Gilbert, 2001:

"The purpose of this report was to gather geographical and statistical information on the Great Barrier Reef Catchment, the majority of which was compiled in 1998. This information is intended to support future studies on predicting the impact of land-based activities on the Great Barrier Reef.

The Great Barrier Reef extends over 2 000 km along the north-eastern coast of Australia. It is the largest reef system in the world, providing habitat for a diversity of marine life. The Great Barrier Reef Catchment Area lies adjacent to the Great Barrier Reef World Heritage Area and comprises approximately 25 % of the land area of Queensland. Forty drainage basins comprise the Great Barrier Reef Catchment Area which drain directly into the Great Barrier Reef lagoon. Land modification associated with increased population, urban development and agricultural expansion has transformed the Great Barrier Reef Catchment Area. Run-off from these land-based activities has reduced the quality of water flowing into the Great Barrier Reef lagoon and is of great concern to researchers and managers of the Great Barrier Reef Marine Park Authority.

Climate within the Great Barrier Reef Catchment Area ranges from tropical to subtropical, with rainfall distribution being highly variable throughout the area. Coastal areas receive considerably higher rainfall than the uplands, hence more dense settlement and intensive agricultural expansion has been concentrated in the coastal zone, particularly in those basins receiving higher rainfall. The Great Barrier Reef Catchment Area has some of the most topographically diverse terrain on the Australian continent.

Changes in land cover since European settlement (200 years ago), has extensively modified the vegetation communities within the Great Barrier Reef Catchment Area. Native vegetation clearance in Queensland has historically been high, and continues at levels far in excess of other Australian States. The largest land-clearing event has occurred in the brigalow biogeographic region within the Great Barrier Reef Catchment Area. Brigalow communities were estimated to have covered 11 % and 30 % of the Burdekin and Fitzroy basin respectively, but now only cover 2 % and 1 % of these basins. Tropical rainforest vegetation along the accessible coastal river plains have also been cleared for settlement and agriculture. Additionally, the expansion of agriculture and urbanisation has resulted in the loss of wetland vegetation. The estimated area of freshwater wetlands that remain in the Great Barrier Reef Catchment Area is 18 408 km2. Further threats to wetlands exist, with the rise in use of ponded pastures for grazing, particularly in the central basins of the Great Barrier Reef Catchment Area. The greatest source of sediment and nutrients is derived from the clearing and cultivation associated with agricultural land uses.

Queensland supported a large proportion of Australia’s pre-settlement indigenous population. Following settlement, the indigenous population in Queensland declined and European population growth was rapid, with a quarter of a million persons in 1883 to 3 million persons in 1992. Queensland has 18.4 % of Australia’s total population. Queensland’s population is urbanised and concentrated along the eastern coastal catchments. The concentration of population and infrastructure within the coastal zone impacts on coastal and reef ecosystems.
The soils of the catchment area are typically of low fertility and exhibit poor soil structure, which has resulted in extensive application of fertiliser and conditioner to maintain agricultural productivity. Since the 1960’s, there has been a dramatic increase in the application of nitrogenous and phosphate fertiliser use in the Great Barrier Reef Catchment Area. Over half of the total volume of nitrogen and phosphorus fertiliser used in agriculture within the Great Barrier Reef Catchment Area is applied to sugarcane. The area of sugarcane in the Great Barrier Reef Catchment Area since 1930 has increased substantially, and in 1995 was over 360 000 hectares.

Grazing occurs in all basins in the Great Barrier Reef Catchment Area to varying degrees. Approximately 4 900 000 cattle are found in the Great Barrier Reef Catchment Area. The two dominant basins in terms of area for grazing of cattle within the catchment are the Burdekin-Haughton and Fitzroy.

Mineral production is the highest source of export revenue for Queensland. Coal production in Queensland has increased rapidly since the 1960’s, from 2.5 million tonnes to just under 100 million tonnes per year. Five statistical divisions within the Great Barrier Reef Catchment have produced 96 % of Queenslands black coal. Port development has been rapid within the Great Barrier Reef Catchment Area and associated with the boom in mineral production. Some of the major ports within the Great Barrier Reef Catchment Area have recorded over 500 vessel arrivals. Major shipping traffic and heavy use by smaller commercial and recreational vessels within the Great Barrier Reef lagoon threaten water quality through potential for shipping accidents and oil spills. Between 1987 and 1997 approximately 186 maritime incidents were reported within the Great Barrier Reef World Heritage Area.

In 1997 there were 123 official weirs and dams within the Great Barrier Reef Catchment in total which have been constructed for the increases in population and agricultural expansion. The dams have a capacity (7 million mega litres) which can potentially capture approximately 10 % of the annual run-off from the Great Barrier Reef catchment. The Burdekin Falls Dam is currently the largest dam in the Great Barrier Reef Catchment Area.

The high variability of Queenslands rainfall and widespread implementation of water regulation schemes has produced a number of irrigation areas for agriculture within the Great Barrier Reef Catchment Area. The area of irrigated agriculture in 1990 was 832 km2 and total water usage delivered to farms was 343 790 mega litres year. Though not all sugarcane was irrigated it was the largest irrigated crop by area, particularly in the Wide-Bay-Burnett and Northern (particularly in the Burdekin) Statistical Divisions.

There is potential for continuing land-use change of coastal environments and downstream effects from catchment modification on the Great Barrier Reef lagoon. Increased areas of cropping lands, particularly those using high fertiliser applications, may impact the Great Barrier Reef through higher sediment and nutrient run-off levels. Such water quality modification threatens the values of the Great Barrier Reef World Heritage Area."

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Citation and/or URL

Gilbert, M. 2001, Population and major land use in the Great Barrier Reef catchment area: spatial and temporal trends, Great Barrier Reef Marine Park Authority, Townsville, Australia

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Spatial Coverage

Great Barrier Reef catchment

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Temporal Coverage

1800 - 2000 

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Update Frequency

 Not applicable 

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Other Information

None