Models can predict how surface slicks will move across the water surface, how they will evaporate to create gaseous plumes in the air above, and how they will dissolve or disperse into the water column.

Trajectory models are used by us, and other National Plan control agencies as essential decision support tools to improve:

• risk assessment
• contingency planning
• exercises and drills
• spill response
• environmental and human impact assessment.

For oil spill trajectory modelling, we rely on a product called OILMAP, and for chemical spills, CHEMMAP.

Each is designed to use information from a hydrodynamic model that allows the modeler to use a wide variety of wind, current and bathymetric data formats, as well as live data feeds from a range of providers such as:

• the CSIRO for satellite observations of large scale currents
• the Bureau of Meteorology for live wind, wave and weather data.

OILMAP primarily focusses on two dimensional outputs, as oils tend to float on the surface. CHEMMAP is designed to model chemical movements in three dimensions.

Both models use built-in databases of the physical and chemical properties of oils and chemicals, together with current and wind data, to make their predictions over hours to days.

Both are able to simulate:

• surface and subsurface dynamics
• dissolution
• evaporation
• adsorption and sedimentation
• shoreline stranding.

CHEMMAP is also able to simulate atmospheric transportation.

In addition, the modeler can update the chemical and environmental parameters to match actual incident conditions.

CHEMMAP will only track one chemical per output (no chemical mixtures).

In addition, CHEMMAP cannot model degradation products or reactions with water, oxygen, acids/bases or other chemicals in the water.

Trajectory modelling requests under the National Plan

Requests for modelling under the National Plan can only be made by Commonwealth, state and Northern Territory spill response control agencies, and by the Australian Marine Oil Spill Centre.

There is no public or commercial access to this service.

An online form is available for lodging spill modelling requests. This will require you to log in to the NEMO portal so that the request can be recorded and processed without delay.

If you are unable to log into the NEMO portal, a request proforma is available which can be emailed to us, but this will take longer to process and activate.

If you have a question, contact us.