states/ countries? Think of at least two examples and give a brief history of the causes of the problems and the consequences that have resulted. Example 1:   Example 2:   Thus, a community can cause changes in the environment, which in turn will alter the hazards in that area, and the changed hazards may in turn alter the environment and the community. This relationship holds true when you consider the hazards confronting an activity, an industry, or an organisation.     3. Can you think of two or three other examples in your area or in other states/countries where there is an interaction between hazards, the community and the environment? Write some down. Perhaps you might like to consider urban development encroaching onto the land bordering hazardous industry, or the desire for some people to live in thickly forested areas. In your descriptions be sure to clearly outline the links between hazard, environment and community. Print this activity

So you see, when we analyse hazards we must take into account the interaction of environment, hazards and the community-and we do this by adopting a process to analyse hazards within a risk assessment.

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