Basalt River

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Vegetation

Riparian Habitat

iTRARC analysis of Riparian Habitat indicates that this subcatchment has a limited range of riparian habitats and has experienced a slight decrease in condition since the 1970s. The absence of forest and closed forest from riparian zones in this catchment contribute to its low 1970s and 2004 scores. The naturally low canopy cover within this catchment may contribute to the low field survey scores. Regeneration is present and weeds appear relatively limited, indicating moderate riparian condition in the future.

iTRARC Scores

Catchment Class 3 C
Maximum iTRARC Score 12 (B+)
1970s Score 5 (C+)
2004 Score 3 (C)
Reduction in Ecosystem Services Very Minor
Increase in Potential for Erosion Small
Reasons for Change in Score
  • Increase in the number of gaps in headwater streams
  • Increase in the amount of low cover hillslopes adjacent to streams

TRARC (field survey) scores

Survey SiteScoreRegenerationWeeds
Basalt R #138.9 (D)1 (C)1 sp; 5% cover (B)
Basalt R #248 (D)2 (B)1 sp; 1% cover (B)
Average 43.45 (D)

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

Wetlands

Stockyard Creek is a largely dry sandy creek but the Basalt River contains numerous large permanent waterholes, maintained by discharge from the basalt aquifers of the area. These waterholes are deep and clear, with relatively high conductivity. They are generally in good condition and have the advantage of large water volumes (dilution) to make them more resistant to disturbance.

These wetlands have not been well studied, but due to relatively low intensity of land use (rangeland cattle grazing), it is considered that changes to water quality and aquatic habitat are typical for this type of land use. Some preliminary water quality and aquatic invertebrate data for this area is available from Burrows and Butler (2003) and several waterholes on the lower Basalt River were part of an aquatic invertebrate study by Betts (2003). The limnology of the Basalt River at Bluff Downs homestead (also a DNRW gauging station) was assessed by Loong et al. (2005). The exotic African fish tilapia have recently invaded the Basalt River (Veitch et al. 2006).

Reference: Assessing the condition of Wetlands in the Burdekin catchment

For more information see Basalt River wetland condition summary

Water

SedNet Modelling of Water Quality

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

  • Sub-catchment modelled area: 2,897 sq. km.
  • Source contributions: Hillslope = 72%; Gully = 17%; Streambank = 11%
  • Area of sub-catchment with <50% ground cover: 737 sq. km or 25% of subcatchment
  • Hillslope sediment supply: 225 kg/ha/yr
  • Total suspended sediment (flow weighted) supply: 91 kt/yr
  • Total suspended sediment supply (flow weighted; normalized to area): 313 kg/ha/yr
  • Total suspended sediment end-of-subcatchment (flow weighted) yield: 80 kt/yr
  • Event Mean Concentration (EMC - flow weighted): 427 mg/L
  • Mean Annual Flow: 186,748 ML

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

Hillslope erosion is identified as the major source of sediment and particulate nutrients affecting water quality within the Basalt River subcatchment. This is thought to be associated with the relatively large proportion of hillslope with low ground cover (25%). Loss of sediment and associated particulate nutrients from all sources (supply) is considered to be relatively low (313 kg/ha/yr). The moderate concentrations of sediments (predicted) are a consequence of the relatively lower rainfall and mean annual flow.

Water Quality Monitoring

The monitoring site in the Basalt River subcatchment is located downstream from the Gregory Developmental Road and has been sampled by the NQ Dry Tropics Volunteers program over 2 wet seasons only (2004-5 & 2006-7). The catchment area for this monitoring site is 2048 sq km, of which 96.9% is used for grazing.

A meaningful comparison between monitored and modelled water quality is limited by the small number of rainfall 'events' sampled and large inter-annual variability in flow. However, both are generally consistent and indicate intermediate concentrations of sediment (mean concentration of the 9 samples collected in the catchment of 822 mg/L) and particulate nutrients (N & P) leaving the Basalt River sub-catchment, similar to those of the Burdekin River at Sellheim. The dissolved inorganic and filterable reactive components of phosphorus contributed a relatively higher proportion of TP for the Basalt River site. This site drains basalt landscapes where naturally high levels of phosphorus are found. A suspended sediment load of 46,000 tonnes was calculated for the 2004/05 wet season, although this was a below average river flow event in this catchment and average annual sediment load is likely to be ~100,000 tonnes, similar to the SedNet model's prediction.

Relevant information of Water Quality Monitoring:

Environmental Uses and Values

Aquatic Ecosystems

The aquatic ecosystem values of the Basalt 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 are identified in the subcatchment.

Stock Watering

There is extensive cattle grazing in the Basalt River sub-catchment. The Basalt River has no water infrastructure and few groundwater bores as the rock is impermeable. Surface water is supplied for production of healthy stock.

Cultural and Spiritual

Custodial use of water by Kudjala traditional owners.

References:

Landuse

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

  • Grazing: 96.3%
  • Conservation & minimal use: 3.3%
  • Water: .06%
  • Urban & semi urban: Limited urban & semi urban water activity use identified.

Grazing Land

Basalt River is a medium sized sub-catchment where the land use is dominated by grazing on natural pastures. Only approximately 3% is set aside for minimal use in the headwaters of Stockyard Creek.

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 Basalt River sub-catchment is proportioned as follows:

  • A Condition: 34%
  • B Condition: 41%
  • C Condition: 21%
  • D Condition: 4%

Data from the Basalt River sub-catchment is based on 180 observations.

On the basis of the rapid assessment, the Basalt River sub-catchment is estimated to have the largest proportion of land in fair (B) condition (41%), followed by good (A) condition (34%) and poor (C) condition land (21%). 4% of observed land was in very poor (D) condition.

Ground Cover

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

  • ( BC) Bare Cover: 2%
  • ( LC) Low Cover: 3%
  • ( MC) Moderate Cover: 34%
  • ( HC) High Cover: 36%
  • (VHC) Very High Cover: 24%

Data from the Basalt River sub-catchment are based on 178 observations.

On the basis of the rapid assessment (2004-2007), the Basalt River sub-catchment is estimated to have the highest proportion of land within the high (HC) ground cover category (36%), followed by moderate (MC) cover (34%) and very high (VHC) cover (24%) categories. 2% of land was estimated to fall into the bare cover (BC) category.

Resource Condition Summary

Basalt River is a medium sized subcatchment where the land use is dominated by grazing on native pastures. Approximately 3% of the land area is set aside for minimal use in the headwaters of Stockyard Creek, while there are many abandoned and operational mines within the eastern part of the subcatchment. Riparian habitat in this subcatchment has undergone limited change over the last 30 years, with a very small increase in the number of gaps in headwater streams, and is currently assessed to be in poor (C) condition. Field surveys show that regeneration is present and weeds appear relatively limited, indicating moderate riparian condition in the future. The Basalt River contains numerous large permanent waterholes that are maintained by discharge from the basalt aquifers of the area. These waterholes are deep and clear, and have the advantage of large water volumes (dilution) to make them more resistant to disturbance. Stockyard Creek, in contrast, is a largely dry sandy creek. Water bodies of the Basalt River subcatchment have not been well studied, but due to the relatively low intensity of land use their condition it is considered to be generally good.

Hillslope erosion is identified by models as the major source of sediment and particulate nutrients affecting water quality within the Basalt River subcatchment. The rate of soil erosion is predicted to be low and well below the basin and BWQIP region averages, while the total soil loss to waterways from this subcatchment is also quite low. Grazing land condition is assessed as having the highest proportions in good (A) and fair (B) condition, while poor (C) condition land is evident. This is also reflected in the rapid ground cover field assessment (2004-07). Analysis of ground cover from satellite imagery identifies areas of low cover, and highly vulnerable and marginal 'D' condition land in the east of the subcatchment.

Water quality in the Basalt River subcatchment is predicted by models to have only slightly elevated sediment concentrations and loads during wet season event flows. Comparisons are difficult to draw between the monitoring and modeling datasets due to the small sample size collected over only two wet seasons but, while generally consistent, the monitoring data recorded higher concentrations of sediment than predicted by the models.

Draft Environmental Values

The aquatic ecosystem values of the Basalt 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 are identified in the subcatchment. Little is known about the human use Environmental Values of the Basalt River subcatchment, which are thought to be limited to use for stock watering, and the cultural and spiritual values of the Kudjala traditional owners.

Maps

Photos

References

Basalt River.jpg
Download Catchment Layer as KML ([http://earth.google.com/ requires Google Earth).

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