A Tool Kit for Effective EIA Practice

This report was prepared as a part of the recently completed International Study of the Effectiveness of Environment Assessment. It focuses on the delineation of the types of methods used within the environmental impact assessment (EIA) process, and on varoius factors for consideration in the selection of one to several methods for usage within the phases of a 'specific' impact study. Numerous types of methods have been developed and used in the EIA process for projects, plans, programs, and policies. However, no single type of method can be used to satisfy the variety of activities in an impact study; therefore, the key issue involves selecting appropriate methods for specific needs within an impact study. Accordingly, the information in this report can be considered as a "tool kit" which can be used by EIA practitioners in planning and implementing impact studies.

A total of 22 types of methods are described for project-level studies; their application, along with several other policy-related methods, are also addressed with reference to cumulative impact assessment and strategic environmental assessment. The most-used types of methods tend to be simpler ones, including analogs, checklists, expert opinion (professional judgment), mass balance calculations, and matrices. Further, EIA methods may not have uniform applicability in all countries due to differences in legislation, procedural frameworks, baseline data, environmental standards, and environmental management programs. Emerging types of methods include geographical information systems, expert sytems, risk assessment, and economic valuation of environmental impacts. Irrespective of the methods used, uncertainty exists in various facets of the EIA process; such uncertainty should be described in impact study documentation.

Even though numerous types of methods are available, research is needed in several areas, including but not limted to: 1) appropriate methods for cumulative impact assessment and strategic environmental assessment; 2) effective use of emerging tools such as GIS and expert systems; and 3) integration of information within the synthesis phase of the EIA process.