Hann Creek

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Vegetation

Riparian Habitat

iTRARC analysis of Riparian Habitat indicates that this subcatchment was already in poor condition in the 1970s based on the satellite imagery analysis, its condition has worsened to very poor (D) on account of headwater clearing and an increase in low cover hillslopes, scalds and gullies.

iTRARC Scores

Catchment Class 3 E
Maximum iTRARC Score 10 (B)
1970s Score 1 (C)
2004 Score -4 (D)
Reduction in Ecosystem Services Minor
Increase in Potential for Erosion Moderate
Reasons for Change in Score
  • Clearing along headwater streams
  • Increased low cover hill slopes next to the channel network
  • Increased number of scalds/gullies

TRARC (field survey) scores = No TRARC scores for this subcatchment

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

Wetlands

This is a largely sandy, dry seasonal creek system with limited habitat availability, though the area is poorly known ecologically, hence the low degree of confidence. Condition is not well known though thought to be similar to adjoining sub-divisions and typical of the upper Burdekin grazing rangelands. The creek and especially its riparian zone were heavily damaged by a flood in 2000.

Reference: Assessing the condition of Wetlands in the Burdekin catchment

For more information see Hann Creek wetland condition summary

Water

SedNet Modelling of Water Quality

Model results for the Hann Creek subcatchment are summarized as follows:

  • Subcatchment modelled area 1867 sq. km.
  • Source contributions: Hillslope = 74%; Gully = 20%; Streambank = 6%
  • Area of subcatchment with <50% ground cover: 660 sq. km or 35% of subcatchment
  • Hillslope sediment supply: 258 kg/ha/yr
  • Total suspended sediment (flow weighted) supply: 65 kt/yr
  • Total suspended sediment supply (flow weighted; normalized to area): 350 kg/ha/yr
  • Total suspended sediment end-of-subcatchment (flow weighted) yield: 57 kt/yr
  • Event Mean Concentration (EMC - flow weighted): 519 mg/L
  • Mean Annual Flow: 110,513 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 Hann Creek subcatchment. 35% of the subcatchment has low ground cover. Gully erosion, nevertheless, is predicted to make a significant contribution (20%) to the total suspended sediment load. Loss of sediment and particulate nutrients from all sources (supply) is low to moderate (350 kg/ha/yr) compared to other Burekin subcatchments. The event mean concentration of sediments is predicted to be moderate (519 mg/L) when compared to other subcatchments, due to the relatively lower rainfall and mean annual flow.

Water Quality Monitoring

The monitoring site on Hann Creek is located off the Gregory Developmental Road and was sampled by ACTFR in the 2004/05 wet season. Suspended sediment concentrations were relatively low (mean concentration of 260 mg/L) compared to other catchments within the Burdekin rangelands. However, with only 1 wet seasons of data available, comparisons with the SedNet model can not be drawn.

Relevant information of Water Quality Monitoring in the Upper Burdekin River Basin:

Environmental Uses and Values

Aquatic Ecosystems

The aquatic ecosystem values of the Hann Creek 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.

Stock Watering

Water supply for production of healthy livestock.

Cultural and Spiritual

Custodial use of water resources by Kudjala traditional owners.

References:

Landuse

Principle land uses within the Hann Creek subcatchment as a proportion of total area:

  • Grazing: 99.6%
  • Conservation & minimal use: 0.2%
  • Mining: Limited mining water activity use identified.
  • Irrigated horticulture & cropping: Limited irrigated horticulture & cropping water use activity identified.
  • Water: Limited water activity use identified.
  • Urban & semi urban: Limited urban & semi urban water activity use identified.

Grazing Land

Hann Creek 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 Hann Creek sub-catchment is proportioned as follows:

  • A Condition: 12%
  • B Condition: 60%
  • C Condition: 28%
  • D Condition: n/a

Data from the Hann Creek sub-catchment is based on 47 observations.

On the basis of the rapid assessment, the Hann Creek sub-catchment is estimated to have the largest proportion of land in fair (B) condition (60%), followed by poor (C) condition (28%) and good (A) condition land (12%). Data not available for (D) condition land.

Ground Cover

Ground Cover in the Hann Creek sub-catchment is proportioned as follows:

  • ( BC) Bare Cover: 0%
  • ( LC) Low Cover: 17%
  • ( MC) Moderate Cover: 37%
  • ( HC) High Cover: 37%
  • (VHC) Very High Cover: 9%

Data from the Hann Creek sub-catchment are based on 46 observations.

On the basis of the rapid assessment (2004-2007), the Hann Creek sub-catchment is estimated to have the highest proportion of land within the high (HC) and Moderate (MC) ground cover category (37%), followed by low (LC) cover (17%). 9% of land was estimated to fall into the very high cover (VHC) category.

Resource Condition Summary

Hann Creek is a relatively small subcatchment where land use is almost exclusively grazing on native pastures, while there are a small number of both abandoned and operational mines within the subcatchment. Riparian condition in this subcatchment was already poor (C) in the 1970s and has deteriorated further over the last 30 years. Its current condition is assessed as very poor (D) due to clearing along headwater streams and an increase in low cover, scalds and gullies adjacent to creeks. The Hann Creek subcatchment is a largely sandy, dry seasonal creek system with limited habitat availability. The ecology and condition of water bodies in the subcatchment is poorly known.

Hillslope erosion is identified by models as the major source of sediment and particulate nutrients affecting water quality within the Hann Creek subcatchment, while gully erosion is also identified as significant. The rate of soil erosion is predicted to be well below the basin average, while the total soil loss to waterways is also comparatively low. Grazing land condition is assessed as having a high proportion in fair (B) condition, with poor (C) and good (A) condition land also quite common. This is also reflected in the ground cover assessment (2004-07). Analysis of satellite imagery (reference) shows that the mean ground cover across the entire subcatchment declined from 93% in 1999 to 68% in 2004, and had recovered to 86% in 2006.

Water quality in the Hann Creek subcatchment is predicted by models to have only slightly elevated sediment concentrations during wet season event flows. While water quality monitoring data have recorded lower concentrations of sediments, comparisons are difficult to draw between the results of monitoring and modelling due to the limited dataset collected over a single wet season.

Draft Environmental Values

The aquatic ecosystem values of the Hann Creek 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 water in the Gray Creek subcatchment, which are thought to be limited to use for stock watering and the cultural and spiritual values of the Kudjala traditional owners.

Maps

References

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

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