The river basin and the seabed are highly dynamic environments, with many hundreds of tonnes of sediment constantly on the move by the currents and tides. When currents slow, the sediments carried by the water are deposited on the seabed. If the currents remain slow, then these sediments can build up over time leading to a reduction in water depth and problems for ships. As a result, dredging of the sediment from the seabed is often a necessary part of development in order to secure sufficient depth of water for boats to pass safely.
While vital to the proper function of the port, thereby providing economic benefits, dredging has the potential to cause major impacts through damage to the seabed habitat and its species, changes to the hydrodynamics, and pollution through the resuspension of contaminated material. In order to minimise these impacts, dredging activities should comply with the following measures to reduce the associated impacts.