Timothy J. Ralph

Dunphy Lake in Warrumbungle National Park, NSW: aquatic animal community after the Wambelong fire in 2013

Publisher: Royal Zoological Society of New South Wales

Date: 09-2018

DOI: 10.7882/AZ.2017.035

Timescales, mechanisms, and controls of incisional avulsions in floodplain wetlands: Insights from the Tshwane River, semiarid South Africa

Publisher: Elsevier BV

Date: 04-2017

DOI: 10.1016/J.GEOMORPH.2017.01.021

Dramatic reduction in size of the lowland Macquarie River in response to Late Quaternary climate-driven hydrologic change

Publisher: Cambridge University Press (CUP)

Date: 09-2018

DOI: 10.1017/QUA.2018.48

Abstract: Palaeochannels of lowland rivers provide a means of investigating the sensitivity of river response to climate-driven hydrologic change. About 80 palaeochannels of the lower Macquarie River of southeastern Australia record the evolution of this distributive fluvial system. Six Macquarie palaeochannels were dated by single-grain optically stimulated luminescence. The largest of the palaeochannels (Quombothoo, median age 54 ka) was on average 284 m wide, 12 times wider than the modern river (24 m) and with 21 times greater meander wavelength. Palaeo-discharge then declined, resulting in a younger, narrower, group of palaeochannels, Bibbijibbery (125 m wide, 34 ka), Billybingbone (92 m, 20 ka), Milmiland (112 m, 22 ka), and Mundadoo (86 m, 5.6 ka). Yet these channels were still much larger than the modern river and were continuous downstream to the confluence with the Barwon-Darling River. At 5.5 ka, a further decrease in river discharge led to the formation of the narrow modern river, the ecologically important Macquarie Marshes, and Marra Creek palaeochannel (31 m, 2.1 ka) and diminished sediment delivery to the Barwon-Darling River as palaeo-discharge fell further. The hydrologic changes suggest precipitation was a driving forcing on catchment discharge in addition to a temperature-driven runoff response.

Longitudinal spatial variation in ecological conditions in an in-channel floodplain river system during flow pulses

Publisher: Wiley

Date: 05-2011

DOI: 10.1002/RRA.1381

Geomorphic controls on the diversity and patterns of fluvial forms along longitudinal profiles

Publisher: Elsevier BV

Date: 08-2021

DOI: 10.1016/J.CATENA.2021.105329

Quantifying fluvial (dis)connectivity in an agricultural catchment using a geomorphic approach and sediment source tracing

Publisher: Springer Science and Business Media LLC

Date: 24-07-2015

DOI: 10.1007/S11368-015-1202-7

Paleoecological responses to avulsion and floodplain evolution in a semiarid Australian freshwater wetland

Publisher: Informa UK Limited

Date: 02-2011

DOI: 10.1080/08120099.2010.534818

Impact of inundation on soil microbiology

Publisher: CSIRO Publishing

Date: 2023

DOI: 10.1071/MA23052

Spatial dissimilarities in plankton structure and function during flood pulses in a semi-arid wetland system.

Publisher: Springer Science and Business Media LLC

Date: 19-11-2014

DOI: 10.1007/S10750-014-2119-7

Matching research and policy tools to scales of climatechange adaptation in the Murray-Darling, a large Australian river basin: A review

Publisher: Springer Science and Business Media LLC

Date: 14-12-2013

DOI: 10.1007/S10750-011-0970-3

Wandering wetlands

Publisher: CSIRO Publishing

Date: 2016

DOI: 10.1071/MF14251

Abstract: In the context of static conservation reserves, dynamic fluvial processes and patterns of river channel and floodplain change are problematic for environmental management. Floodplain wetlands that evolve by erosion and sedimentation experience changes in the location and extent of channels and wetlands regardless of conservation reserve boundaries. We describe historical channel and floodplain change in an Australian wetland of international ecological significance, the southern Macquarie Marshes, and synthesise the role of avulsion in wetlands that move laterally on the broader floodplain. Avulsion has shifted the foci of flooding and areas of aquatic habitat in the system over the last century. By ~1925, active wetlands surrounding the Old Macquarie River and the original conservation area contracted around Monkeygar Creek within the present nature reserve, and the boundary of this reserve has changed little since the 1940s. Ecological changes associated with continued wetland desiccation in the reserve triggered a recent Ramsar Article 3.2 notification for the Macquarie Marshes, prompting management responses from government agencies. Fluvial morphodynamics and their impacts on wetland ecology should be specifically recognised and integrated with adaptive management plans to combine new findings with lessons learned from previous intervention strategies for the long-term ecological sustainability of floodplain wetlands.

The interplay between extrinsic and intrinsic controls in determining floodplain wetland characteristics in the South African drylands

Publisher: Wiley

Date: 14-12-2016

DOI: 10.1002/ESP.4075

A nested hierarchical perspective to enhance interpretations and communication in fluvial geomorphology for use in water resources management: Lessons from the Okavango Delta, Botswana

Publisher: Wiley

Date: 02-04-2018

DOI: 10.1111/GEOJ.12250

Planktonic Metabolism and Microbial Carbon Substrate Utilization in Response to Inundation in Semi‐Arid Floodplain Wetlands

Publisher: American Geophysical Union (AGU)

Date: 04-2021

DOI: 10.1029/2019JG005571

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

Publisher: Elsevier BV

Date: 11-2018

DOI: 10.1016/J.QUASCIREV.2018.09.035

Endmember identification from EO-1 Hyperion L1-R hyperspectral data to build saltmarsh spectral library in Hunter Wetland, NSW, Australia

Publisher: SPIE

Date: 14-10-2015

DOI: 10.1117/12.2195444

Soil carbon dynamics and aquatic metabolism of a wet–dry tropics wetland system

Publisher: Springer Science and Business Media LLC

Date: 08-01-2021

DOI: 10.1007/S11273-020-09745-W

Author Correction: Identifying threshold responses of Australian dryland rivers to future hydroclimatic change

Publisher: Springer Science and Business Media LLC

Date: 22-07-2020

DOI: 10.1038/S41598-020-69597-5

Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Gross primary productivity of phytoplankton and planktonic respiration in inland floodplain wetlands of southeast Australia: habitat-dependent patterns and regulating processes

Publisher: Wiley

Date: 26-06-2013

DOI: 10.1007/S11284-013-1065-6

How seed traits predict floating times: a biophysical process model for hydrochorous seed transport behaviour in fluvial systems

Publisher: Wiley

Date: 03-09-2015

DOI: 10.1111/FWB.12672

Downstream hydrogeomorphic changes along the Macquarie River, southeastern Australia, leading to channel breakdown and floodplain wetlands

Publisher: Elsevier BV

Date: 05-2010

DOI: 10.1016/J.GEOMORPH.2009.12.007

A shifting ‘river of sand’: The profound response of Australia's Warrego River to Holocene hydroclimatic change

Publisher: Elsevier BV

Date: 12-2020

DOI: 10.1016/J.GEOMORPH.2020.107385

Product vs. process? The role of geomorphology in wetland characterization

Publisher: Elsevier BV

Date: 05-2019

DOI: 10.1016/J.SCITOTENV.2019.01.399

Abstract: Wetland classification has become a primary tool to characterize and inventory wetland landscapes, but wetlands are difficult to classify because they straddle the terrestrial and aquatic boundary and occur in a variety of hydroclimatic and topographic settings. Presently, many ecological wetland classification schemes are focused on the 'hydrogeomorphic' unit, which attempts to account for the physical setting of a wetland. In many cases topographic terms (e.g. flats, slopes) rather than geomorphological terms (e.g. oxbow, floodplain) are used to characterize landforms, and little attempt is made to characterize the process-landform relationships within wetland landscapes. The current misrepresentation of product geomorphology (i.e. topographic rather than landform description) and underrepresentation of process geomorphology (i.e. lacking process-landform relationships) means that many current wetland classification schemes represent an incomplete and static attempt to characterize geomorphologically dynamic wetland landscapes. Here, we use ex les from wetlands in the drylands of Africa, Australia, and North America to identify the capacity for adjustment (i.e. form and timescale of adjustment) of wetland landforms and we relate this capacity to the geomorphological concepts of sediment connectivity and landform sensitivity. We highlight how geomorphological insights into process-landform relationships and timescales of landform adjustment can add value to wetland classification efforts, with important implications for wetland management and ecosystem service delivery. We submit that geomorphology has a much larger role to play in wetland characterization and can enhance existing wetland classification schemes. More participation by the geomorphology community in wetland science and more awareness by the ecology community in recognizing and characterizing wetlands as dynamic landscapes will facilitate more effective wetland research and management.

The use of representative species as surrogates for wetland inundation

Publisher: Springer Science and Business Media LLC

Date: 09-03-2012

DOI: 10.1007/S13157-012-0285-9

Identifying threshold responses of Australian dryland rivers to future hydroclimatic change

Publisher: Springer Science and Business Media LLC

Date: 20-04-2020

DOI: 10.1038/S41598-020-63622-3

Abstract: Rivers provide crucial ecosystem services in water-stressed drylands. Australian dryland rivers are geomorphologically erse, ranging from through-going, single channels to discontinuous, multi-channelled 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 ,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 bedrock-alluvial) 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.

Comparative analysis of Worldview-2 and Landsat 8 for coastal saltmarsh mapping accuracy assessment

Publisher: SPIE

Date: 26-05-2016

DOI: 10.1117/12.2222960

A reassessment of the Lower Namoi Catchment aquifer architecture and hydraulic connectivity with reference to climate drivers

Publisher: Informa UK Limited

Date: 03-04-2014

DOI: 10.1080/08120099.2014.900647

Comparison of very near infrared (VNIR) wavelength from EO-1 Hyperion and worldview 2 images for saltmarsh classification

Publisher: Copernicus GmbH

Date: 07-06-2016

DOI: 10.5194/ISPRSANNALS-III-8-85-2016

Abstract: Saltmarsh is one of the important communities of wetlands. Due to a range of pressures, it has been declared as an EEC (Ecological Endangered Community) in Australia. In order to correctly identify different saltmarsh species, development of distinct spectral characteristics is essential to monitor this EEC. This research was conducted to classify saltmarsh species based on spectral characteristics in the VNIR wavelength of Hyperion Hyperspectral and Worldview 2 multispectral remote sensing data. Signal Noise Ratio (SNR) and Principal Component Analysis (PCA) were applied in Hyperion data to test data quality and to reduce data dimensionality respectively. FLAASH atmospheric correction was done to get surface reflectance data. Based on spectral and spatial information a supervised classification followed by Mapping Accuracy (%) was used to assess the classification result. SNR of Hyperion data was varied according to season and wavelength and it was higher for all land cover in VNIR wavelength. There was a significant difference between radiance and reflectance spectra. It was found that atmospheric correction improves the spectral information. Based on the PCA of 56 VNIR band of Hyperion, it was possible to segregate 16 bands that contain 99.83 % variability. Based on reference 16 bands were compared with 8 bands of Worldview 2 for classification accuracy. Overall Accuracy (OA) % for Worldview 2 was increased from 72 to 79 while for Hyperion, it was increased from 70.47 to 71.66 when bands were added orderly. Considering the significance test with z values and kappa statistics at 95% confidence level, Worldview 2 classification accuracy was higher than Hyperion data.

Late Quaternary palaeochannels indicate a threshold response to hydrological change on an alluvial plain of the Murray-Darling Basin, Australia

Publisher: Elsevier BV

Date: 11-2012

DOI: 10.1016/J.QUAINT.2012.08.347

Dust provenance and its role as a potential fertilizing agent for the Okavango Delta, Botswana

Publisher: Wiley

Date: 11-03-2020

DOI: 10.1002/ESP.4840

Abstract: Dust plays a globally important role in supplying biologically essential elements to landscapes underlain by nutrient‐poor substrates. Here we show that dust may play a significant role in sustaining productivity in the vast wetlands of the Okavango Delta in southern Africa, one of the world's richest bio ersity hotspots. Dust accumulates preferentially on tree‐covered islands in the seasonal sw s of the Delta, creating pockets of fine‐grained, nutrient‐rich material within the semi‐arid landscape of the Kalahari Desert. Strontium and neodymium isotopes reveal that this dust likely originates predominantly from the Makgadikgadi salt pans, located 300 km away, and contributes 10–80% of the fine‐grained material present in Okavango island soils. Surface material sourced from the Makgadikgadi Pans contains relatively high amounts of bioavailable phosphorus and iron, potentially influencing Okavango Delta biological productivity. We propose that long‐term ecosystem productivity and nutrient availability in the Okavango may be strongly mediated by regional dust inputs. Understanding the influence of dust deposition on nutrient loads and biogeochemical cycling is thus critical for predicting the response of the Okavango Delta to future changes in climate. We suggest that dust inputs may play a significant role in the supply of nutrients to other large, global wetland systems located in dryland environments. © 2020 John Wiley & Sons, Ltd

Latitude and elevation as factors controlling occurrence of calanoid copepods in marginal lotic waters in New South Wales, Australia

Publisher: Wiley

Date: 07-06-2018

DOI: 10.1007/S11284-018-1628-7

Macquarie University

Location: Australia

View Organisation

Linkage Projects - Grant ID: LP190100314

Start Date: 05-2020

End Date: 05-2025

Amount: $600,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP190100590

Start Date: 11-2020

End Date: 12-2024

Amount: $507,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP220102223

Start Date: 09-2022

End Date: 08-2025

Amount: $443,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP220100358

Start Date: 09-2023

End Date: 09-2026

Amount: $540,183.00

Funder: Australian Research Council