bluuebunny/crossref_metadata_2025 huggingface dataset:
Probability, mechanisms and impact of future coastal urban flooding.
Authors: Olbert Agnieszka Indiana , Kirkpatrick Jennifer IM
Published: March 2021

In coastal floodplains, high river flows and high coastal water levels can result in extensive flooding. Mechanisms of flooding play a crucial role in flood characteristics with distinctive differences in flood wave propagation pattern and geographical extent of inundation. Climate change is expected to alter these flood mechanisms. This paper presents an assessment of urban inundation due to a combined effect of multiple source flooding. Cork City, a coastal city in the south of Ireland, frequently subject to complex coastal-fluvial flooding is used as a case study to investigate changes in flood mechanisms, dynamics and extents due to climate change. The MSN_Flood was used to compute potential future inundation patterns for a range of climate scenarios under various hydrological conditions. Scenarios were based on estimates of current, medium-range and high-end projections of extreme river flows and sea levels. 
Sinking microplastics in the water column: simulations in the Mediterranean Sea
Authors: de la Fuente Rebeca , Drótos Gábor , Hernández Emilio , López Cristóbal , van Sebille Erik
Published: March 2021

We study the vertical dispersion and distribution of negatively buoyant rigid microplastics within a realistic circulation model of the Mediterranean sea. We first propose an equation describing their idealized dynamics. In that framework, we evaluate the importance of some relevant physical effects: inertia, Coriolis force, small-scale turbulence and variable seawater density, and bound the relative error of simplifying the dynamics to a constant sinking velocity added to a large-scale velocity field. We then calculate the amount and vertical distribution of microplastic particles on the water column of the open ocean if their release from the sea surface is continuous at rates compatible with observations in the Mediterranean. The vertical distribution is found to be almost uniform with depth for the majority of our parameter range. Transient distributions from flash releases reveal a non-Gaussian character of the dispersion and various diffusion laws, both normal and anomalous. The origin of these behaviors is explored in terms of horizontal and vertical flow organization.
Flow and residence time in a laboratory aquifer recharged by rainfall
Authors: Lajeunesse Eric , Jules Valentin , Devauchelle Olivier , Guérin Adrien , Jaupart Claude , Lagrée Pierre-Yves
Published: March 2021

During rainfall, water infiltrates the soil, and percolates through the unsaturated zone until it reaches the water table. Groundwater then flows through the aquifer, and eventually emerges into streams to feed surface runoff. We reproduce this process in a  two-dimensional laboratory aquifer recharged by artificial rainfall. As rainwater infiltrates, it forms a body of groundwater which can exit the aquifer only through one of its sides. The outlet is located high above the base of the aquifer, and drives the flow upwards. The resulting vertical flow component violates the Dupuit-Boussinesq approximation. In this configuration, the velocity potential that drives the flow obeys the Laplace equation, the solution of which crucially depends on the boundary conditions. Noting that the water table barely deviates from the horizontal, we linearize the boundary condition at the free surface, and solve the flow equations in steady state. We derive an expression for the velocity potential, which accounts for the shape of the experimental streamlines and for the propagation rate of tracers through the aquifer. This theory allows us to calculate the travel times of tracers through the experimental aquifer, which are in agreement with the observations. The travel time distribution has an exponential tail, with a characteristic time that depends on the aspect ratio of the aquifer. This distribution depends essentially on the geometry of the groundwater flow, and is weakly sensitive to the hydrodynamic dispersion that occurs at the pore scale.
Using an advanced robotic chamber system to detect spatio-temporal short-term responses in measured CO2 exchange to soil manipulation and N fertilization
Authors: Hoffmann Mathias , Vaidya Shrijana , Schmidt Marten , Bonk Norbert , Rakowski Peter , Verch Gernot , Sommer Michael , Augustin Jürgen
Published: March 2021

Improved agricultural practices sequestering additional atmospheric C within the soil are considered as one of the potential solution for mitigating global climate change. However, agricultural used landscapes are complex and their capacity to sequester additional atmospheric C differs substantially in time and space. Hence, accurate and precise information on the complex spatio-temporal CO2 flux pattern is needed to evaluate the effects/benefits of new agricultural practices aiming towards increasing soil organic carbon.

To date, different approaches are used to measure and quantify CO2 flux dynamics of agricultural landscapes, such as e.g. eddy covariance, as well as manual and automatic chamber systems. However, all these methods fail to some extend in either accounting for small scale spatial heterogeneity (e.g., eddy covariance and automatic chambers) or short-term temporal variability (e.g., manual chambers). Although, automatic chambers are in principle capable to detect small-scale spatial differences of CO2 flux dynamics in a sufficient temporal resolution, these systems are usually limited to only a few spatial repetitions which is not sufficient to represent small scale soil heterogeneity such as present within the widespread hummocky ground moraine landscape of NE-Germany.

To overcome these challenges, we developed a novel robotic chamber system. This system was used to detect small-scale spatial heterogeneity and short-term temporal variability of CO2 flux dynamics in a full factorial experimental setup for a range of three different soil types, two N fertilization forms (2; mineral vs. organic) and two soil manipulation status, representing two different tillage practices. Here, we present measured CO2 flux dynamics and cumulative emissions for the 3 repetitions of the 12 randomized treatments (36 subplots) directly following soil manipulation and N fertilization during summer 2020. Our results show distinct differences between the three measured soil types as well as a clear response of all three soil types to conducted soil manipulation, yielding in significantly lower ecosystem respiration (Reco) and net ecosystem exchange (NEE) for manipulated vs. non-manipulated subplots. No clear difference, however, was obtained in case of N fertilization.
ScourBuoy – concept for scour monitoring system
Authors: Harasti Antonija , Gilja Gordon , Varga Matej , Fliszar Robert
Published: March 2021

The objective of this paper is to present the ScourBuoy – concept for scour monitoring system. The ScourBuoy prototype is currently under development within the R3PEAT project (Remote Real-time Riprap Protection Erosion AssessmenT on large rivers), which aims to investigate scouring processes next to the riprap protection around bridge piers. ScourBuoy integrates commercially available technical devices into a functional system for scour monitoring during flood conditions. Sensors used are single beam echo sounder that collects depth and temperature data, multi-GNSS device for 3D positioning, compass for orientation respective to the True North and motion sensor for pitch and roll data. Combined output from the sensors allows user to calculate river depth and monitoring of scour development during floods. Advantage of ScourBuoy is adaptability to the field conditions, such as placement over the scour hole, as well as simpler deployment and reallocation in comparison to fix-mount solutions. ScourBuoy prototype was built using a common small-scale pipe float with an 80 mm inner diameter hole, which was used as a holder for an aluminium pipe. Aluminium pipe is used as a casing for echo sounder, positioned as downward-looking, so it stays submerged during deployment. The rest of the sensors are enclosed in the waterproof housing placed atop of the buoy, permanently above the waterline. The ScourBuoy will be a practical and affordable system which will allow researchers and engineers to collect measurements for scouring estimation. It will be used as a support system for rapid and timely decision making. Finally, developed Scour Buoy will present an alternative for real-time scour monitoring which allows responsive adapting to the specific conditions at the locations affected by scour.
Seasonal Change in the Deep Atmosphere of Uranus, 1981 to 2012
Authors: Hofstadter Mark , Akins Alexander , Butler Byran
Published: March 2021

Our team is using radio observations of Uranus, collected with the Very Large Array (VLA) telescope, to track seasonal changes in the deep troposphere of Uranus between 1981 and the present.  We previously reported on changes between 1981 and 1994, as the Southern Hemisphere moved from mid- to late-summer (Hofstadter and Butler 2003, Icarus 165, https://doi.org/10.1016/S0019-1035(03)00174-X).  During that time, the distribution of opacity sources in the atmosphere (now thought primarily to be H2S) changed in such a way as to suggest an increase in the strength of the planetary-scale circulation pattern in the 5 to 50 bar region of the atmosphere.  More specifically, using wavelengths from 1 to 20 cm, we found that regions poleward of 45 degrees latitude in the Southern Hemisphere are significantly depleted in absorbers compared to more equatorial latitudes, down to a pressure of about 50 bars (which is near the top of where a liquid water cloud is expected to form).  This opacity distribution could be explained by a planetary-scale circulation pattern, with absorber rich air parcels moving upward in equatorial regions, being depleted in absorbers by condensation at higher altitudes, and then moving poleward and descending, keeping the pole depleted in absorbers.  We found that the opacity difference between the pole and equator increased between the 1980's and the 1990's, suggesting a strengthening of the assumed circulation pattern.  Radio observations by our group and others since 1994 have shown that the Northern Hemisphere is roughly symmetric with the Southern, and that smaller-scale latitudinal banding exists (e.g., Molter et al. 2020 https://arxiv.org/abs/2010.11154).  

We are currently analyzing additional Uranus data collected at the VLA, and will present results from a subset of those observations taken in 2012 (during Southern Fall).  We will also discuss plans for extending the time line to the present.  The complete data set will span half a uranian year, allowing all seasons to be observed.  We will also discuss how the composition and chemistry of the ice giant planets (Uranus and Neptune) differ from those of the gas giants (Jupiter and Saturn).
Ensemble climate projections on stratification dynamics in Germany's largest drinking water reservoir and potential adaptation strategies
Authors: Rinke Karsten , Shatwell Tom , Ma Jun , Xu Yaqian , Su Fangli , Mi Chenxi
Published: March 2021

The thermal structure in reservoirs affects the development of aquatic ecosystems and is substantially influenced by changing climate conditions. At the same time, reservoir management strategies can also affect the thermal structure of the water body and may enable adaptation strategies in a warmer world. We applied a two-dimensional hydrodynamicmodel to explore the response of the thermal structure in Germany's largest drinking water reservoir, Rappbode Reservoir, to future climate projections and different water withdrawal strategies. We used projections for representative concentration pathways (RCP) 2.6, 6.0 and 8.5 from an ensemble of 4 different global climate models taken from the ISIMIP project. Simulation results showed that epilimnetic water temperatures in the reservoir strongly increased under all three climate scenarios while the magnitude of warming directly corresponds to the increase in air temperatures. Hypolimnetic temperatures remained rather constant under RCP 2.6 and RCP 6.0 but increased markedly under RCP 8.5. Under the intense warming in RCP 8.5, hypolimnion temperatures were projected to rise from 5 °C to 8 °C by the end of the century. Moreover, the results suggested that surface withdrawal can be an effective adaptation strategy under strong climate warming (RCP 8.5) to reduce surface warming and even avoid hypolimnetic warming. This study documents how global scale climate projections can be translated into site-specific climate impacts to derive adaptation strategies for reservoir operation. Moreover, our results illustrate that the most intense warming scenario, i.e. RCP 8.5, demands far-reaching climate adaptation while the mitigation scenario (RCP 2.6) does not require adaptation of reservoir management before 2100.
The seesaw response of the Intertropical and South Pacific convergence zones to hemispherically asymmetric thermal forcing
Authors: Fedorov Alexey , Zhao Bowen
Published: March 2021

Considerations based on atmospheric energetics and aqua-planet model simulations link the latitudinal position of the global intertropical convergence zone (ITCZ) to atmospheric cross-equatorial energy transport—a greater southward transport corresponds to a more northerly position of the ITCZ. This study, rather than concentrating of the zonally-averaged ITCZ, focuses on the tropical Pacific and looks separately at precipitation in the northern and southern hemispheres. Using numerical experiments, we show that in the tropical Pacific the response of the fully coupled ocean-atmosphere system to a hemispherically asymmetric thermal forcing, modulating atmospheric cross-equatorial energy transport, involves an interplay between the ITCZ and its counterpart in the South Pacific—the Southern Pacific convergence zone (SPCZ). This interplay leads to interhemispheric seesaw changes in tropical precipitation, such that the latitudinal position of each rain band remains largely fixed, but their intensities follow a robust inverse relationship. The seesaw behavior is also evident in the past and future coupled climate simulations of the Climate Model Intercomparison Project Phase 5 (CMIP5). We further show that the tropical Pacific precipitation response to thermal forcing is qualitatively different between the aquaplanet (without ocean heat transport), slab-ocean (with climatological ocean heat transport represented by a “Q-flux”) and fully-coupled model configurations. Specifically, the induced changes in the ITCZ latitudinal position successively decrease, while the seesaw precipitation intensity response becomes more prominent, from the aqua-planet to the slab-ocean to the fully-coupled configuration. The ITCZ/SPCZ seesaw can explain a precipitation dipole pattern observed in paleoclimate without invoking a too strong climate forcing and is relevant to future projections of tropical precipitation.
Highly Heterogeneous Pore Fluid Pressure Enabled Rupture of Orthogonal Faults During the 2019 Ridgecrest Mw7.0 Earthquake
Authors: Shi Qibin , Wei Shengji
Published: March 2021

Here, we show that the 2019 Mw7.0 Ridgecrest mainshock as well as its Mw6.5 foreshock ruptured orthogonal conjugate faults. We invert the waveforms recorded by the dense strong motion network at relatively high frequencies (up to 1 Hz for P; 0.25 Hz for S) to derive multiple‐point source models for both events, aided by path calibrations from a Mw5.4 and a Mw5.5 earthquake. We demonstrate that the mainshock started from a shallow (3 km) depth with a Mw5.2 event and ruptured the main fault branches oriented in the NW‐SE direction. At ~11 s, two Mw6.2 subevents took place on the SW‐NE oriented fault branches that conjugate to the main fault to the NE and SW. The SW branch rupture partially overlapped with the foreshock rupture. We suggest the coseismic rupture on nearly orthogonal faults was enabled by high pore fluid pressure, which greatly weakened the immature fault system in a heterogeneous way.
Influence of Ephemeral Gully Location Prediction on Soil Erosion Estimation
Authors: Wang Chunmei , Cruse Richard , Brian Gelder , Daryl Herzmann , Kelly Thompson , David James
Published: March 2021

Predicting ephemeral gully (EG) location is essential for erosion modeling because it helps confine portions of the hillslope segment above locations that gully and channel soil loss processes dominate. In the Water Erosion Prediction Project (WEPP), the prediction of EG occurrence location influences the model results by shorting or expanding the flow path, which the hillslope erosion modeling relies on. This research aimed to analyze the sensitivity of EG locations prediction accuracy on WEPP model output within the framework of the Daily Erosion Project (DEP) at the regional scale. DEP is a near real-time estimator of precipitation, soil detachment, hillslope soil loss, and water runoff using WEPP as the erosion model. The above estimations are conducted on randomly selected and spatially distributed flowpaths, and the means are reported at the HUC12 watershed level. The flowpaths are identified based on Digital Elevation Model (DEM) grid cell and D8 connectivity to adjacent cells. A flow path starts at a cell such that all adjacent cells are at a lower elevation, that is, no other adjacent cell directs flow into it and ends when sufficient flow concentration and soil conditions occur that channel erosion processes dominate soil loss where usually EGs occurrence. In this research, the DEP flowpaths, down to and including ephemeral gully heads, were surveyed in 8 HUC12 watersheds distributed in 8 different Iowa MLRAs using high-resolution imagery in-field measurement. A grid order model was used as a method for EG location prediction. The sensitivity of accuracy of EG location prediction on WEPP/DEP soil detachment, hillslope soil loss, and water runoff model output was explored at hillslope, watershed, and regional spatial scale with both extreme rainfall events and yearly average erosion modeling. This research will allow a more clear understanding of EG prediction influence on erosion modeling and help improve the accuracy of erosion modeling by using WEPP / DEP.
Seasonal variations of the dinoflagellate algae Noctiluca scintillans abundance in the western Arabian Sea and the northern Black Sea
Authors: Piontkovski Sergey , Al Hashmi Khalid , Zagorodnaya Yuliya , Serikova Irina , Evstigneev Vladislav , Prusova Irina , Alabri Nader
Published: March 2021

Seasonal variability is a powerful component of the spatio-temporal dynamics of plankton communities, especially in the regions with oxygen-depleted waters. The Arabian Sea and the Black Sea are typical representatives of these regions. In both, the dinoflagellate Noctiluca scintillans (Macartney) Kofoid & Swezy, 1921, is one of the abundant plankton species which forms algal blooms. Sampling on coastal stations in the upper mixed layer by the plankton nets with the 120-140 µm mesh size was carried out in 2004-2010. Monthly data were averaged over years. A comparison of seasonal patterns of Noctiluca abundance pointed to the persistence of a bimodal seasonal cycle in both regions. The major peak was observed during spring in the Black Sea and during the winter (Northeast) monsoon in the Arabian Sea. The timing of the second (minor) peak was different over regions as well. This peak was modulated by advection of seasonally fluctuating velocity of coastal currents which transport waters enriched by nutrients by coastal upwelling. The abundance of Noctiluca of the major peak (with the concentration around 1.5*106 cells m-3) was from one to two orders as much high in the western Arabian Sea compared to the northern Black Sea. The remotely sensed chlorophyll-a concentration during the time of the major seasonal peak exhibited a fivefold difference over these regions. In terms of nutrientconcentration in the upper mixed layer (in particular, nitrates and silicates), a difference of about one order of magnitude was observed.
Investigating tectonic geomorphology of three half-graben basins onshore the NE Atlantic margin
Authors: Haaland Linda Cecilia , Osmundsen Per Terje , Redfield Tim , Svendby Katia , Senger Kim
Published: March 2021

Tectonic controls on landscape evolution are well documented globally. In actively extending areas, tectonic geomorphology is typically represented by uplifted footwalls, downthrown hanging walls, distinct bounding escarpments, and characteristic drainage patterns.

In onshore parts of the NE Atlantic margin, several studies suggest that some present-day landforms are inherited from rifting and margin formation in the Late Paleozoic, Mesozoic and Early Cenozoic. Such inheritance can be difficult to recognize because much of the pre-existing landscapes are obscured by erosional features related to post-rift Cenozoic uplift and repeated glaciations during the Quaternary. Interpretations of these landscapes vary considerably; some have suggested the preservation of vast Mesozoic erosion surfaces, whereas others argue that most present-day landforms are Quaternary in origin with little pre-Quaternary inheritance. However, some remnants of Late Paleozoic and Mesozoic rifting are demonstrably preserved directly inboard of the NE Atlantic margin, in the form of sedimentary basins.

In this study we use structural and geomorphological field observations and DTM (Digital Terrain Model) analyses to investigate the landscape surrounding three half-graben basins. Detailed landscape classification and analysis is used to systematically review present-day landscape distribution and bounding faults in and around the remnant basins, in order to distinguish extensional tectonic landforms from other geomorphological features. The half-grabens considered in this study are the Carboniferous Billefjorden half-graben on central Spitsbergen, Svalbard; the Jurassic Sortlandsundet half-graben in Vesterålen, northern Norway; and the Jurassic Beitstadfjorden half-graben in Trøndelag, mainland Norway.

Preliminary results reveal major topographic contrasts between footwall and hanging wall in all three half-grabens, with generally higher topographical elevations and deeper incision in the footwalls compared to the hanging walls. Additionally, the three study areas have very distinct landscape signatures, suggesting a difference in the post-rift landscape evolution. These differences appear to be dependent on a number of factors related to unique post-rift events. The inherited half-grabens display profoundly different degrees of erosional exploitation of pre-rift structures, glacial incision, and possible late-Cretaceous or younger reactivation of the basin-bounding normal faults. This study will provide insight into the relationships between inherited, tectonically controlled landforms, and incising Cenozoic and Quaternary landforms.
Global wave number-4 pattern in the southern subtropics
Authors: Senapati Balaji , Dash Mihir , Behera Swadhin
Published: March 2021

Presence of a stationary zonal wavenumber-4 (W4) pattern is revealed in the sea surface temperature (SST) anomaly over southern subtropics (20°S-55°S) using empirical orthogonal function analysis. This W4 pattern is found to be seasonally phase-locked to the austral summer (persists up to mid-autumn) and independent of other known tropical and extra-tropical climate phenomena. A thermodynamic coupling of atmosphere and the upper ocean helps in generating the W4 pattern, which later terminates due to the breaking of the ocean-atmosphere positive feedback. Due to anomalous convection over western subtropical pacific near the westerly jet, the signal appears first in the atmosphere during early November. Later, the disturbance gets trapped in the westerly waveguide which circumnavigates the globe and produces an atmospheric W4 pattern in early December (20-30 days later). Then, the signal transported to the ocean through the ocean-atmosphere feedback and sustained in the ocean (after it disappears from the atmosphere) as it has high specific heat capacity. During the positive phase of the W4 event, the cold SST anomaly develops over the southeastern and -western side (SE-NW) of Australia creating an anomalous divergence circulation. It favours the moisture transport towards the south-eastern region of the continent. Consequently, the specific humidity increases and causes an above-normal rainfall in a SE-NW axis over Australia. An opposite process is seen in case of a negative W4 event.
Variation in Grain-size Characteristics of Stimulated Shrubs As a Novel Sand-barrier in a Wind Tunnel Experiment
Authors: Pan Xia , Wang Zhenyi , Gao Yong , Meng Zhongjv , Dang Xiaohong , Han Yanlong
Published: March 2021

Sand transport is the main manifestation of sand damage in the arid and semiarid desert regions globally. It is still a challenge for ecologists to stabilize mobile sandy and to change them into stable productive ecosystems. The establishment of stimulated shrubs is one of the most effective measures as a novel sand-barrier. Meanwhile, it has a beautiful visual effect in deserts. To better understand its role in the process of ecological restoration, we conducted a wind tunnel experiment to analyze the overall characteristics of soil grain-size variation of different spatial configurations with simulated shrubs in row spaces under different net wind speeds. The results present that the average grain-size content was dominated by medium sand and fine sand, and the total percentage was more than 90%. The average grain-size content for other soil grain-size was almost the same and the proportion was less than 10%. Moreover, the sand deposition of simulated shrubs with different spatial configurations increased with the improvement of wind speed. And the average sand deposition of spindle-shaped simulated shrubs in 17.5×17.5cm and broom-shaped simulated shrubs in 17.5×26.25cm under different wind speeds was the least. There was less variation of the soil grain-size parameters among different spatial configurations of stimulated shrubs, row spaces, and net wind speeds. The effects of row spaces on average grain-size parameters would be improved with the increase of wind speed. By calculating the “correct” characteristics of any specific shelter device, all of these findings suggest that the application of the simulated shrubs will be an important component to further extend ecological engineering projects in arid and semiarid desert regions.
Assessment of PTE fate in contaminated soils: pedology based approach from the field to the microscopy scale
Authors: Vingiani Simona , Adamo Paola , Agrelli Diana , Caporale Antonio Giandonato , De Mascellis Roberto , Langella Giuliano , Mileti Florindo Antonio , Terribile Fabio
Published: March 2021

In the framework of both characterization plan and sustainable land reclamation, required by the European regulation for contaminated sites, it is fundamental to detail and understand soil processes involved in the dynamics of environmental contamination. Areas affected by potentially toxic elements (PTE) frequently show wide variability of contaminant distribution both in space and in depth. Targeted sampling is meant to reduce the risk of incorrect hazard evaluation, as well as decrease time and cost of this tricky procedure. Therefore, a pedology based multi-scale approach has been tuned and applied to an industrial area inside an automobile-battery recycling plant (operative since 1970) in South of Italy. Field scale investigation, after data fusion of geophysical (EMI), spectrometric (Gamma ray dose rate and XRF elemental content) and penetrometric (cone index data by ultrasonic penetrometer) parameters, enabled to identify 4 main key zones characterized by different intensity of the measured variables. At pedon scale, 6 soil profiles were dug until 2 m of depth in the identified zones and showed presence of massive/no structured soils (thickness ranging from 25 to 85 cm) in which the total Pb content ranged from 1700 and 12000 mg/kg (field measurements by portable XRF). At optical microscopy scale, many discrete particles (larger than 2 mm of diameter), having angular - subangular shape and different color, were identified and preliminary examined by portable XRF spectrometer for a semi-quantitative analysis, in collimator mode, to detect the most PTE enriched fragments; the results showed the presence of several medium (from 0.5 x 1 mm wide), greyish-black particles enriched of S and/or Cl, of some other bigger (1 x 4 mm), very dense (i.e., not porous), anisotropic (black) fragments characterized by higher content of S, Pb, Cl, As and Sn, as a whole incorporated in a mineral matrix  lesser enriched of S (11 g/kg), Cl (0.8 g/kg), Pb (0.6 g/kg), As (0.2 g/kg). Detailed analysis at submicroscopic scale with SEM, equipped with EDXRA for quantitative analyses, enabled to discriminate the biggest particles in sub-particles mainly composed of Pb (87-89%) and others combining Pb (72-75%) with Cd (11%) and Sn (11-12%). At molecular scale, the mobility and bioavailability of the most abundant PTE were assessed by standardized single-step (ultrapure water, 1M NH4NO3 and 0.05M EDTA) and sequential (EU-BCR and Wenzel)analytical procedures. Although the extent of Cd contamination was much lower than that of Pb, Cd was more mobile and bioavailable than Pb, mainly due to its different geochemical properties. As well, the bioavailability of Sb in the soil was greater than that of As (anionic contaminants).
Coastal flooding protection will change salt-marsh sedimentation dynamics
Authors: Tognin Davide , D'Alpaos Andrea , Marani Marco , Carniello Luca
Published: March 2021

Coastal wetlands lie at the interface between submerged and emerged environments and therefore represent unique yet delicate ecosystems. Their existence, resulting from complex interactions between hydrodynamics and sediment dynamics, is challenged by increasing rates of sea-level rise, lowered fluvial sediment input as well as an increasing anthropogenic pressure. The future survival of these peculiar morphologies is becoming even more complicated, because of the construction and planning of coastal defence structures designed to protect urban areas from flooding. Important examples are the flood protection systems built to protect New Orleans (USA), the river Scheldt Estuary (The Netherlands) and Venice (Italy). In this context, understanding the physical processes on which coastal marshes are grounded and how engineering measures can alter them is of extreme importance in order to plan conservation interventions.

To understand marsh sedimentation dynamics in flood-regulated environments, we investigated through field observations and modelling the effect of the storm-surge barrier designed to protect the city of Venice, the so-called Mo.S.E. system, which has in fact become operational since October 2020.

Sedimentation measurements in different salt marshes of the Venice lagoon carried out in the period October 2018-October 2020 show that more than 70% of yearly sedimentation accumulates during storm-surge conditions, despite their short duration. Moreover, the sedimentation rate displays a highly non-linear increase with marsh inundation intensity, due to the interplay between higher water levels and greater suspended sediment concentration. Barrier operations during storm surges to avoid flooding of urban areas will reduce water levels and marsh inundation. Therefore, we computed sedimentation in a flood-regulated scenario for the same observation period, using the relation we obtained between tidal forcing and sedimentation rate. Our results show that some occasional closures during intense storm surges (70 hours/year on average) suffice to reduce the yearly sedimentation of the same order of magnitude of the relative sea-level rise rate experienced by the Venice lagoon during the last century (2.5 mm/y).

We conclude that storm-surge barrier operations can dangerously reduce salt-marsh vertical accretion rate, thus challenging wetland survival in face of increasing sea-level rise.
Chronostratigraphic Analysis of the Evolution of the Christiana-Santorini-Kolumbo Volcanic Field
Authors: Preine Jonas , Hübscher Christian , Karstens Jens , Nomikou Paraskevi , Druitt Timothy , Papanikolaou Dimitris
Published: March 2021

The Christiana-Santorini-Kolumbo (CSK) volcanic field in the South Aegean Sea is one of the most active volcanic-tectonic lineaments in Europe, having produced numerous explosive eruptions, catastrophic earthquakes, and disastrous tsunamis in the past 350,000 years. The present-day Santorini caldera is located in the centre of the NE-SW trending CSK field, which extends for more than 60 km from the extinct Christiana volcano in the southwest to the active submarine Kolumbo volcano northeast of Santorini. While the onshore architecture of Santorini has been well studied, little is known about its offshore architecture. Further, the past volcanism of Kolumbo is only known for its last eruption in 1650 AD and that of Christiana is completely unknown. Based on the available onshore datings of the volcanic formations, it has been proposed that volcanism in the CSK field initiated at Christiana, then migrated northeast towards Santorini and later to Kolumbo. This, however, has yet to be confirmed by offshore investigations. To fully constrain and understand the initiation and evolution of volcanism in the CSK field, we combine an extensive collection of high-resolution multichannel and vintage seismic data covering the entire zone.

With these seismic profiles, we are able to (1) correlate the seismo-stratigraphy of the Christiana basin west of Santorini with that of the Anhydros Basin east of Santorini, (2) identify major phases of extrusive and intrusive activity of individual volcanic vents, and (3) establish a regional chrono-stratigraphic framework in which we chronologically integrate these phases. We conclude that volcanism occurred repetitively during distinct phases of activity, which are separated from each other by periods with little or no volcanic activity. The onset of volcanism occurred without the generation of significant pyroclastic flows and was mainly characterized by shallow intrusions, clearly visible at Christiana, at its neighbouring volcanic cones, and at the southwestern flank of Akrotiri. The next phase saw the formation of the Kolumbo Volcanic Chain in the Anhydros Basin and the formation of sill intrusions in the Christiana Basin, which we find below a chaotic, presumably pyroclastic unit. This was followed by a major regional event on Santorini, during which a thick transparent subunit was deposited in all surrounding basins. The most recent phase was dominated by the volcanoclastic deposits from Santorini’s eruptive cycles and the recent eruption of Kolumbo. Using estimates of sedimentation rates, we convert this chrono-stratigraphic scheme into an approximate timeline, which implies that the initiation of volcanism occurred during Late Pliocene to Early Quaternary - much earlier than revealed by onshore dating.
Sensitivity of global gross primary production to elevated CO2
Authors: Cai Wenjia , Prentice Iain Colin
Published: March 2021

Terrestrial ecosystems have accounted for more than half of the global carbon sink during the past decades and offset 25%-30% of current anthropogenic CO2 emissions. The projected increase in CO2 concentration will depend on the magnitude of terrestrial plants’ feedback to CO2: i.e. the sensitivity of plant carbon uptake in response to elevated CO2, and the strength of the CO2 fertilization effect (CFE) in a changing (and warming) environment. Projecting vegetation responses to future increases in CO2 concentration under climate change is a major uncertainty, as ecosystem models, field experiments and satellite-based models show large disagreements. In this study, using a recently developed, parameter-sparse model (the ‘P model’), we assess the sensitivity of GPP to increasing CO2 under idealized conditions, in comparison with other vegetation models and field experiments. We investigate the impact of two central parameters, the ratio of Jmax to Vcmax (at a common temperature) and the curvature of the light response curve, on the sensitivity of GPP to CO2. We also quantified the spatial-temporal trend of CFE using the β factor, defined as the percentage increase in GPP in response to a 100-ppm increase in atmospheric CO2 concentration over a defined period. We show how modelled β has changed over the satellite era, and infer the possible effect of climatic variables on changes of CFE from spatial patterns of the modelled trend in β.
Scale-dependent dispersion for solute transport in bounded formations
Authors: Liao Qinzhuo , Lei Gang , Zhang Dongxiao , Patil Shirish
Published: March 2021

We present a new method to estimate the displacement covariance and macrodispersivity for solute transport in bounded formations. Here we use circulant embedding, which is based on the fast Fourier transform and is much more efficient than eigen-decomposition for the factorization of random spatial fields. We compute the displacement covariances using the analysis of variance approach and introduce an interpolation process to significantly reduce the number of forward simulations. Once the effect of each eigenvector on the displacement covariance is obtained, it is unnecessary to rerun the simulator for different spatial covariance functions or anisotropy ratios, which saves a large amount of computational effort. The proposed method is validated in various tests in two-dimensional and three-dimensional examples and accurately matches the results from the Monte Carlo simulation. It is found that the longitudinal dispersivity is not sensitive to the boundaries, while the transverse and vertical dispersivities are greatly affected. The method is applied to the Borden site and provides a better explanation of the observed data after considering the effect of vertical boundaries. These results show that our method could serve as a promising tool for studying and predicting the characteristics of solute transport in heterogeneous media.
Geoethics education and climate literacy: Bridging the gap – interactively
Authors: Crookall David , Promduangsri Pimnutcha , Promduangsri Pariphat
Published: March 2021

In previous years, the authors have addressed questions related to geoethics education, or what we have called geo-edu-ethics (GEE), in relation to geo-problems in general (such as global warming, pollution, sea-level rise, deforestation, ocean acidification, biodiversity).

In this session we wish to focus in on the greatest of all geo-problems, that of climate change (CC), which necessarily entails the urgent need for massive, widespread climate literacy (CL) – both education and learning.  We wish to examine the relationships between GEE and CL, their overlaps and differences, and how they may mutually reinforce each other.  In so doing, we will also touch on the ethics of educational and learning methods that are used to help people learn about geoethics and CC.

Currently, it seems that the two areas work in parallel, maybe even separated by a mindset of splendid isolation, and yet the apparent overlap, not least in their visons and missions, beckons us to bring the two closer together.  This is what we will attempt in our presentation.  The questions that we plan to address include the following:

Is it true, or a misconception, that GEE and CL tend to work separately, often ignorant of each other?

What do GEE and CL have in common?

Their ethos, their content, their methods, their audience?

Is it possible to unify the GEE and CL into an overarching rational and thereby form a coherent community of practice?

What can practitioners in each bubble learn from each other? What will it take for the two bubbles to merge?

How can each group maintain its own professional identity (if that is deemed important) and yet work hand in hand with the other, to their mutual benefit?

What are the most effective ways forward, given the geoethical urgency of acting to slow CC?

The presentation will be interactive, as we will invite the audience to contribute their own ideas and experience.  If we are permitted to have breakout rooms, we will divide into small groups for a short time, and then bring everyone together for a plenary sharing.
Millennial seismicity of the Upper Rhine Graben
Authors: Kazmer Miklos , Reicherter Klaus
Published: March 2021

The apparent seismic quiescence of the Upper Rhine Graben, as opposed to the Lower Rhine Graben, inspired authors to put the question whether it is real or due to short sampling (Stein et al. 2015). Lack of destructive earthquakes in the Leydecker (2011)  historical catalogue (except two in the very north and south) made us to survey an alternative source of seismic documentation. We carried out archaeoseismological studies on the built environment: on Roman cities of Mogontiacum (Mainz) and Augusta Raurica (Kaiseraugust) on opposite ends of the Upper Rhine Graben, and on Medieval sites: the cathedrals of Mainz, Worms, Speyer, Strasbourg and Basel, the monastery churches of Lorsch, Ladenburg and Achern, altogether at 19 sites. Buildings were checked for seismic deformation. Detailed architectural history of construction, destruction and repair was created for each. Dating of (re)construction was achieved by studying published historical documents. Known earthquake epicenters were re-positioned, intensities corrected (usually raised), and previously unknown, highly destructive events recognized and dated. The 1080 AD Mainz earthquake (I=VI) is shifted to Speyer, causing collapse and rebuilding of the imperial cathedral there (I=IX). An additional earthquake occurred there in early modern times, damaging the newly built parts. The late 12thcentury has seen the rebuilding of the Strasbourg cathedral: surviving Romanesque parts still carry evidence for earthquake damage, covered by the Gothic cross-nave. A strange belfry was added to the western front to reinforce the two towers in unsatisfactory status in 1384. Destruction of the 1356 Basel earthquake is much larger than previously recorded: churches citywide carry evidence for damage followed by substantial reconstruction. The Upper Rhine Graben was seismically active in the past two millennia: instrumental quiescence is is misleading, causing dangerously low hazard estimates.
Crack propagation and coalescence characteristics of rock-like specimen containing preexisting flaws subjected to internal hydraulic pressure and shear force
Authors: Li Yong , Kong Weiqiu , Zhu Weishen , Wu Guannan , Wang Zhiheng , Dai Feng , Wang Chen
Published: March 2021

Abstract: Based on laboratory direct shear tests and discrete element theory, the crack propagation and coalescence mechanism and numerical simulation of cement mortar specimens considering the combined actions of internal hydraulic pressure and shear force were carried out. We completed the filling of the internal hydraulic pressure in the cement mortar specimens with preexisting flaws, and performed the direct shear tests on the specimens. In the numerical analysis, the pipe domain model in the two dimensional particle flow code (PFC2D) was modified owing to the high brittleness and low permeability of the cement mortar particles in the numerical model. We also modified the calculation rules of the interaction between the fluid and cement mortar particles, and proposed an improved fluid-solid coupling model which is more suitable for the high brittle cement mortar. Under the action of internal hydraulic pressure, a tensile region existed at the tip of the preexisting flaws of the cement mortar specimen, which can also explain the crack initiation and propagation along the horizontal shear direction during the stage of crack initiation. However, the fissure water pressure was not completely dissipated because of the high brittleness of the cement mortar and the existence of a large number of micro-cracks in the failure area, which finally resulted in a relatively concentrated horizontal compressive stress, and roughly formed a compressive region with a smaller stress along the horizontal shear direction.
Multivariate Estimations of Equilibrium Climate Sensitivity from Short Transient Warming Simulations
Authors: Bastiaansen Robbin , Dijkstra Henk , von der Heydt Anna
Published: March 2021

One of the most used metrics to gauge the effects of climate change is the equilibrium climate sensitivity, defined as the long-term (equilibrium) temperature increase resulting from instantaneous doubling of atmospheric CO2. Since global climate models cannot be fully equilibrated in practice, extrapolation techniques are used to estimate the equilibrium state from transient warming simulations. Because of the abundance of climate feedbacks – spanning a wide range of temporal scales – it is hard to extract long-term behaviour from short-time series; predominantly used techniques are only capable of detecting the single most dominant eigenmode, thus hampering their ability to give accurate long-term estimates. Here, we present an extension to those methods by incorporating data from multiple observables in a multi-component linear regression model. This way, not only the dominant but also the next-dominant eigenmodes of the climate system are captured, leading to better long-term estimates from short, non-equilibrated time series.
Robust Future Changes in Meteorological Drought in CMIP6 Projections Despite Uncertainty in Precipitation
Authors: Ukkola Anna , De Kauwe Martin , Roderick Michael , Abramowitz Gab , Pitman Andy
Published: March 2021

Understanding how climate change affects droughts guides adaptation planning in agriculture, water security, and ecosystem management. Earlier climate projections have highlighted high uncertainty in future drought projections, hindering effective planning. We use the latest CMIP6 projections and find more robust projections of meteorological drought compared to mean precipitation. We find coherent projected changes in seasonal drought duration and frequency (robust over >45% of the global land area), despite a lack of agreement across models in projected changes in mean precipitation (24% of the land area). Future drought changes are larger and more consistent in CMIP6 compared to CMIP5. We find regionalised increases and decreases in drought duration and frequency that are driven by changes in both precipitation mean and variability. Conversely, drought intensity increases over most regions but is not simulated well historically by the climate models. These more robust projections of meteorological drought in CMIP6 provide clearer direction for water resource planning and the identification of agricultural and natural ecosystems at risk.
Global Mean Sea-level Changes in the Last Two Millennia
Authors: Gangadharan Nidheesh , Goosse Hugues , Parkes David , Goelzer Heiko
Published: March 2021

Instrumental records show that global mean sea level (GMSL) rose by approximately 15 cm in the 20th Century, with estimates of contributing factors suggesting the major components are ocean thermal expansion and melting of continental ice sheets and glaciers. However, little is known about the individual contributions to GMSL changes over the preindustrial common era (PCE) and the potential differences in the mechanisms controlling those changes between different time periods. Here, we describe the GMSL changes in the PCE by comparing proxy-based reconstructions with estimates derived from model experiments. The ocean thermal expansion is estimated on the basis of Coupled (Paleoclimate) Model Intercomparison Project (CMIP/PMIP) experiments. The contributions of ice sheets and glaciers are based on simulations with an ice-sheet model (IMAU-ICE) and a global glacier model (The Open Global Glacier Model), respectively. We also describe the thermal expansion response in the different ocean basins over the last millennium. The findings provide new insights on the current anthropogenic warming and sea-level rise in a wider context.