M&E at Mt Wickham | Landholders Driving Change

An overview of Monitoring and Evaluation for the LDC project

First large-scale gully project a success

The Mt Wickham site was selected as the LDC project’s first large-scale gully remediation site.

The gully catchment treatment size was 3.03 ha and the control site size was 14.14 ha.

Treatment

The area underwent significant earthworks with tunnels excavated and the area reshaped and compacted with a bulldozer to a gradually sloping shape to reduce the velocity of water moving off the site.  

A series of rock chutes were constructed to manage water flow, and diversion banks were installed to divert runoff.

Revegetation included 538kg seed planted, including deep-rooted legumes, canopy species, pasture grasses, legumes and cover crops.

Results

Remediation was carried out  in 2018 allowing two wet seasons of treatment data to be collected. 

A number of statistically significant positive indicators are demonstrating that the Mt Wickham treatment is effective, independent of natural climate variability. 

The cover and biomass of the hillslope and gully walls have significantly improved, as well as the water quality and total suspended sediment concentrations. 

While land condition overall is showing an improvement from before treatment, it does remain fragile and will require careful management and ongoing monitoring. 

The total suspended sediment (TSS) levels at the control site and the treatment site are dropping from the baseline measurement, one year after treatment and two years after treatment.

Data collected on the adoption and effectiveness of landscape remediation techniques and farm management practices is used in the annual Reef Water quality Protection Plan report card as well as to enhance the catchment models. 

This is facilitated through the Paddock to Reef integrated monitoring, modelling and reporting program.

*Information sourced from the CSIRO report.

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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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