Impact assessment in its various forms such as EIA, SEA, HIA, SIA, etc., which number over 140 (Vanclay, 2004) have been widely recognized as a tool which helps in the task of “trying to decide whether something is a good idea or not”. The city of today is a major performer for the secondary sector of the economy. Manufacturing and processing facilities not only provide the city with the essential commodity inputs but also provide the means of living for the populace. Of late, ad-hoc decisions for industrial development have led to an adverse impact on the local environment at costs which are much higher than the benefits actually accrued. In view of the deteriorating environmental conditions in and around industrial townships, it has become necessary to account for the environment while planning for such areas.

The “traditional” tool to assess secondary risk of capital projects has been environmental impact assessment (EIA). EIA assesses environmental impacts at the project level (Vanclay and Bronstein, 1995; The World Bank, 2002), focusing on identifying, both at the construction and operation stage, key environmental and social impacts; key mitigation measures; and key monitoring tools. EIA has a well-established role as the key decision-making tool concerned with predicting, estimating and evaluating the secondary risks of a proposed capital project from the formulation to the implementation, operation and decommissioning stages of a capital project (Lee and Clive, 2000). EIA is an important instrument as it is the only risk assessment tool for secondary risks which many governments have already accepted as an essential and integrated part of planning processes and have often already made into laws.

Builders and managers of large capital projects such airports, bridges or power plants are, of course, usually well-versed in assessing the primary risks to any given project – e.g. the risk of structural failure of the project, or risks that the project may for any given reason generate less income than projected and therefore may turn out not to be financially viable (Caspary, 2008)

Environmental Impact Assessment (EIA) is a relatively new planning and decision making tool first enshrined in the United States in the National Environmental Policy Act of 1969. It is a formal study process used to predict the environmental consequences of any development project. EIA thus ensures that the potential problems are foreseen and addressed at an early stage in project planning and design.

Environmental Assessment enables us in carrying out Environmental Cost-Benefit Analysis of projects at an initial stage. It is thus a pre-cursor to detailed analysis of environmental impacts, which are taken up only if a need for the same is established. It gives a view of the actors involved in the `development-environment linkages. This is required in view of the fact that the community at large is always at a loss in terms of deterioration of living environment that accompanies industrial development. Based on Environmental Assessment, the regulatory measures can be identified and the roles of concerned agencies defined for achieving more efficient environmental management.

In view of the fact that development is an ever growing process, its impact on the environment is also ever increasing, leading to rapid deterioration in environmental conditions. As such Environmental Assessment provides a rational approach to sustainable development.

Evolution And Forms Of EIA

Environmental impact assessment (EIA) since its formulation in 1969 in the US has been adopted by more than 100 countries, making it the US legislation with maximum impact worldwide (Canter, 1996; Bojorquez-Tapia and Garcia, 1998; Barker and Wood, 1999). EIA in its initial form was formed to identify the potential negative impacts from any activity/project mainly on the biophysical environment. Later, when it was recognized that the social impacts of certain projects, involving large-scale displacement of people are also of higher magnitude, it led to the sub-component of Social impact assessment. Another interesting turn in the evolution of EIA came when it was felt that most of the activities that have the potential to affect the environment (comprising of ecological, social and economic components) are framed at the policy level. Hence, this realization led to the development of Strategic environmental assessment (SEA) to carryout the impact assessment of policy, plan and program (PPP) (Clayton and Sadler, 2005). Lately the focus is shifting to integrating sustainability aspects into the domain of EIA/SEA, which is now a much-debated aspect among the EIA community (Gibson, 2006). This are with claims that progress towards sustainability is the substantive objective of EIA being countered with the view that sustainability is still a fluid concept, which will erode the focus on protection of the environment (Morrison-Saunders and Therivel, 2006).

Historically, the decades following World War II were a period of unprecedented economic development and environmental change. The rapid creation of jobs, housing, transportation, and energy systems were accompanied by widespread negative environmental transformations including air and water pollution, destruction of ecosystems, the conversion of farmlands, and major redevelopment of historic urban centers. These changes were graphically brought into homes each evening by the new medium of television.

The emergent environmental movement of the 1960s played a key role in governments enacting substantive new environmental laws. Typically, each law addressed a specific problem. For example, the U.S. Clean Air Act, and Clean Water Act were designed to regulate pollution by setting specific allowable concentration limits on lists of specific toxic chemicals in air, water, and on land. Other laws focused on such issues as wetlands, endangered species, and historic preservation. These regulatory approaches were highly effective—but necessarily quite narrow in scope. In contrast, a fundamental concept of environmental understanding and stewardship is the need for an integrated holistic approach to knowledge building and decision making. The U.S. National Environmental Policy Act (NEPA) of 1969 was the first legislation to provide a robust framework for allowing all recognized environmental concerns to be addressed simultaneously

Definitions Of Eia

EIA is a systematic process to identify, predict and evaluate the environmental effects of proposed actions and projects. This process is applied prior to major decisions and commitments being made. A broad definition of environment is adopted whenever appropriate social, cultural and health effects are considered as an integral part of EIA. Particular attention is given in EIA practice to preventing, mitigating and offsetting the significant adverse effects of proposed undertakings.

Environmental Impact Assessments (EIA) are interdisciplinary analyses of the natural, human health, and socio-cultural effects which are expected to result from public and private sector actions such as development projects. The purpose of these studies is to comprehensively inform decision makers and the affected public about both the proposed action and its alternatives, so that wherever possible significant negative impacts may be avoided, minimized, or mitigated. (Caldwell, 2008)

Environmental Impact Assessment (EIA) may be defined as a formal process used to predict the environmental consequences of any development project. EIA thus ensures that the potential problems are foreseen and addressed at an early stage in the projects planning and design.

The International Association for Impact Assessment (IAIA) defines an environmental impact assessment as “the process of identifying, predicting, evaluating and mitigating the biophysical, social, and other relevant effects of development proposals prior to major decisions being taken and commitments made.

The purpose of EIA is to:

  • provide information for decision-making on the environmental consequences of proposed actions; and
  • promote environmentally sound and sustainable development through the identification of appropriate enhancement and mitigation measures.

Sustainable development is a key concept that has gained increasing international acceptance during the last two decades. A milestone in this process was the Brundtlanda report, which defined sustainable development as a development that meets the needs of today’s generation without compromising those of future generations. Five years later, the UN Conference on Environment and Development (UNCED), the Earth Summit, established a number of international agreements, declarations and commitments. Agenda 21, the global action plan for sustainable development, emphasizes the importance of integrated environment and development decision-making and promotes the use of EIA and other policy instruments for this purpose.

Importance Of EIA

Reducing the burden of environmental impacts is necessary if development is to become sustainable. These impacts are more complex, larger in scale and further reaching in their potential consequences than thirty years ago when EIA was first introduced. As a result, EIA has become of ever increasing importance as a tool for development decision-making.

This role is formally recognized in Principle 17 of the Rio Declaration on Environment and Development:

“Environmental impact assessment, as a national instrument, shall be undertaken for proposed activities that are likely to have a significant adverse impact on the environment and are subject to a decision of a competent national authority”.

In practice, EIA is applied primarily to prevent or minimize the adverse effects of major development proposals, such as power stations, dams and reservoirs, industrial complexes, etc. It is also used as a planning tool to promote sustainable development by integrating environmental considerations into a wide range of proposed actions. Most notably, strategic environmental assessment (SEA) of policies and plans focuses on the highest levels of decision making, when better account can be taken of the environment in considering development alternatives and options. More limited forms of EIA can be used to ensure that smaller scale projects, conform to appropriate environmental standards or site and design criteria. Such projects include dredging activities, road realignment and upgrading, and housing subdivisions.

Some measures are required to be taken in the future to reduce the anticipated environmental degradation. Before starting a major project, it is essential to assess the present environment without the project, and the likely impact of the project on the environment, when it is completed. Therefore, an Environment Impact Assessment has to be made before starting a project. For analysis of environmental impacts, many professions and disciplines have to be involved. Like economic and engineering feasibility studies, Environmental Impact Assessment is a management tool for officials and managers who make important decisions about major development projects.

EIA helps the stakeholders with the identification of the environmental, social and economic impacts of a proposed development before a decision is taking on whether or not to proceed. Particular attention is given in EIA practice to preventing, mitigating and offsetting the significant adverse effects of proposed undertakings.

EIA provides information for decision-making on the environmental consequences of proposed actions; and promotes environmentally sound and sustainable development through the identification of appropriate enhancement and mitigation measures.

In practice, EIA is applied primarily to prevent or minimize the adverse effects of major development proposals, such as power stations, dams and reservoirs, industrial complexes, etc. It is also used as a planning tool to promote sustainable development by integrating environmental considerations into a wide range of proposed actions. Most notably, strategic environmental assessment (SEA) of policies and plans focuses on the highest levels of decision making, when better account can be taken of the environment in considering development alternatives and options. More limited forms of EIA can be used to ensure that smaller scale projects, conform to appropriate environmental standards or site and design criteria. Such projects include dredging activities, road realignment and upgrading, and housing subdivisions.

Aims And Objectives Of EIA

The aims and objectives of EIA can be divided into two categories. The immediate aim of EIA is to inform the process of decision-making by identifying the potentially significant environmental effects and risks of development proposals. The ultimate (long term) aim of EIA is to promote sustainable development by ensuring that development proposals do not undermine critical resource and ecological functions or the well being, lifestyle and livelihood of the communities and peoples who depend on them.

Immediate objectives of EIA are to:

  • improve the environmental design of the proposal;
  • ensure that resources are used appropriately and efficiently;
  • identify appropriate measures for mitigating the potential impacts of the proposal; and
  • Facilitate informed decision making, including setting the environmental terms and conditions for implementing the proposal.

Long term objectives of EIA are to:

  • protect human health and safety;
  • avoid irreversible changes and serious damage to the environment;
  • safeguard valued resources, natural areas and ecosystem components; and
  • Enhance the social aspects of the proposal.

The EIA Process

The particular components, stages and activities of an EIA process will depend upon the requirements of the country or donor. However, most EIA processes have a common structure and the application of the main stages is a basic standard of good practice. Typically, the EIA process begins with screening to ensure time and resources are directed at the proposals that matter environmentally. It should end with some form of follow up on the implementation of the decisions and actions taken as a result of an EIA report.

The most visible product of the EIA process is an Environmental Impact Statement (EIS), an often lengthy and technical document that describes and comparatively evaluates the proposal and its alternatives. It is important for citizens and interest groups interested in influencing public decisions to understand the EIS in its procedural context. In the early years of EIA, there was confusion about what constituted a proper analysis and when it was appropriate. In response to often costly and sometimes questionable studies, many EIA laws and procedures evolved a “triage” approach to efficiently and effectively focus public attention and analytical resources on issues of primary environmental concern. Figure 1, the EIA Triage Process, is a generic representation of the approach based on NEPA.


Screening is the first key decision of the EIA process. Some type of screening procedure is necessary because of the large number of projects and activities that are potentially subject to EIA. The purpose of screening is to determine whether a proposal requires an EIA or not. It is intended to ensure that the form or level of any EIA review is commensurate with the importance of the issues raised by a proposal. For certain categories of proposal, the responsible authority may consult with people likely to be affected in order to gain a better understanding of the nature and significance of the likely impacts. This information can assist in determining if an EIA is required and at what level.

Screening is performed in order to ensure that proposals that will have a significant impact on the environment will undergo an EIA. The decisions taken during the early stage of the EIA are of fundamental importance to the process.


Scoping is a critical, early step in the preparation of an EIA. The scoping process identifies the issues that are likely to be of most importance during the EIA and eliminates those that are of little concern. Typically, this process concludes with the establishment of Terms of Reference for the preparation of an EIA. In this way, scoping ensures that EIA studies are focused on the significant effects and time and money are not wasted on unnecessary investigations. Scoping refers to the early, open and interactive process of determining the major issues and impacts that will be important in decision-making on the proposal, and need to be addressed in an EIA.

The term scoping is used to describe the process of deciding what should be included in an EIA. It may be seen as a means for identifying the main public concern about a proposal and for organizing the scientific work for the assessment .Scoping is the initial meeting(s) of all available stakeholders and decision makers to determine: jurisdictions; what existing data is available; what studies need to be done (feasible alternatives and impact categories); and workload responsibilities. A lead agency, responsible for all EIS documents is designated.

Impact Identification

Impact identification is establishing the basis for designing appropriate and efficient EIA studies, focused on particular impact areas. The impact identification has been subject of a large number of proposed methods and techniques

Public Involvement

The degree of public involvement in EIA varies between different countries due to different legal requirements as well as to tradition. In many countries like Sweden or the USA the public is supposed to have a large influence on the EIA process, while e g in Thailand the involvement is low.


The purpose of review is to assure the completeness and quality of the information gathered in an EIA. When undertaken as a formal step, it acts as a final check on the quality of the EIA report submitted to obtain a project authorization. Often, this process leads to a requirement for additional information on potential impacts, mitigation measures or other aspects.

Surveillance of the implementation of EIA terms and conditions can be undertaken by regular or periodic site inspections to check on compliance, observe progress and discuss issues. Supervision implies a more intensive direction of the environmental performance of on-site activities, ensuring they are carried out in accordance with the environmental management plan and/or contract specifications.


Monitoring refers to the collection of data through a series of repetitive measurements of environmental parameters (or, more generally, to a process of systematic observation). The main types of EIA monitoring activities are: Baseline monitoring Effects monitoring Compliance monitoring


Auditing is a term borrowed from accounting to describe a systematic process of examining, documenting and verifying that EIA procedures and outcomes correspond to objectives and requirements. This process can be undertaken during and/or after project construction, and draws upon surveillance reports and monitoring data.


Ex-post evaluation involves a policy-oriented review of the effectiveness and performance of the EIA process. It is concerned with the overall balance sheet of an EIA, looking at what it achieved, which aspects were influential, and how the process could be improved. The guiding concepts are: effectiveness and performance. Usually, a post-project analysis is undertaken once the project has been constructed and is about to enter the operational phase. The term implies a focus on project specific EIA experience, e.g. in relation to dams, highways, waste disposal sites or power generation

Limitations Of EIA

However, it has been repeatedly pointed out that EIA has its limitations. One limitation is that EIA procedures focus exclusively on the impact of projects on the environment, but conversely do not provide for the assessment of the impacts of global environmental changes on projects (e.g. due to global climate change). This could have significant implications for very long-lived infrastructure projects, which are likely to be impacted by climate change (e.g. with increased occurrence of extreme weather events such as floods affecting exceeding safety margins of some projects where the calculations for these safety margins are based on past “pre-climate change”, data). Indeed, recent research by the OECD Environment Directorate shows that, e.g. in Nepal a large part of the country’s hydropower facilities are at risk from climate change-related disasters (OECD Environment Directorate, 2005). At least equally importantly, EIA is limited in its scope, notably by focusing only on one project, the immediate project-affected area, while moreover rarely proposing how the hard choices between notably economic benefits and environmental/social costs of large capital projects are to be decided upon with efficient decision-making tools. Cumulative Impact Assessment, Strategic Impact Assessment and Multi-Criteria decision Analysis respectively have been developed to address these three shortcomings, and will therefore be the focus of the remainder of this article.

EIA is also a way of ensuring that environmental factors are considered in decision-making process along with the traditional economic and technical factors. Importantly EIA requires the scientific (technical) and value issues to be dealt with in a single assessment process. This helps in the proper consideration of all advantages and disadvantages of a proposal. Environmental considerations may, therefore, be set aside in favor of what are felt to be more important considerations. Alternatively, predicted adverse effects on the environment might lead to strict conditions being imposed to avoid these effects or remedy any adverse effects, or perhaps lead to the complete abandonment of a proposal.

However, it is most important to recognize that EIA cannot be regarded as a means of introducing an environmental “veto” power into administrative decision-making processes. Decisions that are unsatisfactory from an environmental point of view can still be made, but with full knowledge of the environmental consequences. The final decision about a proposal depends upon the likely severity of the adverse effects, balanced against other expected benefits.

In other words, EIA is an administrative process that identifies the potential environmental effects of undertaking a proposal, and presents these environmental effects alongside the other advantages and disadvantages of the proposal to the decision-makers. In the vast majority of EIA procedures this means that the outcome of the EIA process provides advice to the decision-makers it does not provide a final decision. So, by itself, the EIA procedures cannot be expected to stop a proposal although this is an outcome that some members of the general community and environment groups may expect.

In summary then:

  • only a very small fraction of proposals are halted, permanently or temporarily, as a direct result of EIA at the end of the review process;
  • preemption or early withdrawal of unsound proposals has been reported though it has proved difficult to document;
  • EIA has been useful in developing support for and confirmation of positive environmentally sound proposals;
  • the greening or environmental improvement of proposed activities is frequently seen; and
  • Particular indirect effects of EIA are both instrumental (such as where policy or institutional adjustments are made as a result of EIA experience) and educational where participation in the EIA process leads to positive changes in environmental attitudes and behavior.

With regard to the last point there is considerable advantage to the general community where those people involved with the proposal, as well as decision-makers, are required to think about the environmental effects (and thence avoid negative effects), and the public can be made aware of the details of the proposal.

The limited power of EIA may seem to greatly reduce its value. However, as you have seen there are many benefits that come from using EIA.

Cumulative Impact Assessment (CIA)

Cumulative Impact Assessment assesses the cumulative impacts from various projects in proximity, where the sum of the combined effects may be larger than that of each of its components taken together. For instance, emissions from each power plant in the same region may be well below health hazard thresholds, but taken together they may be above these thresholds. Similarly, none of the dams built on the same river may affect riverflow such as to prevent navigability of the river or destroy riverine ecosystems, but the set of dams taken together may do so.

CIA considers such cumulative impacts, (Smit and Spaling, 1995) and has therefore been repeatedly suggested in the academic literature as an important secondary risk assessment tool in cases where cumulative effects may arise from several large capital projects (McCold, 1991; Ross, 1998). According to Bonnell and Storey (2000)), the concept of cumulative effects is based on the premise that environmental effects are not necessarily mutually exclusive of each other, but may accumulate to bring about significant environmental change. The sources of disturbance may be related (e.g. multiple hydroelectric developments) or unrelated (e.g. a hydro project, a mine, and forest harvesting activity) in nature (Cocklin et al., 1992). In addition, CIA can provide early warning of large-scale effects, including those resulting from a number of smaller-scale projects that individually would fall under thresholds for triggering even a limited project EIA.

Strategic Impact Assessment (SIA)

There has recently been a considerable amount of work on a new approach to Impact Assessment, being so-called “Strategic Impact Assessment” (SIA). SIA is a systematic process to go beyond the narrow project level in assessing the impact of policies, plans, programs or highly complex projects with a view to mitigating and monitoring these impacts. It also has particular applicability for projects with broader regional or transboundary effects. In so doing, SIA makes impact assessment part of a larger planning process. SIA extends the aims and principles of EIA to the higher levels of decision-making when major alternatives are still open and there is far greater scope than at the project level to integrate environmental and social considerations into development goals and objectives. It allows problems of environmental deterioration to be addressed at their “upstream source” in policy and plan-making processes, rather than mitigating their “downstream symptoms” or project-level impacts.

However, for the person carrying out the SIA, this tool represents a greater challenge than EIA. In particular, the broader nature of the policies, plans or complex projects that SIA is concerned with (as opposed to the projects that EIA is concerned with) also mean that the level of uncertainty of impacts which SIA has to deal are likely to be higher. . The fact that a broad set of environmental, social and economic considerations are taken into account in SIA mean that there is a greater array of interlinkages among these effects to be considered.

SIA is a dynamic and systemic process whereby the impacts of policy choices are identified and evaluated, and corrective measures identified and implemented in an iterative fashion. The appropriate SIA methodologies will vary across-sectors and across countries, in line with their unique institutional and other features. However, actual in-country experience with this instrument is still limited and most countries do not yet have relevant legal procedures in place (Dalal-Clayton and Sadler, 2005). SEA is very helpful in addressing strategic policy questions, like how an energy strategy increases or decreases vulnerability to climate changes and, therefore, can address how a capital project affects or is affected by larger or even global environmental threats. Moreover, for project managers, SIA may be useful to gauge the broader impacts of a mega project such as dams (Caspary, 2006).

Eia Case Studies

Ghazi-Barotha Hydropower Project

The Ghazi-Barotha Hydropower Project is a major run-of-river power project designed to meet the acute power shortage in Pakistan. The main project elements include a barrage located on the Indus River, a power channel (designed to divert water from the barrage) and a power complex. Alternative locations for these elements were evaluated based on technical, economic, environmental and social constraints by an interdisciplinary project team and reviewed by an external environmental and resettlement panel.

Initial assessment of five barrage sites identified by the project consultants resulted in two options being selected for detailed evaluation. The preferred option has less storage capacity than the main alternative, but was preferable in terms of environmental impact.

The most economical alignment for the power channel would have necessitated resettlement of an estimated 40,000 people. Moving the alignment to less densely populated areas, although technically more complex and financially less attractive, reduced the resettlement requirement to approximately 900 people. Additional modifications further reduced the impact on archaeological sites and graveyards.

Five power complex sites were initially studied, and three remained for detailed evaluation. Topographical factors determined the preferred option, as the environmental implications were broadly similar in each case. Sub-elements of the power complex, such as access roads, head pond capacity and embankments, were chosen based on environmental and technical considerations.

Finally, four alternative alignments were evaluated for the 500 kV transmission line connections to the main grid station. The selected routes had minimal environmental and socio-cultural impacts. Detailed design focused on choosing alignment and tower locations with minimal impacts on dwellings, agricultural land and archaeological sites.

Chek Lap Kok Airport


A number of major projects in Hong Kong are the subject to environmental monitoring and audit (EMA) as part of EIA implementation and follow up. These programmes are carried out to ensure that the measures recommended in the EIA are actually implemented and appropriate actions are taken in cases where the impact exceeds the established limit.