Environmental impact assessment methodology
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This document discusses different methodologies used for environmental impact assessments (EIA). It describes ad hoc methods, checklist methods, the overlay method, matrix method, and network method. Ad hoc methods involve experts assessing impacts based on their experience but provide minimal guidance and are inefficient. Checklist methods range from simple to more descriptive lists that include guidelines for measuring environmental parameters. The matrix and network methods involve evaluating impacts across different parameters and environments, while the overlay method involves overlaying transparencies of different impact layers to identify interactions.
Environmental impact assessment methodology
- 2. EIA Methodologies Ad hoc Methods Check List Overlay Method Matrix Method Network Method
- 3. Ad hoc Methods A good example of an ad hoc method is a team of experts assembled for a short time to conduct an EIA. Each expert's conclusions are based on a unique combination of experience, training and intuition. Drawbacks the criteria used to evaluate impacts are not comparable, the relative weights of various impacts cannot be compared; it is inherently inefficient as it requires sizeable effort to identify and assemble an appropriate panel of experts for each assessment; and it provides minimal guidance for impact analysis while suggesting broad areas of possible impacts
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- 5. Check List Simple Checklist: a list of environmental parameters with no guidelines on how they are to be measured and interpreted. Descriptive Checklist: includes an identification of environmental parameters and guidelines on how to measure data on particular parameters. Scaling Checklist: similar to a descriptive checklist, but with additional information on subjective scaling of the parameters. Scaling Weighting Checklist: similar to a scaling checklist, with additional information for the subjective evaluation of each parameter with respect to all the other parameters.
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- 12. Overlay Method
- 18. Reference: Methods for EIA ( Author: Unknown; December 1997)
- 19. Thank You………
Editor's Notes
- #3: > Simulation modelling, cost-benefit analysis, Rapid asessments of pollusion, structural guide line method
- #4: > A systematic analysis
- #5: Is this method a good one?
- #6: Checklists are standard lists of the types of impacts associated with a particular type of project. Checklists methods are primarily for organizing information or ensuring that no potential impact is overlooked. They are a more formalized version of ad hoc approaches in that specific areas of impact are listed and instructions are supplied for impact identification and evaluation. descriptive or evaluative. Weighing and Scaling check lists make judgements about magnitude and importance
- #7: There are several major reasons for using checklists: • they are useful in summarizing information to make it accessible to specialists from other fields, or to decision makers who may have a limited amount of technical knowledge; • scaling checklists provide a preliminary level of analysis; and • weighting is a mechanism for incorporating information about ecosystem functions. Westman (1985) listed some of the problems with checklists when used as an impact assessment method: 1. they are too general or incomplete; 2. they do not illustrate interactions between effects; 3. the number of categories to be reviewed can be immense, thus distracting from the most significant impacts; and 4. the identification of effects is qualitative and subjective.
- #8: > Matrix methods identify interactions between various project actions and environmental parameters and components. They incorporate a list of project activities with a checklist of environmental components that might be affected by these activities >One of the earliest matrix methods was developed by Leopold et al. (1971). In a Leopold matrix and its variants, the columns of the matrix correspond to project actions (for example, flow alteration) while the rows represent environmental conditions
- #12: >The stepped matrix technique, developed by Sorenson (1971) to display the possible consequences of land use in the California coastal zone, illustrates how the matrix approach can evolve logically into network diagrams. > (¶) represents a major positive impact («) represents a minor positive impact (¨) represents a major negative impact (¨) represents a minor negative impact
- #13: Simulation modelling, cost-benefit analysis, Rapid asessments of pollusion, structural guide line method Shopley and Fuggle (1984) credited McHarg (1969) with the development of map overlays An overlay is based on a set of transparent maps, each of which represents the spatial distribution of an environmental characteristic (for example, susceptibility to erosion) GIS