6.8

Identifying and predicting impacts

Identifying and predicting impacts is a technical step at the heart of the impact assessment process and therefore needs specialist contributions from a range of relevant disciplines. At a minimum, it is advisable to confirm the results of the impact prediction and evaluation – and mitigation measures for any significant negative impacts – with the environmental and heritage authorities. Rights-holders Actors socially endowed with legal or customary rights with respect to heritage resources. In cases where there are Indigenous people involved, they have the right to free, prior and informed consent before approval of any project affecting their lands or territories and other resources, and need to participate in impact assessment. and other stakeholders should preferably be involved in these stages.

6.8.1 Identifying 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 identification brings together information about the attributes of OUV and other heritage/conservation values (Section 6.6) and the proposed action and alternatives (Section 6.3 and Section 6.7), to determine what would happen to the attributes of 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. if a proposed action took place – for example, Figure 6.7 shows how noise from a proposed action might impact on nesting birds. An impact is the interaction of the proposed action with an 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. , and this can take either negative or positive forms – biophysical, social, cultural, economic, health, visual, etc. All relevant impacts should be considered, including those on intangible attributes which are reflected in physical elements of the property (Figure 6.9).

Figure 6.7. The impact on nesting birds created by noise from a proposed action. An impact is the interaction of the proposed action with an 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. . In this example, the noise from a proposed action may impact on nesting birds, which when disturbed will leave the area. Where birds are an 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. , this would lead to a loss of Outstanding Universal Value.
 

Figure 6.8. The impact on a historic urban environment created by sound and vibration from a proposed action. An impact is the interaction of the proposed action with an 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. . In this example, the vibration from a proposed action may have an impact on the buildings and weaken their structural stability. Where these buildings are an 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. , this would lead to a loss of Outstanding Universal Value.

Figure 6.9. Examples of elements of a heritage place that could be impacted. A proposed action can significantly affect many attributes of 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. , and the impact assessment will need to consider all relevant impacts on these.

The proposed action can directly impact on 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. ’s OUV and other heritage/conservation values. It can also have indirect impacts, where a direct impact has follow-on impacts (e.g. more traffic, leading to air pollution, which could then have further follow-on indirect impacts on human health or vegetation). These also need to be formally identified and assessed. The impacts of a proposed action may also combine with those of other past, existing or future actions and other factors (such as climate change) that may affect 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. , and have a cumulative impact. There may have been changes at or near 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. since the time of its inscription that need to be taken into consideration when assessing a new proposal. The proposed action may create a precedent which then creates cumulative impacts in the future. For this reason, it is important to be aware of other actions and trends in the past, present and future, and not consider a proposed action in isolation. When cumulative impacts are significant, the final impact assessment report will need a separate section to address them clearly.

Box 6.4. Examples of different impacts

Examples of direct impacts include:

  • Demolition, alteration or addition to a historic building
  • Encroachment into 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.         by a road widening project leading to habitat loss
  • Development of a visitor centre on a part 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.         where it affects access, urban layout or spatial planning
  • Significant increase in noise levels at a spiritual or ecologically sensitive 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.

Examples of indirect impacts include:

  • Changes in the natural flow of water downstream from a new dam, affecting 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 which depends on natural water fluctuation patterns
  • A road built to support a proposed action which also increases vehicular access 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.
  • Water damage to fragile building materials or buried archaeology when a ground surface is made impervious in an area, resulting in a change to the hydrology downslope
  • A land-use plan leading to a significant increase in the population of a historic town, with associated increased recreational pressure on 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.

Examples of cumulative impacts include:

  • Multiple projects leading to the progressive loss of natural habitat, which will ultimately have a significant impact on a rare species that is dependent on that habitat
  • A single building project within a green space in a historic town with many green spaces. This may not have a significant impact; however, if a large number of those green spaces are converted into buildings over time the cumulative impacts on the urban layout will be significant
  • Reconstruction of houses in a historic urban fabric. Reconstruction of a single house may not matter but if a large number are reconstructed then the cumulative impact on the authenticity and integrity of the property can be significant.

When identifying impacts on OUV, it is important to remain aware of how 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. is interconnected with its buffer zone and wider setting, and that it cannot be viewed in isolation. All direct, indirect and cumulative impacts occurring in the entire area of influence of the proposed action need to be identified and assessed for their potential to impact 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. .

Impacts may occur at any stage of a proposed action, so the action’s entire life cycle needs to be considered (Figure 6.5). For instance, construction may involve a limited number of heavy goods vehicle movements, while operation may involve a larger number of car movements. Many impact assessments have a separate chapter or sections on construction impacts.

While professional judgement can often be used to identify the impacts of a proposed action, there are a number of tools that can help ensure that all the issues are considered in a more systematic way. These include:

  • Overlay maps: colour-coded plans showing the physical extent of the proposed works and the areas over which any attributes are sensitive (e.g. buffer zones around streams)
  • Checklists: for some types of project, there are checklists that can be used to identify which impacts are likely to occur, e.g. wind farms (UNDP Serbia, 2010) or irrigation and drainage projects (ICID, 1993). These may need to be adapted to the proposed action and location
  • Matrices: a matrix can be created with attributes 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.         along one axis and elements of the proposed action along the other, to show the interaction between the two (see     Tool 2)
  • Network diagrams: these visually represent the links between elements of the proposed action and their potential impacts on attributes 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.
     

6.8.2 Predicting impacts

Once potential impacts have been identified, an informed prediction can be made about the likely scale and nature of those impacts. The impact prediction should compare the baseline conditions 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. (Section 6.6) against the situation with the proposed action; this should be done for each reasonable alternative as well as the proposed action. This is a technical step and its conclusions should be defendable.

Predictions of potential impacts can include a range of characteristics (Table 6.2). It may be possible to quantify the impact (e.g. likely changes to the population of a sensitive species, or number/area of historic structures that are to be altered); in other cases, a narrative description may be the only option. In all cases, the description of the impact should be as precise as possible. Assumptions underlying the predictions should be clearly disclosed and uncertainties described.

Table 6.2. Characteristics of potential impacts and prompt questions as part of an impact assessment

Tool 3 provides a structure for predicting impacts, taking into account the characteristics in Table 6.2. While recognizing that some uncertainty will be unavoidable, the prediction should provide as solid and transparent a basis as possible on which to make decisions. Techniques for impact prediction include:

  • Quantitative analysis: calculating impacts using baseline data and an understanding of the proposed action. Models can be used to analyse more complex situations, including indirect and cumulative impacts
  • Professional judgement: experienced specialists can offer a more qualitative estimate based on similar projects in heritage places in the same geographic region
  • Case studies: examining other similar projects or scientific research that has taken place in a similar context, particularly if monitoring data is available.

Predicting impacts quantitatively can allow clear comparisons between the likely future with and without the proposed action, and between the impacts of the proposed action and any alternatives. However, where this is difficult, impacts can be estimated using, for example, ‘high’, ‘medium’ and ‘low’ categories. If there is a high degree of uncertainty, it may also be useful to provide best- and worst-case predictions. Such approaches, including any definitions of the categories used, should be explained clearly in the final report (Section 6.11).

Impact assessment Impact assessment is the process of identifying, predicting and evaluating the potential environmental impacts of proposed actions prior to major approval decisions being taken and commitments made. It is undertaken for the purpose of avoiding or mitigating adverse impacts, and enhancing beneficial impacts. More generally, impact assessment can be appreciated as a way of thinking and planning that can be applied to all scales of activity. Impact assessment can be applied to development proposals at various levels – projects, plans, programmes and policies.

See also: Environmental and Social Impact Assessment, Heritage Impact Assessment, Strategic Environmental Assessment aims to help protect the natural and cultural environment, and therefore emphasizes negative impacts. However, impacts can be positive, and these should also be identified and predicted.
This allows an understanding of:

  • how far the proposed action and any alternatives would meet stated project objectives and targets
  • who benefits (or not) from the positive impacts
  • how positive impacts could support a State Party’s obligation to protect and conserve World Heritage All inherited assets which people value for reasons beyond mere utility. Heritage is a broad concept and includes shared legacies from the natural environment, the creations of humans and the creations and interactions between humans and nature. It encompasses built, terrestrial, freshwater and marine environments, landscapes and seascapes, biodiversity, geodiversity, collections, cultural practices, knowledge, living experiences, etc.  
  • how World Heritage All inherited assets which people value for reasons beyond mere utility. Heritage is a broad concept and includes shared legacies from the natural environment, the creations of humans and the creations and interactions between humans and nature. It encompasses built, terrestrial, freshwater and marine environments, landscapes and seascapes, biodiversity, geodiversity, collections, cultural practices, knowledge, living experiences, etc.   can play a dynamic role in sustainable development
  • how the action can support disaster risk preparedness and resilience.