5.7 Chapter Summary
In this chapter a critical appraisal of a few easy-to-implement EIA methodologies has been attempted to assess their suitability or upgradability so that they can be useful as effective tools for EIA summarisation in the changed paradigm of human development. That is, suitability of the methodologies per-se has not been considered very important as almost all the methodologies pre-date the Brundtland report. These methodologies were mostly devised to comply with legislative requirements.

Considering the limited resources, absence of data base and relatively lesser number of trained and skilled EIA personnel with required skill the author thought it prudent to exclude methodologies like 'systems diagram' (as developed by Odum (1971)). In this connection the author wishes to point out that in spite of repeated attempts by various scholars including, Odum and Odum (1976), Davis (1975), Zuccheto (1975) and Gilliland and Risser (1977), the method met with very limited applicability to real life situations. Attempted quantification by this methodology to convert all impacts in terms of a single unit (energy) becomes futile as some impacts (e.g. impact on landscape, aesthetics etc.) cannot be quantified in energy units. Some other important parameters (e.g. noise, radiation, etc.) are also used in non-comparable units. For similar reasons methodologies that rely on databases have also not been appraised. Simulation modelling using computers has a very high potential of overcoming the existing shortcomings of the methodologies. But in developing countries these methodologies will require some time to establish. The current trend in EIA research shows increasing interest towards Strategic Environmental Assessment (SEA) and Cumulative Effects Assessment (CEA). The former is applicable to policies, plans and programmes and the later to localities.

In recapitulation the author finds that the methodologies chosen for reporting in this chapter show a bias towards the methodologies that allow arriving at a grand index. This has happened because the author concentrated his attention towards such methodologies that showed initial potential to be upgraded as environmental sustainability tools through incorporation of linkage to carrying capacity.

As may be noted from the description presented, available EIA methodologies show significant variations in terms of data requirement, objectivity of assessment, use of display formats and indexing of impacts. While the methodologies that incorporate techniques of grand indexing present a readily available yardstick for selection among project alternatives such methodologies often do not reveal the value judgements used and this denies the decision-maker some important logical thought inputs that have been used.

In general, the methodologies try to identify, measure and interpret impacts. In addition some of these may be more effective as scoping tools because they allow short-listing of environmental parameters for inclusion in the comprehensive EIA. Some methodologies are definitely better than most others in their ability to evaluate project alternatives in a relative degree of desirability.

Amongst the methodologies described checklists and simple matrices have some common merits and demerits. The author commends them as useful tools for impact identification. Quantitative checklists can be effective in impact measurement. Impact measurement is inbuilt in Leopold type matrices. Aggregation of impacts is possible in both matrices and checklists. Checklists assess impacts against a project as a whole and hence cannot be very effective in identifying critical project components requiring attention or improvement.

Neither checklists nor matrices can address indirect impacts. Both the methods characterise environment in terms of some discrete components and ignore the complex inter relationship among them.

Quantitative checklists have gained considerable popularity amongst EIA thinkers and practitioners. Weighting scaling checklists involve assigning relative weightage to environmental parameters and the scaling of importance of such parameters against a commensurate measure. Several weighting methods are reported in the available literature but only a few of them have been discussed in this chapter.

The author wishes to point out that almost all methodologies involving use of computers are actually based on software developed using the principles of existing methodologies. Some of the computer based methodologies, of-course, incorporate techniques of sophisticated 'data base management systems' or expert systems approaches. While time is not yet ripe for using such sophisticated techniques like 'expert systems', other methods are not focused in this chapter as they have the same applicability as the 'core methodologies' based on which the computerised assessment systems were developed. Important features of using computerised weighting-scaling checklists include the following.
1. Availability of guidance for assigning relative weightage to the environmental parameters.
2. Ability to assign importance rating to the environmental parameters.
3. Provision of converting assessed value of impact into a commensurate scale.
4. Easy accomplishment of sensitivity analysis.

As has been pointed out earlier, high resource requirements in terms of human skills do not permit its wide use in developing countries, at least not yet.

One of the most desirable features of the impact assessment methodologies is the ability to aid in selection of the preferred alternative. Some of the methodologies accomplish this feature by providing for schemes of grand indexing. Some others use explicit preference criteria for environmental factors. It is possible to incorporate probability concept in assessing impacts using quantitative checklists or matrices.

Network methodologies allow identification of indirect impacts. Quantification schemes as proposed by Rau (1980) and modified by Westman (1985), also allow recognition of probabilistic nature of impacts. However, because of an extremely complex interrelationships amongst various parameters simple networks do not represent actual cause condition effects. It is not possible to consider cyclical indirect impacts that take place because of existence of positive and/or negative feedback loops. Moreover the cause-condition-effect interrelationships considered in simple networks are somewhat static which goes against reality.

Simple checklists and matrices often distinguish between short-term and long-term impacts but the quantitative versions of these methodologies can consider the time dimension of impacts only in terms of importance weighing.

All important weighting and scaling methodologies are hinged to the same principle. The principle has been discussed in detail.

A vast majority of the methodologies allow trade-off between impact values. Such trade-offs definitely violate the criteria of environmental sustainability, which consider environmental resources to be complimentary and not supplementary. It is important to incorporate a narrow limit of such tradability so that they are not allowed to be treated as fully substitutable. This of course will mean embracing the weak sustainability criteria. The author is aware of the limitations of such assumptions but, as of now, imposition of more rigid environmental criteria may be counter-productive. The author however, strongly feels that trade off between different types of impacts, e.g., social impact with environmental impacts, should never be allowed. It is further recommended that as proposed in BEES, a scheme of indicating parameters of concern through a red flag mechanism should be a part and parcel of any appropriate EIA methodology. An appropriate EIA methodology should also provide pragmatic information on how to address environmental sustainability at the project level.