Environmental Impact Assessment (EIA) | Ecology

After reading this article you will learn about: 1. Meaning of EIA 2. Issues in EIA Process 3. Process 4. Impact Evaluation Methodology.

Meaning of EIA:

Environmental Impact Assessment (EIA) can be described as a process of identifying the likely consequences for the bio-geophysical environment and for man’s over all interest with respect to imple­mentation of particular developmental activities and also to find out alternatives of developmental proposal.

Thus, EIA is a process having the ulti­mate objective of providing decision makers with an indication of the likely consequences of their action.

EIA is no longer seen as an “add-on” pro­cess. Indeed the greatest contribution of EIA to environmental management may well be in reduc­ing adverse impacts before proposals come through to the authorisation phase. EIA has been regarded as both ‘science’ and ‘art’ reflecting the concern both with technical aspects of appraisal and the effects of EIA upon the decision making process.

An Environmental Impact has both spatial and temporal components and can be described as the change in an environmental parameter, over a specified period and within a defined area, re­sulting from a particular activity compared to the situation which would have occurred had the ac­tivity not been initiated (Fig. 24.1).

The outcome of an EIA is usually some for­mal document called Environmental Impact State­ment (EIS). In general a major deficiency of EIS has been the failure to establish a time frame indi­cator when impacts are likely to be manifested. Impact are also site specific and determination of their spatial distribution is also important. Of course spatial aspects are usually considered more adequately than temporal ones.

In general in an EIA, there is a major empha­sis given on scientific and technical aspect of en­vironmental changes connected with the proposed development programme. There is growing con­cern about the need for social scoping in very early in the assessment process.

The compromise rela­tionship between the subjectivity of value judg­ment and the objectivity of the scientific approach is largely a function of the relative importance of the role of science at various stages in the sequence of impact assessment activities (Fig. 24.2).

Major Issues in the EIA:

The design of effective EIA procedures can be envisaged as the search for mechanisms to deal with issues generated by the need to juxtapose the planning and authorisation of proposals. Some issues deal with technical matters such as impact identification and prediction and other related to the management of information.

There are four major issues that needs to be addressed in the EIA process:

1. Identification of project requiring EIA.

2. Identification of impacts to be assessed.

3. Assessment of impacts.

4. Completion of an appraisal with proper ob­jectivity.

Land use planners have long assigned that all development proposals should be subject to envi­ronmental appraisal, the level of analysis being commensurate. EIA, however, implies a special type of analysis involving a careful, thorough and detailed analysis of the likely implications of a development.

Many countries have developed lists of projects which should be subject to EIA. The main consideration is drawing up in such lists are project type, size and the consequence of likely impacts.

Many of the impacts of a proposed develop­ment may be trivial or of no significance to the de­cisions which have to be taken. In practice, a deci­sion will generally turn upon only a small subject of issues of overwhelming importance. Scoping is the process for determining which issues are likely to be important.

Several groups, particularly deci­sion makers, the local population, and the scientific community have an interest in helping to delineate such issues which should be considered and scoping is designed to camas s their views.

A clear distance should be drawn between techniques for predicting individual changes, such as Guassian dispersion models with which likely ground level concentrations of atmospheric pol­lutants can be calculated and EIA methods used in assessment. EIA methods are used for various activities, viz. impact identification, prediction, in­terpretation and communication and in devising post-project monitoring schemes.

The final decision with respect to project au­thorisation may appear a logical point at which is an appraisal terminated. EIA should be characteri­sed by a stream of data collection and analysis run­ning from information on environmental status at the outset, baseline data, through a gradual pro­cess of refinement and augmentation during im­pact prediction to the collection of data on actual impacts.

Post implementation, that is monitoring, data can be used either to refine the proposal, per­haps by the inclusion of additional remedial mea­sures and the relaxation of constrains found to be unnecessary restrictive or to modify the decision. In the most extreme case, it may be necessary to remind authorisation if predictions severely un­derestimate adverse impacts, then likely impact in the long-run will be disastrous.

The EIA process should then allow for the communication of this information to:

(a) The project proponent

(b) The regulatory agencies, and

(c) All stakeholders and interest groups.

Process of EIA:

The structure of an EIA process is dictated pri­marily by the need to accommodate each of the key issues discussed above. Although there may be variations in the detailed procedures, adopted within a particular country, most systems in es­sence conform to the pattern shown as a broad outline of an EIA system (Fig 24.3).

From technical point of view, an EIA can be thought of as data management process.

It has three components:

First, the appropriate information necessary for a particular decision to be taken must be iden­tified and possibly collected;

Secondly, changes in environmental param­eters resulting from implementation must be de­termined and compared with the situation likely to occur without the proposal;

Finally, actual change must be recorded and analysed.

i. Scoping:

Determining the priority value of society with re­spect to the potential effects of a particular devel­opment proposal is a major concern. There are various issues, which are of concern irrespective of the approach to scoping which is adopted.

ii. Baseline Studies:

Baseline studies are perhaps the most commonly recognised and yet least understood element of EIA. The term usually refers to the collection of background information on the environmental components physicochemical, biological and physiographic information’s including socio-eco­nomic setting for a proposed development project and it is normally one of the first activities under­taken in an EIA.

As baseline data describes the existing envi­ronmental status of the identified study are the site specific primary data should be monitored for the identified parameters and supplemented by secondary data if available.

iii. Impact Prediction:

Impact prediction is a way of ‘mapping’ the envi­ronmental consequences of the significant aspects of the project and its alternatives. Environmental impact can never be predicted with absolute cer­tainty and this is all the more reason to consider all possible factors and take all possible precau­tions for reducing the degree of uncertainty.

iv. Assessing Alternatives:

For every project possible alternatives should be identified and environmental attributes should also be compared. Alternatives should cover both project location and process technologies. Alter­natives should consider ‘no project’ option also. Alternative should then be ranked for selection of the best environmental option for optimum economic benefits to the community at large.

Once alternatives have been reviewed, a miti­gation plan should be drawn up for the selected option and is supplemented with an Environmen­tal Management Plan (EMP) to guide the propo­nent towards environmental improvements. The EMP is a crucial input to monitoring the clear­ance conditions and therefore details of post- project monitoring should be included in the EMP.

An EIA report should provide clear informa­tion to the decision maker on the different envi­ronmental scenario without the project alternatives. Uncertainties should be avoided in the EIA re­port. There were a number of methods adopted for EIA impact evaluation.

The methods were checklist, matrix, network, overlay and Battelle ap­proach. Each of the method has its own merits and demerits. However, in most cases matrix method was used for impact prediction purpose. In some EIA, risk assessment and disaster man­agement plan also has to be prepared along with the EIS report. Otherwise project may not be cleared by the EIA appraisal authority in due course.

Impact Evaluation Methodology:

From the Table 24.2, it appears that for most of the project’s impact evaluation, matrix system is suitable and widely used. Quite consider­able numbers of matrix system were known in re­cent years. Among the different matrix method Leopold method and method from Lohani and Thanh are widely used.

A case study example of a hydroelectric projects impact evaluation is given below:

1. Ad Hoc:

These methodologies provide minimal guidance for impact assessment beyond sug­gesting broad areas of possible impacts (e.g., impacts upon flora and fauna, lakes and forests), rather than defining the specific parameters within the impact area which should be investigated.

2. Simple Checklist:

These methodologies present a specific list of environmental parameters to be investi­gated for possible impacts, or a list of agency activities known to have caused environ­mental concern. They may have considerable value when many repetitive actions are carried out under similar circumstances. They do not, themselves, establish a direct cause- effect link, but merely suggest lines of examination.

3. Overlays:

These methodologies rely upon a set of maps of project area’s environmental character­istics (physical, social, ecological, aesthetic). These maps are overlaid to produce a com­posite characterisation of the regional environment.

Impacts are identified by noting the congruence of inherently antagonistic environmental characteristics within the project boundaries. The Geographic Information System (GIS), is modern development of this method.

4. Matrices:

The matrix methodologies incorporates both a list of project activities and a checklist of potentially impacted environmental characteristics. In a way, the matrix presents both alternatives from the checklist approach (i.e., both attributes and activities) to be consid­ered simultaneously.

The two lists are then related in a matrix which identifies cause and effect relationships between specific activities and impacts. Matrix methodologies may either specify which actions impact which environmental characteristics or may simply list the range of possible actions and characteristics in an open matrix to be completed by the analyst.

5. Networks:

These methodologies work from a list of project activities to establish cause-condition- effect relationships. They are an attempt to recognise that a series of impacts may be triggered by a project action. Their approaches generally define a set of possible net­works and allow the user to identify impacts by selecting and tracing out the appropriate project actions.

6. Combination Computer-Aided:

These methodologies use a combination of matrices, networks, analytical models and a computer-aided systematic approach to:

a. Identify activities associated with implementing major federal programs;

b. Identify potential environmental impacts at different user levels;

c. Provide guidance for abatement and mitigation techniques;

d. Provide analytical models to establish cause-effect relationships to quantitatively de­termine potential environmental impacts;

e. Provide a methodology and a procedure to utilise this comprehensive information in responding to requirements of EIS preparation.

7. Battle Environmental Evaluation System (BEES):

This is a quantitative evaluation system based on assumed values of environmental quality.

In recent years however, a new type of ‘Envi­ronmental Evaluation System’ is often imple­mented. This is called “Battele Environmental Evaluation System” (BEES). This process involves identification of environmental parameters likely to be affected by project implementation, estima­tion of resulting changes in the selected param­eters and aggregating the changes in determining resultant environmental parameters likely to be affected by project implementation, estimation of resulting changes in the selected parameters and aggregating the changes in determining resultant environmental quality.

Thus, this process necessi­tates transformation of parameter estimates into Environmental Quality (EQ) on a scale ranging from zero to one. Such a transformation is achieved through value function graphs which provide functional relationships between the pa­rameter estimates and environmental quality scale.

In addition as each of the selected parameter rep­resents only a part of the total environment, weights are assigned to the parameters to reflect their relative importance for ascertaining impact of the project on natural and socio-economic en­vironment.

These weights are verified by an inter­disciplinary expert team using ranked pair-wise comparison technique and expressed as Param­eter Importance Units (PIU). A total of 1000 ‘PIU’s are allocated amongst all the parameters.

For evaluation of impact of project on envi­ronment, an index expressed as Environmental Impact Units (EIU) has been estimated for three alternative environmental conditions, viz the baseline without project, project without Environ­mental Management Plan (EMP) and project with EMP.

The index value is the summation of the product of EQ and PIU for individual parameters for above three alternatives as follows:

where, EIU = Environmental Impact Unit for i th environmental condition

n = Number of parameters consider for environmental impact evalu­ation

EQ_i = Environmental quality for i th pa­rameter

PIU_i = Parameter Importance units for i th parameter

The inference regarding impact of project is drawn on the basis of extent of positive or nega­tive changes obtained in EIU from the difference in EIU of project with EMP and the EIU for baseline Environmental conditions. EIU of project without EMP is also assessed.

The exhaustive list of parameters selected for impact assessment by BEES methods is prepared along with PIU’s by numbers in parenthesis adja­cent to parameters. The PIUs allocated amongst the selected environmental parameters for impact evaluation of the project, represent consensus in the opinion of experts of an interdisciplinary team. Depending on the type of projects the PIUs allo­cation and parameter selection differs widely.

How­ever, a total of 1000 units in most cases allocated in the three to four major environmental catego­ries viz., ecology, environmental pollution and hu­man interests including socio-economics and aes­thetics. The higher the number of PIUs, greater the relative importance (Table 24.4).

The impact scaling in this process has been accomplished through the use of value functional relationships of identified 45 typical parameters. Functional relationships refer to transforming parameter measurements (baseliner or predicted values) into subjective evaluations through graphical means.

Objective measurements are transformed into subjective interpretation of environmental quality (EQ) on a scale represent­ing, a value of 1.0 for good quality and 0.0 for poor quality.