Determination of low flow requirements for an upland Murray-Darling Basin River; the Belubula River. — ASN Events

Determination of low flow requirements for an upland Murray-Darling Basin River; the Belubula River. (11659)

Patrick D Driver 1 2 , Kaya Michener 1 3 , Jon Fawcett 4 , David Outhet 5
  1. NSW Office of Water, Orange, NSW, Australia
  2. The Australian Wetlands & Rivers Centre (AWRC), University of New South Wales, Kensington, NSW, Australia
  3. Queanbeyan City Council, Queanbeyan, NSW, Australia
  4. Sinclair Knight Merz, Sydney, NSW, Australia
  5. Kelly Scientific Resources , Sydney, NSW, Australia

As part of the development of Water Sharing Plans under the NSW Water Management Act 2000 information is required to identify the relationship between water regimes and ecosystems, and then set rules which protect environmental assets and environmental flows. This paper describes such a study for the Belubula, a tributary of the Lachlan River in western New South Wales, Australia. This study used a combination of field observations, and desktop analysis to recommend the preservation of river pools for threatened fish species, and water quality to meet human water quality guidelines by protecting base flows at Helensholme; a site signifying the floodplain of this river. 

The desktop analysis included a study led by Sinclair Knight-Merz that used remote sensing data (Landsat) to observe the relationship between landscapes and reservoir releases to help define “assets” (e.g., river pools or wetlands) to be used in the development of the Belubula Regulated Water Source Water Sharing Plan. In this analysis, potential assets were defined as landscapes that are; hydrologically and/or photosynthetically responsive to reservoir releases, and remain consistently hydrologically and/or photosynthetically active irrespective of reservoir release.

Wetlands, especially swampy meadows, and river pools were also found in the field. River pools were degraded and in-filled but were still considered significant for low flow protection. For the wetlands there was insufficient evidence that these wetlands needed a high level of attention for the determination of environmental flow rules, although land management in these areas has the potential to significantly improve river water quality.

Low flow protection was clearly required, and these recommendations were used to amend the Water Sharing Plan. However, some ecological risks remain unanswered especially the extent to which riparian tree species and river base flows are affected by consumptive use; especially during drought.

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