Evaluating impacts

Impact The effects or consequences of a factor on the attributes of the heritage place, both in terms of the attributes’ state of conservation and their ability to convey the heritage/ conservation values. An impact is the difference between a future environmental condition with the implementation of a development project, and the future condition without it. Note that for there to be an impact, there must a source of impact (e.g. noise from an industrial site), a receptor or attribute of the World Heritage property A cultural, natural or mixed heritage place inscribed on the World Heritage List and therefore considered to be of OUV for humanity. The responsibility for nominating a property to the World Heritage List falls upon the State(s) Party(ies) where it is located. The World Heritage Committee decides whether a property should be inscribed on the World Heritage List, taking into account the technical recommendations of the Advisory Bodies following rigorous evaluation processes.
When used as a general term, World Heritage refers to all the natural, cultural and mixed properties inscribed on the World Heritage List. that is affected (e.g. residents living nearby) and a pathway or route by which the harmful action or material is able to reach the receptor (e.g. the air). Impacts can be positive or negative, as well as direct or indirect, current or potential and originating within the heritage place, any existing buffer zone(s) and even beyond it.

See also: Direct impact, Indirect impacts Indirect impacts are impacts on the environment which are not a direct result of the project, often produced away from or as a result of a complex pathway. Sometimes referred to as ‘second’ or ‘third-level’ impacts, or ‘secondary’ impacts.

See also: Impact, Direct impacts, Cumulative impacts , Cumulative impacts evaluation determines whether the predicted impacts of the proposed action are significant or not on the basis of the characteristics of the predicted impacts (Section 6.8). Significant negative impacts on the wider heritage will generally be unacceptable, and on a World Heritage property A cultural, natural or mixed heritage place inscribed on the World Heritage List and therefore considered to be of OUV for humanity. The responsibility for nominating a property to the World Heritage List falls upon the State(s) Party(ies) where it is located. The World Heritage Committee decides whether a property should be inscribed on the World Heritage List, taking into account the technical recommendations of the Advisory Bodies following rigorous evaluation processes.
When used as a general term, World Heritage refers to all the natural, cultural and mixed properties inscribed on the World Heritage List. ’s OUV they will always be unacceptable. As this step directly leads to the recommendations that will form the final impact assessment report (Section 6.11), it is important for this evaluation to be transparent and rigorous. Tool 3 can also be used for impact evaluation.

Although impact evaluation is based on the individual attributes that convey a World Heritage property A cultural, natural or mixed heritage place inscribed on the World Heritage List and therefore considered to be of OUV for humanity. The responsibility for nominating a property to the World Heritage List falls upon the State(s) Party(ies) where it is located. The World Heritage Committee decides whether a property should be inscribed on the World Heritage List, taking into account the technical recommendations of the Advisory Bodies following rigorous evaluation processes.
When used as a general term, World Heritage refers to all the natural, cultural and mixed properties inscribed on the World Heritage List. ’s OUV, the proposed action’s overall impacts on OUV also need to be assessed. By definition, World Heritage properties are sensitive and internationally important, so even a small change may have a significant impact. Where there is a significant lack of clarity (e.g. insufficient data or technologies to predict potential impacts on OUV; major uncertainty about whether a significant impact on OUV might occur or not, or the effectiveness of proposed mitigation measures), the impact assessment should follow the Precautionary Principle The Precautionary Principle enables decision-makers to adopt precautionary measures when scientific evidence about an environmental or human health hazard is uncertain and the stakes are high.
The Rio Declaration (United Nations, 1992) defines the Precautionary Principle: ‘Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation’. : alternatives or appropriate mitigation measures should be identified to ensure that World Heritage is never put at risk. In some cases, this might mean taking the decision not to proceed with the proposed action.

The evaluation should result in a clear conclusion about whether the likely impacts of a proposed action on OUV overall are acceptable or not. If the proposed action would have negative impacts on OUV, the report should give one of three conclusions:

• The negative impact would be negligible and raises no concerns
• The negative impact would be significant, but with avoidance and mitigation measures it could be eliminated or minimized to an acceptable level
• The negative impact would be significant and could not be avoided or mitigated, so the proposed action should not proceed.

If the proposed action would have positive impacts on OUV, the report should give one of three conclusions:

• The positive impact is beneficial to the World Heritage property A cultural, natural or mixed heritage place inscribed on the World Heritage List and therefore considered to be of OUV for humanity. The responsibility for nominating a property to the World Heritage List falls upon the State(s) Party(ies) where it is located. The World Heritage Committee decides whether a property should be inscribed on the World Heritage List, taking into account the technical recommendations of the Advisory Bodies following rigorous evaluation processes.
  When used as a general term, World Heritage refers to all the natural, cultural and mixed properties inscribed on the World Heritage List. and raises no concerns
• A more positive impact could be achieved by selecting a project alternative or adjusting the project design
• The positive impact does not reach objectives set for the proposed action (e.g. flood defences would not be effective against predicted flooding events), so the proposed action (or that dimension of the proposed action) should not proceed.