Monitoring Dredging at Hay Point

Location on map of Hay Point, Queensland

Location map of Hay Point, Queensland
© Geoscience Australia

From May to October 2006, the Ports Corporation of Queensland undertook a major capital dredging project to improve access to the port at Hay Point, Mackay. During the dredging it was estimated that around nine million cubic metres of sediment would have to be moved to complete the project. This posed a risk, as the dredging was to occur within the Great Barrier Reef World Heritage Area and could potentially lead to damage of the fringing coral reef communities in the area. To help control the project Geoscience Australia and the Great Barrier Reef Marine Park Authority cooperated to undertake a sediment monitoring program using remote sensing techniques.

The objective of this study was to determine for management purposes sediment plume dynamics and its influence on the fringing coral environment. Sediment monitoring is conventionally done by measuring water quality from discrete sampling sites. However, it is difficult to use this information to discern synoptic information on sediment dynamics as these parameters are spatially heterogeneous. Remote sensing techniques have been successfully employed in the past to monitor total suspended sediment concentrations in coastal waters and to validate sediment transport models. However, because of the limitations created by cloud cover, remote sensing techniques are not used in the day-to-day operational monitoring of dredging projects.

To measure and map the spatial distribution of elevated total suspended sediments produced by the dredging, a number of multispectoral satellite instruments were used, including Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS). Multiple remote sensing systems were used to increase the number of cloud-free images taken during the course of the project. Through this work Geoscience Australia has demonstrated that remotely sensed data can be used to monitor the spatial extent of sediment plumes on a daily basis.

True colour image of the sediment plume during dredging, taken by Landsat.

True colour image of the sediment
plume produced by dredging.
Image taken 27 August 2006
by Landsat Satellite.
© Geoscience Australia

Graph showing sediments in Hay Point area

Graph showing total suspended
sediments in the area.
Landsat satellite image used to
classify density of sediment plume
in sediment monitoring program.
© Geoscience Australia

Topic contact: earth.observation@ga.gov.au Last updated: February 4, 2014