The Tamar Estuary in northern Tasmania is a complex environmental system that is under pressure from a number of man-made sources. With the city of Launceston at the head of the estuary and the Bell Bay port downstream towards Bass Strait; management of this system requires a good understanding of its key dynamical processes, including sediment transport and water quality.
In 2009 BMT WBM had worked with Launceston City Council to develop a two-dimensional hydrodynamic, sediment transport and water quality model of the system using the RMA software. We have recently again worked with NRM North to upgrade to a fully three-dimensional, baroclinic model of the estuary using the TUFLOW FV software. Validation of the three-dimensional model has demonstrated the importance of baroclinically driven circulations as key drivers of estuarine water quality and sediment transport processes. The TUFLOW FV model now successfully reproduces the upstream tidal sediment pumping and estuarine turbidity maxima that was difficult to achieve with the previous model.
Water quality processes, including simulation of dissolved oxygen, nutrients, phytoplankton and pathogens have been simulated using the AED libraries developed at the University of Western Australia and which is now coupled with TUFLOW FV. The open source AED provides a flexible and customisable library for the simulation of aquatic ecodynamics – water quality, habitat and aquatic ecosystem dynamics.
The new Tamar Estuary model is a powerful tool for assessing future management practices and is already being applied on behalf of various stakeholders.