The terms Risk and uncertainty have been in circulation for a very long time and are used in a number of different contexts and show how adaptive any concept of Risk can be (Sayers et al., 2002). For example in the area of natural hazard studies, several interpretations can be found (modified from Kelman and Spence, 2003):

• Total Risk = Impact of Hazard x Elements at Risk x Vulnerability of elements at Risk (Alexander, 1991)

• Risk is the actual Exposure of something of human value to a Hazard and is often regarded as the combination of Probability and loss” (Smith, 1996)

• Risk is “Expected losses (of lives, persons injured, property damaged, and economic activity disrupted) due to a particular Hazard for a given area and reference period. Based on mathematical calculations, Risk is the product of Hazard and Vulnerability” Hazard is “a threatening Event, or the Probability of occurrence of a potentially damaging phenomenon within a given time period and area”. Vulnerability is “Degree of loss resulting from a potentially damaging phenomenon” (UN, 1992)

• The Defra/EA report (Sayers et al., 2002) determines Risk broadly as “a combination of the chance of a particular event (probability), with the impact that the event would cause (Consequence) if it occurred. Helm (1996) warned that a simple product of probability and consequence will never be sufficient to describe Risk fully, but claims that it provides an adequate basis for comparison and decision making. The units in which risk is measured depend on the definition of probability and consequence and enforces the argument that risk is a flexible concept.

References

Alexander, D., 1991. Natural Disasters: A Framework for Research and Teaching. Disasters, 15(3): 209-226.

Helm, P., 1996. Integrated Risk Management for Natural and Technological Disasters. Tephra, 15(1): 4-13.

Kelman, I. and Spence, R., 2003. A flood failure flowchart for buildings. Proceedings Of The Institution Of Civil Engineers-Municipal Engineer, 156(3): 207-214.

Sayers, P.B., Gouldby, B.P., Simm, J.D., Meadowcroft, I. and Hall, J., 2002. Risk, Perfromance and Uncertainty in Flood and Coastal Defence - A Review, DEFRA/Environment Agency - Flood and Coastal Defence R&D Programme, Wallingford.

Smith, K., 1996. Environmental Hazards: Assessing Risk and Reducing Disaster, 2nd ed. Routledge, London/U.S.A./Canada.

UN, 1992. Internationally Agreed Glossary of Basic Terms Related to Disaster Management., United Nations Department of Humanitarian Affairs, Geneva.

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Risk and Uncertainty (Description and Definition)