<p>These datasets were derived from three independently executed numerical models simulated for 20 years between 2004 and 2023 inclusive, for the Bass Strait region, and conducted by ORCAS Consulting (New Zealand):</p><ul><li>A spectral wave model implemented using SWAN (Simulating WAves Nearshore).</li><li>A hydrodynamic model implemented using Delft-3D Flexible Mesh (FM).</li><li>A sediment transport model implemented using D-Water Quality, a module of the Delft-3D FM modelling suite.</li></ul><p>The SWAN model simulated wave conditions on its native unstructured computational mesh. The Delft-3D FM model simulated hydrodynamic currents on a separate unstructured mesh and <span style="color:black;">was forced by tides, non-tidal sea level, wind, atmospheric pressure and nudged salinity and temperature.</span> These two models were not dynamically coupled during simulation.</p><p>To enable combined wave–current bed shear stress calculations, SWAN wave outputs were spatially interpolated from the SWAN grid onto the Delft-3D FM computational mesh. Temporal interpolation was also performed to align SWAN outputs with the Delft-3D FM model time step, ensuring temporal consistency between wave and current fields.</p><p>Following interpolation, combined wave–current bed shear stress and Shields parameter time series were calculated at each Delft-3D mesh element/node. Statistical metrics were then computed from the resulting time series at each mesh location, including:</p><ul><li>Geometric mean (Pa or&nbsp;N m^-2),</li><li>25% trimmed mean (Pa or&nbsp;N m^-2),</li><li>Median (50th percentile) (Pa or N m^-2),</li><li>Mode (not included in this publication) (Pa or&nbsp;N m^-2),</li><li>25th and 75th percentiles (Pa or&nbsp;N m^-2),</li><li>Interquartile range (e.g., difference between the 25^th and 75^th percentiles) (Pa or&nbsp;N m^-2),</li><li>Percentage and ratio exceedance metrics relative to defined critical thresholds (0.4 Pa for bed shear stress; 0.25 for Shields parameter),</li><li>Mean interval between exceedance events (not included in this publication) (day), and</li><li>Ecological Disturbance Index (dimensionless) (not included in this publication).</li></ul><p>These statistical metrics were then spatially interpolated onto a regular rectilinear latitude–longitude grid (WGS84; EPSG:4326) with an approximate 250 m horizontal resolution.&nbsp;</p><p>The D-Water Quality sediment transport model was deployed on the Delft-3D FM computational mesh using hydrodynamic forcing from the Delft-3D FM model output and the combined wave-current bed shear stress. The model was configured with two sediment fractions representing sand and mud.</p><p>Summary fields were then computed from the resulting time series at each mesh location, including:</p><ul><li>Cumulative erosion/accretion of mud (m),</li><li>Cumulative erosion/accretion of sand (m),</li><li>Mean depth averaged sediment flux of mud (g m^-1 s^-1),</li><li>Mean depth averaged sediment flux of sand (g m^-1 s^-1),</li><li>Mean depth averaged suspended sediment concentration of mud (g m^-3), and</li><li>Mean depth averaged suspended sediment concentration of sand (g m^-3).</li></ul><p>The mesh-based statistical outputs were subsequently masked to include results only inside the convex hull of underlying seabed sediment grain size data (d50) before being spatially interpolated onto a regular rectilinear latitude–longitude grid (WGS84; EPSG:4326) with an approximate 250 m horizontal resolution.</p><p>Hourly bottom velocity (u and v components) outputs of the Delft-3D FM hydrodynamic model were aggregated to calculated at each mesh location:</p><ul><li>Long-term autumn mean of bottom current speed (m s^-1),</li><li>Long-term winter mean of bottom current speed (m s^-1),</li><li>Long-term spring mean of bottom current speed (m s^-1),</li><li>Long-term summer mean of bottom current speed (m s^-1), and</li><li>Long-term overall mean of bottom current speed (m s^-1).</li></ul><p>These summary statistics were then spatially interpolated onto a regular rectilinear latitude–longitude grid (WGS84; EPSG:4326) with an approximate 250 m horizontal resolution.&nbsp;</p><p>More details of the modelling processes, their inputs and outputs can be found in the accompanied project report.</p>