OPTIMISING THE DISPOSAL OF DREDGE SPOIL USING NUMERICAL MODELLING
The dredging and disposal of 2.4 million m3 of predominantly muddy sediment from the Port of Richards Bay in South Africa required that a number of dredging options be assessed in order to devise an option having acceptable ecological impacts, without adding extra costs to the dredging project. A coupled suite of hydrodynamic, wave and water quality models were used to simulate the transport and fate of the fine fraction of the dredge spoil, and thus quantify the physical impacts in terms of suspended sediment concentrations and deposition thickness. In addition, the longshore transport and shoreline changes associated with the sand fraction of the dredge spoil were simulated using a shoreline model. The application of advanced numerical models enabled a range of options to be simulated, including some innovative options such as switching between two beach discharge locations based on the prevailing longshore current direction.
