International Riversymposium 2018

LANDHOLDERS Driving Change is facilitating a multidisciplinary approach to designing cost-effective approaches to remediate large-scale dispersive erosion gully features on grazing lands.

Alluvium Consulting Australia, principal consultant overseeing the large-scale remediation works on Mt Wickham, will speak about the project at the International Riversymposium 2018, held in Sydney on 14-18 October.

Many organisations have been working together on the Landholders Driving Change project under the leadership of NQ Dry Tropics, bringing together geomorphologists, engineers, soil scientists, ecologists and social scientists to design and trial cost-effective approaches to remediate large-scale dispersive erosion gully features on grazing lands in the BBB catchment.

The rationale is to deliver strategic guidance and costed, risk-based, transferrable solutions for large-scale gully landscape remediation in the catchment.

At International Riversymposium 2018, representatives from Alluvium will speak about the design process, approach and methods being used in the LDC project.

The Great Barrier Reef is currently experiencing an unprecedented level of investment that represents a shared commitment by the Australian and Queensland State Governments, local municipalities, research organisations, natural resource management and catchment groups, non-government organisations, landowners and private business to mitigate the many and varied risks facing the long-term protection of this natural wonder of the world.

One of the largest investments to date has been by the Queensland Government to design and deliver Major Integrated Projects that are intended to pilot land management and repair approaches within selected target catchments, with the aim of developing a self-sustaining package of interventions and tools transferable to other GBR catchments.

Landholders Driving Change is one of two Major Integrated Project (MIPs) recommended by the Great Barrier Reef Water Science Taskforce.

The other MIP aims to reduce nutrient and pesticide runoff from cane and banana farms in the Wet Tropics region.
The Queensland government has committed a total of $33 million to fund both MIPs, which aim to concentrate efforts at a catchment scale, and evaluate their effectiveness.

Fresh water, the stuff of life

LESS than 1 per cent of the planet surface comprises fresh water, yet it is this fresh water – our rivers, lakes and wetlands – that sustains us.  Rivers underpin our economies, providing water for agricultural lands, fisheries, tourism and cities to support growing populations.

More than ever, we need to embrace innovative practices to manage our rivers and river basins.

The 21st International Riversymposium will facilitate critical thinking, focus on solutions and inspire delegates to move beyond ‘business as usual’ approaches.

More information about the Riversymposium is available here.

More information about Alluvium Consulting Australia is available here.

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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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