Language of Risk - FLOODsite

FLOODsite Language of Risk 2 nd Ed.
Contract No:GOCE-CT-2004-505420
3. Concepts
3.1 What is risk?
Today, the term “risk’” has a range of meanings and multiple dimensions relating to safety, economic,
environmental and social issues. These different meanings often reflect the needs of particular
decision-makers and as a result there is no unique specific definition for risk and any attempt to
develop one would inevitably satisfy only a proportion of risk managers. Indeed this very adaptability
of the concept of risk is one of its strengths. A difficulty with the terminology of “risk” is that it has
been developed across a wide range of disciplines and activities, there is therefore potential for
misunderstanding in technical terminology associated with risk assessment, since technical
distinctions are made between words which in common usage are normally treated as synonyms.
Most important is the distinction that is drawn between the words “hazard” and “risk”.
Consequence
Figure 3.1 Source – Pathway – Receptor-Consequence conceptual model
To understand the linkage between hazard and
risk it is useful to consider the commonly
adopted Source-Pathway-Receptor-
Consequence (S-P-R-C) model (See Figure
3.1).
This is, essentially, a simple conceptual model
for representing systems and processes that
lead to a particular consequence. For a risk to
arise there must be hazard that consists of a
'source' or initiator event (i.e. high rainfall); a
'receptor' (e.g. flood plain properties); and a
pathway between the source and the receptor
(i.e. flood routes including defences, overland
flow or landslide).
A hazard does not automatically lead to a
harmful outcome, but identification of a
hazard does mean that there is a possibility of
harm occurring, with the actual harm
depending upon the exposure to the hazard
and the characteristics of the receptor.
Thus, to evaluate the risk, consideration needs to be made of a number of components:
• the nature and probability of the hazard (p)
• the degree of exposure of the Receptors (numbers of people and property) to the hazard (e).
• the susceptibility of the Receptors to the hazard (s)
• the value of the Receptors(v)
Therefore:
Risk = function (p, e, s, v)
In this context vulnerability is a sub-function of risk. The term encompasses the characteristics of a
system that describes its potential to be harmed. It can be expressed in terms of all functional
relationships between expected damage and system characteristics (susceptibility, value of elements at
risk), regarding the whole range of relevant flood hazards. Or, in functional form:
Vulnerability = function (s, v)
T32_04_01_ FLOODsite_Language_of_Risk_D32_2_v5_2_P1 30 April 2009
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