Optimisation of Channel Dredging at the Port of Karumba Using Numerical Models

The entrance channel to the Port of Karumba traverses broad inter-tidal and sub-tidal flats which support regionally significant seagrass meadows. A shallow outer bar approximately 10km offshore has historically been a major constraint to navigation. The Port managers, the Ports Corporation of Queensland (PCQ), decided to investigate the possibility of dredging the entrance to improve navigation for existing users (live cattle export) and future users (zinc export from the Century Mine). Studies were undertaken to address issues relating to the oceanographic and siltation processes, optimisation of a dredged channel profile, dredge material management options and minimisation of potential environmental impacts. Due to the vast size and complex nature of the area, significant reliance had to be placed on the use of numerical models of the processes, validated with field data in key areas. Initial dredging has been carried out with no significant adverse impacts. Monitoring during dredging confirmed the predictions of the earlier studies. This project illustrates the value of numerical models in the planning, design and assessment of port works.