Rollston River

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Vegetation

Riparian Habitat

iTRARC analysis of Riparian Habitat indicates that this subcatchment has undergone relatively little change since the 1970s and is still in good condition. However the field survey TRARC sites show one good and one poor site, and additional field surveys may pick up on the diversity of conditions beneath the canopy i.e. the areas that remote sensing cannot detect.

iTRARC Scores

Catchment Class 2 B
Maximum iTRARC Score 20 (A+)
1970s Score 14 (B+)
2004 Score 12 (B+)
Reduction in Ecosystem Services No Change
Increase in Potential for Erosion Small
Reasons for Change in Score
  • Increase in the number of low cover hill slopes next to the channel network
  • Increased number of gullies/scalds

TRARC (field survey) scores

Survey SiteScoreRegenerationWeeds
Rollston R54.5 (C)2 (B)1 sp: 5% cover (B)
Cattle Ck71.3 (B)2 (B)1 sp: 5% cover (B)
Average 62.9 (C)

Reference:Assessing the condition of Riparian Vegetation in the Burdekin catchment

Wetlands

Rollston River is a largely dry seasonal river though a few permanent waterholes are present (eg, beside Harvest Home homestead). Condition is considered to be typical of sub-divisions in this area that are dominated by cattle grazing. Limited water quality data is available for the Harvest Home waterhole in Burrows (2000). Pettit and Dowe (2003) examined the age structure of the rare palm in riparian areas of creeks in this area, finding that they were threatened by fire regimes.

Reference: Assessing the condition of Wetlands in the Burdekin catchment

For more information see Rollston River wetland condition summary

Water

SedNet Modelling of Water Quality

Model results for the Rollston River subcatchment are summarized as follows:

  • Subcatchment modelled area: 1,448 sq. km.
  • Source contributions: Hillslope = 54%; Gully = 44%; Streambank = 2%
  • Area of sub-catchment with <50% ground cover: 351 sq. km or 24% of subcatchment
  • Hillslope sediment supply: 220 kg/ha/yr
  • Total suspended sediment (flow weighted) supply: 59 kt/yr
  • Total suspended sediment supply (flow weighted; normalized to area): 405 kg/ha/yr
  • Total suspended sediment end-of-subcatchment (flow weighted) yield: 53 kt/yr
  • Event Mean Concentration (EMC - flow weighted): 608 mg/L
  • Mean Annual Flow: 86,529 ML

Reference: Improved SedNet Modelling of Grazing Land in the Burdekin Catchment

Hillslope and gully erosion are both identified as major sources of sediment and particulate nutrients affecting water quality within the Rollston River sub-catchment (54% & 44% respectively). Hillslope erosion is predicted to contribute 220 kg/ha/yr. It is estimated that approximately 24% of the subcatchment has poor ground cover (<50%). The rate of soil loss from all sources (supply) is considered moderate to low (405 kg/ha/yr) when compared to other sub-catchments. The event mean concentration of sediment is considered moderate (608 mg/L) when compared to other subcatchments.

Water Quality Monitoring

There are no water quality monitoring data available for this catchment.

Relevant information of Water Quality Monitoring in the Cape Campaspe River Basin:

Environmental Uses and Values

Aquatic Ecosystems

The aquatic ecosystem values of the Rollston River subcatchment are poorly known and, while considered to be Slightly to Moderately Disturbed (SMD) as a consequence of the surrounding land use for cattle grazing, the biological communities are thought to remain in a healthy condition and ecosystem integrity is likely to be largely retained. No High Ecological Value (HEV) waters have been identified in the subcatchment.

The Rollston River is a seasonal system with few permanent or semi-permanent water holes. A section of the Rollston River is listed on the Directory of Important Wetlands as the Rollston River and Molly Darling Creek Aggregation. This aggregation includes a large section of the Rollston River and its major tributary Molly Darling Creek. Both streams have sandy beds, with the Rollston forming multiple channels separated by bars. Some of these bars are stable and well vegetated. There are several areas of palustrine wetlands on the site. The two most notable of these are around Old Harvest Home (Old Homestead Swamp) and around the junction of McDonald Creek and the Rollston. The WQIP technical panel did not identify the Rollston River and Molly Darling Creek Aggregation as containing HEV waters. This is most likely due to water quality impacts due to surrounding cattle grazing land use. Therefore, no HEV waters were identified in this subcatchment at this stage. However, the area is being further reviewed for their HEV features potential.

Stock Watering

Water supply for production of healthy livestock.

Cultural and Spiritual

Custodial use of water by Kudjala and Birri traditional owners.

References:

Landuse

Principle land uses within the Rollston River subcatchment as a proportion of total area:

  • Grazing: 93.5%
  • Conservation & minimal use: 6%
  • Mining: Limited mining water activity use identified.
  • Water: Limited water activity use identified.
  • Urban & semi urban: Limited urban & semi urban water activity use identified.

Grazing Land

Rollston River is a relatively small subcatchment where land use is dominated by grazing on natural pastures.

Land Condition

Definition of ABCD land condition framework

Results of a Rapid Land Condition Assessment (adopted from Hassett et al. 2000) are presented below. The assessment has been devised to subjectively characterise condition while traversing the BDT region by vehicle. The data are based on a total of 4666 observations across the Burdekin region between 2004 and 2007.

The data were collected to provide independent information on land condition and provide a regional perspective. Resource assessment data are most useful when interpreted with other sources of data e.g. time-series remote sensing, modelling and water quality monitoring.

The estimated condition of the Rollston River sub-catchment is proportioned as follows:

  • A Condition: n/a
  • B Condition: 3%
  • C Condition: 75%
  • D Condition: 22%

Data from the Rollston River sub-catchment is based on 64 observations.

On the basis of the rapid assessment, the Rollston River sub-catchment is estimated to have the largest proportion of land in poor (C) condition (75%), followed by very poor (D) condition (22%) and fair (B) condition land (3%). Data not available for (A) condition land.

Ground Cover

Ground Cover in the Rollston River sub-catchment is proportioned as follows:

  • ( BC) Bare Cover:6%
  • ( LC) Low Cover: 80%
  • ( MC) Moderate Cover: 14%
  • ( HC) High Cover: 0%
  • (VHC) Very High Cover: 0%

Data from the Rollston River sub-catchment are based on 64 observations.

On the basis of the rapid assessment (2004-2007), the Rollston River sub-catchment is estimated to have the highest proportion of land within the low (LC) ground cover category (80%), followed by moderate (MC) cover (14%). 6% of land was estimated to fall into the bare cover (BC) category.

Resource Condition Summary

Rollston River is a relatively small subcatchment where land use is dominated by grazing on natural pastures. Approximately 6% of the land area is remnant native vegetation with minimal use. Riparian habitat in the subcatchment has undergone relatively little change in the last 30 years and is currently assessed to be in fair (B) condition. Rollston River subcatchment is a largely dry, sandy creek system with few permanent waterholes.

Hillslope and gully erosion are both identified by models as major sources of sediment and particulate nutrients affecting water quality within the Rollston River subcatchment. The rate of soil loss is predicted to be moderate, but only marginally higher the the basin average. The total soil loss from the subcatchment is comparatively low due to its small size. Land condition is assessed as having high proportions of poor (C) and very poor (D) condition land. This is also reflected in the rapid ground cover assessment (2004-07). However, analysis of ground cover from satellite imagery (reference) show that while mean ground cover over the entire subcatchment declined substantially from 1999 to 2006, the subcatchment is not particularly vulnerable to further decline.

Water quality in the Lower Cape River subcatchment is predicted by models to be moderately impacted, with elevated concentrations of suspended sediment at end-of-subcatchment. There are no water quality monitoring data with which to compare the modelled concentrations. Water quality monitoring in this subcatchment would be useful to verify model predictions.

Draft Environmental Values

The aquatic ecosystem values of the Rollston River subcatchment are poorly known and, while considered to be Slightly to Moderately Disturbed (SMD) as a consequence of the surrounding land use for cattle grazing, the biological communities are thought to remain in a healthy condition and ecosystem integrity is likely to be largely retained. No High Ecological Value (HEV) waters have been identified in the subcatchment. Little is known about the human use Environmental Values of the Rollston River subcatchment, which are thought to be limited to use for stock watering, and the cultural and spiritual values of the Kudjala and Birri traditional owners.

Maps

References

RollstonRiver.jpg
Download Catchment Layer as *.kml (requires Google Earth)

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