In Western Australia (WA), the Environmental Impact Assessment process requires dredging proponents to make scientifically sound predictions of the likely extent, severity, and persistence of environmental impacts of the proposed activity under a spatially defined zoning pattern. This is achieved by using coupled hydrodynamic, wave and sediment transport models in conjunction with water quality (ecological) thresholds for sensitive receptors such as corals, filter feeders, or seagrasses/macroalgae. These predictions guide the scale and scope of associated monitoring programs, providing assistance to proponents as to where to establish environmental monitoring and reference sites. Increasingly, modelling is also being used by dredging programs to forecast a few days in advance, so as to understand the potential consequence of various dredging scenarios and optimize the dredging programs to minimize environmental damage. The overall objective of Project 2/3.4 was to improve the predictive capabilities of sediment dispersion modelling that incorporate dynamic plume and passive plume processes through assessing model sensitivity to key forcing and parameter values, such as met-ocean condition, particle settling velocity distribution, critical shear stress, sediment erosion and deposition, provide frequency and duration of biological stressor fields including suspended sediment concentration, sediment accretion and erosion, and available light; and provide guidance on developing best practice algorithms and parametrizations for dredge plume modelling. Based on the outcome Project 2/3.1, an appropriate modelling suite that includes hydrodynamics, waves, and sediment transport was chosen (Delft3D) to model the far-field passive plume. The model was set up and validated using the bathymetry and baseline data collected as part of the Chevron Australia Wheatstone Project, located near Onslow, Western Australia. The model outputs were assessed against monitoring data from Chevron Australia's Wheatstone Dredging program, including, remote sensing and in-situ data collected in Project 2/3.2. A 20 month hindcast of passive plume dispersal from the dredging project to the furthest extent of the passive plume were compared with the field data and MODIS images (where available). Spatial and temporal variability of plume dispersal under different forcing scenarios and sediment release rates were investigated and reported. This metadata record provides a description of the model input data (and where appropriate its location) and a short description of the software and model set-up. The simulation data files are located in the CSIRO DAP.

Australia has gazetted an ambitious national network of Commonwealth Marine Reserves that includes the iconic Huon and Tasman Fracture reserves off Tasmania where seamounts (‘undersea mountains’) support unique deep-water coral reefs. These reefs rank among the most bio-diverse globally. Protection of deep-water coral reefs is a high-priority conservation concern nationally and internationally because deep-water corals are very fragile, easily impacted by human activities including bottom trawling, and are believed to recover very slowly. These corals may also be highly vulnerable to climate change because projected changes in water chemistry could limit the ability of corals to build calcareous skeletons. Despite these concerns, and Australia’s significant investment in marine conservation, several fundamental ecological issues remain to be evaluated. These include defining the spatial extent of deep-sea coral communities inside and outside the Tasmanian reserves, and evaluating the resilience of the communities to bottom trawling. This information is important to understanding the dynamics of deep-sea communities globally, and for developing and implementing conservation management plans. The survey aboard RV Investigator set out to determine the spatial extents of deep-sea coral communities in and adjacent to the Huon and Tasman Fracture reserves, and quantify changes in the communities by comparing samples taken in 2018 to samples taken, using similar methods, in 2007 and 1997. There was supplementary sampling on the heavily trawled St. Helens Seamount which was surveyed in 2008. This metadata record refers to the image data collected during the survey. The imagery collected for this project have been registered to the 2018 incidence of the CSIRO VARS database, where annotations have been added. The annotations collected for this project have also been linked to the Oracle data base BHIMAGE and the associated videos and still images have been archived as described in MarLIN record 14436 'Benthic Habitats Video Image Archive'.