Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics
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The Importance of Using Multi-Level Piezometers to Improve the Estimation of Aquifer Properties from Pumping Tests in Complex Heterogeneous Aquifers
Get PDFReliable estimates of aquifer properties are needed for groundwater resources management and for engineering applications. Pumping tests conducted in fractured aquifers using an open borehole may not produce a proper characterization of the aquifer properties leading to the failure of engineering solutions. In this work, we apply a radial flow model to reproduce the time drawdown curves recorded at an observation borehole instrumented with multi-level piezometers drilled in the Permo-Triassic sandstone, which is a complex fractured hydraulic unit. The radial flow model and the optimization code PEST are used to estimate the aquifer hydraulic parameter values. The model is then used to investigate the implications of replacing the multi-level piezometers with an open borehole. The results show that the open borehole does not only significantly alter the groundwater head and flow patterns around the borehole, but the analysis of the time drawdown curve obtained would produce estimates of aquifer properties that bear no relationship with the actual hydraulic properties of the aquifer. For engineering control studies, the pumping test must be carefully designed to account for the presence of fractures, and these must be represented in the analysis tools to ensure the correct characterization of the hydraulic system
Data-driven eddy closure for oceanic eastward jets
Get PDFClosed parameterizations (aka turbulence closures) are needed for representing the effects of unresolved oceanic mesoscale eddies in non-eddy-resolving and eddy-permitting oceanic general circulation models, such as those used for climate modeling studies. One of the most significant difficulties for parameterizing eddy effects is eddy backscatter, which largely maintains eastward jet extensions of the western-boundary currents and their adjacent recirculation zones. In this paper, we focus on the classical wind-driven, quasigeostrophic double-gyre ocean dynamics and propose and test a novel data-driven eddy closure. For this, the eddy effects are defined as the coarse-grid model errors arising from the approximation of the given eddy-resolving reference solution containing an energetic and coherent eastward jet. Without the eddy effects being taken into account, the coarse-grid non-eddy-resolving version of the model yields no eastward jet at all. These missing eddy effects are restored approximately by the implemented eddy closure that interactively corrects the dynamically resolved potential vorticity field. The closure is data-driven because it utilizes some important information about the actual eddies in the reference solution, which is treated as a substitute for the oceanic observational data. The systematically assessed closure skills are significant because the eddy-parameterized solutions qualitatively correctly recover the eastward jet, which is completely missed otherwise. First, our results serve as a proof of concept for implementing a closure extension into the primitive equations, which are used routinely in comprehensive oceanic general circulation models. Second, our results emphasize the fundamental importance of representing the key eddy/large-scale correlations by any parameterization of the eastward jet eddy backscatter
Tackling temporary names: interim solutions for the taxonomic impediment
Get PDFAgainst a background of the climate and biodiversity crises, there is an urgent need for robust and citable biodiversity information for policy and management decisions. Species are fundamental units of biodiversity and underpin communication in biology. Delineating, describing, and naming species provide the foundation for tracking biodiversity. Taxonomists recognise over 2 million described species, the scientific names of which follow provisions of codes of nomenclature, providing stability for communication about biodiversity. However, described species represent only a fraction of global biodiversity. Current advances in the fields of molecular biology and the growing use of image-based identifications have resulted in an explosion of informal species names globally, herein referred to as temporary names, increasing the rate of discovery of undescribed species and cryptic species complexes. We define two categories of temporary names: Type 1 names that are delineated in a local context but not further assessed; and Type 2 names that have been taxonomically assessed and recognised as either new or part of an unresolved species complex. We explore the different types and uses of temporary names, indicate how they can be managed in a robust and standardised manner and demonstrate how biodiversity databases, such as WoRMS, can be expanded to allow the tracking of both formal and informal scientific names. We propose a solution for the expanding problem of temporary names by defining and recommending the addition of Type 2 temporary names to nomenclatural databases such as WoRMS. We provide practical recommendations on how such names should be selected for entry and then entered to databases in a standardised way. These recommendations are a small step forward, but their broad adoption would support the robust integration of informal and formal taxonomies
Economic valuation of BGS’ National Geological Repository: final summary report
Get PDFThe British Geological Survey (BGS) is the UK’s national geological survey and one of the oldest institutions of its kind globally. Founded in 1835, BGS now operates as a mission-led research centre within UK Research and Innovation (UKRI), under the Natural Environment Research Council (NERC). Its work focuses on improving the UK’s understanding of its subsurface environment – and enabling the best use of this environment to support key policy initiatives, the energy transition, infrastructure delivery and economic development – through systematic geological surveying, long-term monitoring, data curation and applied research.
At the heart of BGS’ work is the National Geological Repository (NGR) — the UK’s principal archive of physical geological samples and subsurface data. Located at BGS’ headquarters in Nottinghamshire, the NGR houses over 16 million geological samples and specimens, including over 600km of drill core (cylindrical sections of subsurface rock, 30-150mm in diameter and 1-3m in length) collected from UK boreholes and wells. These collections are a critical national asset, providing data and insight into the geology of the UK and its Continental Shelf, that can be analysed and examined to inform the nation’s energy transition, management of its natural resources, and resilience to environmental hazards.
This study focuses on the NGR – rather than the work of BGS more broadly – and assesses the value that the NGR has delivered to date for the UK. In doing so it also sets out the key strategic arguments for why further investment in the NGR — particularly in digitisation and expanded storage capacity — is necessary to unleash the potential of its collections as nationally enabling infrastructure. This study was commissioned by BGS, in recognition of the challenges facing the NGR, and was delivered by Human Economics, supported by Ipsos
Faithful transfer of radiolarian silicon isotope signatures from water column to sediments in the South China Sea
Get PDFRadiolarian silicon isotopes (δ30Sirad) hold significant potential as a proxy for constraining past silicon cycling in seawater. However, the extent to which δ30Sirad signatures in sediments accurately represent the isotopic signals of the overlying water column remains unclear, particularly under the influence of radiolarian shell dissolution during sinking and burial in the sediment record. This study presents the first comparative analysis of δ30Sirad compositions and the radiolarian assemblage community using water column and surface sediment samples collected from the South China Sea (SCS). The results indicate that δ30Sirad values range from 1.56 ‰–1.83 ‰ (mean = 1.74 ‰) in the water column and from 1.61 ‰–1.85 ‰ (mean = 1.73 ‰) in surface sediments, with the fractionation factor for δ30Sirad varying from −0.33 ‰ to −0.92 ‰ (mean = −0.58 ‰). δ30Sirad signatures in the water column are primarily contributed to by radiolarians from the 0–100 m water depth layer. No significant discrepancies in δ30Sirad values were observed between plankton and sediment samples at each sampling station, as evidenced by the paired t test (p = 0.75), implying that dissolution has a minimal impact on δ30Sirad during the transfer of radiolarian shells to the sediment record. This finding may be enhanced by the dominance of more dissolution-resistant Spumellaria and Nassellaria taxa (> 99 % relative abundance) within the radiolarian community, coupled with the scarcity or absence of the readily dissolvable radiolarian taxa in the analysed samples. This study demonstrates the faithful preservation of the δ30Sirad signature and its potential for studying past changes in the marine silicon cycle
Late Holocene sedimentation and palaeoagronomy in a carbonate dry valley system using OSL, sedaDNA and geochemistry: implications for understanding anthropogenic slope-sediment transfer in fluvial headwaters
Get PDFThe understanding of landscape stability and erosional regimes from carbonate geological areas has traditionally been limited to fluvial areas due to the lack of lakes and the predominance of clastic-dominated valley fills. The combination of novel Optically Stimulated Luminescence (OSL) dating and sediment ancient DNA opens up new possibilities to study these geomorphological, ecological and agrarian changes in clastic‑carbonate landscapes. Here, we use OSL dating and sedaDNA analyses alongside traditional geoarchaeological techniques to examine potential anthropogenic and palaeoclimatic drivers of sediment transfer within a loessic-dominated dry valley with agricultural lynchets at Sint Martens-Voeren, eastern Belgium, through the late Holocene.
Cultivation of loess-dominated sediments across the dry-valley hilltop occurred from the Bronze Age (1900–700 BCE), with lynchet formation on the steep valley sides occurring from later prehistory (Iron Age 700–50 BCE). Major erosion and valley bottom sedimentation began in the early medieval period (450–1000 CE) and accelerated in the medieval and post medieval periods (1000–1750 CE) in line with an intensification of arable cultivation, particularly beet and hops, the development of open three-field agrarian diversity, landscape connectivity and increased climatic variability. This pattern of late Holocene slope-sediment erosion, transfer and storage mirrors other dry valley sites in the Voer catchments, especially in relation to lynchets, and accelerations in sedimentation in other eastern Belgian fluvial catchments, driven by high-intensity palaeoagronomic systems
Secular compositional changes in granitoids and felsic volcanics: the tectonic setting control
No full textThis study presents results for secular compositional change of 12 geochemical variables in granitoids and felsic volcanics in the last 3 Gyr grouped into two tectonic settings, orogenic and within-plate. Time series are constructed from median values of geochemical data compiled in 250-Myr bins. Within-plate granitoid and felsic volcanic time series (high SiO2, (Na2O + K2O)/CaO, Fe Index, Y + Nb, Ga/Al; low Sr/Y, Eu/Eu*, La/Nb) are displaced from the orogenic series, consistent with shallow depths of magma generation and an overall lower degree of partial melting or/and more fractional crystallization for within-plate magmas through time. Orogenic granitoid and felsic volcanic geochemical time series for La/Yb, Th/Yb, La/Nb, Y + Nb, and Yb are similar and show a transition at the end of the from dominantly restitic garnet-amphibole-rutile to plagioclase control, the latter reflecting shallower depths of magma generation. Relatively high Eu/Eu* in Archean granitoids and felsic volcanics (and high Sr/Y in Archean granitoids) may imply that plagioclase accumulation is more effective before 2.5 Ga than afterwards, consistent with large volumes of TTG (tonalite-trondhjemite-granodiorite) in the Archean. Low Sr/Y and Eu/Eu* of granitoids and felsic volcanics in the last 1750 Myr likely require significant plagioclase removal by fractional crystallization or/and plagioclase presence in the melting restite. Fractionation of Th from La beginning at 1500 Ma may reflect a change to an apatite-dominated restite, perhaps in response to greater amounts of subducted P-rich sediments entering the sources of felsic magma. Increases in Yb, Y + Nb, and Fe Index and decreases in La/Nb, Eu/Eu*, Sr/Y, La/Yb and Th/Yb in orogenic settings during assembly of Columbia (1800–1500 Ma) reflect shallowing of magma sources, perhaps in hot back-arc basins. Our findings show the importance of tectonic setting on the compositional evolution of felsic magmas, highlighting the need to consider the differences between orogenic and within-plate processes when reconstructing the compositional history of the continental crust into deep time
Exploring the role of ethnicity and culture in shaping greenspace practices: a qualitative study from Bristol, UK
Get PDFGreenspaces provide multiple wellbeing and social benefits, yet ethnic minorities often have restricted engagement with these spaces which reinforces health inequalities. Addressing these requires a detailed understanding of the diversity of ethnic minorities’ perceptions, preferences, and practices relating to greenspaces. Through thematic analysis of interview and diary transcripts from 53 people from multiple ethnic minority groups in Bristol, UK, we identify various ways in which ethnicity and culture influence engagement with greenspaces. We find that cultural background and childhood experiences are particularly important in shaping attitudes towards greenspaces; transnational perspectives originating from cultural heritage and familial history influence how people perceive and adapt to UK greenspace conditions; and cultural considerations, perceived exclusion, and gender combine with intersectional identities to mediate experiences and engagement patterns. We draw from a novel integration of theoretical work on affordances with practices to theorise and synthesise these findings, contributing to understanding how cultural and social factors shape greenspace use. Our findings suggest that structured access initiatives, such as peer-led walking groups, and physical environment modifications, including zoning and washing facilities, can enhance the cultural inclusivity of greenspaces while addressing systemic barriers to engagement. These insights offer practical guidance for urban planners and greenspace managers seeking to create more equitable and inclusive spaces that reflect and serve increasingly diverse communities
Controls on dense-water formation along the path of the North Atlantic subpolar gyre
Get PDFThe North Atlantic subpolar gyre (SPG) plays a fundamental role in the global climate system through the formation of dense North Atlantic Deep Water (NADW) as part of the Atlantic Meridional Overturning Circulation. Observations show pronounced decadal variability in SPG water mass properties; however, it remains unclear to what extent such thermohaline changes impact the formation of dense water. Here, we explore the mechanisms governing dense-water formation along the path of the SPG using Lagrangian water parcel trajectories in an eddy-rich ocean sea ice hindcast. We show that neither the rate of transformation of water parcels across density surfaces nor their thermohaline properties on arrival into the eastern SPG are rate-limiting factors governing dense-water formation. Instead, the total amount of dense water formed during transit around the SPG can be skilfully predicted based solely on the volume transport of light, upper-limb waters arriving into the eastern SPG via the branches of the North Atlantic Current. This relationship between upper-limb volume transport and dense-water formation emerges since the SPG boundary current is long enough for all upper-limb thermal anomalies to be damped during transit. Our findings emphasise the close relationship between the strength of the SPG and subpolar dense-water formation on multi-decadal timescales, such that a stronger SPG circulation following persistent positive phases of the North Atlantic Oscillation results in greater NADW formation along-stream. This underscores the importance of monitoring the state of the SPG for both decadal and longer-term climate predictions
Scotland's changing flora: a summary of key findings from Plant Atlas 2020. A report to NatureScot, February 2025
Get PDFReport produced for NaureScot summarising the findings of Plant Atlas 2020 for Scotland and based on the trends for plant species in Scotland and with expert attribution of drivers and interpretation
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