Extent and rate of change of freshwater wetland systems
More than 94% of the pre-European settlement extent of freshwater wetlands in Queensland remained in 2013. Changes in the extent of freshwater wetlands have been monitored in Queensland since 2001. Wetland loss peaked at a rate of 0.12% during 2001–2005. The rate of freshwater wetland loss reduced to 0.04% during 2005-2009 and 0.03% in 2009–2013.
Of the three freshwater wetland systems — lacustrine, palustrine, riverine — the greatest ongoing losses have occurred in palustrine and riverine systems in the Murray Darling and North East Coast Drainage divisions.
At a statewide scale, an estimated 94% of pre-clear extent of freshwater wetland remains. Estimated historical loss of wetlands is unevenly distributed across drainage divisions and catchments:
- 50% remaining in the North East Coast (non-Great Barrier Reef) division
- 80% remaining in the North East Coast (Great Barrier Reef) division
- 84% remaining in the Murray Darling division
- close to 100% remaining in other divisions.
Ongoing loss over the 2001-2005, 2005-2009 and 2009-2013 periods continued. Overall loss during the 2009-2013 period was 1,360ha, a rate of 340ha/yr. This equates to 0.03% of 2013 extent.
Divisions with highest ongoing loss were:
- North East Coast (non-Great Barrier Reef) division (334ha, 0.33%)
- North East Coast (Great Barrier Reef) division (596ha, 0.06%).
The estimated historical and current loss of wetlands has mainly occurred due to drainage, clearing or levelling of lowland parts of catchments associated with intensive agriculture and urbanisation. The greatest losses have occurred in the palustrine and riverine systems. Loss of palustrine wetlands between 2001 and 2013 has decreased from 2,831ha (2001-2005) to 302ha (2009-2013). Loss of riverine wetlands declined from 4,737ha (2001-2005) to around 1,100ha and has remained constant for subsequent periods.
In addition to the drainage divisions, the ‘other’ category represented in the data includes islands within Queensland waters as well as discrepancies in catchment coverages and coastline.
Historical loss of freshwater wetland extent in the Bulloo drainage division has been minimal with close to 100% (of pre-clear extent) remaining.
Loss of palustrine wetlands has been ongoing over the 2001-2005, 2005-2009 and 2009-2013 periods and remained constant between 15-20ha over each period (a rate of 4-5ha/yr).
Historical loss of freshwater wetland extent in the Gulf drainage division has been minimal with close to 100% (of pre-clear extent) remaining. Historical loss is evenly distributed across catchments with more than 97% remaining in all catchments.
Change in extent over the 2001-2005, 2005-2009 and 2009-2013 periods has been variable and difficult to quantify due to natural change caused by meandering river systems on flat plains.
Overall loss for the Gulf drainage division during the 2009-2013 period was 96ha (0.01%)—a rate of 24ha/yr. Riverine wetlands in the Flinders (64ha) and Cloncurry (14ha) catchments were most affected, due to broad acre land clearing.
Historical loss of freshwater wetland extent in the Queensland Lake Eyre drainage division has been minimal with close to 100% (of pre-clear extent) remaining.
Ongoing loss over the 2001-2005, 2005-2009 and 2009-2013 periods has been mostly to palustrine wetlands, decreasing from 124ha in 2001-2005 to 5ha in the latest reporting period.
Historical loss of freshwater wetland extent in the Queensland Murray Darling Basin division is unevenly distributed. The Macintyre, Weir and the Dumaresq have less than, or equal to, 50% remaining. Historical loss of palustrine wetlands in the Moonie, Macintyre and Weir catchments has resulted in less than 25% remaining.
Ongoing net loss of wetlands over the 2001-2005, 2005-2009 and 2009-2013 periods has continued to decrease from an initial high rate of more than 1,500ha to 291ha—a rate of 72ha/yr.
Most of this loss is due to broad acre land clearing of riverine and palustrine wetlands, primarily in the Warrego catchment.
North East Coast (GBR)
Historical loss of freshwater wetland extent in the North East Coast Great Barrier Reef (GBR) drainage division is unevenly distributed across catchments. Eighty per cent (of pre-clear extent) remains for the division. Many of the catchments in Cape York Peninsula have close to 100% remaining whereas the Boyne and Auburn, Upper Burnett, Mossman, Mulgrave, Murray and Tully catchments have about 50% remaining. Historical loss of palustrine wetlands has resulted in less than 25% remaining in the Boyne and Auburn, Upper and Lower Burnett, Calliope, Kolan and North Johnstone catchments.
The Styx and Shoalwater catchments along the east coast have more than 100% (of pre-clearing) extent of palustrine wetlands remaining. This is associated with the conversion of estuarine plains to freshwater wetlands by bunding, a common practice in many coastal catchments.
Ongoing loss over 2001-2013 has been to riverine and palustrine wetlands.
Net loss for the North East Coast GBR drainage division for 2009-2013 was 596ha (0.06% of 2013 extent), a rate of 149ha/yr.
Catchments with highest ongoing net loss of more than 50ha were:
Loss of palustrine wetland for 2009-2013 was highest in the Comet (40ha) and Mackenzie (31ha) catchments.
Increases in palustrine wetland due to bunding were reported in the following catchments:
- Lower Burdekin (56ha)
- Water Park Creek (24ha)
- Baratta Creek (15ha).
Increases in extent due to bunding may affect net results by division or totals for each catchment.
Catchments recording loss of riverine wetland of more than 50ha over the 2009-2013 period were:
- Suttor (118ha)
- Dawson (66ha)
- Don (66ha)
- Isaac (60ha).
Whilst the Lower Burnett and Nogoa River catchments showed a reduction in loss of riverine wetland extent between 2001-2013, the Don catchment recorded an increase in loss (7-66ha).
North East Coast (non-GBR)
Historical loss of freshwater wetland extent in the North East Coast non-Great Barrier Reef (GBR) drainage division is unevenly distributed across catchments. While 50% of the pre-clear extent remains for the division, only two catchments—Noosa and Bremer Rivers—have more than 50%: Coomera and Nerang and South Pine River catchments have less than 25% remaining.
Ongoing loss over the 2001-2013 period has been mostly to palustrine and riverine wetlands, notably (with the exception of Logan catchment) due to loss of natural wetlands incurred with construction of the Wyaralong dam. Overall loss for the division during 2009-2013 period was 334ha or 83ha/yr.
Catchments with highest ongoing loss were:
- Logan (149ha)
- Maroochy River (105ha).
Loss of palustrine wetland over the 2009-2013 period continued to decrease from 580ha in 2001-2005 to 157ha in 2009-2013. Catchments with loss of palustrine wetlands greater than 7ha are:
- Maroochy (88ha)
- Noosa (18ha)
- Logan (17ha)
- Coomera and Nerang (9ha)
- Caboolture (8ha)
- North Pine River (7ha).
This loss is primarily due to urban and industrial development.
Comparison between pre-clear (pre-European settlement extent) and remnant (current extent) freshwater wetland mapping. Categories by broad wetland system definition classes: lacustrine, riverine, palustrine. Data is based on the latest Queensland Wetland Mapping (version 4, 2013).