Can changes to pasture management reduce runoff and sediment loss to the Great Barrier Reef? The results of a 10-year study in the Burdekin catchment, Australia

Bartley, Rebecca; Corfield, J; Hawdon, Aaron; Kinsey-Henderson, Anne; Abbott, Brett N.; Wilkinson, Scott N.; Keen, Rex

doi:10.1071/rj13013

Cited by 54 publications

(59 citation statements)

References 48 publications

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“…The 10-year average ground cover for the two hillslopes were similar at 66% for Hillslope 1 and 68% for hillslope 3. The proportion of persistent bare ground was 5.7% on Hillslope 3, which was more than double that of Hillslope 1 at 2.6% (Bartley et al, 2014b).…”

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 84%

“…To measure the water and sediment flux at the Weany Creek sub-catchment site (~14 km 2 ), an automatic gauging station recorded rainfall, stage height, flow velocity, turbidity and water temperature at one-minute intervals during events. Bartley et al (2014b) and Hawdon et al (2009) gave details of the monitoring equipment and water sampling design of the gauging site.…”

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

“…Ground cover was estimated using a combination of on-ground field measurements and Quickbird satellite imagery (see Bartley et al, 2014b). The 10-year average ground cover for the two hillslopes were similar at 66% for Hillslope 1 and 68% for hillslope 3.…”

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

“…A linear relationship between total suspended solids (TSS) and turbidity was developed and used to calculate the annual suspended sediment load for each year (1 July to 30 June) (Bartley et al, 2014b). A total of 338 samples were collected over the 12 year period.…”

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

“…Samples of total suspended sediment (TSS) were collected using stratified sampling according to depth. For the low to moderate cover 0.29 ha Hillslope 3 site, a cut-throat flume, connected to a bulk sampler was used (Bartley et al, 2014b). A total of 286 samples were collected over the 10 year period at Hillslope 1 (ranging from 3-43 per year) and 38 samples (ranging from 2-5 per year) at Hillslope 3.…”

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

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Combining contemporary and long-term erosion rates to target erosion hot-spots in the Great Barrier Reef, Australia

et al. 2015

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Highlights This paper presents the first non-modelled estimates of contemporary measured erosion rates against background long term erosion rates in the Great Barrier Reef (GBR) catchments. Using an accelerated erosion factor (AEF), this study has highlighted that there are very specific 'hot-spot' areas that warrant priority treatment in terms of catchment remediation (Bowen sub-catchment, Upper Burdekin sub-catchment and low cover grazing areas). Due to the large intra-catchment variability of erosion in space and time, this study highlights that having a single end of catchment water quality target is inappropriate. Sub-catchment monitoring and evaluation is more suitable. The erosion rates presented in this paper represent a more robust way to 'bench-mark' current erosion rates compared with the current water quality 'targets'. AbstractMethods for prioritising catchment remediation are based on understanding the source of sediment over the short-medium timescales (10-10 2 years) using techniques such as sediment finger-printing, sediment flux monitoring, and catchment modelling. Because such approaches do not necessarily quantify the natural variation in sediment flux over the longer timescale, they often represent background or pre-agricultural erosion rates poorly. This study compares long-term (~100 to >10,000 years) erosion rates derived from terrestrial cosmogenic nuclides ( 10 Be) with contemporary erosion rates obtained by monitoring sediment fluxes over ~5-10 years. The ratio of these two data sets provides a measure of the accelerated erosion factor (AEF), which can be used to identify erosion hot-spots at the sub-catchment scale. The study area is the Burdekin catchment, the largest source of contemporary sediment to the Great Barrier Reef lagoon. Long-term erosion rates vary from <0.0077 mm yr -1 in the Suttor and Belyando subcatchments to 0.0296 mm yr -1 in the Bowen. The contemporary erosion rates are highest on small hillslopes with patchy ground cover (0.2726 mm yr -1 ) and in the Bowen sub-catchment (0.2207 mm yr -1 ), and lowest in the Belyando sub-catchment (0.0019 mm yr -1 ). All but two of the sub-catchment sites have an AEF > 1.0, indicating higher contemporary erosion rates than estimated long-term averages. Results confirm that the contemporary or agriculturally-induced erosion rates at these sites have increased considerably. Within the context of the Reef Water Quality Protection Plan, these results provide justification for water quality targets to be set at the sub-catchment scale, particularly for large and geomorphically diverse catchments.

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Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 84%

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

Section: Minor Sub-catchment and Hillslope Scale Samplingmentioning

confidence: 99%

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Combining contemporary and long-term erosion rates to target erosion hot-spots in the Great Barrier Reef, Australia

et al. 2015

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Assimilating catchment processes with monitoring data to estimate sediment loads to the Great Barrier Reef

et al. 2014

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Quantifying riverine sediment loads, and the uncertainty around these estimates, is important for monitoring the impact of land use on ecologically sensitive receiving waters such as the Great Barrier Reef lagoon. We used a Bayesian Hierarchical Modelling approach that assimilates information from a process model for runoff, a mechanistically motivated statistical model for sediment generation and observed runoff and sediment load data. The approach was trialled on a 10-year dataset collected from a 14-km 2 sub-catchment in the Burdekin basin, Australia. Using our model, we were able to estimate daily sediment concentrations, discharges and loads (with credible intervals) over a 10-year period, including 3 years where there were long periods of missing observational data. We found that for the high-frequency monitoring undertaken at the study site, credible intervals around sediment loads were narrow. Credible intervals were substantially wider in years where observational data were not available and load estimates relied on the underlying processes and neighbouring observations. The method presented here is the first attempt at assimilating discharge and concentration measurements with process models for the purpose of sediment load estimation. The potential for quantifying loads entering the Great Barrier Reef lagoon is promising, particularly for ephemeral streams that are typical of arid and semi-arid Australia. Copyright

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Grazing impacts on gully dynamics indicate approaches for gully erosion control in northeast Australia

Wilkinson

Kinsey-Henderson

Hawdon

et al. 2018

Earth Surf Processes Landf

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Drainage network extension in semi‐arid rangelands has contributed to a large increase in the amount of fine sediment delivered to the coastal lagoon of the Great Barrier Reef, but gully erosion rates and dynamics are poorly understood. This study monitored annual erosion, deposition and vegetation cover in six gullies for 13 years, in granite‐derived soils of the tropical Burdekin River basin. We also monitored a further 11 gullies in three nearby catchments for 4 years to investigate the effects of grazing intensity. Under livestock grazing, the long‐term fine sediment yield from the planform area of gullies was 6.1 t ha‐1 yr‐1. This was 7.3 times the catchment sediment yield, indicating that gullies were erosion hotspots within the catchment. It was estimated that gully erosion supplied between 29 and 44% of catchment sediment yield from 4.5% of catchment area, of which 85% was derived from gully wall erosion. Under long‐term livestock exclusion gully sediment yields were 77% lower than those of grazed gullies due to smaller gully extent, and lower erosion rates especially on gully walls. Gully wall erosion will continue to be a major landscape sediment source that is sensitive to grazing pressure, long after gully length and depth have stabilised. Wall erosion was generally lower at higher levels of wall vegetation cover, suggesting that yield could be reduced by increasing cover. Annual variations in gully head erosion and net sediment yield were strongly dependent on annual rainfall and runoff, suggesting that sediment yield would also be reduced if surface runoff could be reduced. Deposition occurred in the downstream valley segments of most gullies. This study concludes that reducing livestock grazing pressure within and around gullies in hillslope drainage lines is a primary method of gully erosion control, which could deliver substantial reductions in sediment yield. Copyright © 2018 John Wiley & Sons, Ltd.

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Can changes to pasture management reduce runoff and sediment loss to the Great Barrier Reef? The results of a 10-year study in the Burdekin catchment, Australia

Cited by 54 publications

References 48 publications

Combining contemporary and long-term erosion rates to target erosion hot-spots in the Great Barrier Reef, Australia

Combining contemporary and long-term erosion rates to target erosion hot-spots in the Great Barrier Reef, Australia

Assimilating catchment processes with monitoring data to estimate sediment loads to the Great Barrier Reef

Grazing impacts on gully dynamics indicate approaches for gully erosion control in northeast Australia

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