According
to Canter (1996) EIA methodologies can be broadly categorised into interaction
matrices and checklists, with networks representing variations of interaction
matrices.
As has been observed by many EIA scholars, including Rau (1980), ad-hoc methods
provide minimal guidelines for total impact assessment. The structural emphasis
of ad-hoc methodology is highly fragmented which does not allow any consideration
of the complex web of interrelationships that link the environmental components.
The methodology provides a list of environmental issues to be addressed, but
does little to support a comprehensive impact analysis (Sheckells 1980). Therefore
ad-hoc methods may be kept outside the scope of this review. It should, however,
be kept in mind that in absence of sufficient data availability the ad-hoc
method may be a useful tool, at least for impact identification. In an ascending
order of resource requirements and human-skills involved EIA methodologies
may be classified as:
* checklists,
* interaction matrices,
* overlay mapping,
* networks, and
* simulation modelling.
* checklists,
* interaction matrices,
* overlay mapping,
* networks, and
* simulation modelling.
5.3 Purposes of EIA Methodologies
Early EIA methodologies had the principal orientation towards impact summarisation
and evaluation. However, of late the focus has changed and the EIA methodologies
find wide application as impact identification, prediction, compilation, summarisation,
interpretation and evaluation tools.
Initial environmental assessment (IEE) techniques deploy methodologies to
assess the need for a comprehensive EIA. The process of 'scoping' is also
facilitated by use of methodologies. EIA methodologies can be very effectively
put to use to ensure that no important factor deserving consideration is excluded
and also to ensure that unnecessary factors are revealed and dropped. Selection
of the 'preferred alternatives' from amongst the 'feasible ones' is one of
the formidable tasks to be accomplished through EIA and EIA methodologies,
almost without exception, allows comparison of alternatives on a common basis
thus facilitating the ultimate selection. In a similar fashion the 'mitigation
measures' can also be ranked by using EIA methodologies. Effectiveness of
proposed mitigation measures in terms of environmental damage reduction can
be assessed.
However it must be borne in mind that no EIA methodology can be equally applicable
for all projects or activities at all sites for all the tasks to be accomplished.
5.4 Review of EIA Methodologies
Over the years numerous EIA methodologies have been developed. Sheckells (1980)
reported that till 1980, more than 200 methodologies were introduced although
none were adequate in fulfilling all the needs of an EIA. These methodologies
have evoked considerable interest and have been critically appraised by various
authors. As has been pointed out in sub-section 5.1 there exists considerable
volume of literature presenting excellent and exhaustive reviews of EIA methodologies.
Sanwal (1995) and Majumdar (1996) have also presented overviews of some of
the important methodologies. It is therefore not the intention here to list
and review all the methodologies developed worldwide. The review presented
here is limited to some of the time tested methodologies so as to select a
few candidate methodologies which may in-turn be modified to devise an appropriate
EIA methodology for industrial and mining projects in India. Some recent developments
in EIA methodology are also reviewed. From the point of view of 'environmental
sustainability' these methodologies contribute towards assuring that the 'environmental
sink resources' are not so excessively stressed as to cause any reduction
in the 'assimilative capacity'. The 'supportive capacity' of the natural capital
may be taken into account only by ensuring non-depletion of capital stock
as a constraint to be satisfied by EIA studies. As has repeatedly been mentioned
before, this has been kept beyond the ambit of the present study, which concerns
itself only with the project level EIA.
5.4.1 Checklist Methodology
Typically checklist methodologies present a specific list of environmental
parameters to be investigated for possible impacts. The EIA study team selects
the parameters likely to have significant impacts and evaluates the impacts
from the project situation under consideration. Checklists do not establish
direct cause-effect links to the project activities. Many of the checklist
methods were developed in USA in response to an US-CEQ recommendation that
all agencies develop 'lists of the full range of impacts likely to be involved
in the typical types of actions they undertake' (US-CEQ 1972).
Over the years this methodology has undergone many improvements and modifications.
Various guidelines have been prepared on how to use data on each item. Explicit
criteria have been developed for determining what constitutes an impact of
a certain magnitude (Drobny and Smith 1973). Principal types of checklists
(Bisset 1987, Smith 1993) include
Over the years this methodology has undergone many improvements and modifications.
Various guidelines have been prepared on how to use data on each item. Explicit
criteria have been developed for determining what constitutes an impact of
a certain magnitude (Drobny and Smith 1973). Principal types of checklists
(Bisset 1987, Smith 1993) include
* Simple checklists
* Descriptive checklists
* Quantitative checklists
# Scaling checklists
# Weighting-scaling checklists
#Weighting-ranking checklists
* Multi-attribute utility theory