Impact evaluation brings together information on:
- the type, magnitude, duration etc. of the strategic action's likely future impacts; and
- the sensitivity and importance of the receiving environment
into a statement of importance or significance. This can help to choose the preferred alternative, fine-tune the draft strategic action, and propose mitigation measures. The figure below shows how impact magnitude and receptor sensitivity are related.
The sensitivity and importance of the receiving environment can be determined in several ways:
- Designations (e.g. national parks, historic monuments) indicate areas that are valued because they are rare or particularly important. The level of their designation (i.e. international, national, local) gives an indication of their importance. These areas may be particularly good for one environmental aspect - for instance bird populations - but not good for others (like landscape);
- Standards and regulations (e.g. air quality standards, standards for insulation in housing) set minimum/maximum levels for many pollutants or actions;
- Where designations and standards do not exist, one may still be able to test against other targets. Targets were discussed in the Baseline section.
- The public or stakeholders can be asked what environmental/ sustainability aspects they consider to be the most important, and how significant they feel the impacts to be. This would ensure that those people likely to be most affected by a strategic action have a chance to influence it, and to propose mitigation measures. However these views would need to be complemented by those of a range of experts, to ensure a well-rounded analysis: otherwise local interests could outweigh national ones, and cute, furry but common animals (e.g. foxes) could be given more priority than less charismatic but more endangered species (e.g. liverwort).
Impact evaluation can also involve the participation of multiple stakeholder groups, including the public and non-government organisations. The figure below shows the potential complexity of SEA evaluation and its links to the decision making process, with a progressive move from 'objective' to more subjective and then political decisions.
Impact evaluation can involve (pseudo)-quantitative method such as land suitability analysis, multi-criteria analysis and testing against an area's carrying capacity. The interactive animation on page 6 provides further information on the range and types of evaluation techniques. However given the techniques' complexity, relative lack of transparency and quite limited use to date, they are likely to be useful in only a limited number of situations.
The Quality of Life Capital approach brings together many of the previous techniques. Its outcome is a series of 'tests' which any development would need to fulfil. Arguably, if the strategic action fulfils the QoLC tests, then a separate impact evaluation stage is not necessary.
However evaluation in SEA is most commonly done through 'expert judgement', and impact prediction and evaluation are often combined into one stage.
Where a significant negative impact is identified, mitigation should always be considered: this is a key concept behind SEA as a tool to improve the strategic action rather than just a camera that takes a 'snapshot' of its impacts. A straightforward way of helping to ensure that this takes place is by structuring the SEA framework so as to immediately trigger the consideration of mitigation measures. The table at the bottom of page 5 (Assessing a draft strategic action) is a good example: see the column entitled "possible changes to sub-component".
Who wins? Who loses? Equity assessment
Impact evaluation should not just consider the affected area as a whole, but also whether any sub-areas or sub-populations are likely to be particularly affected. For instance, will the elderly, or car owners, or rural residents particularly profit or lose from the proposed strategic action?
The question of who wins and loses is one of equity. Equity can be both intra-generational (between groups of people who are currently alive) and inter-generational (between today's and future generations). The concept of equity implies that no group should be affected unfairly. Examples of inequity are unequal access to services such as transport or financial services, as well as fuel poverty, food poverty and water conflict.
Many forms of development have a disproportionate effect on groups that are already disadvantaged. For instance in the UK:
"In general the benefits of car use accrue to those who own and use cars (the better off) but the adverse effects are borne primarily by others. For example, air pollution is worse in more deprived areas and alongside major roads. Injuries show the steepest effects of inequalities. Child pedestrian deaths are five times higher in social class V (least well-off) than I. Children from deprived areas are less likely to be car passengers, more likely to walk, cross more roads that have higher volumes and speeds of traffic, and are less likely to be accompanied by an adult or to have been taught road safety" (London Health Observatory, 2005).
An underlying objective of any strategic action should thus be to help redress -- or at least not exacerbate - any existing imbalances in equity.
There are several ways of testing a strategic action's equity impacts. One can ask, as part of the SEA:
- whether any sub-groups will suffer a significant cumulative impact as a result of the strategic action.
- whether the strategic action will have a differential impact on some sub-groups.
- who would win and lose under the strategic action.
- whether the strategic action helps to promote an equity objective in the SEA framework, for instance "To not disadvantage existing residents as a result of future development of the area" or "To improve living conditions for all".
In either case, the equity assessment could be based on either a list of those groups that are most likely to be significantly affected - the elderly, people who do not have access to cars, children, unemployed people etc. - or on an open question "who wins, who loses?". In some countries, indices of deprivation already exist, along with lists/maps showing areas of relative deprivation: this makes it relatively easy to identify currently disadvantaged groups.
Northern Ireland's 'fair treatment' test is an example of a "differential impact" test that lists specific sub-groups. The test aims to help prevent and mitigate the results of the long-standing religious conflict in the area. The test asks whether a policy would have different impacts on:
- people of different religious beliefs or political opinions;
- men and women;
- married and unmarried people;
- people with or without dependants;
- people of different ethnic groups;
- people with or without a disability;
- people of different ages; and
- people of differing sexual orientations.