Mapping Flood Disadvantage in Scotland 2015: Methodology Report

2. The approach to flood disadvantage assessment

2.1 The assessment framework

This assessment of flood disadvantage in Scotland builds on the methodology used in the assessment of social vulnerability to flooding (Lindley at el., 2011) and flood disadvantage in Scotland assessment (Lindley and O'Neill, 2013). The current assessment further develops the methods used in the original work in terms of the set of indicators used (the modifications to the set of indicators are described and justified in section 4 and Appendix 1 provides more details), but the main principles remain the same. However, due to different sets of indicators used, the outcomes of the 2013 assessment and this assessment are not directly comparable.

The assessment is carried out at the community or neighbourhood level, and therefore has a strong geographical dimension, i.e. it is strongly linked to particular locations. The assessment of vulnerability and disadvantage of neighbourhoods to flooding is based upon a conceptual framework (Lindley et al., 2011; Figure 1), whereby social vulnerability to flooding is a combination of:

• Sensitivity (influenced by a mix of personal factors, e.g. disability or age);
• Enhanced exposure (linked to environmental factors, e.g. elevation of housing, presence of green space); and,
• Adaptive capacity of communities, which is affected by social factors (e.g. levels of income, tenure or extent of social networks) and divided into:
  • The ability to prepare for flooding
  • The ability to respond to flooding during the flood event
  • The ability to recover after flooding

In locations where social vulnerability is high but there is no likelihood of flooding, the negative impacts of flood events on health and well-being will not be realised. Therefore, flood disadvantage is realised only where vulnerable neighbourhoods are located within areas which may be affected by flooding (Figure 1). This means that the level of flood disadvantage reflects two components:

• The magnitude of social vulnerability to flooding, i.e. the combination of the personal, social and environmental factors that, in the event of flooding, would mean that the well-being of people in a given location would be negatively affected;
• The proportion of the vulnerable community that is likely to be exposed to flooding (i.e. the percentage of people living within an area with a particular likelihood of flooding).

Figure 1. The framework of socio-spatial vulnerability and flood disadvantage (after Lindley et al., 2011; adapted for flood hazard).

Different flood types (coastal, river and surface water flooding) and probability of flooding (return periods), which also take into account the effects of climate change, are considered as varying the level of the potential hazard-exposure.

The main report explains the concepts of social vulnerability to flooding and flood disadvantage and the variety of factors influencing them in more detail.

2.2 Area-based approach

The assessment of social vulnerability to flooding and flood disadvantage uses an area-based approach, i.e. datasets were collected and analysed for distinct census units (see section 3) and the indicators are expressed in relation to the area (e.g. % of population in the area characterised by a certain feature; % of the spatial unit area characterised as urban).

Benefits of an area-based approach include:

• It minimises the issues of data protection and confidentiality as it enables the generalisation of personal, social and economic data for census units.
• It provides a broader picture that makes the outputs suitable for strategic planning. Therefore, it may be particularly useful to support decisions when preparing areas of known flood exposure prior to a flood event (e.g. through appropriate planning or neighbourhood design reducing exposure; through actions targeted at raising awareness of the risk of flooding and local authority's actions to reduce that risk across the community).
• It offers the opportunity to represent the results on maps. This may be used to highlight areas of high flood disadvantage (see case studies in the main report), guiding the efforts of local authorities and other local service providers to prioritise the areas for action. It may also ensure that the most effective preventative measures and responses to flooding by considering the characteristics of the community.
• Area-based mapping of vulnerability, instead of focusing on individuals, fits within the UK focus on populations in public health policies, rather than biology and behaviour of individuals, as is the case in the US, for example (Gordon, 2003).

The drawbacks of an area-based approach:

• It does not offer detailed information about the particular vulnerabilities of individual people and households (information which is available to public health services and social care departments of local authorities), and thus may not be sufficiently detailed to guide the action of emergency services in the event of flooding. This is reflected in previous research, where spatial vulnerability assessments were seen by emergency services as meaningful for prevention, planning, recovery and training, but having a limited role during the immediate response phase of a flood incident (Alexander et al., 2011).
• Low overall vulnerability at the census unit level may conceal the high vulnerability of a small number of individuals or households living in that area. Similarly, not all people living in an area classed as highly disadvantaged in terms of flooding would necessarily be exposed to flooding or have high vulnerability.

Due to these limitations, this dataset should be considered as an initial indication of areas affected by social vulnerability to flooding and flood disadvantage. One of its main uses has been identified as a tool to start cross-departmental and multi-stakeholder discussion about the appropriate responses to flood disadvantage (see the case study section in the main report). It is recommended that in the decision-making phase, local authorities and other end users supplement this area-based dataset with a more detailed (and up to date) knowledge pertaining to the specific aspects and levels of vulnerability and exposure to flood in a specific location.