CEMSYS Modelled Data – mapping wind erosion

SNAP-SHOT:

CEMSYS models the extent and severity of wind erosion for each NRM region, July 2006 – June 2008, creating monthly and annual maps of wind erosion in Australia at 50km resolution. View CEMSYS Modelled Data.

The severity of wind erosion is classed in the model as:

1. Very Low
2. Low
3. Moderate
4. High
5. Very High

For each Natural Resource Management (NRM) region in Australia, the percentage land area affected by wind erosion is calculated, for each level of wind erosion severity.

The data can be used by NRM bodies and the Australian Government for resource condition reporting. The same products would also assist in identifying areas for Caring for our Country (C4oC) investments.

Find your NRM region.

The CEMSYS Modelled Data is presented alongside Wind Erosion Histories and Wind Erosion Rankings for NRM regions. Read more about Wind Erosion Histories and Rankings.

Mapping wind erosion using a numerical model

To tackle the problem of wind erosion it is necessary to know where it occurs and how intense it is. To deal with the problem effectively, the Australian and State governments, along with Natural Resource Management (NRM) regional bodies, need to know:

• where the wind erosion is occurring;

• how severe it is; and

• if the NRM investment projects aimed at reducing erosion are making a difference.

Measuring wind erosion as it changes in space and time is very difficult; wind erosion varies across the landscape and occurs at different times of the year.

Numerical models, run on large computers, can assist in natural resource management by calculating (or modelling) wind erosion rates for the entire continent.

The CEMSYS Model

The CEMSYS Project used a numerical model called CEMSYS (Computational Environmental Management System) to create modelled monthly and annual wind erosion maps of Australia at 50 km resolution, for the period July 2006 to June 2008.

For each pixel (50 km x 50km), a wind erosion severity level was calculated and classified as either very low, low, moderate, high or very high erosion.

Then for each Natural Resource Management (NRM) region (see map in Figure 1), the percentage of land area affected by each wind erosion severity class was calculated.

What was found?

Several results came out of this study.

• Wind erosion varies a lot between months and years.

• In 2006-07 the erosion season began in October 2006 and finished in March 2007

• In 2007-08 the season started earlier in August 2007 and remained high through to June 2008, with the exception of May 2008.

• The NRM regions with very high and high erosion levels during this period,  were:

• Queensland: Desert Channels, South West, Border Rivers Maranoa – Balonne, and Condamine;

• New South Wales: Western, Border Rivers – Gwydir, Namoi and parts of Lachlan, Murrumbidgee, Murray and Lower Murray Darling regions;

• South Australia: the Arid Lands region;

• Northern Territory: the Pastoral and Non-Pastoral regions; and

• Western Australia: the Rangeland regions of the Goldfields Nullarbor, Gascoyne Murchison and the Avon region.

• At the state scale, South Australia had the highest percentage area of High-Very High wind erosion, followed by Queensland and NSW, and the Northern Territory with 0-1%.

To find out more, read the Executive Summary below.

Acknowledgements

A collaborative effort between the Department of Environment, Climate Change and Water (DECCW) and the University of Southern Queensland (USQ) was required to complete this project.  Project team members were Dr John Leys (DECCW), Dr Harry Butler (USQ), Dr Xihua Yang (DECCW) and Mr Stephan Heidenreich (DECCW).

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The Leys report on wind and water erosion (Leys et al. 2009) recommended that wind erosion modelling be undertaken to assist in reporting the extent and severity of wind erosion across Australia. The modelling could then be used by the Australian government, states and Natural Resource Management (NRM) bodies for resource condition reporting.  The same products would also assist in identifying areas for Caring for our Country (C4oC) investments.

Modelled monthly and annual wind erosion maps of Australia at 50 km resolution for the period July 2006 to June 2008 were compiled using the Computational Environmental Management System model (CEMSYS). A modified map of Natural Resource Management (NRM) regions and sub-regions developed by an expert panel to report wind erosion status was then used to calculate the monthly and dust-year statistics for the continent, states, NRM regions and sub-regions.

The 2007–08 dust-year had higher levels of wind erosion in the high and very high classes (3 %) compared to the 2006–07 dust-year (1%). The NRM regions with the highest levels of erosion were: Desert Channels, South West, Border Rivers Maranoa – Balonne, and Condamine in Queensland; Western, Border Rivers – Gwydir, Namoi and parts of Lachlan, Murrumbidgee, Murray and Lower Murray Darling regions in NSW; the Arid Lands region of South Australian, the Pastoral and Non-Pastoral regions of the Northern Territory; and the Rangeland regions of the Goldfields Nullarbor, Gascoyne Murchison and the Avon region of Western Australia.

The CEMSYS data produced in this study offers greater spatial resolution and better statistical descriptions than the previous measure of wind erosion, the Dust Storm Index (DSI) which is derived from Bureau of Meteorology observer data. Despite the spatial limitations of the DSI, it still remains a valuable cross validation for CEMSYS and it has the major advantage of longer time series (1960 to present).

The issue of scaling needs to be understood and this project shows the problems of comparing data measured at different scales (10 and 50km). The advantages of smaller scales are better representation of the landscape and statistics.

This study concludes with an implementation plan that proposes improvements to the modelled wind erosion data through the provision of longer time series of maps (2000 to current) and increasing the resolution of the modelling from 50 to 10 km.

Source: Leys, J., Butler, H., Yang, X., and Heidenreich, S. (2010). CEMSYS Modelled Wind Erosion. Technical Report. No. DECCW 2010\. Department of Environment, Climate Change and Water, Sydney. 78 pp.