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Publication - Guidance

Flood protection initiatives: guidance for the Scottish Environment Protection Agency

Published: 2 Jun 2016
Part of:
Environment and climate change

Appraisal guidance for the Scottish Environment Protection Agency (SEPA) and responsible authorities.

73 page PDF


73 page PDF


Flood protection initiatives: guidance for the Scottish Environment Protection Agency
8. Assessing environmental impacts

73 page PDF


8. Assessing environmental impacts

8.1. Introduction

8.1.1. Flooding can have both positive and negative impacts on the environment. Floods are fundamental to the ecology of floodplains and wetlands and the development of river features. But flooding can also have negative environmental impacts: some species and habitats can be damaged by sediment, pollutants or salt in flood water or by the action and movement of flood water itself.

8.1.2. Actions to manage flood risk can have environmental impacts, for example, through changes in land use, alterations to channel morphology, impacts on habitats and species, and impacts on greenhouse gas emissions. Sensitively designed flood risk management actions can make a significant contribution to the environment and appraisers should look for opportunities to deliver multiple benefits.

8.1.3. Early consideration of environmental and heritage protection (Box 4.1) will allow appraisers to identify any negative impacts, take steps to avoid, minimise or mitigate for those impacts, and include the costs of these steps in the appraisal. Furthermore, it can help to identify opportunities to contribute to environmental enhancement.

8.2. Assessing impacts on environmental receptors

8.2.1. Many options, whether 'do something' or 'do nothing', will have significant environmental consequences. In some cases, protecting one site may have consequences for another and a decision will have to be made on their relative values. In other cases, environmental losses may be unavoidable, for example, in reducing the risk of loss of life. An auditable record of the assessment and decision-making process will therefore be required.

8.2.2. Appraisers should assess both the positive and negative impacts of options on the environment: this includes the impacts as a result of changes to flood hazard and from wider impacts. This guidance identifies aspects of the environment that might be impacted (grouped by the topics commonly used for SEA and EIA to assist with integrating statutory impact assessment into the decision-making process). It is not exhaustive and references are provided to other sources of information (Box 8.1)

8.2.3. Consultation with Scottish Natural Heritage, SEPA, Historic Environment Scotland and other stakeholders is recommended at an early stage to help maximise potential benefits and avoid or minimise adverse impacts.

Box 8.1: Reference material for assessing environmental impacts

State of Scotland's environment

  • Scotland's environment web contains a wide range of information and data on the state of Scotland's environment, including pressures and trends, which can be used to help inform appraisal.

Guidance for valuing environmental impacts

8.3. Frameworks for assessing impacts

8.3.1. Using a framework to consider the impacts of actions on the environment can help ensure that all significant impacts are identified and brought into the appraisal. The key purpose is to ensure that these impacts are considered as part of decision-making.

8.3.2. One framework is the ecosystem services framework ( UK National Ecosystem Assessment (2011, 2014). The ecosystem service approach involves valuing the environment according to the range of goods and services it provides to people. Where an option alters the quantity or quality of ecosystem services provided, the impact of the changes should be comprehensively assessed and, where possible and proportionate, quantified and or valued (this may be in monetary terms).

8.3.3. It is recognised that there can be considerable complexity in understanding and assessing the causal links between a policy or intervention, its effects on ecosystems and related services and then valuing the effects. Integrated working with policy, science and economics disciplines will be essential in implementing this approach in practice. The critical importance of the links to scientific analysis, which form the basis for valuing ecosystem services, needs to be recognised.

8.4. Valuing environmental impacts

8.4.1. Appraisers should decide whether it is proportionate to attempt to put a monetary value on environmental impacts. For many appraisals, the use of non-monetised assessments is likely to be sufficient to support decision-making. There are a variety of techniques available that allow these impacts to be considered for example by assigning categorical data, counts, scores, or other qualitative data.

8.4.2. Where environmental costs and benefits are valued in monetary terms, these impacts can be brought into a benefit-cost analysis. As many aspects of the environment are not traded in markets and therefore remain unpriced, the relative economic worth of these goods or services may be assessed using quantitative non-market valuation techniques (such as willingness to pay or contingent valuation). The type of valuation technique chosen will depend on the purpose of the appraisal, the aspect to be valued, as well as the quantity and quality of data available. Some valuation methods may be more suited to capturing the values of certain environmental aspects than others. HM Treasury Green Book (2011) and supplementary guidance (and references therein) provide further information on valuation methods.

8.5. Water environment

8.5.1. Actions to manage flood risk can impact both positively and negatively on the water environment. Given the emphasis on delivering multiple benefits, appraisals should consider the impact on water quality and on coastal/channel morphology, including the potential for contributing to objectives set out in River Basin Management Plans (developed for the EC Water Framework Directive under the Water Environment and Water Services (Scotland) Act 2003). Information on the current chemical and morphology status and objectives for water bodies is available on the SEPA website.

8.5.2. Actions that help to minimise urban and rural pollution can help to protect drinking water quality and bathing water quality. Data are available from the Drinking Water Quality Regulator [5] and SEPA [6] .

8.6. Biodiversity, flora and fauna

8.6.1. Flooding can have positive and negative impacts on biodiversity, flora and fauna. Some types of habitats and species are dependent on periodical flooding. Damage, however, may result from extended water submersion, from the release of sediment or pollutants (e.g. from sewage or from flooding to sites regulated under the Pollution Prevention and Control (Scotland) Regulations 2012), or from exposure to salt water due to coastal flooding. Therefore, appraisals should consider how any changes to flood hazard will impact on habitats and species.

8.6.2. Actions can also impact on biodiversity, flora and fauna, for example through the footprint of the action, through disturbance during construction / operation / maintenance, through impacts on supporting habitats, or through changes to natural processes. These positive and negative impacts should be considered in appraisal.

8.6.3. Appraisals should consider the impacts on protected sites and species, and also on wider biodiversity and habitat connectivity, for example:

  • Impacts on internationally protected sites. Particular reference should be given to impacts on Natura sites. Habitats Regulations Appraisal may be required (see Box 4.1);
  • Impacts on nationally protected sites and species including: Sites of Special Scientific Interest ( SSSIs); Nature Marine Protected Areas; Species listed in Schedule 1 (birds), Schedule 5 (other animals), and Schedule 8 (plants) of the Wildlife and Countryside Act 1981;
  • Impacts on species or habitats listed in the Scottish Biodiversity List [7] ;
  • Impacts on species or habitats listed in Local Biodiversity Action plans;
  • Impacts on habitat connectivity.

Further information on protected sites and species and links to data can be found on the Scottish Natural Heritage website [8] .

8.7. Air and soil

8.7.1. Appraisers should consider whether the options are likely to have significant effects on air quality, both in the short and long-term. For example, green infrastructure may provide benefits to air quality (Forest Research 2010).

8.7.2. Appraisals should also consider the impacts of options on soil and geodiversity [9] (including rocks, minerals and landforms). Soil quality can be affected by pollution, vegetation cover, erosion, acidification, compaction and soil sealing.

8.8. Climatic factors

8.8.1. Part 4 of the Climate Change (Scotland) Act 2009 places duties on public bodies relating to climate change. The duties in the Act (Section 44) require that a public body must, in exercising its functions, act:

  • In the way best calculated to contribute to delivery of the Act's emissions reduction targets;
  • In the way best calculated to deliver any statutory adaptation programme; and
  • In a way that it considers most sustainable.

The Scottish Government (2011c) has produced guidance for public bodies on how to put their duties into practice.

8.8.2. Appraisals should consider the impacts of greenhouse gas emissions associated with different options. This should include the greenhouse gas emissions that are associated with implementing and maintaining the option (e.g. construction and land use change) and those associated with recovery from flooding.

8.8.3. Qualitative comparisons of greenhouse gas emissions may be sufficient for strategic and feasibility appraisals, whereas for more detailed design it may be appropriate to quantify and even value greenhouse gas emissions. When determining whether to describe or quantify greenhouse gas emissions, appraisers should consider whether the difference in emissions between options is likely to be significant (e.g. when comparing two option that differ greatly in the quantity of concrete such as a concrete versus earth embankment). Supplementary guidance to the HM Treasury Green Book provides rules for valuing energy usage and greenhouse gas emissions ( DECC 2014).

8.8.4. Guidance on assessing the impacts of and adapting to climate change is provided in Sections 4.6.5 and 9.8.

8.9. Landscape

8.9.1. The assessment of environmental impacts should include the consideration of impacts on landscape; encompassing all the external environment including cities, towns, villages and the wider countryside. It is a combination of the visual dimension with other factors including geology, topography, soils, cultural heritage, land use, ecology, and architecture that together determine its overall character. It is therefore part of our natural, social, and cultural heritage resource base in both urban and rural areas. Landscape is dynamic, continually evolving in response to natural and man-induced processes. There may be significant overlaps with social impacts such as sense of belonging and sense of place.

8.9.2. Scottish Natural Heritage has published a range of guidance and tools on how to manage and assess landscape change [10] . The Landscape Institute (2013) publish guidelines on assessing the landscape and the visual impacts of development projects. Appraisers should also consider engaging with local communities when assessing impacts on the landscape.

8.10. Cultural heritage

8.10.1. Cultural heritage includes historic buildings, parks, gardens and landscapes, palaeo-environmental and geo-archaeological remains (as indicators of past climates, vegetational and landscape change) and archaeological remains (including wrecks). It can be impacted by flooding and also by actions to manage flood risk.

8.10.2. Some cultural heritage sites have specific protection under legislation and policy, including:

  • UNESCO World Heritage Sites;
  • Listed Buildings;
  • Scheduled Monuments;
  • Inventory of Gardens and Designed Landscapes;
  • Battlefields;
  • Historic Marine Protected Areas;

Information and further advice can be sought from Historic Environment Scotland.

8.10.3. Appraisal of impacts on cultural heritage should consider impacts on:

  • The physical asset;
  • Its setting;
  • Its inter-relationships with other historical assets;
  • Areas where there may not be any known physical assets but where there is potential for archaeological finds (including where any works could disrupt or damage hidden archaeology, including wetland archaeology);
  • The importance of the asset for the community.

8.10.4. The Scottish historic environment policy (Historic Scotland 2011) sets out a framework and principles to help assess, protect and minimise damage to the historic environment.

8.10.5. Flood damages to listed buildings may be captured as part of the depth-damage assessment of residential and non-residential properties so care should be taken not to double count these impacts. This assessment, however, may not capture the full range of impacts on listed buildings:

  • Damages to contents and building fabric may be underestimated (depending on the specific building characteristics and usage);
  • The importance of the asset from a social perspective is not recognised.

8.10.6. In many cases a qualitative or quantitative approach will be an appropriate way to capture impacts. However, where impacts to cultural heritage are likely to be significant and will affect decision-making, the appraisers should consider whether it is worthwhile deriving a proxy or contingent economic value for the impacts on the asset. There may also be benefits transfer values available that can be used to monetise impacts on cultural heritage. Consultation with appropriate specialists is recommended if using these approaches.


Email: Neil Ritchie,

Phone: 0300 244 4000 – Central Enquiry Unit

The Scottish Government
St Andrew's House
Regent Road