bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneity of Holocene freshwater dolomites from central Hungary based on a statistical analysis of rock-forming component properties derived from CT data
Authors: Alzoubi Nour , Gulyás Sándor , Geiger Janos
Published: March 2021

The Danube – Tisza interfluve area in the middle part of the Carpathian Basin harbors numerous mainly groundwater-fed hypersaline (alkaline) ponds which were characterized by carbonate precipitation under varying geochemical, climatic, environmental conditions during the Holocene.  The formation of dolomite attributable to seasonal variations of the climate and concomitant volume, geochemical changes of the groundwater, and the waterbody in these lacustrine environments is a unique feature of the area. A general model of freshwater high magnesium calcite, proto-dolomite, and dolomite precipitation in these lakes has been constructed in the early-mid 1980s via the complex geological, geochemical isotope geochemical investigation of carbonate rocks of extant lacustrine sequences of the mentioned area complemented by geochemical analyses of the lake and groundwater. Seasonal and long-term climate variations are expressed in the form of macro and micro-cycles preserved in the rock record. These however have never been examined in detail.   To unravel and understand the cyclicity present in the mentioned carbonate sequences we need quantitative information on the composition and physical properties of rock. CT analysis of rocks yields data on density differences observable between the building blocks or forming components in the material under study. Groups identified via statistical analysis of the data can be assigned to the various rock-forming components, and these groups can be described quantitatively via statistical parameters characterizing distribution. 3D visualization of the clustered data in the rock samples allows for cross-validation of interpretations. Via studying the vertical and spatial heterogeneity of the identified rock-forming components using their descriptive statistical properties the presence of micro-and macrocycles can be revealed, which serve as a starting point for further investigations to understand the nature and causes of these cycles. We are to present the results of such work done on some carbonate samples of the mentioned area. Research has been carried out within the framework of the University of Szeged, Interdisciplinary Excellence Centre, Institute of Geography and Earth Sciences, Long Environmental Changes Research Team. Support of the Ministry of Human Capacities, Hungary Grants 20391- 3/2018/FEKUSTRAT and NKFIH 129265 are acknowledged. 

 
Comparison of gridding methods for monthly precipitation for trend analysis in Canada
Authors: Abbasnezhadi Kian , Wang Xiaolan
Published: March 2021

During the last couple of decades, Canada’s national and regional climate trend assessment has been based on a set of gridded temperature and precipitation monthly anomalies, known as the Canadian Gridded (CanGRD) data, which were produced using Optimal Interpolation (OI). In CanGRD, temperature anomalies and normalized precipitation anomalies at 463 stations of the Adjusted/Homogenized Canadian Climate Data (AHCCD) are interpolated to a 50-km equal-area grid over Canada. The input AHCCD precipitation data had been previously adjusted for known problems such as wind-induced gauge undercatch, wetting loss, and trace amounts; and joined stations series were also tested and adjusted. However, the performance of the CanGRD gridding method (i.e., the OI method) has never been evaluated against other gridding methods. The objective of this study is to evaluate CanGRD method against an ordinary kriging (KG) method. To this end, an observation-based ANUSPLIN-gridded monthly precipitation dataset (which is based on precipitation data from 3000+ stations) was used as the truth dataset, and ANUSPLIN estimates of monthly precipitation amounts at the 463 AHCCD stations were used as input data to the gridding models. In search for a better way to use KG, we took two approaches to apply KG: (1) KG-GP approach, in which KG was applied directly to the monthly total precipitation amounts; and (2) KG-GNGA approach, in which KG was applied separately to the monthly normals (for each calendar month) and the monthly anomalies. The gridded normals (GN) and the gridded anomalies (GA) were then combined together (GN+GA) for comparison with the gridded precipitation (GP) from the KG-GP approach to find out which of the two approaches is more skillful. The gridded anomalies (GA) from the KG-GNGA approach is comparable, and was compared with the CanGRD data, noting that in the CanGRD method, the anomalies rather than precipitation totals are gridded. In both evaluations, the gridded datasets were compared against their counterparts derived from the truth dataset using skill measurements such as Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), and Pattern Correlation Score (PCS). The results show that (1) the KG-GNGA approach notably outperforms the KG-GP approach, and (2) the KG-GNGA method significantly outperforms the OI method used in CanGRD. This study is being expanded to include other gridding methods in the comparison.
Unravelling the enigmatic Grampian Shear Zone: In-situ monazite and titanite U-Pb analysis of the juxtaposed Badenoch and Grampian Groups
Authors: Evason Lewis , Bird Anna , Dempsey Eddie , Hardman Kit , Smith Martin , Strachan Rob
Published: March 2021

The Grampian Shear Zone (GSZ) represents a highly deformed tectonostratigraphic contact between the Proterozoic metamorphic rocks of the Dalradian Group from the underlying high grade metamorphic Neoproterozoic rocks of the Badenoch Group within the Grampian Highlands. The nature (tectonic suture or palaeo-unconformity), age and structure of the GSZ and indeed the underling Badenoch Group are poorly constrained. Previous studies of the GSZ and synkinematic (intruded during shearing) pegmatites found therein, yielded metamorphic/deformation (and magmatic) ages ranging from c.a. 808 to 440 M. This study reinvestigates this shearzone using in-situ (within section) petrochonological analysis on a range of U-Pb and Rb-Sr chronometers – Monazite, zircon, titanite, rutile and mica. Carrying out this analysis in-situ and using a variety of minerals allows us to directly date deformation fabrics over a wide range of deformation temperatures, giving us a far more detailed picture of the events recorded within these rocks. Large monazite grains (≥100μm) were mapped using in-situ LA-ICP-MS to show within grain variation of major elements and REEs. Monazite U-Pb spot analysis from the GSZ has yielded ages ranging from 784.11 ± 1.2Ma to 442.58 ± 0.58Ma. The same analysis was performed on a sample from the Grampian group which yielded an age of 441.34 ± 037Ma. In addition to this monazite data, in-situ U-Pb Titanite analysis from the Badenoch Group gave ages of 526.96 ± 1.33 Ma from a metabasite sample, with a metasedimentary sample giving a range of titanite U Pb ages from 540 to 460Ma. These age ranges show that the Badnoch Group and the GSZ have recorded a complex polyorogenic history relative to the “simple” overlying Dalradian metasediments. We propose that the Grampian Shear Zone represents a deep-seated Knoydartian (808 to 784Ma) age shear zone within the meso-Neoproterozoic Badenoch Group. This shear zone was then reactivated during the Grampian phase of the Caledonian Orogeny resulting in the tectonic emplacement of the Dalradian metasediments above the Badenoch group.
The drying regimes of non-perennial rivers
Authors: Price Adam , Jones C.Nathan , Hammond John , Zimmer Margaret , Zipper Samuel
Published: March 2021

The paradigm of surface water flow regimes is central to the aquatic sciences, where the timing, duration, frequency, magnitude, and rate of change of flow drive physical, chemical, and biological functions in aquatic systems. However, non-perennial streams comprise the majority of the global river network and there is a need to understand not just whether or not a stream periodically dries, but how it dries. Here, we propose to flip the script on flow regimes by presenting a comprehensive 'drying regime' framework to characterize stream drying.  We then identify similar drying characteristics in streams across watersheds with a broad range of climates, physiographic regions, and land uses. Using daily streamflow from 894 U.S. Geological Survey streamflow gages we isolated over 25,000 unique drying events over a period from 1979 - 2018. From these drying events we identified and calculated streamflow metrics that describe timing, duration, magnitude, frequency, and rate of change of stream drying. Using multivariate statistics, k-means clustering, and random forest analyses we grouped drying events into distinct drying regimes and determined the drivers of the clustered regimes. K-means clustering resulted in 4 distinct drying regimes characterized by (1) more frequent drying, (2) longer no-flow duration, (3) drying occurring following low antecedent flows, and (4) flashy high frequency drying, respectively. The majority of gages had more than one drying regime present at different times within each year, suggesting that dominant flow paths or drivers varied through time  Clustered drying regimes show low event-scale spatial coherence, and while drying regimes (1) and (2) show similar frequency throughout the year, (3) and (4) are substantially more frequent during summer months. Based on random forest analysis, land cover characteristics appear to drive drying event assignment to drying regimes more than climate variables. Furthermore, increased importance of individual watershed properties shows that the structural makeup of the watershed is notably more important to how an intermittent system dries than climate or physiographic characteristics. Non-perennial systems have unique functions due to the occurrence of both flowing and dry states, yet most of the past efforts rely on frameworks built around perennial streamflow behavior. Our work presents a novel drying regime framework to allow future studies to more effectively connect river drying to the physical, chemical, and biological functioning in these systems. This framework may also aid in current sustainable river management, including engineered flow regimes that are designed to balance water allocations with ecosystem requirements.
Late Carboniferous Schlingen in the Gotthard nappe (Central Alps) and their relation to the Variscan evolution
Authors: Buehler Mario , Zurbriggen Roger , Berger Alfons , Herwegh Marco , Rubatto Daniela
Published: March 2021

Many pre‐Mesozoic basements of the Alpine belt contain kilometre‐scaled folds with steeply inclined axial planes and fold axes. Those structures are referred to as Schlingen folds. They deform polymetamorphic gneisses, often Late‐Ordovician metagranitoids and are cross‐cut themselves by Permian intrusions. However, the structural evolution of such Schlingen is still not completely understood and their geodynamic significance for the Variscan evolution is not clear. To close this gap, this study investigates in detail a well-preserved Schlingen structure in the Gotthard nappe (Central Swiss Alps). This Schlingen fold evolved by a combination of shearing and folding under amphibolite facies conditions. Detailed digital field mapping coupled with petrological and structural investigations reveal local synkinematic migmatisation in the fold hinges parallel to axial planes. U‐Pb dating of zircons separated from associated leucosomes reveal cores that record a detrital country rock age of 450 ± 3 Ma, and rims with a range of dates from 270 to 330 Ma. The main cluster defines an age of 316 ± 4 Ma. We ascribe this Late‐Carboniferous age to peak metamorphic conditions of the late‐Variscan Schlingen phase.

The pre-Schlingen structures are subdivided into three older deformation events, which are connected to the Cenerian and post-Cenerian deformations. In addition, until now unknown, post Schlingen-, but pre-Alpine transpressional deformation have been detected and described. This superimposed deformation produced locally a low-grade foliation and minor undulation of the Schlingen structures.

The detail data of the investigated fold structures are linked with already described Schlingen folds in the wider Alpine realm, which all are concentrated in the most southern parts of the Variscides. From a geodynamic point of view and based on the new tectono-metamorphic constraints, we propose Schlingen formation preceded and concurred the crustal-scale transpressional tectonics of the East Variscan Shear Zone. This scenario separates, at least in a structural sense, the Southern Variscides from more northern parts (also Gondwana derived) inside Pangea, where Schlingen folds are absent.
urban vegetation of algiers : urban ecology approach
Authors: Ighil agha Bilal
Published: March 2021

In the 21st century, where problems related to the city are legion (climate change, disease, depression, crime, etc.), urban ecology promises to provide concrete and effective solutions to enable humanity to live and the planet to breathe.

In a southern metropolis such as Algiers, these seemingly endless urban problems are becoming more acute due to a galloping population and an unbridled expansion of the urban fabric. This expansion is often at the expense of green spaces.

In this way, we worked on methodologies that will enable us to quantify the layout, condition and influence of these green spaces and to develop more appropriate management plans to optimize there functions.

We also carried out a preliminary study for the landscape analysis and spatialization of urban plants, to be able to deepen the study later and create an interrogative spatial database to help decision-making.
Recent measurements of subsidence in the Ganges-Brahmaputra Delta, Bangladesh
Authors: Steckler Michael S. , Oryan Bar , Jaman Md. Hasnat , Mondal Dhiman R. , Grall Céline , Wilson Carol A. , Akhter S. Humayun , DeWolf Scott , Goodbred Steven L.
Published: March 2021

Deltas, the low-lying land at rivers mouths, are sensitive to the delicate balance between sea level rise, land subsidence and sedimentation. Bangladesh and the Ganges-Brahmaputra Delta (GBD) have been highlighted as a region at risk from sea level rise, but reliable estimates of land subsidence have been limited. While early studies in the GBD suggested high rates of relative sea level rise, recent papers estimate more modest rates. Our objective is to better quantify the magnitude, spatial variability, and depth variation of compaction and subsidence in the GBD in order to better evaluate the processes controlling it and the pattern of relative sea level rise in this vulnerable region.

With support from the Bangladesh Water Development Board, we have rehabilitated previously installed GNSS and installed new GNSS co-located with Rod Surface Elevation Tables (RSET) to better understand the balance of subsidence and sedimentation in the coastal zone in SW Bangladesh, which is less affected by the active tectonic boundaries to the north and the east. The continuous GNSSs installed in 2003 and 2012 were mounted on reinforced concrete building roofs. GPS stations in the area yield subsidence rate estimates of 3-7 mm/y.  To densify the subsidence data, in early 2020 we resurveyed 48 concrete Survey of Bangladesh geodetic monuments in SW Bangladesh that were installed in 2002. Although only measured at the start and end of the period, the time span between the two measurements is ~18 years enabling us to estimate subsidence over this timespan.

Preliminary results show that about ½ the sites yielded very high subsidence rates; repeat measurements confirm the suspicion that the monuments at these sites are unstable and have undergone localized subsidence from settling or anthropogenic activity. The remaining sites show an increase in subsidence from the NW to the SE, consistent with estimates of average Holocene subsidence (Grall et al., 2018). However, rates from the campaign stations are much higher than those from continuous GNSS sites, but only slightly higher than an RSET site. We interpret that the continuous building GNSS omit very shallow compaction-related subsidence, while RSETs neglect deep subsidence. This is further reinforced by results from a compaction meter consisting of 6 wells from 20 to 300 m depth with vertical optical fiber strainmeters in each well. They show a decrease in compaction with depth. While initial results require further investigation, we highlight the importance of multiple methodologies for interpreting subsidence rates--deep, shallow, natural, anthropogenic--in vulnerable delta regions.
Excess of sulfate and dissolved inorganic carbon in groundwaters fueled by pyrite oxidation and organic matter loads – A multi-isotope approach
Authors: Malik Christoph , Jenner Anna-K. , Schmiedinger Iris , Böttcher Michael E.
Published: March 2021

The biogeochemistry of sulfur and carbon in groundwater of a Quaternary porous aquifer system and associated surface (lake) waters was investigated to identify processes of water mixing and the sources of dissolved sulfate and dissolved inorganic carbon (DIC). The study area is situated in North-Eastern Germany (Mecklenburg-Western Pomerania) close to the Baltic Sea coastline. The area is under impact by agricultural activity on a regional scale. A major goal was to identify the natural and anthropogenic key hydrobiogeochemical processes controlling the coupled element cycles upon groundwater development. Besides major and minor elements, redox-sensitive trace elements, nutrients, and stable mulit-isotope signatures (H, C, O, S) were considered.

While water isotopes of most groundwaters are positioned on the meteoric water line, surface waters are affected by an evaporation-induced enrichment of heavy isotopes. These shifts allow for a quantification of mixing proportions in influenced groundwater wells between direct precipitation-derived groundwater and  infiltrating lake water born fractions.

Major element hydrochemical and the carbon isotope composition of DIC indicate soil CO2 and the subterrestrial dissolution of carbonate minerals within the aquifer matrix as primary sources for DIC. Furthermore, contributions from oxidized dissolved organic carbon (DOC) under water-saturated conditions are found.

The coupled sulfur and oxygen isotope composition of dissolved sulfate indicates an origin dominatly  from the subterrestrial oxidation of iron sulfides, mainly pyrite. These iron sulfides are found in the sediments making the modern porous aquifer, in the study area with a deduced sulfur isotope composition of about -12 per mil vs. VCDT. These findings coupled to enhanced loads in dissolved iron and manganese, but low nutrient concentrations indicate nitrate as an important driver for lithoautothrophic pyrite oxidation. At several sites, the enhanced sulfate loads led to dissimilatory sulfate reduction and, thereby, to in-situ transformation of DOC (and/or Methane) to DIC. The enhancements of sulfate and DIC seems to be a typical feature in North German younger groundwaters and strongly (in)directly impacted by anthropogenic forces.
Atom probe as a tool for understanding mineral physics and rock deformation: a case study of deformed wehrlite
Authors: Cukjati Joseph , Cooper Reid , Parman Stephen , Zhao Ningli , Akey Austin , Laiginhas Fernando
Published: March 2021

Here we report Atom Probe Tomography (APT) analyses of grain and phase boundaries of laboratory-deformed, fine-grained mixtures of clinopyroxene and olivine (Zhao, et al., 2019).  The experiments show that the mixtures deform much more rapidly than either mineral endmember.  This enhanced deformation in the two-phase material is due to stress-driven reactions at the phase boundaries. Lower effective viscosities of phase mixtures may be critical to the initiation of plate tectonics and the formation of mantle shear zones.

The hypothesis presented here is that the ‘bulk rock’ – a wehrlite – deforms rapidly because conversion of one phase to the other occurs at phase boundaries (e.g., Sundberg & Cooper, 2008).  In this model, grain-scale transport of the shared (slowly-diffusing) mineralogical component Si4+ is not required.  The near-boundary gradients of olivine-insoluble ions are presented as evidence of the phase transformation which either dissolves olivine into clinopyroxene or vice versa.  

The resolving power of the APT makes it a promising tool for investigating the microphysics of rock deformation, bridging the atomic scale all the way to the plate-tectonic scale.

References:
Sundberg M, Cooper RF (2008) Crystallographic preferred orientation produced by diffusional creep of harzburgite: effects of chemical interactions among phases during plastic flow. J Geophys Res Solid Earth 113(12):B12208.
Zhao N, Hirth G, Cooper RF, Kruckenberg SC, Cukjati J (2019) Low viscosity of mantle rocks linked to phase boundary sliding. Earth Planet Sci Lett 517:83–94.
Crustal strain and seismic hazard of the NE Tibetan Plateau
Authors: Ou Qi , Daout Simon , Rollins Chris , Weiss Jonathan , Parsons Barry
Published: March 2021

Seismic hazard assessment for the NE Tibetan Plateau is of paramount importance because of the growing population density and the accelerated communication and trade activities along the rejuvenated Ancient Silk Road, following the Belt and Road Initiative, and the opening of the high speed railways. Previous-generation seismic hazard assessments were largely based on earthquake catalogues which are shorter than typical earthquake cycles and are temporally and spatially incomplete. This is exacerbated by the fact that magnitudes of many historical Chinese earthquakes are overestimated. In this study, we present new earthquake rate estimates for the NE Tibetan Plateau derived from both an InSAR strain rate map and a re-estimated magnitude of the 1920 Haiyuan Earthquake. First, we obtain a ~100 m resolution strain rate map from five years of Sentinel-1 InSAR data covering an area of 439254 km2 which shows strain concentrated along the Haiyuan and East Kunlun Faults and distributed across the Qilian thrusts and the West Qingling Fault. Second, the magnitude of the Haiyuan Earthquake has been re-estimated to Mw 7.9 ± 0.2 using both historical seismograms and offset measurements. Taking the total moment release rate given by the strain rate map and the magnitude of the 1920 Haiyuan Earthquake as the largest magnitude in the Gutenberg-Richter relationship, we generate rate-balancing frequency-magnitude models with different b values and percentages of seismic moment release. Comparing our models against four earthquake catalogues covering different periods and magnitude ranges suggests the following: (1) With a b value of 1 and 75% seismic moment release, the calculated relationship fits well the International Seismological Centre - Global Earthquakes Catalogue (ISC-GEM, 97 years) catalogue in the range Mw>6.5, but overestimates all other catalogues not containing the Haiyuan Earthquake; (2) keeping a b value of 1 and in order to fit the Global Centroid Moment Tensor Catalogue (GCMT, 34 years), the China Earthquake Networks Center Catalogue (CENC, 12 years) and the China Historical Strong Earthquakes Catalogue (CHSEC, 411 years), a low seismic release rate of 30% would be required; the resultant relationship also fits the ISC-GEM catalogue excluding the Haiyuan Earthquake and its aftershocks; (3) to fit all of the catalogues, it is necessary to reduce the b value to 0.7, in which case only 25% aseismic moment release would be required, giving confidence that Mw 7.9 ± 0.2 is likely the largest magnitude required to balance the tectonic strain in the NE Tibetan Plateau. This study highlights the dominating strain release by, and the effect on the b value of, the largest earthquake and demonstrates the advantage of combining tectonic strain and earthquake catalogues for seismic hazard assessment.
Simulating reference rainfall scenarios for hydrological applications using a multifractal approach
Authors: Ramanathan Arun , Versini Pierre-Antoine , Schertzer Daniel , Tchiguirinskaia Ioulia , Perrin Remi , Sindt Lionel
Published: March 2021

Abstract

Hydrological applications such as flood design usually deal with and are driven by region-specific reference rainfall regulations, generally expressed as Intensity-Duration-Frequency (IDF) values. The meteorological module of hydro-meteorological models used in such applications should therefore be capable of simulating these reference rainfall scenarios. The multifractal cascade framework, since it incorporates physically realistic properties of rainfall processes such as non-homogeneity (intermittency), scale invariance, and extremal statistics, seems to be an appropriate choice for this purpose. Here we suggest a rather simple discrete-in-scale multifractal cascade based approach. Hourly rainfall time-series datasets (with lengths ranging from around 28 to 35 years) over six cities (Paris, Marseille, Strasbourg, Nantes, Lyon, and Lille) in France that are characterized by different climates and a six-minute rainfall time series dataset (with a length of around 15  years) over Paris were analyzed via spectral analysis and Trace Moment analysis to understand the scaling range over which the universal multifractal theory can be considered valid. Then the Double Trace Moment analysis was performed to estimate the universal multifractal parameters α,C1 that are required by the multifractal cascade model for simulating rainfall. A renormalization technique that estimates suitable renormalization constants based on the IDF values of reference rainfall is used to simulate the reference rainfall scenarios. Although only purely temporal simulations are considered here, this approach could possibly be generalized to higher spatial dimensions as well.

Keywords

Multifractals, Non-linear geophysical systems, Cascade dynamics, Scaling, Hydrology, Stochastic rainfall simulations.
Energy Flux and Conductance from Meso-Scale Auroral Features Observed by All-Sky-Imagers
Authors: Gabrielse Christine , Nishimura Toshi , Chen Margaret , Hecht James , Kaeppler Stephen , Lyons Larry , Deng Yue
Published: March 2021

Earth’s Magnetosphere-Ionosphere-Thermosphere system is inseparably coupled, with driving from above and below by various terrestrial and space weather phenomena. Global models have done well at capturing large-scale effects, but currently do not capture the meso-scale (~10s-500 km) phenomena which often are locally more intense. As computing power improves, and modeling meso-scales now becomes possible, it is vital to provide data-informed inputs of the relevant drivers. In this presentation, we focus on the energy flux deposited into the ionosphere from the magnetosphere by precipitating particles that result in the aurora, specifically at meso-scales, and the resulting conductance. Thanks to NASA’s THEMIS mission, an array of all-sky-imagers (ASIs) across Canada monitors the majority of the nightside auroral oval at a 3 second cadence, providing a global view at temporal & spatial resolutions required to study the aurora on meso-scales. Thus, we present 2-D maps over time of the energy flux, energy, and conductance that result from the aurora during solar storms and substorms, including those features at meso-scales. We determine conductance using the ASI-determined eflux and energy as inputs to the Boltzman Three Constituent (B3C) auroral transport code, compare values with Poker Flat ISR observations, and find a good comparison. We find that meso-scale aurora contributes at least 60-70% of the total precipitated energy flux during the first ten minutes of a substorm. Our results can be utilized by the broad community, for example, as inputs to atmospheric models or as the resulting conductance from precipitation inferred by magnetospheric models or satellite observations.
A concept for sustainable and digitalized hydropower going beyond the sustainable hydropower sustainability tool
Authors: Doujak Eduard , Hočevar Marko , Pummer Elena , Di Federico Vittorio , Finger David
Published: March 2021

The EU energy policy has the ambitious objective to become the first carbon-neutral continent in the world. In order to achieve this objective hydropower will have to play an essential role as energy source and energy storage in pump storage facilities. Hydropower is a clean, low carbon, and cost-efficient energy source that can be exploited sustainably if an adequate management system is implemented. Nevertheless, in the past, hydropower operations have led to conflicting interests over water usage, impacts on aquatic flora and fauna, and significant socio-economic implications. In order to avoid and mitigate possible negative consequences of hydropower plants the Hydropower Sustainability Assessment Protocol (HSAP, https://www.hydrosustainability.org/) provides a helpful tool to minimize related impacts. In this presentation we will delineate how the 26 topics of the HSAP could be complemented in order to provide a fully digitalized sustainability framework for hydropower. In particular, we will outline innovative solutions for the most challenging topics of sustainable hydropower plants, including i) energy supply securing with a high share of renewable energies ii) climate change impacts on water resources and hydropower production, ii) altered flow and changed turbidity dynamics in rivers, iii) long-term downstream effects on river beds and groundwater exchange, iv) degradation of river ecology, v) socio-economic impacts on local stakeholders, vi) adequate assessment of the water-energy-food nexus, vii) near real time digitalisation framework to streamline information. Through the digitalization of the HSAP a standardized and transparent flow of information will be guaranteed. Within the presented digitalized framework, all data will be processed to standardize, harmonize and synthesize results and information from all working tasks into a data lake. We may apply this framework to demonstration hydropower plants of different types to improve their sustainability, efficiency and management.
Multiscale Solar Wind Turbulence Properties inside and near Switchbacks measured by Parker Solar Probe
Authors: Martinović Mihailo , Klein Kristopher , Huang Jia , Chandran Benjamin , Kasper Justin , Lichko Emily , Bowen Trevor , Chen Christopher , Matteini Lorenzo , Stevens Michael , Case Anthony , Bale Stuart
Published: March 2021

Parker Solar Probe (PSP) routinely observes magnetic field deflections in the solar wind at distances less than 0.3 au from the Sun. These deflections are related to structures commonly called 'switchbacks' (SBs), whose origins and characteristic properties are currently debated. Here, we use a database of visually selected SB intervals - and regions of solar wind plasma measured just before and after each SB - to examine plasma parameters, turbulent spectra from inertial to dissipation scales, and intermittency effects in these intervals. We find that many features, such as perpendicular stochastic heating rates and turbulence spectral slopes are fairly similar inside and outside of SBs. However, important kinetic properties, such as the characteristic break scale between the inertial to dissipation ranges differ inside and outside these intervals, as does the level of intermittency, which is notably enhanced inside SBs and in their close proximity, most likely due to magnetic field and velocity shears observed at the edges. We conclude that the plasma inside and outside of a SB, in most of the observed cases, belongs to the same stream, and that the evolution of these structures is most likely regulated by kinetic processes, which dominate small scale structures at the SB edges. 
Understanding the interdependent cycles of soil carbon, nitrogen and phosphorus during soil saturation events 
Authors: Lieberman Hannah , von Sperber Christian , Rothman Maia , Kallenbach Cynthia
Published: March 2021

With climate change, much of the world will experience devastating shifts in weather patterns like increased flooding, intensifying periods of soil saturation. Soil carbon (C), nitrogen (N) and phosphorus (P) cycles are sensitive to changes in soil saturation, where exchange between the mineral-bound and the soluble bioavailable pools can occur with increases in moisture content. With soil saturation, C, N, and P may be mobilized either through greater diffusion or reduced conditions that cause desorption of mineral-bound C, N and P into their respective soluble pools. De-sorption, resorption and diffusion dynamics of C, N, and P may or may not reflect the stoichiometry of the mineral bound pool. Changes in bioavailable soluble C, N and P that could occur with soil saturation and drying may cause unknown consequences for microbial biomass C:N:P. With increases in soil moisture, simultaneous changes in both substrate stoichiometry and microbial growth may occur that impact microbial biomass stoichiometry.  Such changes in microbial stoichiometry and microbial retention of C, N, and P may affect the post-flood fate of soluble C, N, and P. Understanding how releases in mineral bound C, N and P alter the bioavailable C:N:P and how this in turn impacts microbial activity and accumulation of these substrates can inform predictions of retention or losses of C, N and P following soil saturation events.

To determine if mineral-bound, soluble and microbial biomass stoichiometry is maintained or altered during and after soil saturation events, we used a laboratory incubation approach with manipulated soil saturation and duration. Soil incubations were maintained at three water-holding capacity (WHC) levels: 20% (control), 50%, (moderate) and 100% (severe). We maintained the moderate and severe water-logging treatments for  0.5 h, 24 h, 1 week, followed by air-drying to 20% WHC to examine the influence of flood duration. To understand the exchanges of C, N and P between different pools during flooding, we compared changes in soluble and mineral bound soil C, N and P and impacts on microbial C, N, and P exo-cellular enzymes, and microbial biomass C:N:P. Preliminary results indicate that greater soil moisture content increases soluble P and that the 24 hour flood period captures shifts in the mineral bound P pool that do not remain for the longer flood period (1 week). Enzyme activity similarly reflects an increase in microbial activity in the soil held at 50% and 100% moisture content for 24 hours. We also discuss how soil moisture levels and flood duration impact soluble and mineral bound C relative to P, and how microbial biomass C:N:P tracks these fractions. By exploring the combined response of mineral-bound and soluble C, N, and P to variation in soil saturation, we can better understand how different flood scenarios will impact soil C, N and P retention.
Analysis of change in vegetation cover linked to public policies, case study: Tenosique, Tabasco, Mexico.
Authors: Nieto Jacob , Vidal García Gabriela , Jácome Paz Mariana Patricia , Ruiz Santos Tania Ximena , Nuñez Juan Manuel , Ramírez Serrato Nelly Lucero
Published: March 2021

Currently, natural areas are being devastated by anthropogenic activity. Activities such as agriculture, illegal logging, non-organic farms, and livestock exploitation, disrupt an ecosystem that has been in balance for many years. Therefore, regulations implemented by governments are required for their preservation. However, these regulations are not always the most used in terms of conservation. Such is the case of the town "Tenosique", in this area is one of the most important rivers in Mesoamerica, the Usumacinta River, which is a great regulator of ecological processes and is connected to Mexico with Guatemala. This site has been under the influence of regulations applied to the economic impulse of the area, whether for agricultural and livestock activities, which has affected the apparent vegetation cover, unlike Guatemala that has opted for regulations with a forest conservation approach. These policies sought to boost the agricultural sector, but many deforested areas to carry out this activity turned out not to be suitable due to the type of soil. With the change of regime, financing ends and with it economic activity decreases, leaving the area quite affected and the communities with financial problems. Recently, conservation and protection actions were implemented in the area together with support for these communities. The proximity between Mexico and Guatemala visually shows the results of the application of different public policies. The objective of this study is to quantify the loss and gain of vegetation over time from satellite images of the area, in order to compare this statistic with the different government programs of each era. For this, at least 10 multispectral satellite images of free access will be used, from the Landsat 7 satellite, which has 30 meters of resolution but visually adjustable to 15 meters with the union of its panchromatic channel, and that cover a time range from 1999 to 2020. On these, two processes will be carried out: 1) a normalized vegetation index calculation and 2) a supervised classification. With which it is intended to measure the area and the greenness of a mask of the vegetation cover. The results will serve to update the projects carried out on the site and detect areas of priority interest resolution for larger projects, as well as the future estimation of the critical state of the site regarding the loss of vegetation cover and quantify the conservation efforts that have been carried out. carried out from 2008 to the present.
Combinatorial Framework for Obtaining the Optimal Spatial Distribution of Earthquakes on Complex Fault Systems
Authors: Geist Eric , Parsons Tom
Published: March 2021

A critical component of seismic hazard analysis is understanding the frequency and spatial distribution of earthquakes with different magnitudes on nearby faults.  A framework for determining the optimal spatial distribution of earthquakes on a complex fault system is developed using combinatorial optimization methods. Input to the framework is a millennia-scale sample of earthquakes taken from a regional Gutenberg-Richter (G-R) relation.  We then determine the optimal spatial arrangement of each earthquake in the fault system according to an objective function and constraints.  Our previously published results focus on minimizing the total misfit in slip rates as the objective function; constraints were maximum and minimum slip rate values that incorporate uncertainty in slip-rate values for each fault.  Both global and local combinatorial optimization methods have been developed to solve these problems: integer programming and the greedy sequential algorithm, respectively. Resulting on-fault magnitude distributions cannot be simply classified as being either purely characteristic or G-R. For example, faults may exhibit multiple “characteristic” magnitudes or a power-law distribution of magnitudes over a restricted range. Current research involves adapting the general combinatorial framework to include other and multiple objective functions, including minimizing the variation in accumulated stress over millennia.  The framework can also accommodate branching and step-over connections for the slip-rate objective, while current research is underway to include interaction stress loading among the different faults in the fault system for stress-based objectives.  Results from these methods are valuable for verifying the assumed magnitude-frequency distributions for faults in probabilistic seismic and tsunami hazard analyses.
Foliar methane uptake capacity as a critical plant trait in the global carbon cycle
Authors: Thomas Sean , Gorgolewski Adam , Vantellingen Juliana , Caspersen John
Published: March 2021

Until recently it has been assumed that the main site of methane exchange between the terrestrial biosphere and the atmosphere is soils. However, recent research has shown that tree stems can contribute substantial methane flux; moreover, the few studies that have examined foliar methane flux in situ have found non-negligible fluxes. Foliar methane uptake appears to be mediated by methanotrophic endophytes and is appreciable in upland forests where soils also show net methane oxidation. In contrast, foliar release of methane can occur in lowland forests in which soils show net methane release as a result of transport of dissolved methane through the xylem stream. There is evidence that both foliar methane uptake (and release) are mediated by stomatal conductance, suggesting that the capacity for foliar methane fluxes may be closely related to other gas-exchange-related functional traits of leaves that covary along the fast-slow leaf economics spectrum.  Here we compile data on reported rates of foliar methane uptake in upland forests to test this idea. Data from three northern forest sites in Canada and Sweden indicate that: (1) methane uptake capacity is generally higher in broadleaf angiosperms than in conifers; and (2) methane uptake capacity is positively correlated with leaf nitrogen content, but shows a saturating pattern with a maximum rate of ~0.6-0.7 nmol m-2 s-1. We contend that foliar methane uptake has been under-appreciated as an important process in the global carbon cycle, but that patterns suggest a close linkage to other plant traits that will permit integration of this process into existing carbon cycle models.
Decrease in Volcano Jet Noise Peak Frequency from Crater Expansion
Authors: McKee Kathleen , Snee Eveanjelene , Maher Sean , Smith Cassandra , Reath Kevin , Roman Diana , Matoza Robin S. , Carn Simon , Mastin Larry , Anderson Kyle , Damby David , Perttu Anna , Assink Jelle , de Negri Leiva Rodrigo , Degterev Artem , Rybin Alexander , Chibisova Marina , Itikarai Ima , Mulina Kila , Saunders Steve
Published: March 2021

Volcanic jet noise is the sound, often below the human audible range (<20 Hz and termed infrasound), generated by momentum-driven fluid flow through a volcanic vent. Assuming the self-similarity of jet flows and audible jet noise extends to infrasonic volcanic jet noise, the Strouhal number, St=Djf/Uj, connects frequency changes, f, to changes in the jet length (expanded jet diameter, Dj) and/or velocity scale (jet velocity, Uj). We examine the infrasound signal characteristics from the June 2019 VEI 4 eruptions of Raikoke, Kuril Islands and Ulawun, Papua New Guinea volcanoes with changes in crater geometry. We use data from the International Monitoring System (IMS) infrasound network and pre- and post-eruption satellite data (RADARSAT-2 and PlanetScope imaging for Raikoke and Ulawun, respectively). During both eruptions we observe a decrease in infrasound peak frequency during the transition to a Plinian phase, which remains through the end of the eruptions. The RADARSAT-2 data show a qualitative increase in the crater area at Raikoke; quantitative analysis is limited by shadows. At Ulawun, however, we estimate an increase in crater area from ~35,000 m2 on May 25, 2019 to ~66,000 m2 on July 17, 2019. We assume a constant Strouhal number and use the crater diameter as a proxy for expanded jet diameter. Our analysis suggests that the increase in crater diameter alone cannot account for the decrease in peak frequency during the Ulawun eruption. This suggests that the jet velocity also increased, which fits satellite data, and or the fluid properties (e.g. particle loading, nozzle geometry and roughness, etc.) changed. This is reasonable as the Ulawun eruption went Plinian, which likely involved an increase in jet velocity and erosion of the crater walls. This is the first study to corroborate the decrease in infrasound peak frequency with documented increase in crater area. The fortuitous satellite overpass timing, clear skies, and high spatial resolution enabled the quantitative examination of the Ulawun eruption.
Implementation of flood diversion canals and retention ponds to the H08 global hydrological model for flood management
Authors: Padiyedath Gopalan Saritha , Hanasaki Naota
Published: March 2021

Flood diversion canals play a crucial role in assuaging the flood risk by diverting water from the main channel to the nearby rivers, downstream of the same river, or the ocean. For the impact assessment of such canal systems on river discharge worldwide, their explicit inclusion into the global hydrological models (GHMs) is necessary. Despite this fact, such representation is limited due to their complex operations and lack of data. Therefore, we aim to propose a generalized scheme for the flood water diversion in the H08 GHM that ideally requires the universal parameters only. In this scheme, if the discharge exceeds the channel capacity, an amount equivalent to canal capacity is diverted to the canal, which will then flow to the retention ponds, and finally to the destination once the retention ponds get full. A regionalized scheme with site-specific parameters was also considered to evaluate the validity of the simulations.

The proposed scheme was tested in the upper Chao Phraya River basin, which is characterized by four tributaries of Ping, Wang, Yom, and Nan. The government has implemented Yom-Nan canal system to divert water from Yom to Nan River since 2014 to alleviate flooding in the lower Yom basin. The effect of this canal system was analyzed from 1980-2004 using the H08 model with the generalized scheme as well as the regionalized scheme. The simulations showed that the total flood water diverted from the Yom River was around 1.00 km3/year and 1.64 km3/year under the generalized and regionalized schemes, respectively, over the 25 years. This constitutes about 2.62% and 4.29% of the river discharge in the Yom River at the diversion point. In both simulations, nearly 30% of the water has been diverted to the Nan River and the remaining 70% was stored in the retention ponds. To assess the validity of the simulations, we compared the simulation results of the wet water-year 1994 with the observed canal operation data of the wet water-year 2017. The total flood water diverted was around 0.47 km3/year during the year 2017, whereas the same for 1994 was about 0.17 km3/year and 0.48 km3/year under the generalized and regionalized schemes, respectively. This shows that the regionalized simulations are close to the observations, while the generalized simulations reproduced nearly half of the diverted canal flow. The generalized simulations can be further improved by parameterizations.
Saturated carbon dioxide nanofluids enhanced oil recovery in carbonate reservoir cores using nuclear magnetic resonance
Authors: Tan Yongsheng , Li Qi , Xu Liang , Zhang Xiaoyan , Yu Tao
Published: March 2021

The wettability, fingering effect and strong heterogeneity of carbonate reservoirs lead to low oil recovery. However, carbon dioxide (CO2) displacement is an effective method to improve oil recovery for carbonate reservoirs. Saturated CO2 nanofluids combines the advantages of CO2 and nanofluids, which can change the reservoir wettability and improve the sweep area to achieve the purpose of enhanced oil recovery (EOR), so it is a promising technique in petroleum industry. In this study, comparative experiments of CO2 flooding and saturated CO2 nanofluids flooding were carried out in carbonate reservoir cores. The nuclear magnetic resonance (NMR) instrument was used to clarify oil distribution during core flooding processes. For the CO2 displacement experiment, the results show that viscous fingering and channeling are obvious during CO2 flooding, the oil is mainly produced from the big pores, and the residual oil is trapped in the small pores. For the saturated CO2 nanofluids displacement experiment, the results show that saturated CO2 nanofluids inhibit CO2 channeling and fingering, the oil is produced from the big pores and small pores, the residual oil is still trapped in the small pores, but the NMR signal intensity of the residual oil is significantly reduced. The final oil recovery of saturated CO2 nanofluids displacement is higher than that of CO2 displacement. This study provides a significant reference for EOR in carbonate reservoirs. Meanwhile, it promotes the application of nanofluids in energy exploitation and CO2 utilization.