Productivity Commission, 2003:

"The delivery of sediments, nutrients and contaminants into the GBR lagoon occurs primarily through terrestrial (land) runoff, which is transported by rivers and streams that drain into the GBR lagoon. Runoff tends to be washed into rivers as a result of floods. Rivers in the wet tropics typically flood at least once and often several times a year. In contrast, it may be years or decades between major floods for rivers in the dry tropics. For example, the Burdekin River only experiences a significant flood every two to three years, and the Fitzroy River has floods of similar magnitude only every 10 to 20 years (Science Panel 2003). Nevertheless, the greatest average annual water discharges into the GBR lagoon are from the large dry tropics catchments of the Burdekin and Fitzroy.

On average, the Burdekin and Fitzroy catchments accounted for around a quarter of annual freshwater flows from the GBR catchment between 1968 and 1994. However, discharges from these catchments can vary enormously from one year to the next. Year-to-year changes in the quantity (cubic km) discharged from wet tropics catchments, such as the Tully, tend to be far smaller (figure 2).

When river flows reach the coast, flood plumes form in the GBR lagoon. These plumes (and the sediments, nutrients and contaminants they carry) tend to move north and remain within 20 km of the coast. This means that the impacts of terrestrial runoff are likely to be concentrated around inshore reefs, which account for about a quarter of the reefs in the GBR World Heritage Area."

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Citation and/or URL

Productivity Commission 2003, Industries, land use and water quality in the Great Barrier Reef catchment: research report. Department of Communications, IT and the Arts, Canberra, Australia.

Spatial Coverage

Great Barrier Reef- wide 

Temporal Coverage

Up to 2002 

Update Frequency

Not applicable 

Other Information

None