I
read, I study, I examine, I listen, I reflect, and out of all this I
try to form an idea in which I can put as much common sense as I can
- Lafayette
5.0 Introduction Initial approaches to methodological development
in EIA were focussed towards ensuring legislative compliance.
In fact a great majority of EIA researches in early seventies were directed
towards developing EIA methodologies. In consequence numerous methodologies,
varying in conceptual framework but each trying to fulfil the legislative
requirements, emerged. Early contributions of methodologies were limited to
impact evaluation in terms of magnitude and significance. As has been shown
in box 3.1 many of the main conceptual innovations in EIA methodology were
established during the early 1970s (Wathern 1988). After the initial concentration
on impact summarisation, EIA methodologies gradually found wide acceptance
as useful tool for almost every component of the EIA process including screening,
scoping, prediction, evaluation and mitigation. Focus of EIA methodologies
changed from summarisation to a structured approach to facilitate decision
making. Methodologies also help in selection of alternatives and in selection
of appropriate mitigation plan.
This chapter reviews developments in EIA methodologies. Many comprehensive
reviews of EIA methodologies are available. For example Canter (1979) presented
a brief review of over 100 methodologies and techniques which may be used
for water resources assessment. Literature presenting early reviews of EIA
methodologies include Warner and Preston (1973), Smith (1974), Viohl and Mason
(1974), Nichols and Hyman (1980, 1982). Bisset (1980a, 1983), Lohani and Halim
(1983) and Sheckells (1980). EIA textbooks also usually contain brief reviews
of EIA methodologies. Such textbooks include Canter (1977, 1996), Jain et
al. (1977), Jain et al. (1993), Heer and Hagerty (1977), Munn (1979), Glasson
et al. (1994), Gilpin (1994), Smith (1993), Erickson (1994) and Westman (1985).
5.1 Early Developments
While some methodologies, e.g. overlay technique, predate US-NEPA, most of
the EIA methodologies were developed in USA in response to the requirements
imposed by NEPA.
Section 102(2)(A) of US-NEPA call for all Federal Agencies to "utilize a systematic
interdisciplinary approach which will assure the integrated use of the natural
and social sciences and the environmental design arts in planning and in decision-making
which may have an impact on man's environment".
Further, under section 102(2)(B) of the Act, Federal agencies are required
to "identify and develop methods and procedures ……., which will insure that
presently unquantified environmental amenities and values may be given appropriate
considerations in decision making along with economic and technical consideration".
Since 1970, various EIA methodologies have been developed to satisfy the above
requirements imposed by US-NEPA. A wide variety of assessment tools have emerged.
However, most methodologies have been developed to serve only limited number
of functions. Applicability of such methodologies therefore cannot be universal.
Most methodologies are situation-specific and to be applicable to other situations
they require significant modifications.
Bisset (1988) stressed the need to distinguish between EIA techniques and
EIA methodologies. Largely following Scheckells (1980) one can define EIA
technique as standardised means for describing or measuring particular environmental
parameters in the ambient environment and for measuring or predicting their
contributions to the environment as a function of an introduced factor. EIA
study of any particular human action may involve a number of techniques to
predict future states of various environmental parameters, such as noise levels,
air quality, water quality, etc. The data generated by these techniques are
then compiled, collated, interpreted and presented according to the structure
and organisational principle of the EIA methodology followed. Methodologies,
thus, refer to a means for classifying and presenting material for impact
analysis or for aid in presentation of impact results (Sheckells, 1980). EIA
methodologies show wide variation in mechanisms by which information is collected
evaluated and displayed.
EIA techniques are well developed only for a few of the environmental attributes,
viz., noise, air, water etc. These techniques can be successfully employed
to bring into focus the environmental values. EIA techniques employ predictive
models to present future scenario in respect of particular attribute(s). Such
models, in their simplest form predict future concentration of pollutants
as a function of the intensity of proposed human interference in the natural
course of events followed by the attribute under consideration.
EIA techniques are however, not very well developed for biological 'parameters'.
Recent developments in the ecological modelling not withstanding, for assessment
of biological impacts high reliance is therefore, placed on EIA methodologies
to perform.
5.2 Categories of EIA Methodologies
During the early 70s a wide variety of EIA methodologies were developed to
satisfy the requirements of US-NEPA in respect of systematically carrying
out provisions of Sections 102(2)(A), (B) and (C). Early attempts to categorise
EIA methodologies were made among others, by Drobny and Smith (1973), Warner
and Bromley (1974). Warner (1973) divided EIA methodologies into five classes:
* Ad-hoc procedures
* Overlay techniques
* Checklists
* Matrices
* Networks
Canter (1977) reported that some early classifications restricted the division
to two classes, viz., checklists and matrices. Gilpin (1994) included only
checklists and matrices in addition to economic analysis techniques. Based
on the impact identification mechanisms involved, Jain et al (1977, 1993)
added another class to Warner's classification.
* Combination computer aided.
Most EIA scholars favour Warner (1973), for classification of EIA methodologies.
Minor variations have however been made by some of them. For example Banerjee
and Rathore (1993), while reviewing the EIA methodologies did not include
overlay techniques and considered Battelle Environmental Evaluation System
(BEES) a separate class different from checklists. They added 'Computer Aided
EIA' and 'Modelling Approaches' to the existing classes. Bisset (1988) classified
the post 1978 developments in EIA methodologies into index approaches, systems
diagrams, simulation modelling and the 'sound ecological principles' approach.
Westman (1985) divided EIA methodologies into two parts, viz., 'impact identification
techniques' and 'impact evaluation techniques' Westman's classification is
presented in Figure 5.1. Lohani (1974) considered only four classes of EIA
methodologies, i.e. matrices, environmental evaluation system, overlays and
networks. Lohani (1984), however, included economic inputs into EIA under
the topic 'Application of Analytical Techniques to the Environmental Impact
Assessment.'
Above paragraphs establish that while there is near unanimity in categorising
conventional EIA methodologies into ad-hoc, checklist, matrix, overlays and
networks, classification of non-conventional methodologies remain problematic.
The author feels that almost all the recent developments in EIA methodologies
can be satisfactorily included into one class or the other. For example Environmental
Evaluation System (EES) can be considered a scaling-weighting checklist and
'systems diagram' is only a variant of network approach. Likewise most EIA
methodologies involving computer mapping or GIS techniques employ McHarg's
(1969) principles of map overlay.