Atmospheric dispersion modelling provides a mathematical description of the behaviour of pollutants in the atmosphere for a specific period of time. This is an essential tool used by government agencies, industry and consultants for air quality assessment, especially when decisions regarding environmental approvals, compliance and permits have to be made.
In many cases dispersion modelling is the only practical and economically viable method that can be used to understand the interaction of existing or future pollution emission sources with meteorology, topography and air quality at specific locations and times.
Some of the dispersion models are more complex than others and all models require inputs (emissions, meteorology and topography). If input data are inaccurate, incomplete or poorly processed, the model's predictions will be unreliable.
Professionals conducting dispersion modelling are responsible for selecting a model appropriate to the specific situation and site conditions, ensuring that all the input data are suitable and have been checked for completeness and accuracy, and conducting testing to ensure the model has been applied correctly.
It is important to recognise that all dispersion models have limitations. No single model is suitable for every geophysical, atmospheric and emission scenario. After all, air quality modelling relies on the physics and chemistry of pollutant dispersion and reactivity in the atmosphere that are translated into mathematical formulations and implemented in computer programs to perform necessary calculations. Interpreting modelling outputs and assessing how much confidence should be placed in the results involves considerable expertise and experience which are critically important to achieving meaningful outcomes.
Dispersion modelling is an integral part of air quality management in Tasmania. It is used to predict the potential impact of pollutant emissions to the atmosphere from existing and proposed developments as well as a tool to fine-tune the existing or proposed project designs to minimise their potential impact on air quality.
Clause 14 of Tasmania's Environment Protection Policy (Air Quality) 2004 requires dispersion modelling where air quality problems might occur. This modelling is usually carried out by specialised consultants with advice from the EPA.
Several atmospheric dispersion models have been approved by the EPA Director for use in Tasmania. Consultants should contact the EPA modelling specialists for advice on the applicability of specific models to particular situations or for guidance on model settings before beginning any modelling.
Atmospheric Dispersion Modelling Guidelines outline the EPA requirements for conducting atmospheric dispersion modelling for projects located in Tasmania.
Atmospheric Dispersion Modelling Guidelines
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