3rd International Conference on Coastal Zones and Oceanography
Oleg Makarynskyy
Australian Institute of Marine Science, Brinkin, Australia
Biography
This paper presents the outcomes of a sensitivity study aimed at assessing suspended sediment concentrations from dredge disposal operations. The study was focused at a near-shore area of southern New South Wales. The bathymetry of the area is typical for the region with a relatively steep slope and depths up to 80 m within 5 km offshore. A curvilinear, three-dimensional hydrodynamic model was developed to properly describe the modelling domain and oceanographic processes within it. The domain incorporated a 5-meter thick surface water layer and for a 10-meter thick near-bottom water layer, both required for further detailed assessments of suspended sediment transport and diffusion and models’ sensitivity. To provide the open-ocean boundary conditions to the three-dimensional hydrodynamic model, two sources of information were used: space varying tidal constituent data and regional-scale, three-dimensional ocean currents. It was assumed that the used open boundary forcing realistically reflected existing oceanographic conditions in the project area for the modelling period. A three-dimensional disposal plume model was then used to evaluate impact zones and exceedances from periodic dumping operations. The modelled sediments consisted of fine fractions of silt and clay. The obtained results demonstrated that using tides only, tides and wind, or currents and tides and wind as the forcing for hydrodynamic and then sediment transport models essentially changes the exceedance map configuration. The outcomes of this study emphasise that any model, independently of how plausible the forcing functions are, needs to be properly calibrated and validated based on the field monitoring data from the area of interest.