Impact prediction, evaluation and mitigation - Introduction to Environmental Impact Assessment - page 138

Figure 5.3 A simple multiplier model
for the prediction of local economic
impacts.
Physical/architectural models and experimental methods
Physical, image or architectural models are illustrative or scale models that replicate
some element of the project-environment interaction. For example, a scale model (or
computer graphics) could be used to predict the impacts of a development on the
landscape or built environment. Photo-montages can be used to show the views of the
project site from the “receptor” areas, with images of the project superimposed to give an
impression of visual impact. The image could be a photograph of a model of the project,
or a simple “wire-line” profile of the project as it will appear to the viewer, showing just
its skyline or a more sophisticated 3D impression.
Field and laboratory experimental methods use existing data inventories, often
supplemented by special surveys, to predict impacts on receptors. Field tests are carried
out in unconfined conditions, usually at approximately the same scale as the predicted
impact; an example would be the testing of a pesticide in an outdoor pond. Laboratory
tests, such as the testing of a pollutant on seedlings raised in a hydroponic solution, are
usually cheaper to run but may not extrapolate well to conditions in natural systems.
Expert judgements and analogue models
All predictive methods in EIA make some use of expert judgement. Such judgement can
make use of some of the other predictive methods, such as mathematical models and
cause-effect networks or flow charts, as in Figure 5.2. Expert judgement can also draw on
analogue models—making predictions based on analogous situations. They include
comparing the impacts of a proposed development with a similar existing development;
comparing the environmental conditions at one site with those at similar sites elsewhere;
comparing an unknown environmental impact (e.g. of wind turbines on radio reception)
with a known environmental impact (e.g. of other forms of development on radio
reception). Analogue models can be developed from site visits, literature searches or the
monitoring of similar projects.
Other methods for prediction