An oil spill occurred on Lake Rosebery in January 2025 prompting a joint incident response involving EPA, Hydro Tasmania and other agencies. The spill was unusual, being on a freshwater dam storage, as most response resources focus on oil spills on oceans. Entura was engaged to provide insights into the hydrodynamic characteristics of Lake Rosebery and preliminary oil dispersion patterns to support cleanup operation planning.
This presentation discusses the rapid development process of the 3D hydrodynamic model constructed in TUFLOW-FV. The model spatially represents the lake with a 3D computational mesh, with time-series boundaries for climatic, hydrologic and hydraulic conditions. This model captures the smaller circulation patterns driven by wind and temperature differences, the impact of larger inflows from catchments, and impacts of power station operations.
As immediate information was needed to inform incident response, the ability to gather new data was restricted and existing datasets had to be used. Initial investigations identified the key data requirements of the model, such as lake bathymetry. Previously developed data acquisition, validation and boundary condition construction methods enabled efficient data interrogation and model development.
Oil was represented as a passive tracer with no buoyancy, decay or settlement. This provided insights to possible dispersion of oil within the short timeframe. How the oil was modelled and other assumptions needed to be communicated to a range of people with different technical backgrounds to ensure appropriate understanding.
The presentation discusses what was required from work processes and data sources for rapid development of the model. Recommendations for critical datasets and workflows are provided to aid water system managers in preparing rapid and orderly modelling. This can be applied for response modelling that informs incident management and longer-term operational requirements