Bowen River

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Subcatchments

Smaller subcatchments within the Bowen River Catchment include:

  • Bowen River
  • Basin Creek
  • Mount Pollux
  • Sandalwood Creek

Vegetation

Riparian Habitat

iTRARC analysis of Riparian Habitat indicates that this subcatchment has had a decrease in condition from fair (B) to poor (C) condition. The reduction in condition is primarily due to floodplain clearing and an increase in the number of erosional features visible within the imagery. The field surveys indicate that the sites visited are in fair to poor condition (B-C), with high levels of regeneration, and relatively high levels of weediness. High levels of regeneration and high levels of weediness may indicate lower grazing pressures at the sites at which these surveys were conducted.

iTRARC Scores

Catchment Class 3 D
Maximum iTRARC Score 16 (A)
1970s Score 10 (B)
2004 Score 3 (C)
Reduction in Ecosystem Services Moderate
Increase in Potential for Erosion Large
Reasons for Change in Score
  • An increase in the number of gaps in headwaters
  • Floodplain clearing
  • An increase in the number of low cover hillslopes adjacent to streams
  • An increase in the number of gullies/scalds

TRARC (field survey) scores

Survey SiteScoreRegenerationWeeds
Bowen R [#1]57.1 (C)1 (C)2 spp: 6% cover (C)
Bowen R [#2]57.4 (C)2 (B)1 sp: 5% cover (B)
Bowen R [#3]64.6 (C)1 (C)2 spp: 3% cover (C)
Bowen R [#4]65.3 (B)3 (A)3 spp: 91% cover (D)
Bowen R [#5]68.4 (B)3 (A)2 spp: 30% cover (C)
Average 62.5 (C)

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

Wetlands

This is one of the major tributaries of the Burdekin catchment, with many major waterholes and clear water flowing for most of the year in most years, providing very significant aquatic habitat. Condition is generally typical of the Burdekin rangelands, but ground cover has been poor in recent dry years, bank erosion is significant in the middle reaches and weeds are an ongoing riparian management issue. The sub-division includes the Bowen River Weir near Collinsville, providing a large, non-flowing deepwater habitat which creates a weir pool quite different from a natural waterhole. The weir is considered a barrier to upstream movement of fish and has a dysfunctional fishway on it (Hogan and Vallance 1999). Large deep waterholes are particularly common around Birralee and Myuna. The Bowen River is home to a turtle (Elseya irwini) that is only known from the Bowen-Broken system. Waterholes in this area were described by Blackman et al. (2002) who considered them to be particularly ecologically valuable and water quality data for some waterholes is available in Loong et al. (2004).

Reference: Assessing the condition of Wetlands in the Burdekin catchment

For more information see Bowen River wetland condition summary

Water

SedNet Modelling of Water Quality

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

  • Subcatchment modelled area: 1,227 sq. km.
  • Source contributions: Hillslope = 47%; Gully = 29%; Streambank = 24%
  • Area of subcatchment with <50% ground cover: 445 sq. km or 36% of subcatchment
  • Hillslope sediment supply: 665 kg/ha/yr
  • Total suspended sediment (flow weighted) supply: 173 kt/yr
  • Total suspended sediment supply (flow weighted; normalized to area): 1,414 kg/ha/yr
  • Mean Annual Flow: 1,618,299 ML

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

Hillslope, gully and streambank erosion are all identified as significant sources of sediment and particulate nutrients affecting water quality within the Bowen River subcatchment (47%, 29% & 24% respectively). This subcatchment is largely a floodplain and a relatively high proportion of the sub-catchment has low ground cover (36%). Riparian habitat is reported to be in poor condition with extensive floodplain clearing and gullying. Total suspended sediment loss from all sources is predicted to be very high (1,414 kg/ha/yr).

Water Quality Monitoring

One monitoring site in the Bowen River catchment is located at Myuna Station and has been sampled by CSIRO and BDTNRM for 5 years. The second monitoring site is located just below the Little Bowen and Broken River junction (Dartmoor Station) and has been sampled by the NQ Dry Tropics Volunteers program for 1 year.

The catchment area for Myuna is 7,112 sq km, of which 56.4% is used for grazing. Dartmoor is 3,889 sq km and with 31% grazing. As these sampling sites incorporte several other sub-catchments (e.g. Little Bowen, Broken, Glenmore Creek, Pelican Creek, Rosella Creek), the data are not useful for investigating the event water quality of Bowen River sub-catchment. However, the Bowen River at Myuna site provides data for the Bowen River Basin, while the Bowen River site at Dartmoor Station provides data from the both the Little Bowen and Broken River sub-catchments.

Relevant information of Water Quality Monitoring in the Bowen Broken Bogie River Basin:

Environmental Uses and Values

Aquatic Ecosystems

The aquatic ecosystem values of Bowen River subcatchment are considered to be Slightly to Moderately Disturbed (SMD) as a consequence of the surrounding land use and flow modification, nevertheless, 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) areas have been identified in the subcatchment.

The Directory of Important Wetlands lists the Bowen River: Birralee – Pelican Creek Aggregation and a section of the Burdekin – Bowen Junction and Blue Valley Weir Aggregation in this subcatchment. However, water quality in these sections of the Bogie River was considered degraded from natural and no wetlands were in this subcatchment were considered to be “effectively unmodified” (ANZECC 2000) and no HEV waters were identified in this subcatchment at this stage. However, the area is being further reviewed for their HEV features potential.

Irrigation

Irrigated horticulture around Birralee. Water supplied for irrigation from the Bowen River Weir.

An area of approx. 20,000 ha of land has been identified as being suitable for irrigation

Stock Watering

Extensive cattle grazing. Use of water for stock watering.

Visual Recreation

Bowen river supports swimming, fishing and has aesthetics value.

Drinking Water

Collinsville and Glendon town water supply from Bowen River Weir.

Industrial Uses

Bowen River Weir supplies mining operations at Newlands and Collinsville. Collinsville mine is expected to close in 2015 and Newlands mine in 2020. It also supplies water for the Collinsville Power Station.

Cultural and Spiritual

Custodial use of water by Wirri traditional owners.

References:

Landuse

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

  • Grazing: 95.6%
  • Water: 3.1%
  • Irrigated horticulture & cropping:.8%
  • Conservation & minimal use: .5%
  • Urban & semi urban: Limited urban & semi urban activity use identified.

Grazing Land

Bowen River is a relatively small subcatchment where land use is almost exclusively 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 Bowen River sub-catchment is proportioned as follows:

  • A Condition: 9%
  • B Condition: 44%
  • C Condition: 42%
  • D Condition: 4%

Data from the Bowen River sub-catchment is based on 97 observations.

On the basis of the rapid assessment, the Bowen River sub-catchment is estimated to have the largest proportion of land in fair (B) condition (44%), followed by poor (C) condition (42%) and good (A) condition land (9%). 4% of observed land was in very poor (D) condition.

Ground Cover

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

  • ( BC) Bare Cover: 2%
  • ( LC) Low Cover: 8%
  • ( MC) Moderate Cover: 43%
  • ( HC) High Cover: 45%
  • (VHC) Very High Cover: 2%

Data from the Bowen River sub-catchment are based on 60 observations.

On the basis of the rapid assessment (2004-2007), the Bowen River sub-catchment is estimated to have the highest proportion of land within the high (HC) ground cover category (45%), followed by Moderate (MC) cover (43%) and low (LC) cover (8%) categories. 2% of land was estimated to fall into the bare (BC) and very high cover (VHC) category.

Resource Condition Summary

Bowen River is a very small subcatchment where land use is almost exclusively grazing on natural pastures. The condition of riparian habitat in the subcatchment has declined over the last 30 years due to floodplain clearing and gullying. The catchment was in fair (B) condition in the 1970s, but by 2004 its riparian condition had declined to poor (C). The Bowen River is one of the major tributaries of the Burdekin catchment, with many waterholes and clear flowing water for most of the year, thus providing very significant aquatic habitat. The Bowen River Weir, near Collinsville, is an artificial impoundment that provides a large, non-flowing deepwater habitat.

Hillslope, gully and streambank erosion are all identified by models as significant sources of sediment and particulate nutrients affecting water quality within the Bowen River subcatchment. The rate of soil erosion is predicted to be very high and well above the Basin average, while the total soil loss from the subcatchment to waterways is also comparatively high. Land condition is assessed as being fairly evenly divided between fair (B) and poor (C) condition. This is also reflected in the rapid ground cover assessment (2004-07), while analysis of ground cover from satellite imagery identifies large areas of land with low ground cover that are particularly vulnerable to 'D' condition. Bank erosion and gullying is reported to be significant in the middle reaches of the Bowen River.

Water quality in the Bowen River subcatchment is predicted by models to be moderately impacted during wet season event flows, with elevated concentrations of sediment at end-of-subcatchment. However, the sediment load at end-of-catchment is derived not only from this subcatchment, but also from others entering upstream. Water quality monitoring data from the Broken River at Myuna are not useful to specifically characterise water quality for the Bowen River subcatchment because it drains almost the entire Bowen Broken Basin.

Bowen River is identified as a priority subcatchment for rehabilitation on the basis of its poor land condition and vulnerability to 'D' condition, very high rate of soil erosion and predicted contribution to the total sediment load within the basin. The Bowen River is expected to contribute a considerable proportion to the suspended sediment export from the Burdekin River due to its close proximity to the Burdekin River mouth.

Draft Environmental Values

The aquatic ecosystem values of the subcatchment are considered to be Slightly to Moderately Disturbed (SMD) as a consequence of the surrounding land use and flow modification, nevertheless, 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) areas have been identified in the subcatchment. The human use Environmental Values of Bowen River subcatchment are understood to include recreation (swimming, fishing & visual appreciation), irrigation, industry, stock watering, human consumption, drinking, and the cultural and spiritual values of the Wirri traditional owners.

Maps

References

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

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