Grazier Christian Cormack and gully expert Associate Professor Andrew Brooks inspect a large active gully.

International Gully Symposium in Townsville

THE Eighth International Symposium on Gully Erosion (ISGE) is being held in Townsville 21-27 July, the first ISGE in the southern hemisphere, and NQ Dry Tropics is involved.

NQ Dry Tropics is a gold sponsor, our NRM implementation manager Peter Gibson is on the organising committee, and several staff members from our Sustainable Agriculture Program and Landholders Driving Change (LDC) project will present at the event.

The NQ Dry Tropics’ LDC project, along with a number of other organisations, is helping to organise one of the post conference field trips to Bowen River to visit one of the gully erosion hotspots of the Great Barrier Reef catchments.

Symposium participants will visit major alluvial gully rehabilitation sites and see how these sites are being used as major test beds to evaluate rehabilitation methods and monitoring techniques.

Below are the links to the abstracts that NQ Dry Tropics staff will address at the symposium.

“Developing a cost-effective and prioritised approach to gully remediation in the Bowen, Bogie and Broken Catchments”

Presented by Matthew Miles, LDC Landscape Remediation Officer, Lisa Hutchinson, LDC Project Manager, and Andrew Brooks, Associate Professor at the Centre for Coastal Management – Griffith University.


“A production systems approach to point source sediment remediation – enhancing landscape function and farm resilience through erosion control”

Presented by Sam Skeat, NQ Dry Tropics Grazing Project Officer and Neil Cupples, NQ Dry Tropics Soil Conservation Officer.

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Figure 1. Total fine sediment reduction by project type and erosion source. Inset shows the proportion of the total project area for each project type.

These estimates have been calculated using two methods: 

1) The pollutant reduction component of the Alluvium/Great Barrier Reef Foundation (GBRF) investment tool for hillslope and streambank erosion management projects; 

2) The Reef Trust Gully Toolbox method for gully erosion management projects. The LDC Water Quality Report 2020 (Waterhouse et al., 2020) highlights that a number of assumptions underlay these calculations, therefore these figures should be treated as the best available estimate of sediment reductions to date.

Preventing sediment from reaching the Great Barrier Reef

Each wet season sediment is washed into local waterways and out to the Great Barrier Reef (GBR). 

Most sediment is very fine, and can stay suspended for a long time and can travel great distances. Valuable topsoil is lost from production, and increased concentrations on the reef can be harmful to seagrasses and corals. 

Landholders in the BBB have completed 69 on-ground water quality practice changes, and it is estimated that these have contributed a fine sediment reduction of 6,154 tonnes per year from reaching the GBR. 

Of this, approximately half of the sediment savings are attributable to grazing land management changes on hillslopes and streambanks, and the other half as a result of gully remediation treatments across a broad range of scales, as shown in the graphs above. 

The table below also highlights the relatively small area of intervention in the gully management projects compared to the large sediment savings that these can achieve - 60 per cent of the sediment savings over only 4 per cent of the project area.

Table 1. Estimated sediment reductions (tonnes) from projects completed in the LDC Project to date.

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*GLMWW = Grazing Land Management Wire and Water

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*The Exploring New Incentives activity area has provided an opportunity for graziers to adopt improved land management practices through a range of activities. For some of these properties, it was the first time they signed contracts for on-ground works.

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The LDC project monitors four gully sites (represented in this table) with gold standard equipment and analysis, carried out by CSIRO.

Results have been compiled in a preliminary report from Bartley et al (2020), with the final report expected to be released by the end of 2020. The preliminary report shows all four sites have indicators of improvements, notably the Strathbogie and Mt Wickham sites.

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Reef regulations - grazing, standard conditions

  1. For land in good or fair condition (more than 50 per cent ground cover at 30 September), continue using measures to maintain land condition.
  2. For land in poor condition (less than 50 per cent ground cover at 30 September), steps must be taken to improve land condition.
  3. For land in degraded condition (less than 20 per cent ground cover at 30 September), steps must be taken to improve land condition OR prevent areas from further degrading or expanding.
  4. Keep records of measures taken and also of agricultural chemicals, fertiliser and mill mud or mill ash applied to land.
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