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Fran Sheldon Australian Rivers Institute Griffith School of Environment Griffith University

Climate Variability and Freshwater Systems Lessons for protecting freshwater systems from climate change impacts. Fran Sheldon Australian Rivers Institute Griffith School of Environment Griffith University. 0.8. Summary medians. Cooper. (23 hydrological measures). 0.7. Diamantina.

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Fran Sheldon Australian Rivers Institute Griffith School of Environment Griffith University

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  1. Climate Variability and Freshwater Systems Lessons for protecting freshwater systems from climate change impacts Fran Sheldon Australian Rivers Institute Griffith School of Environment Griffith University

  2. 0.8 Summary medians Cooper (23 hydrological measures) 0.7 Diamantina 0.6 Burdekin 0.5 Limpopo 0.4 Fitzroy 0.3 Mekong Mississippi Colorado Vaal 0.2 Darling Danube Rhine 0.1 0 NIG FRA NIL KOL SEV MIS RHI TIS DNI IND STH RIO ASS FIT NEV SAN BAN PET ZIJ SYR VIS NTH LOI COL REA BAH ARK YAN GOD KRI DON REE AUX SNA VAA LIM DIA COO OGO MEK OUB DAN AMU SAO SON KUR WIN URA HUA ODE DAR BUR We know Australia’s rivers are variable….. from Puckridge et al. (1998). Mar. Freshw. Res. 49, 55-72

  3. Predictions are that variability will increase with climate change……. • Rainfall & consequently river flow will become more variable • There will be less frequent, but perhaps larger, floods • Rivers will be influenced by longer, and more severe, no flow or drought conditions • There will be an increase in the number of highly variable rivers • Understanding flow variability and its influence on rivers will become important for • looking at resilience of systems in the face of climate change • determining environmental flows and • assessing ecosystem health

  4. Scales of Variability in Dryland Rivers Catchment scale responses to flood – drought cycles Reach scale responses to ‘boom and bust’ cycles Spatial Scale (m) Within channel water level fluctuations Temporal Scale (years)

  5. Within channel variability:Lower River Murray

  6. Depth Depth Depth Time Time Time UP MP LP UP MP LP Water level variability changes along the channel

  7. Axis 2 Axis 2 Lower Pool Lower Pool Middle Pool Middle Pool Upper Pool Upper Pool Axis 1 Axis 1 Assemblage differences along the channel reflect different levels of variability • Discrete assemblages between channel sections • Overall diversity very low compared to other large rivers • Differences in assemblages reflect different microhabitats MDS Plot, Bray-Curtis Dissimilarity, log10(x+1) abundance data

  8. Photo by Peter Unmack Reach scale responses to Boom & Bust • We know that: • Temporal changes in flow (boom and bust) have strong influences on dryland river ecosystems Photo by Stephen Balcombe Data from CRCFE Dryland River Refugia Project

  9. 4 Windorah Water Quality PCII – 27% Total N Total P 1000 800 2 600 Discharge (ML/day *000) Dry Samples April 2001 September 2001 400 Flood Samples October 2002 200 May 2003 January 2004 Dec-99 Jan-01 Feb-02 Mar-03 Apr-04 0 March 2004 June 2004 October 2004 Flow Samples December 2004 -2 PCI – 47% Conductivity, Total Hardness, TDS -2 0 2 4 Flow variability drives water quality - Cooper Creek PCA Plot, Water Quality Data from Windorah reach

  10. 1400 1200 1000 800 Discharge (ML/day) x 103 600 September 2001 Octoberr 2002 April 2001 May 2003 400 200 0 Jan-00 Jul-00 Jan-01 Jul-01 Jan-02 Jul-02 Jan-03 Temporal Variability Cooper Creek - Invertebrates Tanbar April 2001 Windorah April 2001 w w Noonbah April 2001 w w Springfield April 2001 w May 2003 w Oct 2002 w Stress = 0.16 Sept 2001 MDS Plot, Bray-Curtis Dissimilarity, log10(x+1) abundance data Data from CRCFE Dryland River Refugia Project: Marshall, Sheldon, Thoms & Choy 2006

  11. ? Connection Disconnection Prolonged Disconnection Temporal shifts in community composition driven by hydrological connection

  12. 30 20 7000000 10 6000000 0 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 5000000 SOI -10 Condamine 4000000 Macintyre Mungindi Darling Bourke 3000000 Darling Wilcannia -20 2000000 -30 1000000 -40 0 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 SOI Sequential flooding Larger catchment scale responses Darling River

  13. A large scale sequence of wetlands Upper Middle Lower Wetlands The BIG ‘booms’

  14. Removing water from the top end….. Upper Middle Lower Wetlands The BIG ‘booms’

  15. Protecting variability at all scales • We recognise variability is important in driving large river ecology across a range of scales • To protect large rivers we need to protect this variability • Intrinsic resilience to variability – adapted to cope with climate change, but • Climate change + human pressure may be too much……

  16. Photo by Peter Unmack Photo by Jon Marshall Summary

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