Identifying and Evaluating Impacts - Mining and the Environment: From Ore to Metal - page 423

TABLE 9.7
(Continued)

Noise propagation
Individual source propagation models
Others
Noise impact indices

Biology Chronic toxicity testing (e.g. LD 50 ) *

Habitat-based methods
Species population models
Diversity indices
Indicators
Biological assessments
Ecologically based risk assessment

People Demographic models

Econometric models
Descriptive checklists
Multiplier factors based on population or economic changes
Quality-of-life (QOL) indices
Health-based risk assessment

Visual Baseline inventory

Questionnaire checklist
Photographic or photomontage approach (still models)
Computer simulation modelling (moving models)
Visual impact index methods

Historical/Archaeological Inventory of resources and effects

Predictive modelling
Prioritization of resources

Accidental Effects Hazard and operability studies

Event and fault tree analysis
Consequence modelling

* LD50 (“Lethal Dose, 50 %”): The basic idea (and practice) of the test (and similar
lethal dose tests) is to take healthy animals (usually mice or rats but sometimes dogs,
monkeys or other animals) and force feed them enough poison to kill (usually slowly)
approximately 50% of them. (Variations include starving the individual before testing,
injecting the tested substance, or coating the animal's skin with the tested chemical.)

Source:
modifi ed from Canter and Sadler (1997)

and second, there is a diminishing return achieved in terms of accuracy in impact predic-
tion relative to modelling effort, compared with simple predictive models.
The number of independent variables to be considered in mathematical modelling and
the nature of the relationships between them are determined by the complexity of the
environmental system. The aim in mathematical modelling is to minimize the number of
variables and keep the relationships as simple as possible, at the same time retaining a suf-
i ciently accurate and workable representation of the environmental system.