In this chapter - Environmental stress | Potential adjustments - the options available | Choice of adjustment | What influences choice of adjustment? | Development and adjustment

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The extent to which hazards affect what we do and how we do it depends partly on the type and level of environmental stress involved. Low levels of environmental stress are easy for individuals and society to cope with, usually without ever realizing it. At the threshold of awareness (Figure 7) people realise that the threat of hazard exists, but they regard it as not serious enough to warrant conscious action. Losses are accepted either by the individual who bears the loss personally (such as the farmer who looses a crop during a rare drought), or by society at large through institutions designed to share the loss broadly (such as insurance and disaster relief schemes).

When hazard stress reaches the higher threshold of action, the search for effective adjustments begins. Action is regarded as necessary, and positive moves are made to reduce losses by seeking to control the hazard event or by reducing - if not preventing - adverse impacts.

The river floodplain problem illustrates the spectrum of environmental stress. In areas of low flood risk (such as on high river terraces), there is little need to take precautions against flooding and floodplain users and residents absorb the limited losses from infrequent flooding by paying for their own repairs and accepting the cost of damage. Little preventative action is taken, other than perhaps taking out insurance on property and house contents, and this is often confined to a minority. In more moderate flood-prone areas (such as low-lying riverside zones), the search for effective adjustments might include flood-proofing of basements, moving valuable possessions upstairs above expected flood levels, and keeping supplies of sand-bags available to seal outside doors should a flood occur. At sites where flooding is very frequent or where there is a real possibility of a devastating flood, either buildings are designed to be flood-proof (for example with a garage downstairs and living quarters upstairs) or people abandon the site and move somewhere safer.

Adjustment to hazard threat is a basic feature of human survival and prosperity. Some measures may be enforced by legislation (such as the minimum height for a living floor in a house of 15 feet above mean sea-level on the eastern coast of the United States). Most measures are adopted voluntarily.

The search for effective adjustments to hazard threats involves two key steps - examining the range of potential adjustments open to us, and then selecting an appropriate one.

There is a range of options for adjusting to hazards and they can be classified in various ways. One distinction is between corrective (or remedial) measures and preventative measures. For most hazards "prevention is better than cure". Corrective measures for reducing river flood losses include flood control schemes (such as dams and reservoirs, channel improvements and watershed land-use changes), evacuation, flood forecasting and urban redevelopment. Preventative measures include floodplain regulation (such as by zoning land-use), tax adjustments and flood insurance schemes.

A second distinction is between adjusting nature (technological measures) and adjusting people (behavioural or structural measures).

Burton, Kates and White (1978) identify three broad groups of option for coping with hazards;

(a) modify the cause of the hazard. Although our capacity to alter the nature of the geophysical or biological processes responsible for most natural hazards is limited, it is sometimes possible to modify the timing or intensity of a hazard event. For example, cloud-seeding can reduce the velocity of hazardous hurricanes and thus influence the location of intense rainstorms, and orchards can be heated to prevent frost from cold air. Seismic stresses in some fault zones can be reduced by pumping down a lubricating fluid to prevent high-intensity movements. Planned land-use changes and integrated watershed management can be used to modify flood hazard potential.

(b) modify vulnerability to the hazard. Among the engineering measures which may be used to reduce vulnerability hazards are retaining walls to stabilise unstable hillslopes, sea-wave barriers to protect threatened coastlines, and flood control dams to protect settlements downstream. Buildings with deep pile foundations and extra reinforcement of walls and floors are common in earthquake-affected cities like Tokyo and Mexico City. Hazard loss potential can also be reduced through early-warning systems, emergency evacuation procedures, adoption of appropriate building designs and conventions, planned land-use changes or permanent evacuation of threatened sites.

Risk reduction should aim to reduce the risk of hazard loss to a low (or acceptable) level; it cannot eliminate the hazard completely. Some residual risk will almost always remain, which has still to be coped with, although the level of environmental stress may fall below the threshold of awareness, making most people unaware that the threat (albeit a reduced one) still exists.

(c) redistribute the losses. Hazards are common, and loss and damage (to people and property) occurs whether or not it has been possible to minimize vulnerability. Burdens - particularly to finances, resources and lifestyle - are much more tolerable if they are shared broadly. Public relief and subsidized insurance schemes seek to spread losses from the people directly involved in a hazard event over a wider group of policy holders and tax payers. Insurance and reserve fund schemes are also often available - the "pay now, suffer (and be compensated) later" principle. In other cases, responsibility for bearing losses falls on the individual, who may or may not have sufficient reserves to cope with the hazard losses.

The way in which events and vulnerabilities can be modified, or losses distributed, differs from one type of hazard to another (Table 7).

SOURCE: summarised from White and Haas (1975)

Once we have some idea of the options open to us for adjusting to a given type of hazard, we can select the most appropriate one. This requires an evaluation of the pros and cons of each option for which information is available. The choice is affected by a host of factors such as what we think, what we know, what we would like, what we can afford, that we think is necessary, what we think is possible, and how we rationalise these often incompatible issues.

Decision-making is always less than totally rational. Economic geographers recognize three models of decision-making (for example in the choice of location of economic activities) - economic optimisation, bounded rationality and cognitive behaviouralism.

One view is that choice is determined by the quest to maximise gain. This "gain" might be economic or social, and it might benefit the individual, a group or society at large. The model assumes that we have a good understanding of the probability of hazard events (nature's tax), and a realistic basis of weighing up costs and benefits of alternative courses of action in economic, social and environmental terms.

One approach for evaluating alternatives is cost-benefit analysis (CBA), widely used in economics and resource management (Figure 10). The marginal benefit of increasing investment for a given adjustment (mb) represents demand, or willingness to pay; this decreases with increasing effort or expenditure on hazard prevention. Marginal cost (mc) represents supply. The optimum state exists when marginal costs and marginal benefits are equal.

Figure 10. Fundamentals of cost-benefit analysis

Such economic evaluations are useful, but they are not without problems - particularly when the real impact of hazard events cannot be expressed in simple monetary terms. What is the "value" of human life, for example? The Warsaw Convention places a value of $360,000 per death, but how meaningful is this? Monetary values are also difficult to place on long-term or wide-spread reductions in environmental quality. How much is an attractive view worth, or a stable hillslope?

Because of environmental variability, perceptual uncertainty and imperfect knowledge about hazard potential, rational maximisation of gain does seem a rather optimistic goal.

The assumption that people can act rationally to minimise risk and maximise gain is clearly untenable. Early studies of human adjustment to hazards such as river flooding showed that sub-optimal solutions are often adopted. Some hazard threat remains, but this is balanced against expected gain. H.A. Simon stressed the tendency of decision-makers to seek rational judgements about location of economic activities within the bounds of acceptable risk, and he proposed the concept of "satisfiable behaviour". This sub-optimal solution model has since been applied in many studies of human adjustment to natural hazard.

The most realistic model of hazard decision-making is based on the assumption that the real world lies beyond our complete understanding, and so everything we perceive in the environment is filtered through a complex selective process (Figure 5). This process is based on cognitive perception, which is how we select, organise and interpret signals from the environment around us, in order to build up a coherent picture in our minds of what the environment is like. The selection process can be influenced by many factors such as our own powers of seeing and thinking, our cultural setting, previous experience and training, and motivation at the time of sensing.

Decision-makers are faced with information on natural hazards and estimated risks, which they accept will be the best available but still less-than-perfect. The eventual choice of adjustment will thus represent a compromise between many competing and incompatible goals, claims and objectives,

White (1974) has examined the factors which influence choice of adjustment to flood hazard in the United States. He distinguished between decisions made by floodplain managers and those made by floodplain residents, because each group has different perceptions, time horizons, responsibilities and bases for decision-making.

The managers' choice was influenced by factors such as their knowledge of available options, their perceptions of the real likelihood of flood events, their interpretation of the economic viability and technical feasibility of available alternatives, and the social and institutional frameworks in which they operate. Residents' choices were more influenced by personal factors such as their perception of the likelihood of a hazard event, their faith in public relief schemes, and previous experience of flood hazards. Both groups tended to have far more faith in upstream dams and flood levees than was justified.

Choice of adjustment is often closely related to frequency of hazard event (Figure 11).

Figure 11. Relationship between frequency of events and likelihood of people adopting some form of adjustments. Few adjustments will be adopted if there is relative certainty that hazard events will not occur; most people adopt adjustments when there is a high certainty that events will occur.

Adjustment strategies to hazards normally fall into two types - folk (or pre-industrial) responses and modern technological (or industrial) responses.

Folk responses rely more on adjustment of human behaviour than on engineering control of the environment, so they require relatively little capital, are based on actions by individuals and small groups, and tend to be flexible and thus easily altered or even abandoned. Such adjustments are very variable from place to place, and through time, because choice of adjustment is left largely to the individual. They can be remarkably effective, benefiting from experience handed down over successive generations.

Modern technological responses, on the other hand, are more likely to involve control of the environment. They generally require large capital investment, long-term planning, co-ordinated social organisation and the involvement of many groups and bodies. Such responses tend, therefore, to be less flexible, with an emphasis on technological change which tends to promote uniformity of adjustments over wide areas. They have the mixed blessing of reducing the frequency of minor events but failing to eliminate major events. They also lead to unjustified complacency amongst those at risk.

A more comprehensive (post-industrial) response would incorporate both types of adjustment, and it would be characterised by a wide range of adjustments, high level of flexibility and a range of capital and organisational requirements.

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Last modified: 17 August 1999