Southeast Australia Research Articles

The Impact of Climate Shocks on Dryland Crop Production in South-East Australia

The Impact of Climate Shocks on Dryland Crop Production in South-East Australia

Climate change is associated with asynchrony in arrival between two sympatric cuckoos and both host arrival and prey emergence.

Matching the timing of spring arrival to the breeding grounds with hosts and prey is crucial for migratory brood parasites such as cuckoos. Previous studies have focused mostly on phenological mismatch between a single cuckoo species and its hosts but information regarding climate-driven mismatch between multiple sympatric cuckoo species and their hosts and invertebrate prey is still lacking. Here, we analysed long-term data (1988-2023) on the first arrival date of two declining migratory cuckoo species and their 14 migratory host species breeding in sympatry and prey emergence date in Tatarstan (southeast Russia). We found that the common cuckoo (Cuculus canorus; wintering in Africa) generally arrived on breeding grounds earlier than the oriental cuckoo (Cuculus optatus; wintering in southeast Asia and Australia). Both cuckoos have advanced their arrival dates over 36 years but less than their hosts, potentially resulting in an increasing arrival mismatch between cuckoos and their hosts. Moreover, cuckoo arrival advanced less than the emergence date of their prey over time. These observations indicate that climate change may disrupt co-fluctuation in the phenology of important life stages between multiple sympatric brood parasites, their hosts and prey with potential cascading consequences for population dynamics of involved species.

Новые и старые герои истории: государства в поисках идентичности

A conference titled ‘Old and New Heroes of History: Nation States in Quest for Identity’ was held on the 8th of February 2024, at the Primakov National Research Institute of World Economy and International Relations of the Russian Academy of Sciences (IMEMO). It was organized by the Center of the Indo-Pacific region of IMEMO. The conference Chief-moderators were Semenenko I.S., Corresponding Member of the RAS, Doct. Sci. (Polit. Sci.), Head of Centre for Comparative Socioeconomic and Political Studies, Deputy Director for Scientific Work of IMEMO and Prokhorenko I.L. Doct. Sci. (Polit. Sci.), Head of the Sector for International Organizations and Global Political Governance, Department for International Political Problems, IMEMO. The questions under analysis included the following points: the features and key directions of identity politics of various states of the world, the role and significance of identity conflict in world politics, rethinking the heritage of the past and the search for new ‘heroes’ for modern societies. The discussion was focused on the role of identity personifiers and the study of identity conflict in the context of the formation of a polycentric world. The speakers were as follows: Semenenko I.S. and Prokhorenko I.L. addressed the plenary meeting; staff members of IMEMO: the Center of the Indo-Pacific region– Head of the Center Cand. Sci. (Hist.) Kupriyanov A.V., Junior Research Fellow Makarevich G.G., Senior Research Assistant Kosareva E.S., Cand. Sci. (Polit. Sci.) Research Fellow Terskikh M.A., Junior Research Fellow Zaitsev I.A., Cand. Sci. (Polit Sci.) Research Fellow Lomova A.A., Turayanova L.T.; staff members of the Center for Middle East Studies – Research Fellow Ibragimov I.E. and Junior Research Fellow Guzhev I.A.; staff members of the Center for Development and Modernization Studies – Research Fellows Arabadzhyan A.Z. and Karamaev S.G.; staff member of the Center for European Studies Cand. Sci. (Hist.) Research Fellow Podchasov N.A. Fellows of the Institute of Oriental Studies of the Russian Academy of Sciences delivered their speech: Cand. Sci. (Econ.) Leading Researcher of the Center for Middle East Countries Studies Arabadzhyan Z.A., members of the Center for Southeast Asia, Australia and Oceania: Cand. Sci. (Hist.), Academic Secretary of the Center Senior Researcher Astafieva E.M., Cand. Sci. (Econ.) Leading Researcher of the Center and the Institute of China and Contemporary Asia of RAS Popov A.V., staff members of the Institute of China and Contemporary Asia of the Russian Academy of Sciences: Research Fellows of the Center for Vietnam and ASEAN Studies Burova E.S., Kucherenko G.N., Shaternikov P.S., Research Fellow of the Center for the Study of Contemparary History of China and Its Relations with Russia Voloshina A.V.; staff members of the Institute for African Studies, Russian Academy of Sciences (IAS RAS): Head of the Center for Tropical African Studies Cand. Sci. (Hist.) Leading Researcher Denisova T.S., Head of the Center for Southern Africa Studies Cand. Sci. (Hist.) Senior Research Fellow Tokarev A.A., Senior Research Fellow of the Center for Southern Africa Studies Cand. Sci. (Hist.) Cand. Sci. (Hist. of Arts) Skubko Y.S., Junior Researcher Nesterova E.S., Senior Research Fellow of the Center for History and Cultural Anthropology Cand. Sci. (Hist.) Associate Professor of the Department of General History, P.G. Demidov Yaroslavl State University (YarSU) Khokholkova N.E., YarSU students and staff members Cand. Sci. (Hist.) Associate Professor of the Department of Regional Studies and Tourism Savin D.A., Professor and Doct. Sci. (Hist.), Professor of the Department of General History Gavristova T.M., post-graduate student of the Department of General History of YarSU, history teacher of the Municipal educational institution ‘Nekrasov Secondary school No. 4 with in-depth study of the English language’ of Yaroslavl city Tsvetkov E.G., Georgy Arbatov Institute for U.S. and Canada Studies, Russian Academy of Sciences (ISKRAN) staff member – Senior Research Fellow of the Center for History and Cultural Anthropology of the Department of Internal Political Research Cand. Sci. (Hist.) Vorobiev D.N.; staff member of the Russian State University for the Humanities, Cand. Sci. (Hist.) Associate Professor of the Department of American studies of the Faculty of International Relations, Political Science and Foreign Regional Studies RSUH Panov A.S. and Master’s student of the Department of Theory and History of Humanities, Institute of Philology and History of RSUH Grebneva N.I.; and master's student of the MGIMO University Kupalov-Yaropolk A.I. The review of the conference materials was compiled by the staff members of the Center of the Indo-Pacific region of IMEMO Cand. Sci. (Polit. Sci.) Research Fellow Lomova A.A. (lomova.dip@list.ru, ORCID: 0009-0004-3178-7480) and Junior Research Fellow Shirgazina E.R. (e.shirgazina8@imemo.ru, ORCID: 0000-0001-7715-2991) and Research Fellow of the Center for Development and Modernization Studies Karamaev S.G. (tiomkin@imemo.ru, ORCID: 0000-0001-5137-3948).

Seasonal ammonia emissions from an intensive beef cattle feedlot in Victoria Australia

Ammonia (NH3) emitted from concentrated animal feeding operations can cause environmental and health problems, and indirectly contribute to greenhouse gas emissions. Cattle feedlots are known to be large sources of NH3, but few studies have documented seasonal emissions from Australian feedlots. We conducted two field campaigns to measure NH3 emissions from an intensive beef cattle feedlot in southeast Australia, and these results were combined with previous measurements at the same feedlot to document seasonal variations in emissions and to derive annual feedlot emission factors (EFs). Emission rates were calculated with an inverse dispersion modelling (IDM) technique, based on NH3 concentrations measured at the feedlot with open-path lasers (OPLs). The average area emission rates in spring, summer, autumn and winter were 90.5, 167.4, 96.2 and 86.8 μg NH3 m−2 s−1 from the cattle pens, and 22.5, 18.1, 7.7 and 20.7 μg NH3 m−2 s−1 from the manure stockpile area, respectively. The total per-animal EFs ranged from 126.0 (autumn) to 190.2 g NH3 animal−1 d−1 (summer), representing a loss of 47.5–64.6% of the fed N. Seasonal variations in emissions were related to air temperature. Slight changes in crude protein content of the cattle diet may also have impacted seasonal variability. Taking seasonal variations into consideration, the average feedlot EF was 160.4 g NH3 animal−1 d−1, with 90% of the emissions coming from the cattle pens. Extrapolating the EF to all feedlot cattle in the country, the direct NH3 emissions from Australian feedlots amount to 65.2 Gg NH3 annually, or 3.7% of the national total. Our study benchmarks seasonal and annual EFs and N losses for Australian commercial feedlots, and provides a baseline for extrapolating the impacts of mitigation efforts.

Ecological and statistical models to configure flow regime for environment benefit in highly engineered rivers: a case study in the MacKenzie River, Southeast Australia.

Ecological and statistical models were developed using freshwater algal assemblages to assess water quality and ecological health of a regulated river. These models were used to inform configuration of flows to maintain or improve environmental conditions of the waterway whilst meeting consumptive water supply commitments. The flow regime of the MacKenzie River, western Victoria, Australia, has been substantially modified since the construction of a water supply reservoir on its upper reach in 1887. Water is withdrawn at several locations downstream of the reservoir, creating a substantially modified flow regime, impacting key environmental values of the river. To assess the impact of the different flow regimes on river health and ecosystem function, ten sites were repeatedly sampled along the river between February 2012 and April 2014. Physical and chemical characteristics of water, including pH, temperature, turbidity, electrical conductivity, dissolved oxygen, total nitrogen, total phosphorous, cations, and anions, were measured. Biological properties of the algal periphyton communities, including dry mass, ash-free dry mass, chlorophyll-a concentration, and species composition, were also measured. Exploration of the algal assemblage and water chemistry data using the computationally unconstrained ordination technique such as principal component analysis principal component analysis (PCA), correspondence analysis (CA), detrended correspondence analysis (DCA), and canonical correspondence analysis (CCA) indicated two strong gradients in the data sets. Furthermore, the quantitative ecosystem response models have been developed as the prototype tool to assist in the future configuration of flows in this river. The empirical data and models showed the lower reaches of the river to be in poor condition under low flows, but this condition improved under flows of 35 ML/day, as indicated by the reduction in green algae and cyanobacteria and improvement. Finally, the results are presented to tailor discharge and duration of water volume by amalgamation of consumptive and environmental flows to improve the condition of the stream thereby supplementing the flows dedicated to environmental outcomes.

Forest mosaics, not savanna corridors, dominated in Southeast Asia during the Last Glacial Maximum.

The dominant paradigm is that large tracts of Southeast Asia's lowland rainforests were replaced with a "savanna corridor" during the cooler, more seasonal climates of the Last Glacial Maximum (LGM) (23,000 to 19,000 y ago). This interpretation has implications for understanding the resilience of Asia's tropical forests to projected climate change, implying a vulnerability to "savannization". A savanna corridor is also an important foundation for archaeological interpretations of how humans moved through and settled insular Southeast Asia and Australia. Yet an up-to-date, multiproxy, and empirical examination of the palaeoecological evidence for this corridor is lacking. We conducted qualitative and statistical analyses of 59 palaeoecological records across Southeast Asia to test the evidence for LGM savannization and clarify the relationships between methods, biogeography, and ecological change in the region from the start of Late Glacial Period (119,000 y ago) to the present. The pollen records typically show montane forest persistence during the LGM, while δ13C biomarker proxies indicate the expansion of C4-rich grasslands. We reconcile this discrepancy by hypothesizing the expansion of montane forest in the uplands and replacement of rainforest with seasonally dry tropical forest in the lowlands. We also find that smooth forest transitions between 34,000 and 2,000 y ago point to the capacity of Southeast Asia's ecosystems both to resist and recover from climate stressors, suggesting resilience to savannization. Finally, the timing of ecological change observed in our combined datasets indicates an 'early' onset of the LGM in Southeast Asia from ~30,000 y ago.

Southeast Australia encapsulates the recent decade of extreme global weather and climate events

Southeast Australia encapsulates the recent decade of extreme global weather and climate events

Ethnomedicinal uses, phytochemistry, pharmacology and toxicological aspects of genus Wendlandia: an overview

The genus Wendlandia includes around 70 species and is native to southeast Asia, northeast Africa, China, Australia, and Turkey. Mnay plant species of this genus have ethnomedicinal properties, which are used to deal various health complications, including dysentery, severe fever, cough, diabetes, hypertension, hyperlipidemia, constipation, and inflammation. This review sought to summarize details on the ethnomedicinal uses, phytochemical composition, safety aspects, and toxicology of Wendlandia species. Additionally, it covered the nomenclature, distribution, taxonomy, and botanical characteristics of this genus. Several electronic databases were used to retrieve the information, including Google Scholar, PubMed, Web of Science, Scopus, Science Direct, and Springer Link. The Plant List (www.theplantlist.org) was used for taxonomical authentications. SciFinder and PubChem were utilized for the verification of chemical structures and IUPAC (International Union of Pure and Applied Chemistry) name of the compounds. Numerous examinations of chemical constituents of the Wendlandia genus have identified approximately 60 essential plant compounds, such as iridoid glycosides, flavonoids, flavonoid glycosides, carotenoids, and triterpenes. Various research studies have showcased the therapeutic potential of Wendlandia species, highlighting their abilities in treating diabetes, combating oxidation, reducing inflammation, fighting microbes, lowering blood pressure, and potentially hindering cancer growth. The significance of Wendlandia in traditional medicine systems and its role as a valuable origin of impactful natural compounds are evident. This review provided scientific basis for future endeavors, including chemical investigations into already studied species and other less studied species of Wendlandia for finding future lead compounds. J. Bangladesh Acad. Sci. 47(2); 139-154: December 2023

Controls on rapid rare earth element enrichment in sediments deposited by a continental-scale river system

Clay-hosted rare earth element (REE) deposits, generally considered products of extended subtropical weathering of REE-rich igneous protoliths, are a critical source of REEs globally.The Koppamurra deposit of southeast South Australia, in contrast, is developed in Pleistocene lacustrine clays overlying a REE-poor marine limestone. Here we examine the REE + Y (REY) sources and enrichment mechanisms of this unusual setting. We find that the greatest REY enrichment (up to 5000 ppm) occurs in lacustrine clays at the base of a ∼1–2 m thick contact zone with the underlying limestone. This zone features an increased proportion of leachable REYs (>50 %), increased smectite abundance and a sharp increase in pH from ∼5.0 to ∼8.3. Co-variation of HREEs with a suite of clay-specific elements demonstrates that HREEs are hosted mainly by Fe-rich smectite, with separate sorbed vs structurally bound HREE pools that are of similar magnitude. LREEs are mainly hosted in secondary LREE carbonates, these are preferentially intergrown with smectite but are only rarely present in kaolinite domains. Cerium occurs mainly as cerianite. The narrow range and overlapping εNd of samples within and above the REY enriched zone suggests that enrichment is related to internal redistribution within the clay unit. The clays are isotopically incompatible with local igneous or metasedimentary rocks, but 87Sr/86Sr and εNd isotopic fingerprinting shows that they were deposited by the Murray River, Australia’s largest river system. Murray sediments are enriched in REY due to the presence of material eroded from the Lachlan Orogen granites of southeast Australia. Deposition of these sediments occurred in a coastal lacustrine setting analogous to the modern-day Coorong, with tectonic uplift and shoreline progradation allowing the onset of subaerial weathering ∼1–2 Mya. We propose that vertical and lateral solute transport allowed for the concentration of REEs in local depressions in the karst-weathering surface which separates the limestone and overlying clay, facilitated by water table oscillation and pore water redox cycling driven by seasonally contrasted rainfall. Poor soil drainage, evaporative concentration of soil waters and alkaline pH adjacent to the limestone immobilized REEs in secondary carbonates and Fe-rich smectite. Our findings illustrate that REE mobilization and enrichment in clay deposits can occur more rapidly, over a larger area and in a broader range of host phases and geologic settings than is currently appreciated, with important implications not only for REE exploration but also for the use of REEs as tracers in the Earth Sciences.

Pregnant women’s experiences of extreme exposure to bushfire associated smoke: a qualitative study

In 2019/2020, multiple bushfires burned across south-east Australia converging into unprecedented megafires that burned 5.8 million hectares. From October 2019–February 2020, 80% of Australians were affected by smoke from these fires, exposing them to dramatic increases of PM2.5 in the air at an average level of ∼70 μg m3 per day, well above the World Health Organisation recommendation of ∼10 μg m3. Maternal exposure to PM2.5 has been associated with negative birth outcomes and an increased rate of birth defects, yet there is a dearth of literature regarding how pregnant women deal with exposure to bushfire smoke. The aim of this study was thus to investigate how pregnant and postpartum women experienced severe bushfire smoke associated with the 2019–2020 bushfires in south-east Australia and the strategies they used to mitigate exposure to smoke for themselves and their unborn or newborn children. Forty-three women who were exposed to fire and/or smoke from the 2019–2020 bushfires participated in one-on-one semi-structured interviews via phone or videoconference. These women were selected purposively from a larger group of women who had elected to be interviewed. After interview, data were transcribed and thematically analysed using the four phases of disaster response (prevention, preparedness, response, recovery) as a frame. Overall, our results indicated that public health advice failed to meet the unique needs of this group. While many protected their properties appropriately and were reasonably well prepared for evacuation, they were unprepared for the disruption to vital services including power and communications. Women exposed to smoke inundation were unprepared for this outcome and self-initiated a variety of strategies. The support of community was also key to recovery. There is a clear need for specific recognition of the needs of pregnant women across all phases of disaster response, incorporating public health messaging, peer support, and access to resources.

Restoring ex mining area using Pongamia pinnata in Central Kalimantan: a reclamation program alternative base on bioenergy species

Malapari (Pongamia pinnata (L) Pierre) is an endemic species of Leguminosae from southeast Asia, Australia and Afrika. Malapari is one species alternative of Reclamation Program in PT Asmin Bara Bronang. The aims of this study are to know the growth and adaptation rate of Malapari in extrime area after charcoal mining and to introduce the malapari for a alternative species for reclamation program with bioenergy potential species. The research method used is the census method in areas planted with malapari at PT ABB which was observed from 2020 with parameters including malapari growth; survival rate; analysis of soil fertility; biodiversity and carbon estimate. The results showed that malapari growth on post-mining land was very rapid where within 4 years it increased in height by an average of 184,92cm with a diameter growth of 10.76 cm and a survival rate of 87,78%, above ground biomass 584,04kg (274,5kg carbon) with very good leaf growth in fresh dark green The condition of early soil fertility becomes increased after planting. The great hope in this program is that malapari can be an alternative species for post-coal mining forest restoration from local superior species of use that has the potential to be a bioenergy source.

East Asian analogues for early Alpine orogenesis

The Alpine orogeny is a consequence of the collision of Africa with Eurasia, which eliminated the Western Tethys Ocean. Processes similar to those that would have taken place early in that collision can today be seen operating in the islands of the Indo-Pacific gateway between Southeast Asia and Australia and have the potential to offer insights into the beginnings of orogenesis in the Alps. Studies of the gateway area emphasise the importance of the impact on subduction zones of topography on the downgoing plate, and of the effects of flows in the asthenosphere on lithosphere tectonics.

Machine learning based parameter sensitivity of regional climate models—a case study of the WRF model for heat extremes over Southeast Australia

Heatwaves and bushfires cause substantial impacts on society and ecosystems across the globe. Accurate information of heat extremes is needed to support the development of actionable mitigation and adaptation strategies. Regional climate models are commonly used to better understand the dynamics of these events. These models have very large input parameter sets, and the parameters within the physics schemes substantially influence the model’s performance. However, parameter sensitivity analysis (SA) of regional models for heat extremes is largely unexplored. Here, we focus on the southeast Australian region, one of the global hotspots of heat extremes. In southeast Australia Weather Research and Forecasting (WRF) model is the widely used regional model to simulate extreme weather events across the region. Hence in this study, we focus on the sensitivity of WRF model parameters to surface meteorological variables such as temperature, relative humidity, and wind speed during two extreme heat events over southeast Australia. Due to the presence of multiple parameters and their complex relationship with output variables, a machine learning (ML) surrogate-based global SA method is considered for the SA. The ML surrogate-based Sobol SA is used to identify the sensitivity of 24 adjustable parameters in seven different physics schemes of the WRF model. Results show that out of these 24, only three parameters, namely the scattering tuning parameter, multiplier of saturated soil water content, and profile shape exponent in the momentum diffusivity coefficient, are important for the considered meteorological variables. These SA results are consistent for the two different extreme heat events. Further, we investigated the physical significance of sensitive parameters. This study’s results will help in further optimising WRF parameters to improve model simulation.

Performance of potential evapotranspiration models across different climatic stations in New South Wales, Australia

Study regionNew South Wales, southeast Australia Study focusEstimating potential evapotranspiration (ETp) rates, detecting its temporal trends and analysing its interannual oscillation are critical for long-term assessment of water availability and regional drought. This study aimed to evaluate the comprehensive performance of 12 simplified models in characterising ETp against the benchmark Penman model across different climate sites in southeast Australia. This study used Taylor skill score (S), normalised root mean square error (nRMSE) and relative mean bias error (rMBE) to estimate models’ capability in estimating ETp rates. Then, this study adopted Mann-Kendall test and continuous wavelet transform (CWT) to test temporal trends and periodicity of ETp estimated by all models. New hydrology insights for the regionJensen-Haise model was capable to produce fair (nRMSE ≤ 30%) estimates of daily ETp across all stations. Models except Mak1 were generally able to produce reasonable estimates of ETp at larger time scale. In addition, we found that the 12 alternative ETp models generally agreed with the Penman model on the primary (9.6–12.4-year) and quasi (2.6–3.9-year) periods of ETp, but they did not show matchable ability in detecting ETp temporal trends. The comprehensive investigation on models’ performance will shed light on models’ selection in estimation of drought and hydrological cycle.

Hepatic concentrations of per- and polyfluoroalkyl substances (PFAS) in dolphins from south-east Australia: Highest reported globally

Per- and polyfluoroalkyl substances (PFAS) concentrations were investigated in hepatic tissue of four dolphin species stranded along the south-east coast of Australia between 2006 and 2021; Burrunan dolphin (Tursiops australis), common bottlenose dolphin (Tursiops truncatus), Indo-Pacific bottlenose dolphin (Tursiops aduncus), and short-beaked common dolphin (Delphinus delphis). Two Burrunan dolphin populations represented in the dataset have the highest reported global population concentrations of ∑25PFAS (Port Phillip Bay median 9750 ng/g ww, n = 3, and Gippsland Lakes median 3560 ng/g ww, n = 8), which were 50–100 times higher than the other species reported here; common bottlenose dolphin (50 ng/g ww, n = 9), Indo-Pacific bottlenose dolphin (80 ng/g ww, n = 1), and short-beaked common dolphin (61 ng/g ww, n = 12). Also included in the results is the highest reported individual ∑25PFAS (19,500 ng/g ww) and PFOS (18,700 ng/g ww) concentrations, at almost 30 % higher than any other Cetacea reported globally.Perfluorooctane sulfonate (PFOS) was above method reporting limits for all samples (range; 5.3–18,700 ng/g ww), and constituted the highest contribution to overall ∑PFAS burdens with between 47 % and 99 % of the profile across the dataset. The concentrations of PFOS exceed published tentative critical concentrations (677–775 ng/g) in 42 % of all dolphins and 90 % of the critically endangered Burrunan dolphin.This research reports for the first time novel and emerging PFASs such as 6:2 Cl-PFESA, PFMPA, PFEECH and FBSA in marine mammals of the southern hemisphere, with high detection rates across the dataset. It is the first study to show the occurrence of PFAS in the tissues of multiple species of Cetacea from the Australasian region, demonstrating high global concentrations for inshore dolphins. Finally, it provides key baseline knowledge to the potential exposure and bioaccumulation of PFAS compounds within the coastal environment of south-east Australia.

Estimation of grain protein content in commercial bread and durum wheat fields via traits inverted by radiative transfer modelling from Sentinel-2 timeseries

Wheat (Triticum spp.) is crucial to food security. Grain protein content (GPC) is key to its nutritional and economic value and is controlled by genetic and agronomic factors, soil properties and weather. GPC prediction from remote sensing could reduce nitrogen (N) losses, help management decisions, and improve profit. However, GPC prediction is complex because multiple plant traits influence GPC and their effects change through the growing season. Traits with known physiological links to GPC, which can be retrieved from imaging spectroscopy, include leaf area index (LAI), chlorophyll (Ca+b), and stress indicators. Further inspection of these and other traits retrieved from satellite data can advance research relevant to precision agriculture. Sentinel-2 (S2) timeseries (TS) were acquired for 6,355 ha of commercial dryland bread (T. aestivum) and durum (T. durum) wheat fields in south-east Australia through two consecutive years with dissimilar rainfall. Wheat growers provided ∼ 92,000 GPC data points from harvester-mounted protein monitors. For each, Ca+b, leaf dry matter, leaf water content (Cw) and LAI were retrieved from the S2 images by radiative transfer model inversion. A gradient boosted machine learning algorithm was applied to analyse these traits’ importance to GPC and to predict GPC in 30% of samples unseen by the algorithm in training. The strongest relationships between predicted and observed GPC (R2 = 0.86, RMSE = 0.56 %), in a model built from five S2 images across a season, were better than those from single-date hyperspectral (HS). In severe water stress, LAI was the main predictor of GPC early in the season, but this switched to Cw later. Trait importance was more evenly distributed in milder conditions. S2 TS had a clear accuracy advantage over single-date S2 and HS, especially in benign conditions, emphasising the potential of S2 TS for large-scale GPC monitoring.

Bayesian analysis of ground motion models using chimney fragility curves: 2021, 5.9-Mw Woods Point intraplate earthquake, Victoria, Australia

The 22 September 2021 (AEST) MW 5.9 Woods Point earthquake occurred in an intraplate setting (southeast Australia) approximately 130 km East Northeast of the central business district of Melbourne (pop. ∼5.15 million). A lack of seismic instrumentation and a low population density in the epicentral region resulted in a dearth of near-source instrumental and “felt” report intensity data, limiting evaluation of the near-source performance of ground motion models (GMMs). To address this challenge, we first surveyed unreinforced masonry chimneys following the earthquake to establish damage states and develop fragility curves. Using Bayesian inference, and including pre-earthquake GMM weightings as Bayesian priors, we evaluate the relative performance of GMMs in predicting chimney observations for different fragility functions and seismic velocity profiles. At the most likely VS30 (760 m/s), the best performing models are AB06, A12, and CY08SWISS. GMMs that were preferentially selected for utility in the Australian National Seismic Hazard Model (NSHA18) prior to the Woods Point earthquake outperform other GMMs. The recently developed NGA-East GMM performs relatively well in the more distal region (e.g. >50 km) but is among the poorest performing GMMs in the near-source region across the range of VS30. Our new method of combining analysis of engineered features (chimneys) with Bayesian inference to evaluate the near-source performance of GMMs may have applicability in diverse settings worldwide, particularly in areas of sparse seismic instrumentation.

Integrating major ion geochemistry, stable isotopes (18O, 2H) and radioactive isotopes (222Rn, 14C, 36Cl, 3H) to understand the interaction between catchment waters and an intermittent river

Determining the locations and sources of baseflow and the transit times of water is important for understanding catchment behaviour and functioning. Major ion geochemistry, stable isotopes (18O and 2H), and radioisotopes (222Rn, 3H, 14C, and 36Cl) were used to investigate the sources and transit times of water in the upper catchment of the intermittent Avoca River in southeast Australia. 222Rn activities and Cl concentrations implied the presence of baseflow inputs and the distribution was mainly controlled by local topography. Fluctuation of Cl concentrations implied that low-salinity near-river water was an important component of baseflow. The 3H activities of laterally disconnected pool waters during the summer months were 1.64 to 5.11 TU. The higher of these values exceed those of average annual rainfall (2.8–3.2 TU), probably due to the input of later winter to spring rainfall. The stream water had 3H activities ranging from 2.21 to 2.40 TU in July and 2.39 to 2.77 TU in August, which yield mean transit times of 4.0 to 7.0 years and 1.4 to 4.8 years respectively. These 3H activities were significantly higher than those of regional groundwater (3H activities <0.1 TU), implying that the river is largely sustained by young near-river stores at all flow conditions. Regional groundwater had 14C activities of 34.0 to 98.1 pMC, which yield mean residence times of up to 12,900 years. R36Cl values of regional groundwater (50.9–61.9 × 10−15) were higher than those of modern rainfall, probably reflecting the R36Cl values of recharge. Similar R36Cl values of the pool and stream water (33.3–58.7 × 10−15) implied that some Cl is derived from the regional groundwater influx. As with other intermittent streams in southeast Australia, the upper Avoca River was mainly sustained by relatively small water stores, and it will be vulnerable to short-term changes in climate and land use.

Peaks-Over-Threshold-Based Regional Flood Frequency Analysis Using Regularised Linear Models

Regional flood frequency analysis (RFFA) is widely used to estimate design floods in ungauged catchments. Most of the RFFA techniques are based on the annual maximum (AM) flood model; however, research has shown that the peaks-over-threshold (POT) model has greater flexibility than the AM model. There is a lack of studies on POT-based RFFA techniques. This paper presents the development of POT-based RFFA techniques, using regularised linear models (least absolute shrinkage and selection operator, ridge regression and elastic net regression). The results of these regularised linear models are compared with multiple linear regression. Data from 145 stream gauging stations of south-east Australia are used in this study. A leave-one-out cross-validation is adopted to compare these regression models. It has been found that the regularised linear models provide quite accurate flood quantile estimates, with a median relative error in the range of 37 to 47%, which outperform the AM-based RFFA techniques currently recommended in the Australian Rainfall and Runoff guideline. The developed RFFA technique can be used to estimate flood quantiles in ungauged catchments in the study region.

Dinoflagellate cyst distribution over the past 9 kyrs BP from offshore east Tasmania, southeast Australia

Southeastern Australia’s marine waters are notably warming, surpassing global averages. This region has emerged as a strategic location for researching planktic microfossils, particularly dinoflagellate cysts, in modern and Late Quaternary sediments, offering crucial insights into the biophysical properties of mid-latitude waters. This study examined cyst distribution in marine sediment cores near Maria Island, Tasmania, southeastern Australia, up to 9000 years before present (kyrs BP). Dominant cysts included Protoceratium reticulatum, Protoperidinium spp. (P. avellana, P. conicum, P. oblongum, P. subinerme, P. shanghaiense), and Spiniferites spp. (S. bulloideus, S. hyperacanthus, S. membranaceus, S. mirabilis, S. pachydermus, and S. ramosus). Inshore, Spiniferites spp. constituted a higher proportion (up to 61%), while offshore was dominated by P. reticulatum (up to 80%). Impagidinium spp. and Nematosphaeropsis labyrinthus were exclusively found offshore and displayed increased abundance from ∼6 kyrs BP, suggesting a shift from a shallow to a deep-water habitat. Alexandrium tamarense species complex cysts were present over 140 years inshore and approaching 9 kyrs BP offshore, indicating a longstanding endemic presence. Gymnodinium catenatum cysts were detected exclusively inshore from ∼50 years ago, indicating a relatively recent bloom phenomenon. The East Australian Current’s limited southward reach is suggested by the absence of the warm-water cyst-producing taxon Lingulodinium polyedra. Similarly, the non-detection of the cold-water species Spiniferites antarctica and Impagidinium pallidum reflects Subtropical Front boundaries against subantarctic incursions from the south. In contrast to coccolithophores in the same core, no noticeable shift from cold to warm-water dinoflagellate cyst species was observed. This documentation of dinoflagellate cysts aids in predicting environmental impacts on local communities and beyond.