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”.
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 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.
Figure 1a Source – Pathway – Receptor-Consequence Conceptual model
Figure 1b Source – Pathway – Receptor-Consequence Conceptual model
Some relevant definitions (drawn from the Language of Risk – FLOODsite Report T32-04-01) are given below:
Risk analysis - A methodology to objectively determine risk by analysing and combining probabilities and consequences.
Flood risk management - Continuous and holistic societal analysis, assessment and mitigation of flood risk.
Flood event management which can be considered as a sequence of four activities:
- detection of the likelihood of a flood forming (hydro-meteorology),
- forecasting of future river flow conditions from the hydro-meteorological observations,
- warning issued to the appropriate authorities and the public on the extent, severity and timing of the flood, and
- response to the emergency by the public and the authorities.
Source - The origin of a hazard (for example, heavy rainfall, strong winds, surge etc).
Pathway - Route that a hazard takes to reach Receptors. A pathway must exist for a Hazard to be realised.
Receptor - Receptor refers to the entity that may be harmed (a person, property, habitat etc.). For example, in the event of heavy rainfall (the source) flood water may propagate across the flood plain (the pathway) and inundate housing (the receptor) that may suffer material damage (the harm or consequence). The vulnerability of a receptor can be modified by increasing its resilience to flooding.
Consequence - An impact such as economic, social or environmental damage/improvement that may result from a flood. May be expressed quantitatively (e.g. monetary value), by category (e.g. High, Medium, Low) or descriptively.
|Where can I find out about flood risk where I live?
For people living in the UK, the (UK) Environment Agency provides an online service showing indicative floodplain areas. This can be accessed through the floods section of the Environment Agency website. It should be noted that these indicative flood plain areas show areas of inundation that would likely occur without taking into consideration the effect of any flood defence structures.
For people living in the Netherlands, the following website allows the user to identify ground level, relative to mean sea level, simply by entering a postcode. This gives property owners the opportunity to assess potential flood risk in the event of dike failure. See www.ahn.nl/hoogtetool
The new EU Directive requires that flood risk maps will available to the public in all Member States once the Directive is implemented
FLOODsite specifically provides material to support training and education for post graduates and professionals. However, general background information on flood risk analysis and flood risk management can be found via the Task Outcomes pages, in particular by viewing subsequent pages under “An introduction…”. Photographs, figures, videos and animations can be accessed directly via the Visual Material Library. As the project progresses, more information will become available through the Guidance Documents.
|Where can I find details of tools/models developed by FLOODsite?
Models can be accessed via three different routes on this website:
- Toolkit – providing direct access to tools/models via an itemised list.
- Task Outcomes – providing details of FLOODsite outputs from the context of the Work Programme.
- Modelling Facility – providing details of FLOODsite outputs from the context of flood risk analysis and management processes.