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close this bookAn Overview of Disaster Management (Department of Humanitarian Affairs/United Nations Disaster Relief Office - United Nations Development Programme , 1992, 136 p.)
close this folderChapter 8. Vulnerability and risk assessment 1
View the document(introduction...)
View the documentRisk management
View the documentRisk probability
View the documentAcceptable levels of risk
View the documentAssessing risk and vulnerability
View the documentHow is risk determined?
View the documentVulnerability evaluation
View the documentReducing vulnerability for displaced persons

Assessing risk and vulnerability

The estimation of probably future losses is a matter of increasing interest to those concerned with development planning in hazard-prone regions. Fundamental to disaster preparedness and mitigation planning is an understanding of what to expect. This needs to be quantified, if only in a crude and approximate way, in terms of the degree of risk faced, the size of event that is likely, and the consequences of an event if it occurs.

The calculation of risk generally needs to consider several types of loss. The most common parameter of loss, and the one most easily dealt with, is economic cost. Cost is widely used because many types of loss can be converted into economic cost. Effects which are considered in terms of economic costs are known as tangible losses. But there are a range of other effects resulting from disasters which are important but which cannot be converted into a monetary equivalent, and these are referred to as intangible losses.

A full consideration of risk would include a complete range of effects, both tangible and intangible, and of several qualitatively different types. The range of undesirable consequences of natural hazards what we might consider as loss parameters are listed in Table 1.

Table 1 Loss parameters for risk analysis







Number of people

Loss of economically active individuals

Social and psychological effects on remaining community


Number and injury severity

Medical treatment needs, temporary loss of economic activity by productive individuals

Social and psychological.
Pain and recovery

Physical damage

Inventory of damaged elements, by number and damage level

Replacement and repair cost

Cultural losses

Emergency operations

Volume of manpower, man-days employed, equipment and resources expended for relief

Mobilization costs, investment in preparedness capability

Stress and overwork in relief participants

Disruption to economy

Number of working days lost, volume of production lost

Value of lost production

Opportunities, competitiveness, reputation

Social disruption

Number of displaced persons, homeless

Temporary housing, relief, economic production

Psychological, Social contacts, cohesion, community morale

Environmental impact

Scale and severity

Clean-up costs, repair cost

Consequences of poorer environment, health risks, risk of future disaster