Palaeohydrology of lowland rivers in the Murray-Darling Basin, Australia

Hesse, Paul; Williams, Rory; Ralph, Timothy J.; Fryirs, Kirstie; Larkin, Zacchary T.; Westaway, Kira; Farebrother, Will

doi:10.1016/j.quascirev.2018.09.035

Cited by 45 publications

(42 citation statements)

References 75 publications

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“…Alternatively, indirect approaches to discharge estimation in dryland rivers 52 could be used to generate supporting hydrological or hydraulic information to help establish modern climate-hydrology-geomorphology relations across hydroclimatic gradients, as has been done successfully for different dryland rivers worldwide (e.g. 10,22,53 ). By applying ergodic reasoning, these relations could then be used as the basis for predicting river response under altered hydroclimates.…”

Section: Developing the Approach To Assess River Response In Drylandsmentioning

confidence: 99%

Identifying threshold responses of Australian dryland rivers to future hydroclimatic change

Larkin

Ralph

Tooth

et al. 2020

Sci Rep

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Rivers provide crucial ecosystem services in water-stressed drylands. Australian dryland rivers are geomorphologically diverse, ranging from through-going, single channels to discontinuous, multichannelled systems, yet we have limited understanding of their sensitivity to future hydroclimatic changes. Here, we characterise for the first time the geomorphology of 29 dryland rivers with catchments across a humid to arid gradient covering >1,800,000 km 2 of continental eastern and central Australia. Statistical separation of five specific dominantly alluvial river types and quantification of their present-day catchment hydroclimates enables identification of potential thresholds of change. Projected aridity increases across eastern Australia by 2070 (RCP4.5) will result in ~80% of the dryland rivers crossing a threshold from one type to another, manifesting in major geomorphological changes. Dramatic cases will see currently through-going rivers (e.g. Murrumbidgee, Macintyre) experience step changes towards greater discontinuity, characterised by pronounced downstream declines in channel size and local termination. Expanding our approach to include other river styles (e.g. mixed bedrockalluvial) would allow similar analyses of dryland rivers globally where hydroclimate is an important driver of change. Early identification of dryland river responses to future hydroclimatic change has far-reaching implications for the ~2 billion people that live in drylands and rely on riverine ecosystem services. Rivers are lifelines in climatically variable and water-stressed drylands, the dry subhumid through hyperarid environments that cover 40-50% of the Earth's land surface and host ~28% of the world's population 1,2. Dryland rivers are fundamentally important for human populations, providing a plethora of provisioning, regulating, supporting and cultural ecosystem services 1,3. Yet dryland rivers exist in marginal environments and are threatened by declines in water availability due to the impacts of climate change (e.g. decreased rainfall, increased temperature and evapotranspiration, and greater climatic variability) and other human activities (e.g. river regulation, flow diversion and abstraction, and land use change) 4-6. Rivers are not static conduits of water, sediment and nutrients, but adjust dynamically to a suite of internal and external drivers. Among various external drivers (e.g. tectonic activity, sea level fluctuations, climate), research has shown that late Quaternary hydroclimatic changes have driven substantial geomorphological changes to many dryland rivers globally, including during the mid to late Holocene [e.g. 7-10 ]. Indeed, in tectonically stable settings such as continental Australia, and in reaches where rivers are free from significant bedrock influence, hydroclimatic changes are the principal driver of river response and resulting channel-floodplain geomorphology. To date, however, assessment of the potential likelihood and pathways of hydrological and geomorphological changes in dryland rivers due...

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Section: Developing the Approach To Assess River Response In Drylandsmentioning

confidence: 99%

Identifying threshold responses of Australian dryland rivers to future hydroclimatic change

Larkin

Ralph

Tooth

et al. 2020

Sci Rep

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“…Glacial treelessness in southern Australia, as in many other regions, has been widely interpreted as indicating climates more arid than today (Hope, 1994;Kershaw et al, 1991). On the other hand, since low atmospheric CO 2 should have altered competitive outcomes between Eucalyptus and shrublands, it remains unclear to what extent deforestation at Mammoth Cave was driven by reduction in effective precipitation (precipitation minus evaporation; Hesse et al, 2018), since initial deforestation between 28 and 26 ka coincided with high Restionaceae values (indicative of relatively moist soils) and very low Chenopodiaceae values (indicative of a regional absence of aridadapted shrublands). At the same time, potential evapotranspiration was reduced under low glacial temperatures, contributing to greater retention of moisture in landscapes (Scheff et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Vegetation and Climate Change in Southwestern Australia During the Last Glacial Maximum

Sniderman

Hellström

Woodhead

et al. 2019

Geophysical Research Letters

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The nature and duration of the Last Glacial Maximum (LGM) in Australia are poorly understood, with little regional agreement on the timing and direction of LGM climate changes. One reason for this is that Australian Late Pleistocene terrestrial sediments typically are both sparse and inorganic, inhibiting the development of detailed radiocarbon chronologies. To address this problem, we extracted fossil pollen from radiometrically dated stalagmites collected in southwest Western Australia. Our pollen record, supported by 30 U‐Th dates, reveals the vegetation response to Late Pleistocene climates between ~34 and 14 ka, through the body of the LGM. Before ~28 ka, sclerophyll forests were more open than today, but at ~28 ka forest cover was essentially eliminated, and treeless conditions were maintained until progressive reforestation at ~17.5 ka. This ~10‐ka‐long full glacial episode correlates with other mid‐high latitude Southern Hemisphere records, suggesting that LGM environmental changes were closely coordinated across the hemisphere.

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“…Chronologically staggered and abrupt hydroclimatic deterioration starts around 48 ka in the LEB 20,28 (Fig. 3a), then from 45 ka in the MDB 25,26,28 (Fig. 3b and c), and then from 40 ka in the FRB 24,28 (Fig.…”

Section: Supplementary Notes 5-8)mentioning

confidence: 99%

“…b Palaeodischarge of the Darling River (adapted from ref. 26 ). c Mungo Lake levels and dune development (adapted from ref.…”

Section: Supplementary Notes 5-8)mentioning

confidence: 99%

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Extinction of eastern Sahul megafauna coincides with sustained environmental deterioration

et al. 2020

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Explanations for the Upper Pleistocene extinction of megafauna from Sahul (Australia and New Guinea) remain unresolved. Extinction hypotheses have advanced climate or humandriven scenarios, in spite of over three quarters of Sahul lacking reliable biogeographic or chronologic data. Here we present new megafauna from northeastern Australia that suffered extinction sometime after 40,100 (±1700) years ago. Megafauna fossils preserved alongside leaves, seeds, pollen and insects, indicate a sclerophyllous forest with heathy understorey that was home to aquatic and terrestrial carnivorous reptiles and megaherbivores, including the world's largest kangaroo. Megafauna species diversity is greater compared to southern sites of similar age, which is contrary to expectations if extinctions followed proposed migration routes for people across Sahul. Our results do not support rapid or synchronous human-mediated continental-wide extinction, or the proposed timing of peak extinction events. Instead, megafauna extinctions coincide with regionally staggered spatio-temporal deterioration in hydroclimate coupled with sustained environmental change.

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Palaeohydrology of lowland rivers in the Murray-Darling Basin, Australia

Cited by 45 publications

References 75 publications

Identifying threshold responses of Australian dryland rivers to future hydroclimatic change

Identifying threshold responses of Australian dryland rivers to future hydroclimatic change

Vegetation and Climate Change in Southwestern Australia During the Last Glacial Maximum

Extinction of eastern Sahul megafauna coincides with sustained environmental deterioration

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