South Basin Research Articles

Warming events and their causes at the Bering Sea section B in summer of 1999–2019

Based on hydrological data for the Bering Sea from 1999 to 2019 during the Chinese National Arctic Research Expeditions (CHINAREs), along with oceanographic and meteorological data from the National Centers for Environmental Information (NCEI) and the European Centre for Medium-Range Weather Forecasts (ECMWF), we investigated trends in summer at the Bering Sea section B over the past 20 years and their underlying causes. The results revealed a pronounced rise in temperature at the Bering Sea section B in 2003, 2014, 2016, 2018, and 2019, suggesting a shift towards a new phase of warmth starting in 2014. In warm years (2003, 2014, 2016, 2018, and 2019), the mean maximum temperature in the upper layer in the basin north of 57°N and on the continental shelf were roughly 2.7 °C, 2.6 °C higher than that in cold years (1999, 2008, 2010, and 2012). Additionally, the mean minimum temperature of the cold water in the middle layer in the basin was roughly 0.7 °C higher in the warm years compared to the cold years. This difference between the warm and cold years was evident in the heat content: the average heat content in the upper to middle layers in the basin north of 57°N and on the continental shelf were about 1.2 and 0.9 GJ/m2 higher, respectively, in the warm years than the cold years. However, there was a modest warming trend in the basin south of 57°N, and the temperature in the mid-layer on the continental shelf showed year-to-year stability, in contrast to the significant warming observed elsewhere. Further study suggested that temperature fluctuation in the basin was closely tied to seasonal 2-m air temperature. In addition, the southern basin, divided at 57°N, experienced larger positive or negative anomalous wind stress curl compared to the northern basin. This discrepancy resulted in differing causes of temperature variation between the two regions. Temperature change in the upper layer on the continental shelf was attributed to an increase in cumulative net heat flux resulting from reduced sea ice, while the temperature in the middle layer on the continental shelf was limited by the enhanced density gradient between the upper and middle layer caused by melt ice, preventing significant warming. Overall, the thermal state for the Bering Sea section B was influenced by a combination of factors, including net heat flux, sea ice, and atmospheric conditions, contributing to the year-to-year variation characterized by alternating cold and warm regimes.

Remote Sensing of Chlorophyll-a in Clear vs. Turbid Waters in Lakes

Chlorophyll-a (Chl-a), a proxy for phytoplankton biomass, is one of the few biological water quality indices detectable using satellite observations. However, models for estimating Chl-a from satellite signals are currently unavailable for many lakes. The application of Chl-a prediction algorithms may be affected by the variance in optical complexity within lakes. Using Lake Winnipeg in Canada as a case study, we demonstrated that separating models by the lake’s basins [north basin (NB) and south basin (SB)] can improve Chl-a predictions. By calibrating more than 40 commonly used Chl-a estimation models using Landsat data for Lake Winnipeg, we achieved higher correlations between in situ and predicted Chl-a when building models with separate Landsat-to-in situ matchups from NB and SB (R2 = 0.85 and 0.76, respectively; p < 0.05), compared to using matchups from the entire lake (R2 = 0.38, p < 0.05). In the deeper, more transparent waters of the NB, a green-to-blue band ratio provided better Chl-a predictions, while in the shallower, highly turbid SB, a red-to-green band ratio was more effective. Our approach can be used for rapid Chl-a modeling in large lakes using cloud-based platforms like Google Earth Engine with any available satellite or time series length.

Simulating springtime extreme rainfall over Southern East Asia: unveiling the importance of synoptic-scale activities

This study investigates the influence of synoptic-scale activities on extreme precipitation during March–April–May (MAM) over Southern East Asia (SEA) using observational data and compares the results with the outputs from 20 Coupled Model Intercomparison Project phase 6 (CMIP6) historical runs. Observations show that SEA intense daily precipitation in MAM is linked to enhanced upper-level synoptic-scale waves; these disturbances are associated with significant anomalous temperature advection as well as moisture flux convergence, creating favorable conditions for extreme rainfall. Furthermore, it is found that a temperature advection index (TAI) can be utilized to characterize such synoptic-scale activities. Inspection of CMIP6 historical runs reveals that, among 20 models, 13 models perform well in accurately capturing the observed SEA rainfall pattern; such extreme events are also closely linked to TAI in the model environment. Overall, observed (simulated) results show that 78% (75%) of extreme events in the Yangtze River Basin–South Korea–south of Japan region can be attributed to positive TAI. Additionally, the related circulation anomalies such as the upper-level synoptic-scale wave feature, temperature advection, and moisture anomalies from these models closely resemble those observed during extreme precipitation days in SEA. Our findings suggest that TAI can effectively indicate both the frequency and intensity of extreme rainfall events in SEA, along with the associated synoptic-scale activities. Further study reveals a close lead-lag correlation between TAI and rainfall patterns over SEA. This correlation is characterized by eastward-propagating wave trains across the entire troposphere. Consequently, TAI not only acts as a benchmark for quantifying synoptic-scale extreme rainfall in SEA but also shows potential in predicting SEA rainfall linked to synoptic-scale disturbances.

Earthquake-induced soft-sediment deformation in the Pleistocene succession, Noarlunga Embayment, South Australia

ABSTRACT A suite of soft-sediment deformation structures occurs within the basal sands and gravels in the non-marine Pleistocene succession in the Noarlunga Embayment of the Cenozoic St Vincent Basin south of Adelaide, South Australia, the significance of which has hitherto gone unrecognised. The inclusion of large, isolated blocks of well-bedded sands randomly encased within fluidised, structureless clayey sands indicates that the soft-sediment deformation was intense, occurring soon after deposition by liquefaction of a still saturated sediment. Seismic activity has been, and continues to be, a regular occurrence along the adjacent Adelaide fold belt. The intensity of the deformation is comparable to the thixotropic response to earthquake activity observed during the Christchurch (New Zealand) earthquakes of 2010 and 2011, the earthquakes and aftershocks near Quorn, South Australia, in January 1887, in the southeast of South Australia in May 1899, and west of Adelaide in April 1954. This, however, is the first record of an interpreted seismite in the St Vincent Basin, although its full extent is yet to be mapped.

Long-term patterns of stream macroinvertebrates in an alpine cirque landscape

Alpine landscapes are notable regarding their sensitivity to environmental change. Surface waters are especially sensitive as many are influenced by glacial meltwaters that are diminishing with the retreat of glaciers worldwide. The Macun Lakes region, Swiss National Park, is an alpine cirque landscape housing a number of lakes interconnected by streams. The area has been non-glaciated for decades, although rock glaciers are still present in the south basin. Surface waters, 10 stream sites in the present study, have been monitored in mid-summer since the year 2001 for physico-chemistry, periphyton and macroinvertebrates (including 74 species of chironomids). Water physico-chemistry revealed that the two main basins in the catchment differed, reflecting the inputs of rock glacier waters in the south basin. However, trends suggest that waters are becoming more similar as rock glacier inputs diminish over time along with a general decrease in nitrogen levels in all waters. Periphyton biomass showed some spatial differences among sites and a general decrease after 2010. Macroinvertebrate assemblages, including chironomids, clearly differed among basins and spatially along the stream network in each basin. Notably, no significant temporal trend was observed in the long-term data for macroinvertebrates, including chironomids, at the monitored sites. The results suggest that lotic macroinvertebrates may be buffered by the interconnectedness of streams and lakes in the landscape, which mitigates major response patterns of running waters to environmental change.

Seasonal hot spots of pollution and risks in Western Kenya: A spatial-temporal analysis of almost 800 organic micropollutants

The release of chemicals into the environment presents a significant threat to aquatic ecosystems dependent on the proximity to emission sources and seasonal dynamics of emission and mobilization. While spatial-temporal information on water pollution in Europe is increasing, there are substantial knowledge gaps on seasonal pollution dynamics in tropical countries. Thus, we took Lake Victoria South Basin in western Kenya as a case study to identify spatial and seasonal hot spots of contamination, quantified toxic risks to different groups of organisms, and identified seasonal risk drivers. For this purpose, we analyzed grab water samples from five rivers with agricultural and wastewater treatment plants in their catchment in four different seasons. We used liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) with a target list of 785 organic micropollutants. A total of 307 compounds were detected with concentrations ranging from 0.3 ng/L to 6.6 μg/L. Using a Toxic Unit (TU) approach based on mixture toxicity to standard test organisms, crustaceans were identified as the most affected group followed by algae and fish. For crustaceans, chronic risk thresholds were exceeded in 96 % of all the samples, while 56 % of all samples are expected to be acutely toxic, with the highest risk in February during the dry season. High toxic unit values for algae and fish were recorded in July dry season and May wet season. Diazinon, imidacloprid, clothianidin and pirimiphos-methyl were the major drivers for crustacean toxicity while triclosan and different herbicide mixtures drive risks to algae in dry and wet seasons, respectively. A total of 18 chemicals were found to exceed acute and chronic environmental risk thresholds. With this study, strong spatial-temporal patterns of pollution, risks and risk drivers could be confirmed informing prioritization of monitoring and abatement to enhance water quality and reduce toxic risks.

Characteristics of sediments and regolith alterations in the Plio-Pleistocene succession, coastal cliff sections, St Vincent Basin, South Australia

Syn- and post-depositional alterations are distinguished in a detailed lithological and mineralogical study of the largely unconsolidated Plio-Pleistocene non-marine succession in coastal cliff sections in the St Vincent Basin south of Adelaide. At its base, the sequence interfingers with Late Pliocene estuarine marine sediments in places but mostly unconformably overlies older Cenozoic marine sediments or Neproterozoic bedrock. The fluvial and alluvial siliclastics have bioturbation, blocky-prismatic macro-peds and subtle Fe-mottling indicators of hiatuses in deposition, and imprints of soil and shallow groundwater environments. A relative abundance of kaolinite, illite and randomly interstratified illite-smectite reflects both sediment source and conditions in the local depositional environment. A thick deposit of aeolian calcareous silt with associated pedogenic calcretes blankets the succession. Conspicuous bleached Fe mega-mottled intervals and zones of alunite-halloysite within the sequence record post-depositional, groundwater-related alterations in regolith environments. These formed during incision and erosion of the sedimentary fill in the basin in response to regional falls in base level. Each marks a different time and specific geomorphic environment according to the chemistry of the discharge of local groundwaters from aquifers that were intersected by incision and scarp retreat.

Estimation of the annual amount of submerged macrophytes collected for fertilizer purposes in the south basin of Lake Biwa in the 1930s.

Estimation of the annual amount of submerged macrophytes collected for fertilizer purposes in the south basin of Lake Biwa in the 1930s.

Temporal and Spatial Comparison of Mercury Bioaccumulation in the Lower Trophic Levels of a Post-glacial Lake Food Web.

Total mercury (Hg) concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotopes were quantified among aquatic invertebrate and sediment samples collected from Keuka Lake in New York's Finger Lakes region to evaluate temporal and spatial variability in Hg bioaccumulation and trophic ecology among these lower trophic levels. Hg concentrations ranged from 6.3 to 158.8ng/g (dry wt) across dreissenid mussel, zooplankton, and juvenile (< 10mm) and adult (≥ 10mm) mysid shrimp (Mysis diluviana) samples. Hg concentrations were higher in samples collected from the western basin in 2015 relative to those for samples collected from this basin in 2022 (p < 0.001). While no specific mechanisms could be identified to explain this difference, higher δ15N values for zooplankton collected in 2015 support conclusions regarding the role of zooplankton trophic status on Hg concentrations in these populations. Spatial patterns in Hg concentrations were of generally low variability among samples collected from the lake's east, west and south basins in 2022. Trophic positions as inferred by δ15N were represented by adult mysids > juvenile mysids > large zooplankton (≥ 500µm) > dreissenid mussels ≥ small zooplankton (64-500µm). Differences were evident among the regression slopes describing the relationships between sample Hg concentrations and δ15N values across the lake's three basins (p = 0.028). However, this was primarily attributed to high δ15N values measured in dreissenid mussels collected from the south basin in 2022. Biota sediment accumulation factors ranged from 0.2 to 2.3 and were highest for adult M. diluviana but mysid δ13C values generally supported a pelagic pathway of Hg exposure relative to benthic sediments. Overall, these results provide additional support regarding the contributions of lower trophic levels to Hg biomagnification in aquatic food-webs.

Insights into Temporal Evolution of Induced Earthquakes in the Southern Delaware Basin Using Calibrated Relocations from the TXAR Catalog (2009–2016)

Abstract The Texas Seismological Network (TexNet) has enabled real-time monitoring of induced earthquakes since 2017. Before 2017, location uncertainties and temporal gaps in seismic data obscure correlations across Texas between seismicity and saltwater disposal or hydraulic fracturing. Depth biases also complicate linking anthropogenic stress changes to faults. We relocate 73 M 1.5+ earthquakes from the TXAR catalog (2009–2016) relative to the centroid of a calibrated core cluster consisting of 116 earthquakes from the TexNet catalog post-2020, in the southern Delaware basin south of the Grisham fault zone. Hypocentroidal decomposition relocation reduces spatial uncertainties of the TXAR events to &amp;lt;5 km and provides updated depths. The core cluster has uncertainties less than &amp;lt;300 m and depth constrained from near-source stations and S−P differential times. The majority of relocated TXAR events indicate the triggering of northwest-trending faults at a mean depth of 1 km below sea level, suggesting a causal connection with shallow saltwater disposal and consistency with post-2017 seismicity. Spatiotemporal patterns of pre-2017 seismicity and saltwater disposal highlight initial triggering via pore-pressure stress perturbations from nearby low-volume injections and later from southeastward pressure diffusion along permeable anisotropic conduits and fracture zones. The comparison between pre- and post-2017 seismicity indicates shallow fault reactivation through similar triggering mechanisms since 2009.

Nutrient structure dynamics and microbial communities at the water-sediment interface in an extremely acidic lake in northern Patagonia.

Lake Caviahue (37° 50 'S and 71° 06' W; Patagonia, Argentina) is an extreme case of a glacial, naturally acidic, aquatic environment (pH ~ 3). Knowledge of the bacterial communities in the water column of this lake, is incipient, with a basal quantification of the bacterioplankton abundance distribution in the North and South Basins of Lake Caviahue, and the described the presence of sulfur and iron oxidizing bacteria in the lake sediments. The role that bacterioplankton plays in nutrient utilization and recycling in this environment, especially in the phosphorus cycle, has not been studied. In this work, we explore this aspect in further depth by assessing the diversity of pelagic, littoral and sediment bacteria, using state of the art molecular methods and identifying the differences and commonalties in the composition of the cognate communities. Also, we investigate the interactions between the sediments of Lake Caviahue and the microbial communities present in both sediments, pore water and the water column, to comprehend the ecological relationships driving nutrient structure and fluxes, with a special focus on carbon, nitrogen, and phosphorus. Two major environmental patterns were observed: (a) one distinguishing the surface water samples due to temperature, Fe2+, and electrical conductivity, and (b) another distinguishing winter and summer samples due to the high pH and increasing concentrations of N-NH4+, DOC and SO42-, from autumn and spring samples with high soluble reactive phosphorus (SRP) and iron concentrations. The largest bacterial abundance was found in autumn, alongside higher levels of dissolved phosphorus, iron forms, and increased conductivity. The highest values of bacterial biomass were found in the bottom strata of the lake, which is also where the greatest diversity in microbial communities was found. The experiments using continuous flow column microcosms showed that microbial growth over time, in both the test and control columns, was accompanied by a decrease in the concentration of dissolved nutrients (SRP and N-NH4+), providing proof that sediment microorganisms are active and contribute significantly to nutrient utilization/mobilization.

Middle Pleistocene history of vegetation in the Lotus Lake basin in the extreme south of the Russian Far East

The evolution of vegetation in the Lotus Lake basin in the Middle Pleistocene has been studied. Six phases of paleovegetation evolution based on palynological data have been identified. It has been established that in warm epochs correlating with MIS 11, 9 and 7 in the Lotus Lake Basin were dominated by broad-leaved and coniferous forests with a diverse species composition. Under cooling in MIS 10, the distribution of coniferous-small-leaved forests with the participation of shrubby birch increased. In MIS 8 and 6, the main type of vegetation was represented by coniferous-small-leaved forests with the dominance of pine, birch, spruce and the participation of elm and oak.

Fractal modeling for geochemical data of deep-sea surface sediments: A case study from Zhongsha Island, Southern China Sea

This study applied principal component analysis (PCA), concentration-area (C-A) and spectrum-area (S-A) fractal models to identify geochemical element combination anomalies related to heavy metals from the data for 43 geochemical elements in surface sediments of the Zhongsha Islands. The relationships between these 43 elements were first examined by applying correlation and cluster analysis to the surface sediment sample dataset. The multifractal spectral functions of the 43 elements were then calculated and all elements were classified using the curve shape of the spectral function. The results of classification were consistent with that of cluster analysis, thereby verifying the reliability of fractal analysis of the study area. PCA was then used to identify element combination anomalies and to assess high-value areas of element contents, and the S-A model was used to distinguish between the anomaly and background signal. The results of this multiple-analysis approach show that the element combination anomaly is mainly located in the deep-sea plain area, with a few elevated values in the Zhongsha South Basin. This study showed that quantitative evaluation of anomalies of multi-element associations can effectively delineate a target area and that anomalies of element associations extracted by the S-A fractal method can provide a more accurate outline areas containing high contents of combined elements. This study can act as a theoretical reference for the environmental assessment of the Zhongsha sea area.

Spatial distribution of the biomass of submerged macrophytes in the south basin of Lake Biwa in late August 2022 and significant changes in the macrophyte flora

Spatial distribution of the biomass of submerged macrophytes in the south basin of Lake Biwa in late August 2022 and significant changes in the macrophyte flora

Post-rift magma plumbing system in the northern Great South Basin, New Zealand

Late Cretaceous magmatism has been widely documented in the Great South Basin (GSB) of New Zealand, which is mainly relevant to the Gondwana break-up (105–83 Ma) and the separation of Zealandia from Australia and Antarctica (83–66 Ma). However, the magma plumbing system in the GSB is still poorly understood. In this study, we used a high-resolution 3D seismic reflection data to investigate the igneous intrusions that developed in the northern part of GSB. These igneous intrusions occurred from ∼75 Ma to ∼58 Ma that corresponded to the spreading of the Tasman Sea and the Southern Ocean. Most of the igneous intrusions developed above listric faults which formed during rifting stage. Moreover, dykes are also observed between the listric faults and igneous intrusions. Listric faults, dykes and sills formed the magma plumbing system of GSB. This study explored the possible origin of post-rift magmatism in the GSB, and addressed the post-rift magma plumbing system in detail, which greatly promoted the understanding of GSB’ evolution, resource exploration and marine geological hazard assessment.

Heterogeneous Strain Distribution in the Malawi (Nyasa) Rift, East Africa: Implications for Rifting in Magma‐Poor, Multi‐Segment Rift Systems

AbstractHalf‐graben basins bounded by border faults typify early‐stage continental rifts. Deciphering the role that intra‐rift faults play in rift basin development is challenging as patterns of early‐stage faulting are commonly overprinted by subsequent deformation; yet the characterization of these faults is crucial to understand the fundamental controls on their evolution, their contribution to rift opening, and to assess their seismic hazard. By integrating multiple offshore seismic reflection data sets with age‐dated drill core, late‐Quaternary and cumulative faulting patterns are characterized in the Central and South Basins of the Malawi (Nyasa) Rift, an active, early‐stage rift system. Almost all intra‐rift faults offset a late‐Quaternary lake lowstand surface, suggesting they are active and should be considered in hazard assessments. Fault throw profiles reveal sawtooth patterns indicating segmented slip histories. Observed extension on intra‐rift faults is approximately twice that predicted from hanging wall flexure of the border fault, suggesting that intra‐rift faults accommodate a proportion of the regional extension. Cumulative and late‐Quaternary throws on intra‐rift faults are correlated with throw measured on the border fault in the Central Basin, whereas an anticorrelation is observed in the South Basin. Viewed in a regional context, these differences do not relate solely to the proposed southward younging of the rift. Instead, it is inferred that the distribution of extension is also influenced by variations in lithospheric structure and crustal heterogeneities that are documented along the rift axis.

Seasonality and lake water temperature inferred from the geochemistry and sclerochronology of quaternary freshwater bivalves from the Turkana Basin, Ethiopia and Kenya

Reconstructing past environmental variability at short (annual-decadal) time scales is critical for understanding ecosystem change and ecological drivers of evolution. One promising approach to reconstructing that variability is through the use of stable isotope geochemistry and sclerochronology, the study of growth banding in organisms that undergo accretionary growth. We used a combination of sclerochronology, conventional stable isotope ratios and clumped isotope paleotemperatures to improve our understanding of past seasonality and climate variability in the Turkana Basin (Kenya, Ethiopia), which experiences a highly seasonal (tropical semi-desert) climate. In this case study, we apply these approaches to both Early Pleistocene and Holocene bivalve shells (Etheria and Pseudobovaria) to develop a model using various proxies of seasonal-interannual temporal variability in lake temperature and isotope chemistry. We leverage this model to better understand how lakes in the Turkana Basin have changed over short time-scales in the past. One modern (1979) river oyster has exclusively negative δ18O values through ∼1.5 yrs of growth and clumped isotope temperature reconstructions (30.1–31.5 °C) consistent with a river delta provenance. Late Holocene shells show a wider range of isotopic variability within each shell's growth history than the modern sample (∼2‰ for the modern sample vs. 5–7‰ for the Late Holocene samples) and near modern paleotemperatures, suggesting growth under both seasonal Omo flood pulse and lacustrine conditions. Middle Holocene shells exhibit less δ18O variability, consistent with growth in fresher Lake Turkana water at the end of the African Humid Period (12-5 ka), and with both surface water temperatures and water column temperature range similar to the Late Holocene. The Early Pleistocene shells have large seasonal δ18O cycles (4–7‰), with δ18O values comparable to modern and Holocene deltaic shells, and a large range of paleotemperatures (21.8–31.3 °C, including temperatures notably cooler than those measured in the modern lake: 25–31 °C), reflecting growth under significant seasonality in paleo-Omo River runoff. Oxygen isotope cycles suggest high degrees of seasonality of the paleo-Omo River runoff (or that of other major influents) into paleolake Lorenyang at ∼1.6 Ma, which may be similar to modern hydroclimate conditions. Comparison to prior datasets from nearby outcrops in the same basin suggests an increase in hydroclimate seasonality between 1.9 and 1.6 Ma. The combination of clumped isotope paleotemperature estimates from shallow water species such as E. elliptica with TEX86 measurements (derived here from previously published, contemporaneous sediment core studies from the south basin of Lake Turkana), which record temperatures near the oxycline, may provide a new approach to estimating past temperature variability along a vertical profile in lakes, thereby providing information on water column mixing regimes. Our approach greatly expands our toolkit for understanding coupled climate seasonality and variability in the Turkana Basin.

Gravity inversion by second order approximation applied to the Styrian Basin (Austria)

AbstractAn approximative second order gravity inversion scheme by a truncated power series expansion is applied to derive the thickness of the Neogene, mostly clastic, sedimentary section of the Styrian Basins in South–East Austria, which are sub‐basins of the Pannonian Basin System. These sub‐basins with a derived thickness of up to 4 km are of interest for geothermal exploitation because of the increased geothermal gradient and heat flow observed in the Pannonian Basin in general and a geothermal gradient of 4°–5°/100 m measured in some wells in the Styrian Basin. The Styrian Basin also has been an area for hydrocarbon exploration in the past 50 years, with oil and gas show encountered in several exploration wells and one sub‐commercial gas discovery. The Miocene and Plio–Pleistocene volcanism in the Styrian Basin caused by Miocene crustal thinning is discussed in terms of the influence to the gravity inversion taking the aeromagnetic field into account. The volcanism is of relevance for the geothermal prospectivity but poses problems for the single layer‐based gravity inversion scheme. Results are discussed from a computational side comparing observed and calculated gravity fields but also the match with well data is discussed. In terms of gravity inversion methodology, the presented can be viewed as an approximative fast‐track approach.

Characterising the regional growth of on-farm storages and their implications for water resources under a changing climate

Water demand for agricultural activities has caused a growth in small on-farm storages (i.e., ≥ 0.1 ha to ≤ 10 ha) in many areas worldwide, thereby increasing the capture of landscape runoff which otherwise would enter the catchment drainage system. The cumulative effects of these on-farm storages (colloquially known as farm ponds or farm dams) can result in reduced mean annual flows, particularly during dry years. Climate change, which will very likely exacerbate extreme weather conditions including droughts, may accelerate the growth of farm dams in semi-arid agricultural areas with limited access to surface water. The aim of this study is to evaluate farm dam development and total farm dam water volumes at regional scales using Landsat water indices (WIs). The Murray-Darling Basin (MDB, 1.061 million km2) in south and eastern Australia, which has experienced a sustained growth in farm dams in the 1990s and early 2000s, is used as a case study. Using a pixel validation dataset, four WIs were trialled for their capabilities to detect the presence of water in farm dams. Of the WIs tested here, AWEIshadow showed the best performance. As a result, AWEIshadow was used to establish the year in which water was first observed (i.e., its year of commission) in 727,081 farm dams across the MDB and to calculate the total farm dam volume in the region. Farm dams’ volume in the MDB increased more than twofold between 1990 and 2020, from 1241.0 MCM (million cubic meters) to 2,629.5 MCM. The growth differed across MDB regions, generally accelerating during the ‘Millennium Drought’ (2001–2009). In the entire MDB, there was rapid development in the 1990s with 3.1% growth. Growth was 2.5% from 2000 to 2010, tapering off to 0.6% from 2010 to 2020.In Robertson et al. (this issue), the year-by-year growth in farm dams’ volume were used in a rainfall-runoff model thereby incorporating the time-varying effects of farm dams. Robertson et al. (this issue) show that explicitly modelling farm dams improves the model’s performance relative to a traditional rainfall-runoff model that ignores the effects of farm dams. Hence, this improves the capability of assessing the direct impacts of farm dams and their potential growth in climate change studies.

First Archaeological Record of the Torture and Mutilation of Indigenous Mapuche During the “War of Arauco,” Sixteenth Century

Abstract Newen Antug is a multicomponent (residential and funerary) archaeological site located in the Lácar basin south of Neuquén, Argentina, in the east Andean section of the binational basin of the Valdivia River. Two human skeletons were discovered during the excavation of the site. Based on radiocarbon dating and associated material contexts, the burials can be associated with the period of first contact between the indigenous people of the region with the Spanish. Based on the analysis of historical sources, bioanthropological studies, and forensic data, we postulate that these individuals were tortured victims of the war waged by the Spaniards against the indigenous inhabitants. The skeletal remains present various perimortem trauma. The left hand and distal end of the left forearm was absented in situ and which are discussed as being possible form of mutilations of the upper limbs. Individual 1♀ had a horse (Equus caballus) leg replacing or symbolising the missing left limb. The mutilation practice is recorded as part of the power devices characteristic of the Warfare Phase (1536–1655) of the conquest, when the Spanish were attempting to establish a pre-disciplinary machinery of their “Sovereign Power” in the south-central Chile. The findings reported here extend this process to Northeastern Patagonia in Argentina.