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Geosciences, Volume 11, Issue 9 (September 2021) – 44 articles

Cover Story (view full-size image): High-elevation, low-relief limestone plateaus such as the forefield of the Vorab glacier are common landscapes. It is suggested that their formation is related to the inability of glaciers to erode thick-bedded, flat-lying limestone, due to the effective water drainage system into the karst system. By combining cosmogenic nuclide techniques with numerical modeling, we determined glacial erosion rates directly on glacial abraded surfaces. Extremely low glacial erosion rates (0.16 mm a−1) across the glacier forefield were observed, highlighting that Alpine limestone plateaus evolved over many glacial cycles. The lack of subglacial water inhibited glacier sliding, reducing glacial erosion. View this paper
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Article
Morphoneotectonics of the Abruzzo Periadriatic Area (Central Italy): Morphometric Analysis and Morphological Evidence of Tectonics Features
Geosciences 2021, 11(9), 397; https://doi.org/10.3390/geosciences11090397 - 20 Sep 2021
Cited by 2 | Viewed by 1248
Abstract
Drainage basin-scale morphometric analysis and morphological evidence of tectonics represent helpful tools to evaluate and investigate morphoneotectonic processes in tectonically active regions. In this perspective, we applied an integrated analysis to the Abruzzo Periadriatic Area, between the Tronto and Sinello rivers (Central Italy). [...] Read more.
Drainage basin-scale morphometric analysis and morphological evidence of tectonics represent helpful tools to evaluate and investigate morphoneotectonic processes in tectonically active regions. In this perspective, we applied an integrated analysis to the Abruzzo Periadriatic Area, between the Tronto and Sinello rivers (Central Italy). It involved morphometric analysis, structural geomorphological field mapping, and detailed analysis of fluvial terraces. Geomorphic indexes and markers (e.g., Irta, SL index, ksn, and knickpoints) were used in this study to detect the response of landscapes to drainage systems’ unsteadiness and tectonic deformation processes, possibly induced by the ongoing activity of the buried tectonic structures. Furthermore, the investigation of morphological field evidence of tectonics, integrated with the analysis of fluvial terraces’ spatial and temporal arrangement, was performed to assign relative, geomorphologically-based, age constraints of the landscape evolution. The resulting data allowed us to define domains affected by different morphostructural and morphoneotectonic processes, related to the impact and ongoing activity of the five detected families of structural elements (S1, F1, F2, F3, and F4), mainly characterized by compressive, extensional, and transtensive kinematics. Finally, this study could represent a scientific basis for integrating morphometric, fluvial, and tectonic geomorphology analysis to better define the main phases of the landscape evolution and the impact of morphoneotectonic processes on fluvial environments in uplifting piedmont areas. Full article
(This article belongs to the Section Structural Geology and Tectonics)
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Editorial
Editorial of Special Issue "Modern Surveying and Geophysical Methods for Soil and Rock"
Geosciences 2021, 11(9), 396; https://doi.org/10.3390/geosciences11090396 - 20 Sep 2021
Viewed by 510
Abstract
Thanks to the rapid development of technology, the field of soil and rock investigation has made significant progress in recent decades [...] Full article
(This article belongs to the Special Issue Modern Surveying and Geophysical Methods for Soil and Rock)
Article
Surface and Subsurface Damage Caused by Bullet Impacts into Sandstone
Geosciences 2021, 11(9), 395; https://doi.org/10.3390/geosciences11090395 - 17 Sep 2021
Viewed by 828
Abstract
The shift of armed conflicts to more urbanised environments has increased the risk to cultural heritage sites. Small arms impacts are ubiquitous in these circumstances, yet the effects and mechanisms of damage caused are not well known. A sandstone target was shot under [...] Read more.
The shift of armed conflicts to more urbanised environments has increased the risk to cultural heritage sites. Small arms impacts are ubiquitous in these circumstances, yet the effects and mechanisms of damage caused are not well known. A sandstone target was shot under controlled conditions to investigate surface and subsurface damage. A 3D model of the damaged block, created by structure from motion photogrammetry, shows that internal fracturing was at least as extensive as the visible surface fractures. Backscatter electron imaging of the damaged surface shows a shift from intragranular fracturing and grain size reduction at <5 mm from the impact point to primarily circumgranular fracturing and grain ‘plucking’ at 20 mm from the impact point. Internal fracture intensity decreased with distance from the centre of the crater. Volumes around the impact point are therefore at greater risk of subsequent weathering deterioration, but significant damage extends to the periphery of the target, rendering whole blocks vulnerable. The surface crater, despite being one of the most conspicuous aspects of conflict damage, has many times less area than internal and surface fractures. Full article
(This article belongs to the Section Geoheritage, Geoparks and Geotourism)
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Article
Securing the Limits of Large Ocean States in the Pacific: Defining Baselines Limits and Boundaries amidst Changing Coastlines and Sea Level Rise
Geosciences 2021, 11(9), 394; https://doi.org/10.3390/geosciences11090394 - 17 Sep 2021
Viewed by 685
Abstract
The Pacific Island States and Territories are traditionally described as ‘small island’ nations. However, they are also ‘large ocean’ nations with jurisdiction over substantial maritime spaces stretching to at least 200 nautical miles. The article addresses issues related to baselines along the coast [...] Read more.
The Pacific Island States and Territories are traditionally described as ‘small island’ nations. However, they are also ‘large ocean’ nations with jurisdiction over substantial maritime spaces stretching to at least 200 nautical miles. The article addresses issues related to baselines along the coast on which these broad maritime claims depend. The article then examines geodynamic considerations coupled with sea and land level projections in the Pacific leading to an assessment of the vulnerability or resilience of atolls in particular. The article then discusses potential implications for the coastlines and baselines of the Pacific Island States and Territories, the limits of their maritime entitlements and both delimited and undelimited maritime boundaries. Potential response options, prospects, and concluding thoughts are then offered. Full article
(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)
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Article
Formation of Gas-Emission Craters in Northern West Siberia: Shallow Controls
Geosciences 2021, 11(9), 393; https://doi.org/10.3390/geosciences11090393 - 17 Sep 2021
Cited by 2 | Viewed by 1104
Abstract
Gas-emission craters discovered in northern West Siberia may arise under a specific combination of shallow and deep-seated permafrost conditions. A formation model for such craters is suggested based on cryological and geological data from the Yamal Peninsula, where shallow permafrost encloses thick ground [...] Read more.
Gas-emission craters discovered in northern West Siberia may arise under a specific combination of shallow and deep-seated permafrost conditions. A formation model for such craters is suggested based on cryological and geological data from the Yamal Peninsula, where shallow permafrost encloses thick ground ice and lenses of intra- and subpermafrost saline cold water (cryopegs). Additionally, the permafrost in the area is highly saturated with gas and stores large accumulations of hydrocarbons that release gas-water fluids rising to the surface through faulted and fractured crusts. Gas emission craters in the Arctic can form in the presence of gas-filled cavities in ground ice caused by climate warming, rich sources of gas that can migrate and accumulate under pressure in the cavities, intrapermafrost gas-water fluids that circulate more rapidly in degrading permafrost, or weak permafrost caps over gas pools. Full article
(This article belongs to the Special Issue Permafrost and Gas Hydrate Response to Ground Temperature Rising)
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Article
Influence of a Thin Horizontal Weak Layer on the Mechanical Behaviour of Shallow Foundations Resting on Sand
Geosciences 2021, 11(9), 392; https://doi.org/10.3390/geosciences11090392 - 16 Sep 2021
Viewed by 553
Abstract
The presence of minor details of the ground, including soil or rock masses, occurs more frequently than what is normally believed. Thin weak layers, shear bands, and slickensided surfaces can substantially affect the behaviour of foundations, as well as that of other geostructures. [...] Read more.
The presence of minor details of the ground, including soil or rock masses, occurs more frequently than what is normally believed. Thin weak layers, shear bands, and slickensided surfaces can substantially affect the behaviour of foundations, as well as that of other geostructures. In fact, they can affect the failure mechanisms, the ultimate bearing capacity of footings, and the safety factor of the geotechnical system. In this research, numerically conducted through Finite Element Code Plaxis 2D, the influence of a horizontal thin weak layer on the mechanical behaviour of shallow footings was evaluated. The obtained results prove that the weak layer strongly influences both the failure mechanism and the ultimate bearing capacity if its depth is lower than two to four times the footing width. In fact, under these circumstances, the failure mechanisms are always mixtilinear in shape because the shear strains largely develop on the weak layer. However, the reduction in the ultimate bearing capacity is a function of the difference between the shear strength of the foundation soil and the layer. The presence of a thin weak layer decreases the ultimate bearing capacity up to 90%. In conclusion, this research suggests that particular attention must be paid during detailed ground investigations to find thin weak layers. Based on the obtained results, it is convenient to increase the soil volume investigation to a depth equal to four times the width of the foundation. Full article
(This article belongs to the Special Issue Numerical Modeling in Geotechnical Engineering)
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Article
SNR-Based GNSS-R for Coastal Sea-Level Altimetry
Geosciences 2021, 11(9), 391; https://doi.org/10.3390/geosciences11090391 - 16 Sep 2021
Cited by 1 | Viewed by 765
Abstract
Geodetic Global Navigation Satellite System reflectometry (GNSS-R) uses ground-based signals of opportunity to retrieve sea levels at an intermediate spatial scale. Geodetic GNSS-R is based on the simultaneous reception of Line-of-Sight (LoS) and its coherent GNSS sea surface reflection (non-LOS) signals. The scope [...] Read more.
Geodetic Global Navigation Satellite System reflectometry (GNSS-R) uses ground-based signals of opportunity to retrieve sea levels at an intermediate spatial scale. Geodetic GNSS-R is based on the simultaneous reception of Line-of-Sight (LoS) and its coherent GNSS sea surface reflection (non-LOS) signals. The scope of this paper is to present geodetic GNSS-R applied to sea level altimetry. Signal-to-Noise Ratio (SNR) measurements from a Commercial Off-The-Shelf (COTS) geodetic-quality GNSS station at the Haiti Coast Guard Base in Port-au-Prince is used to retrieve sea levels in the International Terrestrial Reference Frame 2014 (ITRF2014). The GNSS-R sea levels are compared with those of the OTT Radar Level Sensor (RLS) installed vertically below the GNSS antenna. The Root-Mean-Square Error (RMSE) between the geodetic GNSS-R sea levels and OTT RLS records is 3.43 cm, with a correlation of 0.96. In addition, the complex differences between the OTT RLS records and 15-min GNSS-R sea levels using Global Positioning System (GPS) and Globalnaya Navigazionnaya Sputnikovaya Sistema (or Global Navigation Satellite System; GLONASS) signals for all the eight major tidal constituents are in mm-level agreement. Therefore, geodetic GNSS-R can be used as a complementary approach to the conventional method for sea level studies in a stable terrestrial reference frame. Full article
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Article
Cosmogenic Exposure Dating (36Cl) of Landforms on Jan Mayen, North Atlantic, and the Effects of Bedrock Formation Age Assumptions on 36Cl Ages
Geosciences 2021, 11(9), 390; https://doi.org/10.3390/geosciences11090390 - 15 Sep 2021
Cited by 2 | Viewed by 1218
Abstract
Jan Mayen is a small volcanic island situated 550 km north of Iceland. Glacial sediments and landforms are relatively common on the island but, so far, only a few of them have been dated. In this study, we present and discuss 89 36 [...] Read more.
Jan Mayen is a small volcanic island situated 550 km north of Iceland. Glacial sediments and landforms are relatively common on the island but, so far, only a few of them have been dated. In this study, we present and discuss 89 36Cl dates of primarily glacial and volcanic events on Jan Mayen. Calculations of sample exposure ages were complicated by young exposure ages, young rock formation age, and high native Cl contents, leading to updates in CRONUScalc to enable accurate exposure age calculations. The samples provide good evidence against an equilibrium assumption when subtracting background production (e.g., 36Cl produced by neutron capture from fission of U or Th) for samples on young bedrock, with younger exposure ages most significantly affected. Exposure ages were calculated with a range of assumptions of bedrock formation ages appropriate for Jan Mayen, including the assumption that the rock formation age equaled the exposure age (i.e., the youngest age it could possibly have), and we found that although the effect on most of the ages was small, the calculated ages of 25 of the samples increased by more than 1 standard deviation from the age calculated assuming equilibrium background production, with a maximum deviation of 6.1 ka. Due to the very young bedrock on Jan Mayen, we consider the nonequilibrium ages to be the most reliable ages from the island and conclude that large-scale deglaciation on the south and central, lower-lying, parts of the island, started around 20 ka and lasted until ~7 ka. On northern Jan Mayen, the slopes of the 2277 m high stratovolcano Beerenberg are currently partly glaciated; however, outside of the Little Ice Age moraines, all but two samples give ages between 14 and 5.7 ka. Full article
(This article belongs to the Special Issue Cutting Edge Earth Sciences: Three Decades of Cosmogenic Nuclides)
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Article
Stabilization of the Lower Jamuna River in Bangladesh—Hydraulic and Morphological Assessment
Geosciences 2021, 11(9), 389; https://doi.org/10.3390/geosciences11090389 - 14 Sep 2021
Cited by 1 | Viewed by 1346
Abstract
This paper presents a hydraulic and morphological analysis of the Lower Jamuna in Bangladesh with a focus on two key bifurcations that are important for stabilization of the Lower Jamuna reach. We used ground measurements, historical data, multispectral satellite images from various sources [...] Read more.
This paper presents a hydraulic and morphological analysis of the Lower Jamuna in Bangladesh with a focus on two key bifurcations that are important for stabilization of the Lower Jamuna reach. We used ground measurements, historical data, multispectral satellite images from various sources as well as numerical models. We carried out hydraulic analyses of the changes and their peculiarities, such as flow distributions at the bifurcation and hysteresis of the stage–discharge relationships. We supplemented our analysis by using numerical models to simulate discharge distribution at the bifurcations under various flow and riverbed conditions. We developed an advanced and automated satellite image processing application for the Lower Jamuna, referred to as Morphology Monitor (MoMo), using the Google Earth Engine. MoMo was found to be an effective tool for a rapid assessment and analysis of the changes in deep-channel and sandbar areas. It is also useful for monitoring and assessing riverbank and char erosion and accretion, which is important not only for morphological but also ecological impact assessment. The application can be adapted as an operational tool as well. Furthermore, we assessed the evolution of deep channels at the bifurcations based on regularly and extensively measured bathymetry data. The analysis was carried out in complement with morphological modeling, particularly for short-term prediction. In this paper we present the major findings of the analysis and discuss their implications for adaptive river management. Full article
(This article belongs to the Special Issue Recent Advances on Sediment Transport and River Morphodynamics)
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Article
Identification of Near-Fault Impulsive Signals and Their Initiation and Termination Positions with Convolutional Neural Networks
Geosciences 2021, 11(9), 388; https://doi.org/10.3390/geosciences11090388 - 13 Sep 2021
Viewed by 986
Abstract
Ground motions recorded in near-fault regions may contain pulse-like traces in the velocity domain. Their long periodicity can identify such signals with large amplitudes. Impulsive signals can be hazardous for buildings, creating large demands due to their long periods. In this study, a [...] Read more.
Ground motions recorded in near-fault regions may contain pulse-like traces in the velocity domain. Their long periodicity can identify such signals with large amplitudes. Impulsive signals can be hazardous for buildings, creating large demands due to their long periods. In this study, a dataset was collected from various data centres. Initially, all the impulsive signals, which are in reality rare, are manually identified. Furthermore, then, synthetic velocity waveforms are created to increase the number of impulsive signals by using the model developed by Mavroeidis and Papageorgiou, and k2 kinematic modelling. In accordance, a convolutional neural network (CNN) was trained to detect impulsive signals by using these synthetic impulsive signals and ordinary signals. Furthermore, manually labelled impulsive signals are used to detect the initiation and the termination positions of impulsive signals. To do so, the velocity waveform and position and amplitude information of the maximum and minimum points are used. Once the model detects the positions, the period of the pulse is calculated by analysing spectral periods. Although our detection algorithm works relatively worse than three robust algorithms used for benchmarks, it works significantly better in the determination of initiation and termination positions. At this moment, our models understand the features of the impulsive signals and detect their location without using any thresholds or any formulations that are heavily used in previous studies. Full article
(This article belongs to the Section Natural Hazards)
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Article
Why Disaster Subcultures Matter: A Tale of Two Communities: How and Why the 2007 Western Solomon Islands Tsunami Disaster Led to Different Outcomes for Two Ghizo Communities
Geosciences 2021, 11(9), 387; https://doi.org/10.3390/geosciences11090387 - 11 Sep 2021
Viewed by 662
Abstract
At 07:45 a.m. on 2 April 2007, a tsunami hit Ghizo Island, western Solomon Islands in the south-west Pacific. Thirty-three people died on Ghizo, of whom 31 originated from a relatively small migrant Gilbertese community (transmigrated in the 1950s–1970s from Kiribati), while only [...] Read more.
At 07:45 a.m. on 2 April 2007, a tsunami hit Ghizo Island, western Solomon Islands in the south-west Pacific. Thirty-three people died on Ghizo, of whom 31 originated from a relatively small migrant Gilbertese community (transmigrated in the 1950s–1970s from Kiribati), while only two were from the majority Melanesian community. This paper documents an extensive 4-year study that addresses the potential core reasons for this asymmetrical casual impact. Community-participatory social science research was undertaken in two Gilbertese villages and two Melanesian villages. The four villages had similar spatial vulnerabilities due to their coastal location, although they had variable access to the safer higher ground. Gilbertese villages had less diverse ocean-reliant livelihoods, a limited knowledge of hinterland bush resource utilisation, uncertainties regarding land rights, and perceived ethnic discrimination. Melanesian villages had strong wantok and kastom social reciprocity cultures, a diverse set of livelihoods, wider social capital with other Melanesian communities, and greater security regarding land rights. This paper argues that these key factors—linked to the lower status as a migrant community of the Gilbertese, a limited sharing of knowledge between communities, government blind spots and power hierarchies—explain both the disproportionate impacts of the disaster and issues that impact longer-term aid intervention and social cohesion. Full article
(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)
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Article
GPR Detection of Fossil Structures in Conductive Media Supported by FDTD Modelling and Attributes Analysis: An Example from Early Pleistocene Marine Clay at Bargiano Site (Central Italy)
Geosciences 2021, 11(9), 386; https://doi.org/10.3390/geosciences11090386 - 11 Sep 2021
Cited by 1 | Viewed by 791
Abstract
The application of Ground Penetrating Radar (GPR) prospecting to the search of fossil structures, particularly using advanced techniques like Finite-difference time-domain (FDTD) modelling and GPR attribute analysis, is currently poorly exploited in paleontology. Here, we promote the use of such a GPR workflow [...] Read more.
The application of Ground Penetrating Radar (GPR) prospecting to the search of fossil structures, particularly using advanced techniques like Finite-difference time-domain (FDTD) modelling and GPR attribute analysis, is currently poorly exploited in paleontology. Here, we promote the use of such a GPR workflow at Bargiano (Umbria, central Italy), a unique paleontological site known for the discovery of cetacean skeletons, dolomitized sperm-whale cololites (Ambergrisichnu salleronae), and layered fossil assemblages. The study site is characterized by a very uneven topography shaping highly conductive clayey deposits, representing not exactly ideal conditions for GPR surveying. After generating models encompassing a real topography and variable electrical properties of media, we simulated buried fossil structures at variable depth with different size and geometry, using different operative frequencies. After obtaining information on the characteristics of reflections, investigation depth, and detectability, we provide a comparison with experimental data, also used to compute instantaneous amplitude and phase attributes. Upon depicting a peculiar GPR signature for our targets, we discuss the results in light of ground-truthing performed through trenching. Our workflow allowed us to restrict the excavation areas, extending the surface information in depth in a non-invasive way, and optimizing the field operations, necessary for the preservation of the study site. Full article
(This article belongs to the Section Geophysics)
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Article
Influence of Sediment Cycling on the Rare-Earth Element Geochemistry of Fluvial Deposits (Caculuvar–Mucope, Cunene River Basin, Angola)
Geosciences 2021, 11(9), 384; https://doi.org/10.3390/geosciences11090384 - 11 Sep 2021
Viewed by 783
Abstract
The rare-earth element (REE) geochemistry of sedimentary deposits has been used in provenance investigations despite the transformation that this group of elements may suffer during a depositional cycle. In the present investigation, we used the geochemistry and XRD mineralogy of a set of [...] Read more.
The rare-earth element (REE) geochemistry of sedimentary deposits has been used in provenance investigations despite the transformation that this group of elements may suffer during a depositional cycle. In the present investigation, we used the geochemistry and XRD mineralogy of a set of sand and mud fluvial deposits to evaluate the ability of REE parameters in provenance tracing, and the changes in REE geochemistry associated with weathering and sorting. The analyzed deposits were generated in a subtropical drainage basin where mafic and felsic units are evenly represented, and these crystalline rocks are covered by sedimentary successions in a wide portion of the basin. A few element ratios appear to hold robust information about primary sources (Eu/Y, Eu/Eu*, LaN/YbN, LaN/SmN, and GdN/YbN), and the provenance signal is best preserved in sand than in mud deposits. Sediment cycles, however, change the REE geochemistry, affecting mud and sand deposits differently. They are responsible for significant REE depletion through quartz dilution in sands and may promote discernible changes in REE patterns in muds (e.g., increase in Ce content and some light REE depletion relative to heavy REE). Full article
(This article belongs to the Special Issue Rare Earth Elements (REEs) in Fluvial Sediments)
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Review
Marine Monitoring for Offshore Geological Carbon Storage—A Review of Strategies, Technologies and Trends
Geosciences 2021, 11(9), 383; https://doi.org/10.3390/geosciences11090383 - 11 Sep 2021
Viewed by 805
Abstract
Carbon capture and storage (CCS) could significantly contribute to reducing greenhouse gas emissions and reaching international climate goals. In this process, CO2 is captured and injected into geological formations for permanent storage. The injected plume and its migration within the reservoir is [...] Read more.
Carbon capture and storage (CCS) could significantly contribute to reducing greenhouse gas emissions and reaching international climate goals. In this process, CO2 is captured and injected into geological formations for permanent storage. The injected plume and its migration within the reservoir is carefully monitored, using geophysical methods. While it is considered unlikely that the injected CO2 should escape the reservoir and reach the marine environment, marine monitoring is required to verify that there are no indications of leakage, and to detect and quantify leakage if it should occur. Marine monitoring is challenging because of the considerable area to be covered, the limited spatial and temporal extent of a potential leakage event, and the considerable natural variability in the marine environment. In this review, we summarize marine monitoring strategies developed to ensure adequate monitoring of the marine environment without introducing prohibitive costs. We also provide an overview of the many different technologies applicable to different aspects of marine monitoring of geologically stored carbon. Finally, we identify remaining knowledge gaps and indicate expected directions for future research. Full article
(This article belongs to the Special Issue Mechanical Integrity of CO2 Storage Sites)
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Article
The Sacred Waterscape of the Temple of Bastet at Ancient Bubastis, Nile Delta (Egypt)
Geosciences 2021, 11(9), 385; https://doi.org/10.3390/geosciences11090385 - 10 Sep 2021
Cited by 1 | Viewed by 997
Abstract
Sacred water canals or lakes, which provided water for all kinds of purification rites and other activities, were very specific and important features of temples in ancient Egypt. In addition to the longer-known textual record, preliminary geoarchaeological surveys have recently provided evidence of [...] Read more.
Sacred water canals or lakes, which provided water for all kinds of purification rites and other activities, were very specific and important features of temples in ancient Egypt. In addition to the longer-known textual record, preliminary geoarchaeological surveys have recently provided evidence of a sacred canal at the Temple of Bastet at Bubastis. In order to further explore the location, shape, and course of this canal and to find evidence of the existence of a second waterway, also described by Herodotus, 34 drillings and five 2D geoelectrical measurements were carried out in 2019 and 2020 near the temple. The drillings and 2D ERT surveying revealed loamy to clayey deposits with a thickness of up to five meters, most likely deposited in a very low energy fluvial system (i.e., a canal), allowing the reconstruction of two separate sacred canals both north and south of the Temple of Bastet. In addition to the course of the canals, the width of about 30 m fits Herodotus’ description of the sacred waterways. The presence of numerous artefacts proved the anthropogenic use of the ancient canals, which were presumably connected to the Nile via a tributary or canal located west or northwest of Bubastis. Full article
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Article
The “Sant’Angelo in Criptis” Cave Church in Santeramo in Colle (Apulia, South Italy): A Multidisciplinary Study for the Evaluation of Conservation State and Stability Assessment
Geosciences 2021, 11(9), 382; https://doi.org/10.3390/geosciences11090382 - 10 Sep 2021
Viewed by 661
Abstract
Sant’Angelo in Criptis (Santeramo in Puglia, South Italy) is a karst cave located in the Alta Murgia National Park (aspiring geopark), presently degraded, but with signs of intense past visiting activity for worship, as testified by the beautiful wall paintings and the large [...] Read more.
Sant’Angelo in Criptis (Santeramo in Puglia, South Italy) is a karst cave located in the Alta Murgia National Park (aspiring geopark), presently degraded, but with signs of intense past visiting activity for worship, as testified by the beautiful wall paintings and the large number of inscriptions and engravings on the cave walls. With the aim to permit the desirable restoration and the following fruition of this ancient geo-cultural heritage, a multidisciplinary investigation of the cave was carried out in this study. The 3D cave model permitted a detailed map of the area and highlighted that the cave vault, although very regular, somewhere presents chimneys that develop upwards, indicating areas where the rock thickness is now very small. The stability analysis indicates that presently, the cave does not show remarkable signs of instability, but block failures, toppling and roof collapse are possible. Archaeometry investigations confirmed the past importance of this holy site, as testified by the overlapping in the paintings of three different pictorial cycles and the use of precious pigments, thus confirming the necessity of preservation through a conservation management strategy for a full future fruition of the cave. Full article
(This article belongs to the Section Geoheritage, Geoparks and Geotourism)
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Review
From Geoheritage to Geoeducation, Geoethics and Geotourism: A Critical Evaluation of the Greek Region
Geosciences 2021, 11(9), 381; https://doi.org/10.3390/geosciences11090381 - 09 Sep 2021
Cited by 10 | Viewed by 957
Abstract
The purpose of this review is, initially, to emphasize the importance of geoenvironmental education for the promotion and preservation of geological heritage and geoethical values, and based on these, to present the current situation in Greece. Geoeducation is a broader component of environmental [...] Read more.
The purpose of this review is, initially, to emphasize the importance of geoenvironmental education for the promotion and preservation of geological heritage and geoethical values, and based on these, to present the current situation in Greece. Geoeducation is a broader component of environmental education which aims to promote the geological heritage of a place and its geoconservation. It is a key integral tool for tackling environmental issues and therefore further assisting in sustainable development. Greece is known for its exceptional and rare natural beauty, as well as for the abundance of natural resources and its remarkable geological features. For this reason, six global geoparks have already been established in this country. However, its nature protection is mainly considered as the protection of biodiversity, while the term “geodiversity” is almost absent in Greek law. The importance of establishing a legal framework for the protection of geotopes is underlined by the fact that their promotion and rational management create opportunities for sustainable development, as well as to become quality tourist destinations (geotourism) through nature protection and education. Geodiversity can gain public attention and have a positive impact on geotopes protection. Such initiatives can not only improve the protection of geological sites, but also play an important role in their sustainable development. Full article
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Article
Machine Learning Applied to K-Bentonite Geochemistry for Identification and Correlation: The Ordovician Hagan K-Bentonite Complex Case Study
Geosciences 2021, 11(9), 380; https://doi.org/10.3390/geosciences11090380 - 09 Sep 2021
Viewed by 616
Abstract
Altered tephras (K-bentonites) are of great importance for calibration of the geologic time scale, for local, regional, and global correlations, and paleoenvironmental reconstructions. Thus, definitive identification of individual tephras is critical. Single crystal geochemistry has been used to differentiate tephra layers, and apatite [...] Read more.
Altered tephras (K-bentonites) are of great importance for calibration of the geologic time scale, for local, regional, and global correlations, and paleoenvironmental reconstructions. Thus, definitive identification of individual tephras is critical. Single crystal geochemistry has been used to differentiate tephra layers, and apatite is one of the phenocrysts commonly occurring in tephras that has been widely used. Here, we use existing and newly acquired analytical datasets (electron probe micro-analyzer [EPMA] data and laser ablation ICP-MS [LA-ICP-MS] data, respectively) of apatite in several Ordovician K-bentonites that were collected from localities about 1200 km apart (Minnesota/Iowa/Wisconsin and Alabama, United States) to test the use of machine-learning (ML) techniques to identify with confidence individual tephra layers. Our results show that the decision tree based on EPMA data uses the elemental concentration patterns of Mg, Mn, and Cl, consistent with previous studies that emphasizes the utility of these elements for distinguishing Ordovician K-bentonites. Differences in the experimental setups of the analyses, however, can lead to offsets in absolute elemental concentrations that can have a significant impact on the correct identification and correlation of individual K-bentonite beds. The ML model using LA-ICP-MS data was able to identify several K-bentonites in the southern Appalachians and establish links to K-bentonites samples from the Upper Mississippi Valley. Furthermore, the ML model identified individual layers of multiphase eruptions, thus illustrating very well the great potential of applying ML techniques to tephrochronology. Full article
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Article
Seismicity Patterns Prior to the Thessaly (Mw6.3) Strong Earthquake on 3 March 2021 in Terms of Multiresolution Wavelets and Natural Time Analysis
Geosciences 2021, 11(9), 379; https://doi.org/10.3390/geosciences11090379 - 09 Sep 2021
Cited by 6 | Viewed by 650
Abstract
On 3 March 2021, a strong, shallow earthquake of moment magnitude, Mw6.3, occurred in northern Thessaly (Central Greece). To investigate possible complex correlations in the evolution of seismicity in the broader area of Central Greece before the Mw6.3 event, [...] Read more.
On 3 March 2021, a strong, shallow earthquake of moment magnitude, Mw6.3, occurred in northern Thessaly (Central Greece). To investigate possible complex correlations in the evolution of seismicity in the broader area of Central Greece before the Mw6.3 event, we apply the methods of multiresolution wavelet analysis (MRWA) and natural time (NT) analysis. The description of seismicity evolution by critical parameters defined by NT analysis, integrated with the results of MRWA as the initiation point for the NT analysis, forms a new framework that may possibly lead to new universal principles that describe the generation processes of strong earthquakes. In the present work, we investigate this new framework in the seismicity prior to the Mw6.3 Thessaly earthquake. Initially, we apply MRWA to the interevent time series of the successive regional earthquakes in order to investigate the approach of the regional seismicity at critical stages and to define the starting point of the natural time domain. Then, we apply the NT analysis, showing that the regional seismicity approached criticality a few days before the occurrence of the Mw6.3 earthquake, when the κ1 natural time parameter reached the critical value of κ1 = 0.070. Full article
(This article belongs to the Special Issue Morphogenic Faulting: Current Practices and Future Challenges)
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Article
Carbon Isotopic Signature and Organic Matter Composition of Cenomanian High-Latitude Paleosols of Southern Patagonia
Geosciences 2021, 11(9), 378; https://doi.org/10.3390/geosciences11090378 - 08 Sep 2021
Viewed by 787
Abstract
The Cenomanian Mata Amarilla Formation (MAF) in southern Patagonia (~55° S paleolatitude, Austral-Magallanes Basin, Argentina) is composed mainly of stacked fluvial deposits with intercalated paleosols, which document Cenomanian environments at high-paleolatitudes in the Southern Hemisphere. We performed a multiproxy study of the paleosols [...] Read more.
The Cenomanian Mata Amarilla Formation (MAF) in southern Patagonia (~55° S paleolatitude, Austral-Magallanes Basin, Argentina) is composed mainly of stacked fluvial deposits with intercalated paleosols, which document Cenomanian environments at high-paleolatitudes in the Southern Hemisphere. We performed a multiproxy study of the paleosols and sediments of the MAF in order to (1) understand the composition of the soil- and sediment-derived organic matter (OM), (2) apply carbon isotope stratigraphy as a tool to correlate patterns obtained from the MAF with existing marine and non-marine δ13Corg records worldwide, and (3) investigate the relationship between variations in spore-pollen assemblages of the MAF and the climatic conditions prevailing in the Cenomanian Southern Hemisphere. An integrated dataset was generated, including total organic carbon content, Rock-Eval pyrolysis data, stable isotope (δ13Corg) composition, and palynological data, combined with published paleosol-derived mean annual temperatures and mean annual precipitations. The results indicated that the OM preserved in the MAF paleosols allowed its use as a chemostratigraphic tool. The MAF δ13Corg curve showed the rather stable pattern characteristic for the Early to Late Cenomanian interval. The absence of the major positive carbon isotope excursion associated with oceanic anoxic event 2 provided an upper limit for the stratigraphic range of the MAF. The palynological data suggested the development of fern prairies during warmer and moister periods at the expense of the background gymnosperm-dominated forests. Overall, the multiproxy record provided new insights into the long-term environmental conditions during the Cenomanian in the high latitudes of the Southern Hemisphere. Full article
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Article
Bridges as Geoheritage Viewpoints in the Western Caucasus
Geosciences 2021, 11(9), 377; https://doi.org/10.3390/geosciences11090377 - 07 Sep 2021
Cited by 1 | Viewed by 656
Abstract
Distant observation of unique geological and geomorphological features facilitates comprehension and tourism of these important resources. Bridges offer an opportunity for such observation, and the idea of bridge-based geoheritage viewpoints is proposed. In the geologically-rich area of the Western Caucasus (southwestern Russia), eleven [...] Read more.
Distant observation of unique geological and geomorphological features facilitates comprehension and tourism of these important resources. Bridges offer an opportunity for such observation, and the idea of bridge-based geoheritage viewpoints is proposed. In the geologically-rich area of the Western Caucasus (southwestern Russia), eleven bridges were assessed semiquantitatively with the newly proposed approach. The results indicated their different but moderate utility as geoheritage viewpoints. The utility of two bridges is high. Bridges differ not only by the quality of the views they offer but also by their accessibility. Mandatory permissions and entrance fees reduce this property in several cases. Although the study area is somewhat specific due to the relatively large number of bridges and their utility, similar situations can be found in other geographical localities. Bridge-based geoheritage viewpoints are important to geotourism development, and, particularly, they contribute to establishing optimal and comfortable routes. Full article
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Article
The Potential of Tufa as a Tool for Paleoenvironmental Research—A Study of Tufa from the Zrmanja River Canyon, Croatia
Geosciences 2021, 11(9), 376; https://doi.org/10.3390/geosciences11090376 - 07 Sep 2021
Cited by 2 | Viewed by 723
Abstract
Tufa is a fresh-water surface calcium carbonate deposit precipitated at or near ambient temperature, and commonly contains the remains of macro- and microphytes. Many Holocene tufas are found along the Zrmanja River, Dalmatian karst, Croatia. In this work we present radiocarbon dating results [...] Read more.
Tufa is a fresh-water surface calcium carbonate deposit precipitated at or near ambient temperature, and commonly contains the remains of macro- and microphytes. Many Holocene tufas are found along the Zrmanja River, Dalmatian karst, Croatia. In this work we present radiocarbon dating results of older tufa that was found for the first time at the Zrmanja River near the Village of Sanaderi. Tufa outcrops were observed at different levels, between the river bed and up to 26 m above its present level. Radiocarbon dating of the carbonate fraction revealed ages from modern, at the river bed, up to 40 kBP ~20 m above its present level. These ages fit well with the hypothesis that the Zrmanja River had a previous surface connection with the Krka River, and changed its flow direction toward the Novigrad Sea approximately 40 kBP (Marine Isotope Stage 3). Radiocarbon AMS dating of tufa organic residue yielded a maximum conventional age of 17 kBP for the highest outcrop position indicating probable penetration of younger organic material to hollow tufa structures, as confirmed by radiocarbon analyses of humin extracted from the samples. Stable carbon isotope composition (δ13C) of the carbonate fraction of (−10.4 ± 0.6)‰ and (−9.7 ± 0.8)‰ for the Holocene and the older samples, respectively, indicate the autochthonous origin of the carbonate. The δ13C values of (−30.5 ± 0.3)‰ and (−29.6 ± 0.6)‰ for organic residue, having ages <500 BP and >5000 BP, respectively, suggest a unique carbon source for photosynthesis, mainly atmospheric CO2, with an indication of the Suess effect in δ13C during last centuries. The oxygen isotopic composition (δ18O) agrees well with deposition of tufa samples in two stages, the Holocene (−8.02 ± 0.72‰) and “old” (mainly MIS 3 and the beginning of MIS 2) (−6.89 ± 0.34‰), suggesting a ~4 °C lower temperature in MIS 3 compared to the current one. Full article
(This article belongs to the Special Issue Changing Quaternary Environment in the Mediterranean)
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Article
Rain, Snow and Frozen Soil: Open Questions from a Porescale Perspective with Implications for Geohazards
Geosciences 2021, 11(9), 375; https://doi.org/10.3390/geosciences11090375 - 06 Sep 2021
Cited by 1 | Viewed by 645
Abstract
Climate change is already affecting high mountain regions, such as the European Alps. Those regions will be confronted with a significant rise of temperatures above the global average, and more and heavier rain events, also during wintertime. The system response to the coincidence [...] Read more.
Climate change is already affecting high mountain regions, such as the European Alps. Those regions will be confronted with a significant rise of temperatures above the global average, and more and heavier rain events, also during wintertime. The system response to the coincidence of rain, snow, and possibly frozen soil depends on the almost infinite number of possible combinations of thermo-hydraulic states of the involved phases. Landslides, snow avalanches, debris flows, or extensive surface runoff are just a few of the possible hazardous outcomes. With rising temperatures and increased precipitation, those hazardous outcomes are expected to occur even more frequently in the future, requiring a better understanding of those coupled processes for hazard mitigation strategies. The macroscopic phenomena are controlled by porescale processes, such as water freezing and ice grains blocking pores, which are only barely understood. The strong coupling between thermal state and hydraulic parameters, the possible phase change, and material heterogeneity pose great challenges for investigation. This work provides an overview of documented hazard events regarding rain, snow, and possibly frozen soil. The current state in theoretical and experimental research is presented before several knowledge gaps are derived and possible techniques to address those gaps are discussed. Full article
(This article belongs to the Collection Early Career Scientists’ (ECS) Contributions to Geosciences)
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Article
Analysis of Volcanic Thermohaline Fluctuations of Tagoro Submarine Volcano (El Hierro Island, Canary Islands, Spain)
Geosciences 2021, 11(9), 374; https://doi.org/10.3390/geosciences11090374 - 04 Sep 2021
Viewed by 761
Abstract
Temperature and conductivity fluctuations caused by the hydrothermal emissions released during the degasification stage of the Tagoro submarine volcano (Canary Islands, Spain) have been analysed as a robust proxy for characterising and forecasting the activity of the system. A total of 21 conductivity-temperature-depth [...] Read more.
Temperature and conductivity fluctuations caused by the hydrothermal emissions released during the degasification stage of the Tagoro submarine volcano (Canary Islands, Spain) have been analysed as a robust proxy for characterising and forecasting the activity of the system. A total of 21 conductivity-temperature-depth time series were gathered on a regular high-resolution grid over the main crater of Tagoro volcano. Temperature and conductivity time series, as manifestations of stochastic events, were investigated in terms of variance and analysed by the Generalised Moments Method (GMM). GMM provides the statistical moments, the structure functions of a process whose shape is an indicator of the underlying stochastic mechanisms and the state of activity of the submarine volcano. Our findings confirm an active hydrothermal process in the submarine volcano with a sub-normal behaviour resulting from anti-persistent fluctuations in time. Its hydrothermal emissions are classified as multifractal processes whose structure functions present a crossover between two time scales. In the shorter time scale, findings point to the multiplicative action of two random processes, hydrothermal vents, which carries those fluctuations driving the circulation over the crater, and the overlying aquatic environment. Given that both temperature and conductivity fluctuations are nonstationary, Tagoro submarine volcano can be characterised as an open system exchanging energy to its surroundings. Full article
(This article belongs to the Special Issue Present and Past Submarine Volcanic Activity)
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Article
Analysis of the Northern Hemisphere Atmospheric Circulation Response to Arctic Ice Reduction Based on Simulation Results
Geosciences 2021, 11(9), 373; https://doi.org/10.3390/geosciences11090373 - 04 Sep 2021
Cited by 2 | Viewed by 705
Abstract
The amplified warming of the Arctic is one of several factors influencing atmospheric dynamics. In this work, we consider a series of numerical experiments to identify the role of Arctic sea ice reduction in affecting climate trends in the Northern Hemisphere. With this [...] Read more.
The amplified warming of the Arctic is one of several factors influencing atmospheric dynamics. In this work, we consider a series of numerical experiments to identify the role of Arctic sea ice reduction in affecting climate trends in the Northern Hemisphere. With this aim in mind, we use two independent mechanisms of ice reduction. The first is traditionally associated with increasing the concentration of carbon dioxide in the atmosphere from the historic level of 360 ppm to 450 ppm and 600 ppm. This growth increases air temperature and decreases the ice volume. The second mechanism is associated with a reduction in the reflectivity of ice and snow. We assume that comparing the results of these two experiments allows us to judge the direct role of ice reduction. The most prominent consequences of ice reduction, as a result, are the weakening of temperature gradient at the tropopause level in mid-latitudes; the slower zonal wind at 50–60 N; intensification of wave activity in Europe, Western America, and Chukotka; and its weakening in the south of Siberia and Kazakhstan. We also consider how climate change may alter regimes such as blocking and stationary Rossby waves. The study used the INM-CM48 climate system model. Full article
(This article belongs to the Topic The Arctic Atmosphere: Climate and Weather)
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Article
Sediment-Peridotite Reaction Controls Fore-Arc Metasomatism and Arc Magma Geochemical Signatures
Geosciences 2021, 11(9), 372; https://doi.org/10.3390/geosciences11090372 - 03 Sep 2021
Cited by 4 | Viewed by 1533
Abstract
Subduction of oceanic crust buries an average thickness of 300–500 m of sediment that eventually dehydrates or partially melts. Progressive release of fluid/melt metasomatizes the fore-arc mantle, forming serpentinite at low temperatures and phlogopite-bearing pyroxenite where slab surface reaches 700–900 °C. This is [...] Read more.
Subduction of oceanic crust buries an average thickness of 300–500 m of sediment that eventually dehydrates or partially melts. Progressive release of fluid/melt metasomatizes the fore-arc mantle, forming serpentinite at low temperatures and phlogopite-bearing pyroxenite where slab surface reaches 700–900 °C. This is sufficiently high to partially melt subducted sediments before they approach the depths where arc magmas are formed. Here, we present experiments on reactions between melts of subducted sediments and peridotite at 2–6 GPa/750–1100 °C, which correspond to the surface of a subducting slab. The reaction of volatile-bearing partial melts derived from sediments with depleted peridotite leads to separation of elements and a layered arrangement of metasomatic phases, with layers consisting of orthopyroxene, mica-pyroxenite, and clinopyroxenite. The selective incorporation of elements in these metasomatic layers closely resembles chemical patterns found in K-rich magmas. Trace elements were imaged using LA-ICP-TOFMS, which is applied here to investigate the distribution of trace elements within the metasomatic layers. Experiments of different duration enabled estimates of the growth of the metasomatic front, which ranges from 1–5 m/ky. These experiments explain the low contents of high-field strength elements in arc magmas as being due to their loss during melting of sedimentary materials in the fore-arc. Full article
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Article
Multiscale Characterisation of Fracture Patterns of a Crystalline Reservoir Analogue
Geosciences 2021, 11(9), 371; https://doi.org/10.3390/geosciences11090371 - 03 Sep 2021
Cited by 2 | Viewed by 776
Abstract
For an accurate multiscale property modelling of fractured crystalline geothermal reservoirs, an enhanced characterisation of the geometrical features and variability of the fracture network properties is an essential prerequisite. Combining regional digital elevation model analysis and local outcrop investigation, the study comprises the [...] Read more.
For an accurate multiscale property modelling of fractured crystalline geothermal reservoirs, an enhanced characterisation of the geometrical features and variability of the fracture network properties is an essential prerequisite. Combining regional digital elevation model analysis and local outcrop investigation, the study comprises the characterisation of the fracture pattern of a crystalline reservoir analogue in the Northern Odenwald, with LiDAR and GIS structural interpretation. This approach provides insights into the 3D architecture of the fault and fracture network, its clustering, and its connectivity. Mapped discontinuities show a homogeneous length distribution, which follows a power law with a −2.03 scaling factor. The connectivity of the fracture network is heterogenous, due to a fault control at the hectometric scale. Clustering is marked by long sub-vertical fractures at the outcrop scale, and strongly enhance heterogeneity around weathered fracture and fault corridors. The multi-variable dataset created within this study can be used as input data for accurate discrete fracture networks and fluid-flow modelling of reservoirs of similar type. Full article
(This article belongs to the Section Structural Geology and Tectonics)
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Perspective
Thinking about the Biodiversity Loss in This Changing World
Geosciences 2021, 11(9), 370; https://doi.org/10.3390/geosciences11090370 - 03 Sep 2021
Cited by 1 | Viewed by 1089
Abstract
Extinction of species has been a recurrent phenomenon in the history of our planet, but it was generally outweighed in the course of quite a long geological time by the appearance of new species, except, especially, for the five geologically short times when [...] Read more.
Extinction of species has been a recurrent phenomenon in the history of our planet, but it was generally outweighed in the course of quite a long geological time by the appearance of new species, except, especially, for the five geologically short times when the so-called “Big Five” mass extinctions occurred. Could the current decline in biodiversity be considered as a signal of an ongoing, human-driven sixth mass extinction? This note briefly examines some issues related to: (i) The hypothesized current extinction rate and the magnitude of contemporary global biodiversity loss; (ii) the challenges of comparing them to the background extinction rate and the magnitude of the past Big Five mass extinction events; (iii) briefly considering the effects of the main anthropogenic stressors on ecosystems, including the risk of the emergence of pandemic diseases. A comparison between the Pleistocene fauna dynamics with the present defaunation process and the cascading effects of recent anthropogenic actions on ecosystem structure and functioning suggests that habitat degradation, ecosystem fragmentation, and alien species introduction are important stressors increasing the negative impact on biodiversity exerted by anthropogenic-driven climate changes and their connected effects. In addition, anthropogenic ecological stressors such as urbanization, landscapes, and wildlife trade, creating new opportunities for virus transmission by augmenting human contact with wild species, are among the main factors triggering pandemic diseases. Full article
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Review
Modelling of Nutrient Pollution Dynamics in River Basins: A Review with a Perspective of a Distributed Modelling Approach
Geosciences 2021, 11(9), 369; https://doi.org/10.3390/geosciences11090369 - 01 Sep 2021
Viewed by 889
Abstract
Nutrient pollution is one of the major issues in water resources management, which has drawn significant investments into the development of many modelling tools to solve pollution problems worldwide. However, the situation remains unchanged, even likely to be exacerbated due to population growth [...] Read more.
Nutrient pollution is one of the major issues in water resources management, which has drawn significant investments into the development of many modelling tools to solve pollution problems worldwide. However, the situation remains unchanged, even likely to be exacerbated due to population growth and climate change. Effective measures to alleviate the issues are essential, dependent upon existing modelling tools’ capacities. More complex models have been developed with technological advancement, though applications are mainly limited to academic reach. Hence, there is a need for a paradigm shift in policymaking that looks for a reliable modelling approach. This paper aims to assess the capacity of existing modelling tools in the context of process-based modelling and provide a future direction in research. The article has categorically divided models into plot scale to basin-wide applications for evaluation and discussed the pros and cons of conceptual and process-based modelling. The potential benefits of distributed modelling approach have been elaborated with highlights of a newly developed distributed model and its application in catchments in Japan and Australia. The distributed model is more adequate for predicting the realistic details of pollution problems in a changing environment. Future research needs to focus on more process-based modelling. Full article
(This article belongs to the Special Issue Advances and Applications in Computational Geosciences)
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Article
An Age Scale for the First Shallow (Sub-)Antarctic Ice Core from Young Island, Northwest Ross Sea
Geosciences 2021, 11(9), 368; https://doi.org/10.3390/geosciences11090368 - 01 Sep 2021
Cited by 2 | Viewed by 1543
Abstract
The climate of the sub-Antarctic is important in understanding the environmental conditions of Antarctica and the Southern Ocean. However, regional climate proxy records from this region are scarce. In this study, we present the stable water isotopes, major ion chemistry, and dust records [...] Read more.
The climate of the sub-Antarctic is important in understanding the environmental conditions of Antarctica and the Southern Ocean. However, regional climate proxy records from this region are scarce. In this study, we present the stable water isotopes, major ion chemistry, and dust records from the first ice core from the (sub-)Antarctic Young Island. We present and discuss various dating approaches based on commonly used ice core proxies, such as stable water isotopes and seasonally deposited ions, together with site-specific characteristics such as melt layers. The dating approaches are compared with estimated precipitation rates from reanalysis data (ERA5) and volcanic cryptotephra shards likely presenting an absolute tie point from a 2001 CE eruption on neighboring Sturge Island. The resulting ice core age scale spans the period 2016 to 1995, with an uncertainty of ±2 years. Full article
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