Environmental Impact Assessment (EIA): Characteristics, Structure, Stages and Techniques!
Nature and Characteristics:
EIA is the prior assessment of the future impact of the consequences of any decision on the quality of the total human environment on which man largely depends for his well-being.
There is no universal definition of what exactly EIA is, but a simple explanation might be “an approach which seeks to improve development by a priori assessment”.
It is difficult to provide a clear definition of an EIA, although its characteristics can be listed as follows:
1. It is a systematic evaluation of all significant environmental consequences.
2. It is a structured, systematic and comprehensive approach.
3. It is a process which forces developers to reconsider proposals.
4. It is a process leading to a statement to guide decision-makers.
5. It is a process which has the potential to increase developer’s accountability to the public.
6. It should be subject to independent, objective review of results.
7. It should include clear statement of identified impacts as well as possible alternative development options.
8. It is the study of a proposed development project on the environment.
9. It considers both environmental and economic costs and benefits.
10. It is a predictive mechanism and estimates the changes in the quality of the current environment as a result of the proposed action.
The growth of EIA is associated with the legislation passed in the United States on 1st January 1970, arising out of the National Environment Policy Act (NEPA) of 1969, requiring EIA for major projects. The complete report of the EIA is called an Environmental Impact Statement (EIS), but it is not necessary that all EIAs lead to an EIS. In general, an EIA is an objective evaluation of the environmental problems that may arise from the implementation of a project, and it should provide the public with this information, clearly and completely.
Structure and Stages:
The structure of an EIA varies according to the project, location and the authorship. EIA, which deals only with project impacts, includes an a current environmental conditions (known as the baseline study) and accounts of project impact as well as available alternatives to the proposed project. EIA differs in both structure and their emphasis.
A general design can be constructed by dividing EIA into several sections. These are as follows:
1. Preliminary activities
3. Baseline study
4. Environmental impact evaluation
5. Mitigation measures
6. Assessment of alternative measures
7. Preparation of final document
9. Monitoring of project implementation and impacts
EIA = Environmental Impact Assessment
EIS = Environmental Impact Statement
EQM = Environmental Quality Management
EIR = Environmental Impact Remedies
A project can impact a given environment under three circumstances. In the first instance, it may arise from project location. This happens because the project would change the existing attributes of environment in the locality.
Every such change would release specific process- bound changes. Secondly, some impacts may take place during construction of the project. These can produce temporary or permanent changes in the environment. Then, after completion of the given project, the manner of envisaged uses of it may cause impacts upon environment. All such expected impacts are to be stated in the EIA report.
The essential steps in an EIA are:
(i) Prediction of the anticipated changes in the environment.
(ii) Determination of the magnitude or scale of the particular change.
(iii) Application of an important significant factor for the change. Figure 5.1 represents the stages involved in an EIA.
Various techniques are used for identifying environmental impacts. These include:
(iii) Networks, and
(iv) Overlay techniques.
Checklists used for identifying project impacts are expected to encompass all possible impacts of this kind. Table 5.1 illustrates a section of a checklist designed for a small water power project.
Earlier, simple checklists which only included a list of the environmental indices that could be affected were used. But, now detailed descriptions of the impact of each environmental factor are used in the form of questionnaire.
In more sophisticated checklists, the relative importance of individual factors can be shown by varying weights being given to different factors along with the total ranking calculated for all the versions of the project.
Matrices are very suitable for EIA as they link a particular environmental factor to a specific action of the development project. Leopold and his associates, in the late 1960s designed techniques for evaluating landscape. The Leopold matrix is a large arrangement with 88 environmental factors along the vertical axis and 100 development characteristics along the horizontal one, giving rise to 8,800 cells.
Parts of a Checklist for Evaluating a Water Power Project:
A. Physical Impacts:
I. Change in sediment transport downstream
II. Change in water quality
III. Change in river hydrology
IV. River erosion
V. Slope instability
VII. increased erosion on slopes
VIII. Increased seismic disturbance in the area
IX. Inundation of significant amounts of natural vegetation
X. Disturbance of the local fauna
XI. Alteration of aquatic life
XII. Alteration of soil fertility
XIII. Loss of rare or unique features or life forms
B. Impact on Local Population:
I. Inundation of settlements
II. Resettlements of people
III. Problems of sanitation
IV. Availability of river water downstream
V. spread of endemic diseases
VI. Introduction of new diseases
VII. Psychological stresses due to changes in lifestyle and economy
C. Impact on Local Economy:
I. Disturbances in local economy
II. Inundation of existing transport network disruptions in river transport
III. Submergence of objects of cultural heritage
IV. Inundation of historicity sites
V. Availability of electricity
VI. Improvement of agriculture
VII. Industrial expansion
Each cell is divided by a diagonal line, and magnitude and importance of the impact are written on a scale 1 to 10. This type of matrix is called an interaction matrix. A part of Leopold matrix is given in Figure 5.2.
The Leopold matrix has following characteristics:
a. It is excellent as a basic scanning tool.
b. It allows the application of only a section of the matrix, as required.
c. It can be used to indicate both beneficial as well as adverse impacts by writing a plus or minus sign in front of the entries in the cells.
d. It can be used repeatedly throughout a project, to estimate the impact at different stages and also for different parts of the project areas.
There are also other types of matrix. At times, a particular development step may affect an environmental factor which in turn alters other factors. Such changes are examined by using a stepped interaction matrix.
Networks are used to show interrelationships among the different components of the environment of the area and also to indicate the flow of energy or impact throughout the environment such as an upland ecosystem or a drainage basin.
Different types of network are known as sequence diagrams, directed diagrams or impact trees. Networks can be used to show both temporal and spatial flows of impacts.
Overlay techniques are used in planning before formal EIA process starts. It provides a base for the study of EIA. Individual impacts, such as affecting soil, water, settlements and noise conditions, are separately summarised and mapped over the area using choropleths to indicate the intensity of the impact.
These maps are transferred on to transparencies which are then laid over one another to produce a composite effect. Summing up the total impact as shown in Figure 5.3 with the advent of Geographic Information System (GIS) and computer technology, this system has now become more useful.