Bass Strait Hydrodynamic and Sediment Transport Modelling Outputs

Updated: 2026-09-06

ORCAS Consulting Ltd (New Zealand) were contracted by Geoscience Australia to investigate sediment mobility and seabed disturbance in the Bass Strait region. This was undertaken by developing numerical models to run long-term simulations with the aim of determining typical bed velocities, shear stresses, sediment transport pathways and suspended sediment concentrations within the project’s area of interest. Geoscience Australia provided bathymetry data and sediment data as part of the inputs to the numerical models.There are three groups of datasets in this publication. The first group of datasets describes the seabed shear stress at the Bass Strait region. The datasets include measures of central tendency (geometric mean, trimmed mean, median), distributional statistics (25th and 75th percentiles, interquartile range), and exceedance metrics relative to defined critical thresholds (0.4 Pa for bed shear stress and 0.25 for Shield’s parameter) listed as follows:<ul><li>Geometric mean of the seabed shear stress (ShearStress_geoMean_BS.tif),</li><li>Trimmed mean of the seabed shear stress (ShearStress_trimmedMean_BS.tif),</li><li>25th percentile of the seabed shear stress (ShearStress_p25_BS.tif),</li><li>Median of the seabed shear stress (ShearStress_p50_BS.tif),</li><li>75th percentile of the seabed shear stress (ShearStress_p75_BS.tif),</li><li>Interquartile range of the seabed shear stress (ShearStress_iqr_BS.tif),</li><li>Percentage of time the seabed shear stress exceeding 0.4 Pa (N m-2 ) (ShearStress_pctExceed_BS.tif),</li><li>The integrated seabed shear stress exceeding 0.4 Pa (N m-2 ) divided by the integrated total seabed shear stress (ShearStress_ratioExceed_BS.tif),</li><li>Percentage of time the Shield’s parameter exceeding 0.25  (ShearStress_pctShieldsExceed_BS.tif), and</li><li>The integrated Shields parameter exceeding 0.25 divided by the integrated total Shields parameter (ShearStress_ratioSheildsExceed_BS.tif).</li></ul>The second group contains measurements extracted from a sediment transport model. They include: <ul><li>Cumulative erosion/accretion of mud (CumulativeErosionAccretion_mud_BS.tif),</li><li>Cumulative erosion/accretion of sand (CumulativeErosionAccretion_sand_BS.tif),</li><li>Mean depth averaged sediment flux of mud (SedimentFlux_mud_BS.tif),</li><li>Mean depth averaged sediment flux of sand (SedimentFlux_sand_BS.tif),</li><li>Mean depth averaged suspended sediment concentration of mud (SuspendedSedimentConcentration_mud_BS.tif), and</li><li>Mean depth averaged suspended sediment concentration of sand (SuspendedSedimentConcentration_sand_BS.tif).</li></ul>The third group describes long-term averages of bottom current speed extracted from a hydrodynamic model. They include four seasonal means and the overall mean:<ul><li>Long-term autumn mean of bottom current speed (CurrentSpeed_mean_autumn_BS.tif),</li><li>Long-term winter mean of bottom current speed (CurrentSpeed_mean_winter_BS.tif),</li><li>Long-term spring mean of bottom current speed (CurrentSpeed_mean_spring_BS.tif),</li><li>Long-term summer mean of bottom current speed (CurrentSpeed_mean_summer_BS.tif), and</li><li>Long-term overall mean of bottom current speed (CurrentSpeed_mean_overall_BS.tif).</li></ul> The details of the modelling processes, their inputs and outputs can be found in the lineage information and the accompanied project report.These datasets are part of the products delivered by the Resourcing Australia’s Prosperity Initiative (RAPi), under the National resource assessment component and the Offshore Energy Project.