underpinning the decision to return low flows in the Mt Lofty - - PowerPoint PPT Presentation

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underpinning the decision to return low flows in the Mt Lofty - - PowerPoint PPT Presentation

Aug 30, 2023 329 likes •498 views

Evidence underpinning the decision to return low flows in the Mt Lofty Ranges Presented by Doug Green Water Allocation Planning Water Allocation Plans (WAPs) need to address the needs of Water Dependent Ecosystems (WDEs)

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SLIDE 1

Evidence underpinning the decision to return low flows in the Mt Lofty Ranges

Presented by Doug Green

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SLIDE 2

Water Allocation Planning

  • Water Allocation Plans (WAPs) need to

address the needs of Water Dependent Ecosystems (WDEs)

  • Environmental water requirements (EWRs)

inform the environmental water provisions (EWPs)

  • EWPs developed to maintain WDEs at an

acceptable level of risk

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SLIDE 3

Round 1 Jason VanLaarhoven and Mardi van der Wielen (2009-2012)

  • EWRs characterised

by hydrological metrics

  • Hydrological modelling used to assess number
  • f metrics passing
  • Number of metrics passing related to fish and

waterbug community condition

  • Scenario modelling used to link scenario →

passing metrics → WDE condition

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SLIDE 4

Round 1 Jason VanLaarhoven and Mardi van der Wielen (2009-2012)

  • Acceptable level of risk = 85% metrics

passing

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SLIDE 5

Round 1 Jason VanLaarhoven and Mardi van der Wielen (2009-2012)

  • Scenario without low flows showed

maximum allocation 5% resource capacity

  • Current development ~15-20% on average
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SLIDE 6

Round 1 Jason VanLaarhoven and Mardi van der Wielen (2009-2012)

  • Scenario with low flows showed maximum

allocation 20-25% resource capacity.

  • Same water allocations – healthier WDEs
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SLIDE 7

Round 2 Doug Green and others (2013-2014)

  • Using data to derive ecological response
  • Ecological monitoring has been

undertaken under various monitoring programs

  • Flow data is collected at flow monitoring

stations

  • Possible to link the two
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SLIDE 8

Round 2 Doug Green and others (2013-2014)

  • Fish data from EMLR used
  • Several monitoring sites located at, or in

close proximity to flow gauges

  • Response modelling undertaken using

several techniques

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SLIDE 9

20 40 60 80 100 120 140 160 180 0-8 9-29 30-59 60-115 116-231 232+ Riffle Flow Days Estimated Number of Recruits Median Riffle Flow Days Modelled Riffle Flow Days

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Round 2 Doug Green and others (2013-2014)

  • Deviation Index
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0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Current Water Use with TFR

  • n all Dams

>10ML Current Water Use with TFR

  • n all Dams

>10ML 15% Allocation with TFR 25% Allocation with TFR Full Allocation with TFR 15% Allocation 25% Allocation Current Water Use Dam Capacity Reduction by 30% Dam Capacity Reduction by 15% Full Allocation

Low Flow Scenarios Not Low Flow Scenarios

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SLIDE 12

Round 3 Maxwell and others 2014-2016

  • Goyder Water Allocation Planning Project
  • Focused on ecological response to

changes in intermittency

  • Used trait groups to characterise changes

in community composition and function

  • Used empirical data to develop models
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SLIDE 13
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Round 4 (Deane et al. 2016)

  • International Literature Review
  • Common problem across Mediterranean

climates

  • Conclusions

– Increase habitat availability – More complex food webs – Macroinvertebrates and Fish respond to wetter conditions – Vegetation should improve (decrease in terrestrials in channel) – Results will vary

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SLIDE 15