Early EIA methodologies had the principal orientation towards impact summarisation and evaluation. However, the focus has changed and nowadays EIA methodologies find wide applications as tools for identification, prediction, compilation, summarisation, interpretation and evaluation. EIA methodologies show significant variations in terms of data requirement, objectivity of assessment, use of display formats, and indexing of impacts.

Checklists and simple matrices have some common merits and demerits. These methodologies may be useful for impact identification. Quantitative checklists and Leopold type matrices can be very effective in impact measurement but neither of them can address indirect impacts. Secondary and higher order matrices can be identified and assessed by 'networks' and cross impact matrices.

No single methodology represents a panacea for all the objectives of EIA. Many methodologies are project specific and none allow linkage to carrying capacity.

Although many theoretically sound EIA methodologies have been developed, few EMPs in India are prepared based on them. As a result more EMPs are rejected on technical ground (inadequate information) than on environmental ground. Comparison and selection of alternatives are not attempted with seriousness. Coverage of EIA/EMP reports in respect of impacts on biophysical environment is generally very inadequate.

EIA procedures followed in India do not incorporate 'screening' and 'scoping'. Absence of 'scoping' has caused a general lack of focus, as key issues are not identified. Impacts are often not measured, predicted or evaluated at the parameter level. Generally impact scores are subjectively assigned to certain chosen areas of environment (e.g. air quality, water quality, etc.) As a direct estimate of impact in commensurate unit is provided, assessment of prediction efficiency becomes impossible.

There is a general lack of any real understanding of the EIA procedure. An acute dearth of qualified and experienced EIA practitioners exists. EIA is invariably undertaken as a post planning exercise and often regarded as a process to produce evidence as to why a project should be cleared from environmental angle.

Under the situations prevailing in India a highly sophisticated EIA methodology will not be successful. In order to meet the objectives of EIA -a weighting-scaling checklist may be adopted.

7.2 Limitations of the Study and Scope for Further Research
This study looked upon EIA as an instrument of sustainable development. To this end the accomplishment of the research can at best be termed partial and that too mostly conceptual. This study has however argued that sustainable development being a macro-economic problem can not be addressed through project level EIAs. Environmental assessment of policies, plans and programs may be done by strategic environmental assessment (SEA). In the recent past SEA has generated considerable interest in developed countries. Time has now arrived to take up SEA research in India. The author recommends to future researchers that initial conceptual research on SEA may be taken up. The outcome of the research may subsequently be shaped into an appropriate instrument for sustainable development.

This research has largely been confined towards achieving environmental sustainability goals through EIA. Sustainability as a whole must include social sustainability and economic sustainability. It is recommended that methodological research be undertaken on these aspects of sustainability and a holistic perspective be taken to ensure non-declining maintenance of all forms of natural, man-made and economic capital per-capita.

This study has put forward a refined input-output rule for ensuring environmental sustainability of resource depleting projects. The existing EIA methodologies can at best be modified to assess the possibility of maintaining assimilative capacity only. Supportive capacity assessment can not be adequately done even if extension in the scope and content of these EIA methodologies are undertaken. The input rule of environmental sustainability can be complied only through ensuring long-term full functioning of the natural resource base. In other words sustainability criteria may be applied to conventional project level EIA by measuring the project-induced changes on the natural resource base. This would invariably require internalisation of environmental damage costs. Natural resource depletion must also be charged as costs. At the present level of development in environmental economics there exists a real problem of valuing environmental resources. The author strongly feels that an interdisciplinary research should be under taken to solve the valuation problem. Subsequent studies may then focus on revealing the implications involved to meet the environmental sustainability objectives. Such studies may devise ways and means for independent and separate counting of environmental damage costs and the exhaustible resource depletion costs. Research may then be advanced to incorporate into EIA a total system environmental cost benefit analysis. The environmental damage cost may be compensated through equivalent environmental benefits by investing in protection, restoration and replacement of renewable natural resources. This will of course require reorientation of mitigation planning process, which again may form another area of research interest. The author feels that in this study the development in EIA against the changing context of human development paradigm has been presented fairly well. There still remains some scope to expand the review by carrying out literature survey in the fields of environmental economics and ecological economics.

EIA methodology forms a very important component of the literature review presented in this study. Only a few time-tested methodologies have been reviewed. Considering the prevailing constraints most of the sophisticated methodologies have not been taken up for review. However, in India the available human resource base on EIA is expanding very fast. Also the information technology has come within the reach of developing countries. It may therefore be necessary for future studies to incorporate important sophisticated EIA methodologies.

Lack of quantitative data is often cited as a reason for not using computers in EIA. There has however been significant development in the technique of decision making under imprecise knowledge and it is increasingly being felt that computers can more effectively handle data inadequacy. EIA scholars have of-late been showing interest in techniques like fuzzy set theory and expert systems. Future studies in EIA should consider adoption of computer based EIA methodologies. Some of the existing EIA methodologies presented in this study can be suitably modified to relax the deterministic model. As the situation become conducive in India appropriate expert systems for EIA may be developed. This will necessitate development of an appropriate rule-base that will focus on man-nature balance. EIA may then be expected to reveal the degree to which the dynamic equilibrium maintained by nature may be upset due to an upcoming project. By relaxing the fixed level assumption a better opportunity may be provided to compare the combination of factors and the influence they exert on the supportive capacity.

This study has presented a review criteria for EIA reports. Opinions of EIA scholars, on what should be expected from an EIA, vary widely. The review criteria presented in this study are not based on a synthesis of various approaches. An approach developed in UK has been modified to suit Indian conditions. The author recommends that future studies should attempt to carry out a synthesis of various EIA evaluation criteria proposed by various scholars. EIA evaluation procedure may be restructured on the basis of the outcome of the synthesis.

This study has dealt only with EIA methodologies. EIA technique has been kept outside the realm of this study. In order to make the EIA system a complete package both methodology and technique should be improved. In fact it has been observed that the EIA technique followed in India are far from satisfactory. Detailed procedures should be developed for environmental data generation. Further research on environmental modelling ought to be carried out to better the quality of assessment in respect of air and water quality.

In summary it may be said that a very humble contribution has been made by this principally conceptual research towards betterment of EIA methodology for development projects in India. Further studies should be carried out to overcome the limitations of the present study. Studies should also be carried out on other aspects of EIA not covered in this monograph. The author feels that with continued research and development it would be possible to devise an appropriate EIA system in India which if backed by a proper institutional arrangement, would ensure that EIA system in India can be used as a tool to ensure environmental sustainability.

7.3 Conclusion
Ever since its emergence EIA has been a very important tool for environmental management. In some form or the other EIA has been practised in India for well over two decades. But the potential of EIA could not be fully tapped. With the paradigm shift in human development to sustainable development the objectives of EIA have been expanded to include ensuringce of environmental sustainability as the most important one. This aspect has however not fully been operationalised. At the culmination of the present study the author submits that it has all through been his endeavour to make a humble contribution in that direction.

EIA has been particularly enduring in providing passive advise to decision-makers with respect to environmental soundness. The author expects that as EIA capability is built up in India through institutional strengthening, training and manpower development EIA will play a more active role and would gradually become a part and parcel of the project planning exercises. It is also expected that in future the scope of environmental assessment will be expanded to include policies, plans and programmes. This will render project level EIA to be at the lowest echelon of a tiered EIA system.

It is high time a serious attempt is made to ensure that EIA plays its envisaged role in environmental management. The approach taken by the industry towards environmental issues has mostly remained reactive in nature. By merely attempting to comply with the legislative requirements, EIA studies for development projects actually ignore the strategic perspective and thus give up the ability of the industry to improve its competitive position. Once this aspect is understood, the industry leaders would themselves like to take lead in ensuring appropriate environmental assessment.

In the current days of rising environmental concern a proactive approach to environmental assessment is no longer a luxury but an absolute necessity. There has, of late, been significant improvement in the understanding of the relationship between environment and development. This understanding calls for a suitable change in the framework of project planning so that the objectives of maintaining long-term environmental source and sink functions are included in the planning process itself. The EIA system in future will have to adjust to this new framework of planning.