Land: Wind erosion
- Authors
- Key findings
- Indicators and summary of status
- Importance
- Pressure and condition
- Response
- References
Authors
Grant McTainsh and Kenn Tews, Griffith School of Environment, Griffith University, Brisbane
Key findings
- Wind erosion is widespread in central inland and western Queensland.
- Climatic conditions have a major influence on wind erosion and land use pressures can accelerate erosion rates. In the years 2002-06 the extent of wind erosion was greater than the long-term average (1960-2006) largely because of the severe drought conditions during 2002.
- Land use pressures that have accelerated wind erosion include grazing by livestock, kangaroos, rabbits and feral camels.
Indicators and summary of status
Indicator |
Status of indicator |
Dust Storm Index (DSI) below long-term average |
The Cape York, Wet Tropics, Burdekin Dry Tropics, Mackay-Whitsunday, Fitzroy and South East NRM regions have below-average DSI. [ |
Dust Storm Index (DSI) at long-term average |
The Northern Gulf, Southern Gulf and Desert Channels NRM regions have average DSI. [ |
Dust Storm Index (DSI) above long-term average |
The South West, Burnett-Mary and Murray-Darling NRM regions have above-average DSI. [ |
]
]
]
Importance
Wind erosion is an important land degradation process in Queensland because it reduces soil fertility and soil water storage capacity, reducing the capacity of soils to sustain biodiversity and support pastoralism and agriculture. The timing, intensity and spatial distribution of wind erosion are controlled by a range of environmental factors, and the strongest driver is climate, through its influence on vegetation cover. Rural land use activities can accelerate natural wind erosion rates by reducing vegetation cover. Wind erosion data are needed over long periods to allow comparison of erosion trends with climate and land use. These issues have been discussed in more detail in submissions to past Queensland state of the environment reports (McTainsh and Tews 1999, 2002).
Pressure and condition
Land use pressures
A number of rural land use pressures can accelerate wind erosion rates. Tree clearing in erosion-prone regions can lead to increased erosion rates by exposing soils. Grazing of protective vegetation can expose soils to erosion, and trampling by stock can disturb protective soil crusts. The largest area of wind erosion-prone land in the arid west of the state is grazed by cattle, while sheep grazing predominates in the semi-arid regions of central Queensland.
Grazing pressure from increasing numbers of kangaroos and other native macropods represents a significant pressure on pasture grasses in the state's drier regions. Grazing by rabbits has long been acknowledged as a land-degrading influence. The accidental release of the rabbit calicivirus in 1995, followed by the planned release in 1996, has reduced rabbit numbers but not eliminated the animals (Neave 1999). Feral camels increase grazing pressure on pasture species, a particular problem in the Simpson Desert region (Edwards 2007).
The invasion of woody weeds into the grazing lands of the mulga region around Charleville has detrimentally changed the vegetation species composition of the region. Most woody weeds are unpalatable to sheep, however, so this will often increase overall vegetation cover and can decrease wind erosion.
Cultivation also exposes soil to wind erosion, but this is generally less of a problem in Queensland than in most other states because cultivated land rarely extends west of the 500 mm rainfall isohyet into the active wind erosion region, and because only 2% of the state is cultivated.
Condition and trends
Estimates of land condition in relation to wind erosion measured by the Dust Storm Index (DSI) are presented here in two forms: (i) a table showing wind erosion activity and trend within each NRM region for the reporting period in relation to the period 1992-95, and (ii) maps of wind erosion activity for the reporting period (2002-06) and the long term (1960-2006).
Comparing the period 2002-06 with the long term
Table 4.3 shows that wind erosion during the reporting period was above the long-term average in the South West, Burnett-Mary and Murray-Darling NRM regions. In the Northern Gulf, Southern Gulf and Desert Channels NRM regions wind erosion was at the long-term average. The Cape York, Wet Tropics, Burdekin Dry Tropics, Mackay-Whitsunday, Fitzroy and South East NRM regions have experienced below-average wind erosion activity.
Comparison of the DSI map for 2002-06 (Figure 4.3) with the long-term map (Figure 4.4) shows that wind erosion activity has increased (to DSI >5) in the Simpson Desert, lower Channel Country and Thargomindah regions. The zone of moderate erosion activity (DSI 1-3) extended north into the Gulf and further east into the Longreach area. A significant reduction in the DSI (from the long-term DSI of 2.1 to 1.0) has occurred in the mulga lands around Charleville, which may reflect the improved soil protection provided by the expansion of woody weeds in this area. In the area of cultivated land around Goondiwindi the DSI has increased more than threefold (from 0.5 to 1.7), which may reflect the expansion of cultivated land in this region. Conversely, erosion activity is significantly reduced in the north-eastern part of the state, particularly around Cardwell, which may reflect an improvement in land management in this area.
The overall increased wind erosion activity during the reporting period was largely in response to the severe drought conditions which peaked in 2002, and resulted in the largest dust storm since the 1960s (McTainsh et al. 2005). The drought conditions also resulted in the zone of moderate erosion activity in the central west around Longreach moving further east, and increased erosion activity in the cultivated lands around Goondiwindi.
NRM region |
2002-06 |
1992-95* |
Cape York |
Below average [ |
Below average [ |
Northern Gulf |
Average [ |
Above average [ |
Southern Gulf |
Average [ |
Average [ |
Desert Channels |
Average [ |
Above average [ |
South West |
Above average [ |
Above average [ |
Wet Tropics |
Below average [ |
n |
Burdekin Dry Tropics |
Below average [ |
Above average [ |
Mackay-Whitsunday |
Below average [ |
n |
Fitzroy |
Below average [ |
Below average [ |
Burnett-Mary |
Above average [ |
n |
South East |
Below average [ |
n |
Murray-Darling |
Above average [ |
Above average [ |
Desert Uplands |
x |
x |
* Wind erosion activity measurement from the previous reporting period is based on 1960-2001 long-term statistics.
n: Insufficient activity to calculate reliable measure
x: Not assessed as no stations in region
Source: McTainsh and Tews 2002
Comparing the periods 2002-06 and 1992-95
More recent trend information is available from a comparison of the current reporting period with the 1992-95 period of dry conditions and active wind erosion (Table 4.3). A more detailed picture also emerges from a comparison of the 2002-06 DSI map with the 1992-95 map in the wind erosion section of State of the Environment Queensland 2003 (Figure 4.5, page 4.21) (McTainsh and Tews 2002). Overall, for the period 2002-06 the mean DSI of 0.73 is slightly lower than the mean DSI of 0.91 in the period 1992-95. Table 4.3 shows that wind erosion has decreased in the Northern Gulf, Desert Channels and Burdekin Dry Tropics NRM regions and decreased slightly in the South West. The Northern Gulf trend is a measurement artefact arising from the reduction in the number of meteorological stations in the region from three to one. The overall wind erosion reduction in the Desert Channels NRM region is real, and a comparison of the DSI maps shows that conditions improved slightly in the southern Simpson Desert (around Birdsville) and in the Thargomindah area, indicating that the grazing impacts of cattle, kangaroos and feral camels may not have been as severe as in 1992-95. Conversely, conditions deteriorated in the up-catchment areas of the Desert Channels NRM region (around Winton-Longreach-Isisford), which might indicate that the combination of the drought with sheep and kangaroo grazing has had more serious impacts on land condition. Also, the slight increase in DSI in the mulga lands around Charleville suggests that even the protection offered by the woody weeds in this region may have been diminished by the drought.
Although the improvement in the Burdekin Dry Tropics NRM region is statistically significant, the absolute DSI values are very low; therefore this result may not reflect a real change in land condition. While wind erosion remains high in the Murray-Darling region and average in the Southern Gulf, both regions experienced a slight deterioration, possibly indicating that these cultivated lands were made more erodible by the drought.
Figure 4.3 Wind erosion patterns based on the mean Dust Storm Index for 2002-06
Source: McTainsh and Tews 2002
Figure 4.4 Long-term wind erosion patterns based on the mean Dust Storm Index for 1960-2006
Source: McTainsh and Tews 2002
Response
Increasing environmental awareness among rural landholders, within NRM regional bodies and the community as a whole is likely to have resulted in improved land management. It is still necessary, however, to convert this improved environmental awareness into specific land management strategies that can prevent accelerated wind erosion.
A DustWatch network of volunteer wind erosion observers was set up in 2002 and includes a significant number of DustWatchers throughout western Queensland. DustWatch also has the important benefit of raising awareness within rural communities of wind erosion. It provides wind erosion data compatible with Bureau of Meteorology records, and will help to compensate for the reduced number of Bureau of Meteorology stations recording weather phenomena (the number declined from 46 stations in 2001 to 32 in 2006). The DustWatch network will be funded by the National Landcare Programme in 2007-08.
References
Edwards, G. 2007, National feral camel management plan more urgent than ever, says Desert Knowledge Cooperative Research Centre, Desert Knowledge Cooperative Research Centre media release, March 2007.
McTainsh, G.H. and Tews, E.K. 1999, Wind erosion, State of the Environment Queensland 1999, pp. 3.30-3.32, Environmental Protection Agency, Brisbane.
McTainsh, G.H. and Tews, E.K. 2002, Wind erosion, a contribution to State of the Environment Queensland 2003, Environmental Protection Agency, Brisbane.
McTainsh, G.H., Chan, Y.C., McGowan, H.A., Leys, J.F. and Tews, E.K. 2005, 'The 23rd October, 2002 dust storm in eastern Australia: characteristics and meteorological conditions', Atmospheric Environment 39: 1227-1236.
Neave, H.M. 1999, Rabbit Calicivirus Disease Program Report: Overview, report of research conducted by participants in the Rabbit Calicivirus Disease Monitoring and Surveillance Program and Epidemiology Research Program, Bureau of Rural Sciences, Canberra.
Acknowledgements
Funding for this project by th e Queensland Department of Natural Resources and Water is gratefully acknowledged. The Bureau of Meteorology provided data for calculating the Dust Storm Index.
<<Return to State of the Environment Queensland 2007 content page
Last reviewed 16 May 2011
Last updated 4 September 2007