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Abstract Flow resistance through riparian forests due to drag on trees is often expressed in hydraulic models with an increase in a boundary resistance factor such as Manning's n. However, when Manning's n is used as a proxy for vegetation drag, this parameter is dependent on flow conditions and a single, uniform value may be inadequate for simulating a broad range of flood magnitudes. To investigate this issue, flow resistance, and the commensurate Manning's n values through a riparian forest were computed using measured drag forces and estimates of the forest structure and tree morphology. The computed Manning's n values were applied to a 2D hydraulic model (TUFLOW) to simulate an observed flood and a range of design floods. Modelled peak flood levels for the observed flood were 0.16 m lower on average than that recorded at debris marks. There was little difference in modelled flood levels when using the computed Manning's n compared to a traditional, uniform Manning's n. Reassuringly, the traditional method appears adequate when reliable calibration data is available. Otherwise, the method developed here provides a useful alternative in cases where calibration data is limited or for testing reforestation as a nature‐based solution in river or flood management.

The causes of the Upper Pleistocene megafauna extinction in Australia and New Guinea are debated, but fossil data are lacking for much of this region. Here, Hocknull and colleagues report a new, diverse megafauna assemblage from north-eastern Australia that persisted until ~40,000 years ago.

Abstract Coastal ecosystems can be degraded by poor water quality. Tracing the causes of poor water quality back to land-use change is necessary to target catchment management for coastal zone management. However, existing models for tracing the sources of pollution require extensive data-sets which are not available for many of the world’s coral reef regions that may have severe water quality issues. Here we develop a hierarchical Bayesian model that uses freely available satellite data to infer the connection between land-uses in catchments and water clarity in coastal oceans. We apply the model to estimate the influence of land-use change on water clarity in Fiji. We tested the model’s predictions against underwater surveys, finding that predictions of poor water quality are consistent with observations of high siltation and low coverage of sediment-sensitive coral genera. The model thus provides a means to link land-use change to declines in coastal water quality.

The present study investigated whether drying and desiccation substantially increase the biologically available phosphorus (P) in riverbed sediments from a dry subtropical river. Sequential extraction and batch equilibrium experiments were undertaken on sediments with contrasting organic matter content, percentage fines and P content. The response of sediments to drying differed predominately as a result of drying time rather than as a result of the different physiochemical properties and total P content of the sediments. For both in situand laboratory drying, major changes in P speciation occurred in the surface-layer sediment (0–2cm) where NH4Cl-P (loosely sorbed P) was higher in partially dried and desiccated sediments than in wet sediments. Conversely, NaOH-nrP (labile organic and poly-P) was significantly lower (P<0.05) in partially dried and desiccated sediments than in wet sediments, suggesting that a substantial transformation from a relatively unavailable organic form to a readily available inorganic form of P had occurred with drying. The equilibrium phosphate concentration (EPC0), which is a measure of the potential for sediments to function as a source or a sink of phosphate (PO43–), was higher in sediments desiccated in situand in the laboratory than in submerged and partially dried sediments. Together with the speciation results, the higher EPC0indicates that the potential for sediments to release P during the next flow event is substantially increased as a result of desiccation. The lower EPC0in partially dried sediments suggested that the degree of drying may be an important factor in terms of the long-term potential for sediments to act as a source or a sink of PO43–after rewetting. The results from the present study have important implications because natural or anthropogenic processes which lead to riverbed drying may increase the flux of bioavailable P from bed sediments when flow returns. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are a foundation of our social, cultural, spiritual and economic well being. The degraded condition of many of Australia's river ecosystems is testament to our failure to manage these resources wisely. Ecosystem science involves the holistic study of complex biophysical systems to understand the drivers that influence ecological pattern and process. Ecosystem science should underpin both water management and policy. Our understanding of aquatic ecosystems lags behind the increasing problems caused by past land and water management. Current post-graduate training programmes will not provide the aquatic ecosystem scientists needed by government and management agencies to prevent further degradation. We advocate new initiatives to capture the skills, knowledge and innovation of our research community by engaging scientists and managers in large-scale, long-term ecosystem science programmes across Australia and to integrate these programmes with community aspirations, policy, planning and management. We call on management agencies to increase their support for and uptake and use of ecosystem science. We also advocate establishment of national archives for long-term ecologically-relevant data and samples, and clear custodial arrangements to protect, update and facilitate knowledge-transfer. These initiatives need to be supported by more extensive, better-funded post-graduate and post-doctoral programmes in ecosystem science and management. [ABSTRACT FROM AUTHOR]

Flow resistance through riparian forests due to drag on trees is often expressed in hydraulic models with an increase in a boundary resistance factor such as Manning's n. However, when Manning's n is used as a proxy for vegetation drag, this parameter is dependent on flow conditions and a single, uniform value may be inadequate for simulating a broad range of flood magnitudes. To investigate this issue, flow resistance, and the commensurate Manning's n values through a riparian forest were computed using measured drag forces and estimates of the forest structure and tree morphology. The computed Manning's n values were applied to a 2D hydraulic model (TUFLOW) to simulate an observed flood and a range of design floods. Modelled peak flood levels for the observed flood were 0.16 m lower on average than that recorded at debris marks. There was little difference in modelled flood levels when using the computed Manning's n compared to a traditional, uniform Manning's n. Reassuringly, the traditional method appears adequate when reliable calibration data is available. Otherwise, the method developed here provides a useful alternative in cases where calibration data is limited or for testing reforestation as a nature‐based solution in river or flood management. [ABSTRACT FROM AUTHOR]

Sedimentation refers to a systematic process of particle transport to, placement on, withdrawal from, and maintenance on the seabed. Sediment is a naturally occurring component of aquatic habitats. However, the quantity and features of sediment have an impact the marine ecosystems' physical, chemical, and biological integrity. Deep sediments are the nation's most significant geological deposits. They serve as a record of our planet's reaction to circumstances at the sea surface, from which the majority of the material comes. They are also crucial aspects of energy flow through food webs and contribute to the operating of marine ecosystems. In addition, they are essential in sedimentary procedures such as carbon cycling and, nutrient and, waste malfunction, and abolishment. By studying the living and non-living variables contributing to the coastal system, the study of studying these sediments can be a tremendous asset for studying climate change and anthropogenic consequences (pollution associated with chemicals or metals)), and it can be a biological indicator of climatic changes anthropogenic consequences. So, the purpose of this review is to focus on the study of these sediments that are attributed to the impacts of urbanization along the marine coast by evaluating the Physicochemical characteristics of marine sediments that affect the marine bio-communities negatively or positively, and thus assessing the climatic changes and anthropogenic consequences that are associated with human health, industrial, and economic fields. [ABSTRACT FROM AUTHOR]

Global understanding of past food systems is based on many lines of evidence, involving complex multidisciplinary contributions. It has long been considered that since Australia's first colonisation, now dated to 65,000 years ago, its peoples were supported largely through foraging as opposed to farming. Recent research has challenged that perspective, contentiously proposing that Australia's first nations peoples developed agricultural systems before European colonisation. This proposal has been subject to significant critique, but support of the food-producing nature of Aboriginal society has been boosted by new multi-disciplinary evidence for early aquaculture and possibly cultivation, as well as for the translocation of plants though trans-continental trade systems. While this analysis has generated new discussion and debate, it has also highlighted systemic empirical biases; archaeological data for pre-European plant exploitation remains sparse, and we consistently rely on potentially unrepresentative and historically shallow ethnographic information to fill that gap. We argue that by employing collaborative transdisciplinary research that incorporates Western scientific and Indigenous knowledge pathways, we can more effectively explore the diverse and complex nature of Aboriginal foodways in Australia's past, from the earliest human arrivals to its current mosaic of different food systems. [ABSTRACT FROM AUTHOR]

Buildings and monuments constructed from stone provide some of the best‐preserved surface archaeology, but their construction ages can be difficult to determine using radiocarbon techniques. In Australia, stone arrangements are recognised as architectural or symbolic features belonging to Aboriginal societies. The structures are predominantly inorganic with shallow infill, hampering attempts to determine their antiquity. Optically stimulated luminescence (OSL) techniques have the potential to date these features, but their complex geometry requires careful consideration of the background radiation. Here, we present the first ages for Australian Aboriginal stone construction using single‐grain OSL techniques on quartz from stone arrangements in central Australia. Beta and gamma dose rates and the cosmic ray dose have been estimated from mapping the gross geometry of stone and sand courses. The resulting OSL ages are internally consistent and, together with fallout radionuclides 137Cs and 210Pb, indicate a minimum age for construction between 1959 and 1981 AD. We demonstrate that single‐grain OSL techniques can be used to determine the age of emplaced sand between stones and, assuming a stable substrate, can be used to date stone building construction as well as building occupation, providing chronologies for sites where organic material for radiocarbon analysis is limited or unavailable. [ABSTRACT FROM AUTHOR]

Hydraulic models used to simulate floods through riparian forests along rivers need to account for flow resistance caused by tree drag. Tree drag formulations have been developed for this purpose in previous studies, using drag force measurements on several broad-leaved, temperate species at tree scale to calibrate model parameters. However, tree reconfiguration and reduction in drag force in response to increased flow velocity are still not fully understood, particularly for subtropical tree species with sclerophyllous foliage. An established towing tank method was adapted to a field setting using a motorboat to tow submerged she-oak and tea trees through still water. Drag coefficients for both genera decreased with increasing velocity due to stem and foliage reconfiguration, except for the lowest velocity measurements on some she-oak trees, indicating the emergence of a rigid regime. The rigid regime has also been observed in previous studies and is important for flood modeling because drag forces could otherwise be overestimated at low velocities. Therefore, a new Cauchy number has been formulated and tested to predict regime transition for she-oak trees. [ABSTRACT FROM AUTHOR]

Embayments and the biota they support are highly susceptible to disturbance within adjacent catchments. Examining the timing and magnitude of impacts arising from human-induced disturbance in these systems is often limited due to the absence of long-term monitoring. Moreton Bay in south-eastern Queensland is a shallow embayment that receives inflows from a 21 220-km2 catchment. In this study, diatom abundances, pigment (chlorophyll-a, phaeopigments) and biogenic silica concentrations were evaluated in a composite sediment from central Moreton Bay to explore temporal trends in the photosynthetic community. The record extends from 1200 to 2011, incorporating the period of European settlement (c. 1840s) and rapid population growth and urbanisation of the catchment. The record shows that in central Moreton Bay bloom-forming marine diatoms (Thalassiosira, Thalassiothrix, Thalassionema) have increased in relative abundance since the mid-20th century, whereas the dominant benthic diatom (Paralia fenestrata) has declined. This transition most likely occurred in response to the compounding effects of increased delivery of nitrogen, fine sediments and pollutants to Moreton Bay as a consequence of changes in land use. The inferred historical decline in relative contributions of benthic microalgae to total primary production in central Moreton Bay has likely had wide-ranging ecological effects. [ABSTRACT FROM AUTHOR]

The science of geomorphology is increasingly used to inform river management efforts; however, the complexity of fluvial systems makes predictions of future channel adjustment difficult at best. The geomorphic concepts of landform sensitivity and sediment connectivity are well suited to aid river managers in assessing the probability and variability of river channel responses. This can be especially helpful in planning for impacts of future climate change or changes in management activity. River sensitivity and sediment connectivity datasets provide a necessary reach-in-catchment perspective to inform geomorphic interpretations of river behaviour. Such interpretations constitute a first step towards providing the contextual geomorphic understanding necessary to establish expectations of future channel behaviour. In this paper, we use geomorphic interpretations based on river sensitivity and sediment connectivity datasets to describe the historical trajectory and future adjustment possibilities for four channel reaches in the Lockyer Valley, southeast Queensland (SEQ). We apply our interpretations to three different scenarios of future climate and river management conditions to constrain what forms of geomorphic adjustment are possible for resilient-disconnected, resilient-connected, sensitive-connected, and sensitive-disconnected channels. Using scenario-building exercises to forecast possibilities of river adjustment can aid river managers by establishing expectations of future channel behaviour. This information can then be fed into the decision-making process regarding where to prioritize management actions as part of catchment action planning that works with, not against, the natural behaviour of riverine environments. [ABSTRACT FROM AUTHOR]

Explanations for the Upper Pleistocene extinction of megafauna from Sahul (Australia and New Guinea) remain unresolved. Extinction hypotheses have advanced climate or human-driven scenarios, in spite of over three quarters of Sahul lacking reliable biogeographic or chronologic data. Here we present new megafauna from north-eastern 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. The causes of the Upper Pleistocene megafauna extinction in Australia and New Guinea are debated, but fossil data are lacking for much of this region. Here, Hocknull and colleagues report a new, diverse megafauna assemblage from north-eastern Australia that persisted until ~40,000 years ago. [ABSTRACT FROM AUTHOR]

This study uses species distribution modeling and physiological and functional traits to predict the impacts of climate change on native freshwater fish in the Murray-Darling Basin, Australia. We modelled future changes in taxonomic and functional diversity in 2050 and 2080 for two scenarios of carbon emissions, identifying areas of great interest for conservation. Climatic-environmental variables were used to model the range of 23 species of native fish under each scenario. The consensus model, followed by the physiological filter of lethal temperature was retained for interpretation. Our study predicts a severe negative impact of climate change on both taxonomic and functional components of ichthyofauna of the Murray-Darling Basin. There was a predicted marked contraction of species ranges under both scenarios. The predictions showed loss of climatically suitable areas, species and functional characters. There was a decrease in areas with high values of functional richness, dispersion and uniqueness. Some traits are predicted to be extirpated, especially in the most pessimistic scenario. The climatic refuges for fish fauna are predicted to be in the southern portion of the basin, in the upper Murray catchment. Incorporating future predictions about the distribution of ichthyofauna in conservation management planning will enhance resilience to climate change. [ABSTRACT FROM AUTHOR]

Kiacatoo Man, a large, rugged Aboriginal adult buried in the Lachlan riverine plains of southeastern Australia, was discovered in 2011. Laser‐ablation uranium series analysis on bone yielded a minimum age for the burial of 27.4 ± 0.4 ka (2σ). Single‐grain, optically stimulated luminescence ages on quartz sediment in which the grave had been dug gave a weighted mean age of 26.4 ± 1.5 ka (1σ). Luminescence samples from the grave infill and from sediment beneath the grave exhibit overdispersed dose distributions consistent with bioturbation or other disturbance, which has obscured the burial signal. The overlap between the minimum (U‐series) and maximum (luminescence) ages places the burial between 27.0 and 29.4 ka (2σ). Luminescence ages obtained from the channel belt of between 28 ± 2 and 25 ± 3 ka indicate that fluvial sedimentation was occurring before the Last Glacial Maximum, which is consistent with the broader geomorphic setting. Together, these results are internally and regionally consistent, and indicate that Kiacatoo Man was one of the more ancient individuals so far identified in Australia. His remains are important to our understanding of patterns of biological variation and other processes that have shaped people in the Murray‐Darling Basin through time. Copyright © 2019 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The identification of the sources of sediment is a key part of the management of waterways. This is typically achieved through the well‐established technique known as sediment source fingerprinting that uses tracers and statistical mixing models. Until recently, the approach for solving these mixing models has been dominated by frequentist methods. This review focuses on the growing interest in Bayesian methods for sediment fingerprinting and presents them as an alternative or complementary addition to the frequentist methods. Bayesian methods emphasize flexibility, for example, in the choice of probability distributions for tracers, inclusion of parameter probability terms, the choice of how to characterize tracer proportion, and the choice of fully or empirical Bayesian techniques. The Bayesian approach flexibly combines previous known and current information, to produce results that aim to accurately reflect the real‐world environment. Under the Bayesian paradigm, all model parameters are treated as random variables, and this allows all sources of variation to be explicitly communicated and modelled. Although there are considerable advantages to using a Bayesian approach for sediment tracing, there are some possible problems the practitioner should be aware of. These include computational issues and potential difficulties in choosing probability distributions to realistically represent model parameters. Though there are choices as to what Bayesian approach to implement (i.e., fully or empirical Bayesian), a fully Bayesian approach has been found to best retain fidelity to the Bayesian paradigm of treating all parameters as random variables. It has been recognized that the field of sediment source fingerprinting would greatly benefit from the development of a model that incorporates the tracer selection process into the modelling framework allowing for an all‐in‐one approach, and the flexibility of a Bayesian approach makes this development possible. [ABSTRACT FROM AUTHOR]

Abstract: Concentrations of major and trace elements in freshwater fauna are often a reflection of local sediment chemistry. Biogeochemical profiles of freshwater species can be used to provide accurate and affordable assessments of species distribution, movement, and connectivity within river systems. Incorporating additional elements could significantly increase the precision and accuracy of population discrimination and movement analyses. To increase the variety of elements in biogeochemical tracing studies, we compared the concentrations of 38 major, trace, and rare earth elements (REEs) in bulk sediment (< 10 μm) and atyid shrimp from three rivers in South East Queensland, Australia. We determined which elements were correlated between sediment and shrimp samples and if these elements could distinguish different sample populations. This process identified elements that can directly associate shrimp with local sediment geochemical profiles. We found potassium (K), aluminum (Al), yttrium (Y), and the REEs cerium (Ce), lanthanum (La), and samarium (Sm) were spatially correlated between shrimp and sediment samples. Concentration ratios indicated K may be a relatively conservative tracer. Aluminum, REEs, and Y may undergo characteristic fractionation between sediment and shrimp tissue. Multivariate analysis indicated these elements could distinguish shrimp populations between sample sites. Results suggest that this small number of elements can link shrimp with specific rivers in accordance with local geochemistry, and thus may be valuable tracers with which to distinguish freshwater populations. As we measured bulk sediment concentrations, sampling these tracers is a relatively simplistic process that could be applied in a range of field conditions. [ABSTRACT FROM AUTHOR]

Understanding the flux and fate of nutrients and sediments from rivers is of global importance because of the effects of these materials on coastal ecosystems. The present study followed three flood events from upper tributaries of the Normanby River to Princess Charlotte Bay in the northern Great Barrier Reef (GBR) lagoon, Australia. During each event, nutrients and suspended sediment concentrations were measured along a freshwater to marine transect. The upper catchment provided the majority of suspended sediments and nutrients supplied to the river system, although concentrations of most materials decreased by 52-85% between the upper catchment and estuary. As an exception, ammonium concentrations doubled within the estuary, indicating that undisturbed coastal ecosystems can provide a significant source of dissolved inorganic nitrogen to tropical river flood plumes. The dissolved nutrients in floodwaters stimulated phytoplankton blooms that inundated seagrass meadows and coral reefs. Northern GBR marine ecosystems are increasingly threatened by climate change and catchment development. The results of this study show that increased anthropogenic loads of nutrients and sediments from the upper Normanby catchment have the potential to affect the condition of marine ecosystems at Princess Charlotte Bay. [ABSTRACT FROM AUTHOR]

Hydrologic variability is a fundamental driver of ecological processes and species distribution patterns within river systems, yet the paucity of gauges in many catchments means that streamflow data are often unavailable for ecological survey sites. Filling this data gap is an important challenge in hydroecological research. To address this gap, we first test the ability to spatially extrapolate hydrologic metrics calculated from gauged streamflow data to ungauged sites as a function of stream distance and catchment area. Second, we examine the ability of statistical models to predict flow regime metrics based on climate and catchment physiographic variables. Our assessment focused on Australia's largest catchment, the Murray-Darling Basin (MDB). We found that hydrologic metrics were predictable only between sites within ~25 km of one another. Beyond this, correlations between sites declined quickly. We found less than 40% of fish survey sites from a recent basin-wide monitoring program (n5777 sites) to fall within this 25 km range, thereby greatly limiting the ability to utilize gauge data for direct spatial transposition of hydrologic metrics to biological survey sites. In contrast, statistical model-based transposition proved effective in predicting ecologically relevant aspects of the flow regime (including metrics describing central tendency, high- and low-flows intermittency, seasonality, and variability) across the entire gauge network (median R² ~ 0.54, range 0.39-0.94). Modeled hydrologic metrics thus offer a useful alternative to empirical data when examining biological survey data from ungauged sites. More widespread use of these statistical tools and modeled metrics could expand our understanding of flow-ecology relationships. [ABSTRACT FROM AUTHOR]

Sediment tracing using geochemical properties is an efficient way to identify the spatial sources of transported sediments delivered to waterways. Here, the contribution of soil sources to river bed sediments has been quantified in Emu Creek, a headwater catchment in south eastern Queensland, Australia. Soil samples were collected from the eight major rock types present in the catchment and were related to river bed sediments collected from eight sites along the main channel. Geochemistry, as characterized by 39 elemental concentrations, was measured using inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry. Three particle size fractions were examined, <10, 10-63 and 63-212 µm, with the three resultant mixing models showing divergent results. We conclude that the results of sediment mixing models based on the analysis of one grain size should not be assumed to apply across the entire particle size range of transported sediment, emphasizing the need to match the size fraction used in tracing studies to that size fraction of interest in downstream sinks. Furthermore, we present results highlighting the control transport distance plays in source dominance, with this particularly evident in the coarser fraction, where local sources dominate over more distant sources. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Understanding food webs is important and useful for planning environmental conservation, management and restoration. However, research on food webs is not uniform globally; it tends to be concentrated in specific areas or ecosystem types, and would hinder our understanding of food webs and ecosystem processes. This study examined the trends in food web research over the past decades by analysing publication data from Web of Science; in particular, it focused on the ecosystem types studied, countries in which the studies were done, and which countries collaborated on the studies. A total of 20,239 publications were examined. The results showed that research on food webs has dramatically increased since the 1990s. Most publications related focused on aquatic ecosystems. North American and European countries contributed much more in terms of research productivity than those from Africa and South America. Collaboration among individual authors and countries has become increasingly intensive. The USA and Canada were consistently the top two productive countries, and had the most frequent collaborations. Our study indicates that food webs from ecosystems other than aquatic ones, such as terrestrial ecosystems, also require more attention in the future; in particular those that exist within countries from Africa and South America. [ABSTRACT FROM AUTHOR]

A decline in the ecosystem health of Australia's Moreton Bay, a Ramsar wetland of international significance, has been attributed to sediments and nutrients derived from catchment sources. To address this decline the regional management plan has set the target of reducing the loads by 50%. Reforestation of the channel network has been proposed as the means to achieve this reduction, but the extent of revegetation required is uncertain. Here we test the hypothesis that sediment and nutrient loads from catchments decrease proportionally with the increasing proportion of the stream length draining remnant vegetation. As part of a routine regional water quality monitoring program sediment and nutrient loads were measured in 186 flow events across 22 sub-catchments with different proportions of remnant woodland. Using multiple linear regression analysis we develop a predictive model for pollutant loads. Of the attributes examined a combination of runoff and the proportion of the stream length draining remnant vegetation was the best predictor. The sediment yield per unit area from a catchment containing no remnant vegetation is predicted to be between 50 and 200 times that of a fully vegetated channel network; total phosphorus between 25 and 60 times; total nitrogen between 1.6 and 4.1 times. There are ~48 000 km of streams in the region of which 32% drain areas of remnant vegetation. Of these 17 095 km are above the region's water storage dams. We estimate that decreasing the sediment and phosphorus loads to Moreton Bay by 50% would involve rehabilitating ~6350 km of the channel network below the dams; halving the total nitrogen load would require almost complete restoration of the channel network. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Increased sediment loads from accelerated catchment erosion significantly degrade waterways worldwide. In the South East Queensland region of Australia, sediment loads are degrading Moreton Bay, a Ramsar listed wetland of international significance. In this region, like most parts of coastal Australia, sediment is predominantly derived from gully and channel bank erosion processes. A novel approach is presented that uses carbon and nitrogen stable isotope ratios and elemental composition to discriminate between these often indistinguishable subsoil sediment sources. The conservativeness of these sediment properties is first tested by examining the effect of particle size separation (testing for consistency during transport) and the effect of sampling at different times (testing for temporal source consistency). The discrimination potential of these sediment properties is then assessed with the conservative properties, based on the particle size and temporal analyses, modelled to determine sediment provenance in three catchments. Nitrogen sediment properties were found to have significant particle size enrichment and high temporal variance indicative of non-conservative behaviour. Conversely, carbon stable isotopes had very limited particle size and temporal variability highlighting their suitability for sediment tracing. Channel erosion was modelled to be a significant source of sediment ( μ 51%, σ 9%) contrasting desktop modelling research that estimated gully erosion is the predominant sediment source. To limit the supply of sediment to Moreton Bay, channel bank and gully erosion must both be targeted by sediment management programs. By distinguishing between subsoil sediment sources, this approach has the potential to enhance the management of sediment loads degrading waterways worldwide. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The identification of sediment sources is fundamental to the management of increasingly scarce water resources. Tracing the origin of sediment with elemental geochemistry is a well-established approach to determining sediment provenance. Fundamental to the confident apportionment of sediment to their lithogenic sources is the modelling process. Recent approaches have incorporated distributions throughout the modelling process including source contribution terms for two end-member sources. The shift from modelling source samples to modelling samples drawn from distributions has removed relationships, including potential correlations between elemental concentrations, from the modelling process. Here, we present a novel modelling approach that re-incorporates correlations between elemental concentrations and models distributions for source contribution terms for multiple source end members. Artificial mixtures, based on catchment sources samples, were created to test the accuracy of this correlated distribution model and also examine modelling approaches used in the literature. The most accurate model incorporates correlations between elements, uses the absolute mixing model difference and does not use any weighting. This model was then applied to identify the sources of sediment in three South East Queensland catchments and demonstrated that Quaternary Alluvium is the most dominant source of sediment in these catchments ( μ 44%, σ 12%). This study demonstrates that it is important to understand how different weightings may impact modelling results. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper updates our previous analyses of the evidence for the timing of human arrival in Sahul. It reviews advances in dating technologies, summarises new data for sites published a decade ago or earlier, and examines the evidence from sites published since 2004. Extensions in time for first arrival can be attributed to improvements in both luminescence and radiocarbon dating techniques and especially the refinement of 14C calibration. The similarity of the ages of the earliest dates and their consistency with data from eastern Asia and Wallacea suggests that the discipline has now defined an event horizon that places first colonisation near but somewhere short of 50,000 years ago. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. © 2021 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including use of radionuclides for quantification of soil and rate of redistribution in catchments, sediment source tracing and sediment source fingerprinting techniques in Kharaa River, Mongolia.

Previous studies using fallout radionuclides (137Cs and 210Pbex) to determine the relative contributions of surface-soil and channel erosion (including gullies and channel banks) to stream sediments have used a relatively small number of composite samples (<25) to characterize the source end members, and concentrations in each of the source end members have, through the use of means and standard errors, been assumed to be normally distributed. Here, we examine 137Cs activity concentrations to determine the erosion processes supplying sediment in seven water supply catchments in South-east Queensland. First, we test some of the underlying assumptions in the method using concentrations of 137Cs and 210Pbex in composite samples collected from 109 surface-soil sites and 39 channel-bank sites. Paired composite samples, each consisting of 20 subsamples, from five sites are used to demonstrate that this sampling approach was sufficient to average out any local variations in surface-soil 210Pbex and 137Cs concentrations across the 300 m2 sampled. We derive probability distributions for 137Cs and 210Pbex concentrations in the group of samples from each of the end members and show that only the distribution of 210Pbex in samples from surface soils is normally distributed. We use the probability distributions for 137Cs, which provides the greatest discrimination between sources, to show that the 137Cs concentrations on the river sediment samples are consistent with channel erosion being the dominant source. Conservation works aimed at reducing the supply of sediments in these catchments should therefore focus on rehabilitation of the channel network and decreasing the runoff to the channel network. These findings are consistent with other similar studies on tropical Australian rivers. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study investigated the storage of nitrogen (N) and phosphorus (P) in the biomass, bed sediments and water column of representative reaches of a sub-tropical river, the upper Brisbane River (UBR), Queensland, Australia, and contrasted instream storage with total wet season exports. In reaches which contained accumulated fine sediments, more than 87% of total P and between 50% and 92% of total N were stored in the surface sediments. The lower proportion of N in sediment at some sites was attributed to substantial differences in the N/P ratios of sediments and macrophytes. At one site, the riverbed was dominated by cobbles and boulders and total nutrient stocks were comparatively low and dominated by the biomass. In reaches with a narrow channel and intact riparian cover, biomass N and P were stored predominately in leaf litter, while in wider unshaded reaches, macrophytes dominated. Total instream storage in the mid to lower reaches of the UBR was ∼50.9 T for N and ∼18.1 T for P. This was considerably higher than total wet season N (∼15.6 T) and P (∼2.7 T) exports from the UBR. The first flow event in the river after a prolonged period of no flow resulted in the export of free-floating, emergent species Azolla. The estimated biomass of Azolla in the mid to lower reaches of the river was equivalent to approximately 24% and 9% of the total N and P flux, indicating that this may be a significant, previously unaccounted for, source at peak flow. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is often a key limiting nutrient in freshwater systems, and excessive P can result in algal blooms, with flow-on effects to aquatic food webs. P sorption is an important process in aquatic and terrestrial ecosystems whereby phosphate (PO) is exchanged between liquid and solid phases. This study shows that differences in the concentration of PO in a subtropical river system during high and low flow can be attributed to differences in P sorption characterises of its catchment soils and sediments. The sediments have lower Equilibrium Phosphate Concentrations (EPC) and higher binding energy (K); the surface soils have higher EPC and higher easily desorbed P (NHCl-P). A comparison of filterable reactive phosphorus (frP) in water samples collected at high and low flows, with soil and sediment EPC, suggested that during event flows, the high EPC and NHCl-P of surface soils is producing a net movement of PO from the soil/sediment system into runoff and stream flow. At baseflow, there is more likely a net movement of PO into the riverbed sediments. This has important implications for management actions aimed at reducing P loads to river systems and downstream water storages, namely the need to increase the infiltration of rainfall to decrease the amount of PO being flushed from the surface soil. [ABSTRACT FROM AUTHOR]

The optically stimulated luminescence (OSL) dating method was used to determine the geochronology of seven relict beach ridges that sit immediately behind the modern beach at Beachmere, a low-energy sandy coast within Moreton Bay, Queensland. Between 2600 ± 400 and 1700 ± 130 years ago, the shoreline eroded and foreshore sediment was deposited over the older beach deposit. Subsequently, there was a 1500-year period of shoreline progradation: the shoreline advanced 0.16 m/y between 1700 ± 130 and 1140 ± 80 years ago; and 0.41 m/y between 1140 ± 80 and around 200 years ago. Shortly after 690 ± 60 years ago, a series of well-developed regularly spaced beach ridges gave way to an intertidal flat and then deposition of a set of lower amplitude, closely spaced beach ridges. The younger ridges were deposited between 230 ± 40 and 140 ± 50 years ago, at a rate of around 1.06 m/y. During the last several decades, much of the Beachmere shoreline has eroded into these younger relict ridges. Drivers of these changes in shoreline sedimentary regime are yet to be accurately determined; however, it seems likely they are related to switches that occur in the nearshore sand transport pathway. Our results demonstrate the utility of the OSL method for providing insights into coastal change that occurred in the historical and recent geological period. Better understanding the tempo of shoreline change in the recent past is particularly relevant for assessments of vulnerability to erosion of rapidly developing, low-lying sandy coasts such as northern Moreton Bay. [ABSTRACT FROM AUTHOR]

River discharges vary strongly through time and space, and quantifying this variability is fundamental to understanding and modelling river processes. The river basin is increasingly being used as the unit for natural resource planning and management; to facilitate this, basin-scale models of material supply and transport are being developed. For many basin-scale planning activities, detailed rainfall-runoff modelling is neither necessary nor tractable, and models that capture spatial patterns of material supply and transport averaged over decades are sufficient. Nevertheless, the data to describe the spatial variability of river discharge across large basins for use in such models are often limited, and hence models to predict river discharge at the basin scale are required. We describe models for predicting mean annual flow and a non-dimensional measure of daily flow variability for every river reach within a drainage network. The models use sparse river gauging data, modelled grid surfaces of mean annual rainfall and mean annual potential evapotranspiration, and a network accumulation algorithm. We demonstrate the parameterization and application of the models using data for the Murrumbidgee basin, in southeast Australia, and describe the use of these predictions in modelling sediment transport through the river network. The regionalizations described contain less uncertainty, and are more sensitive to observed spatial variations in runoff, than regionalizations based on catchment area and rainfall alone. [ABSTRACT FROM AUTHOR]

Most of the marine sediment cores collected in the past 10 years by the ODP and IMAGES programs have been processed using a multi-sensor core logger (MSCL, Geotek). This system estimates the density of sediment using the γ-ray attenuation of a 137Cs source. To date, optically stimulated luminescence (OSL) dating has not been applied to sediments from cores treated in this way, because of the possible impact of this exposure on the existing luminescence signal. We have investigated the effect of such γ-ray irradiation by test exposure, measurement and estimation, and conclude that the usual 137Cs exposure from γ-ray attenuation densitometry has no impact on the luminescence signal of quartz grains in sediment cores. For longer exposure to the 137Cs source, a formula is provided to calculate the received dose. This result will permit the OSL dating technique to be applied to the voluminous body of marine cores already collected and processed by MSCL. [ABSTRACT FROM AUTHOR]

This paper proposes a theoretical explanation of the variations of the sediment delivery ratio (SDR) versus catchment area relationships and the complex patterns in the behavior of sediment transfer processes at catchment scale. Taking into account the effects of erosion source types, deposition, and hydrological controls, we propose a simple conceptual model that consists of two linear stores arranged in series: a hillslope store that addresses transport to the nearest streams and a channel store that addresses sediment routing in the channel network. The model identifies four dimensionless scaling factors, which enable us to analyze a variety of effects on SDR estimation, including (1) interacting processes of erosion sources and deposition, (2) different temporal averaging windows, and (3) catchment runoff response. We show that the interactions between storm duration and hillslope/channel travel times are the major controls of peak-value-based sediment delivery and its spatial variations. The interplay between depositional timescales and the travel/residence times determines the spatial variations of total-volume-based SDR. In practical terms this parsimonious, minimal complexity model could provide a sound physical basis for diagnosing catchment to catchment variability of sediment transport if the proposed scaling factors can be quantified using climatic and catchment properties. [ABSTRACT FROM AUTHOR]

A digital terrain model is used with process thresholds to predict the extent of a stable gully network in a 5 km2 catchment of the southeastern highlands of Australia. The model, developed by Dietnch et al. [1992, 1993], predicts the topographic controls on channel networks and interprets these in terms of a critical shear stress for channel incision (τ c) applied by saturation overland flow. We adapt the model slightly to compare the shear stress applied by Hortonian overland flow to that applied by saturation overland flow. The limits to gully erosion in the catchment are controlled strongly by a topographic threshold that has an inverse relationship between upslope catchment area and local gradient. The topographic threshold for channel incision is reproduced using a simple model of Hortonian overland flow and a τ c appropriate for incision into a degraded grass surface (τ c = 245 dyn/cm2). This is consistent with historical evidence for the timing of gully erosion. The study confirms a strong topographic control on the extent of the channel network in a catchment significantly different from the western North America catchments where the topographic threshold was first demonstrated. Despite its simplicity, the model for incision by overland flow appears capable of distinguishing the hydrological processes responsible for channel incision when these are reflected in the relationship between channel network and landscape morphology. The model requires relatively simple inputs, suggesting it may be useful for mapping gully erosion hazard in actively eroding catchments. [ABSTRACT FROM AUTHOR]

The article presents an obituary for lecturer and author Geoffrey Steel Humphreys.

No abstract is available for this article. Copyright © 2018 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

No abstract is available for this article. Copyright © 2018 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]