bluuebunny/crossref_metadata_2025 huggingface dataset:
South African Land Degradation Monitor (SALDI) – A German – South African SPACES collaboration to advance land degradation assessments
Authors: Baade Jussi , Kaiser Andreas ,   team of SALDi
Published: March 2020

South Africa is greatly affected by land degradation, partly due to the high variability of its climatic conditions, the strong population growth and resulting economic demands. Thus reaching a number of SDGs, like achieving food security (#2), access to clean water (#6), and the sustainable use of terrestrial (#15) and marine (#14) resources represents a clear challenge under the present global change pressures. Land degradation has been linked in South Africa to the terms veld degradation and soil degradation and has been addressed by numerous measures. But there is still uncertainty on the extent of human induced land degradation as compared to periodic climate induced land surface property changes.

In cooperation with South African institutions and stakeholders (ARC-ISCW, SAEON, SANParks, SANSA, Stellenbosch University and University of the Free State, Equispectives Research and Consulting Services, Nuwejaars Wetlands SMA), the overarching goal of SALDi is to implement novel, adaptive, and sustainable tools for assessing land degradation in multi-use landscapes in South Africa. Building upon the state of the art in land degradation assessments, the project aims to advance current methodologies for multi-use landscapes by innovatively incorporating inter-annual and seasonal variability in a spatially explicit approach. SALDi takes advantage of the emerging availability of high spatio-temporal resolution Earth observation data (e.g. Copernicus Sentinels, DLR TanDEM-X, NASA/USGS Landsat program), growing sources of in-situ data and advancements in modelling approaches. Particularly, SALDi aims to:

i) develop an automated system for high temporal frequency (bi-weekly) and spatial resolution (10 to 30 m) change detection monitoring of ecosystem service dynamics,

ii) develop, adapt and apply a Regional Earth System Model (RESM) to South Africa and investigate the feedbacks between land surface properties and the regional climate,

iii)    advance current soil degradation process assessment tools for soil erosion, as this process represents an intrinsic limiting factor for biomass production and other regulating, supporting and provisioning ecosystem services, like providing clean water.

The aim of this presentation is to introduce this new cooperative research project to the EGU Community and to seek new opportunities for collaboration.
An investigation of methods for Fault Displacement Hazard Assessment for offshore studies
Authors: Fiorini Emilia
Published: March 2020

The expected surface displacement in the aftermath of an earthquake is an important issue to consider, among others, for pipeline damage. While estimates of permanent ground deformation after an earthquake event is often performed nowadays through the acquisition of Interferometric Synthetic Aperture Radar (InSAR) scenes, this method is only applicable to onshore regions.

In this work we explore possible methodologies for fault hazard assessment to be applied in offshore regions.

Methods to estimate the surface rupture hazard for faults of known location and geometry are reviewed, such as the Okada equations available in the Coulomb3 software. However since fault data may be lacking or scarce in offshore areas we also explore the availability of methods to estimate a probabilistic surface rupture assessment, to be applied within the same framework of Probabilistic Seismic Hazard Assessment studies. A simple application of both methods is presented in a hypothetic case study where an early warning system for pipeline damage inspection is required.
Effect of secondary succession in abandoned fields on some properties of acidic sandy soils
Authors: Surda Peter , Lichner Lubomir , Nagy Viliam
Published: March 2020

Abandonment of agricultural lands in recent decades is occurring mainly in Europe, North America and Oceania, and changing the fate of landscapes as the ecosystem recovers during fallow stage. The objective of this study was to find the impact of secondary succession in abandoned fields on some parameters of acidic sandy soils in the Borská nížina lowland (southwestern Slovakia). We investigated soil chemical (pH and soil organic carbon content), hydrophysical (water sorptivity, and hydraulic conductivity), and water repellency (water drop penetration time, water repellency cessation time, repellency index, and modified repellency index) parameters, as well as the ethanol sorptivity of the studied soils. Both the hydrophysical and chemical parameters decreased significantly during abandonment of the three investigated agricultural fields. On the other hand, the water repellency parameters increased significantly, but the ethanol sorptivity did not change during abandonment. As the ethanol sorptivity depends mainly on soil pore size, the last finding could mean that the pore size of acidic sandy soils did not change during succession.
Impact of climate change and variability on maize yield in Tropical Africa
Authors: Bangelesa Freddy , Pollinger Felix , Paeth Heiko
Published: March 2020

 Tropical Africa has been experiencing a long term drying trend for the last two decades. Climate change and variability has an influence on rain-fed agriculture under the Tropics. Many studies have investigated on the role of climate change and variability on crop yields, but with a limited number of predictors. We use detailed gridded crop statistics time series data to examine how recent climate inter-annual variability led to variations in maize yields. The added-value of this study is, that it integrates for the first time different sets of variables on different spatial scales, 107 in total: local, regional and global. A cross-validated model output statistics (MOS) approach is applied to choose physically motivated predictors. Both climate variables and maize yields were de-trended. The results revealed that inter-annual climate variability accounts for globally more than 35 percent of the observed maize variability in Tropical Africa. Our study uniquely illustrates spatial patterns in the relationship between climate variability and maize yield variability, highlighting where variations in different group of predictors interact and explain maize yield variability. Overall, temperature and precipitation principal component variables are preferably selected by the model. The next step of the study will consist of using the MOS equation to forecast future maize yield changes based on climate model output. The implication of the study is that, it will generate policy interventions towards buffering future crop production from climate variability.
Towards opensource LOD2 modelling of urban spaces using an optimised machine learning and rules-based approach.
Authors: Rowan Tom , Butler Adrian
Published: March 2020

In order to enable community groups and other interested parties to evaluate the effects of flood management, water conservation and other hydrological issues, better localised mapping is required.  Although some maps are publicly available many are behind paywalls, especially those with three dimensional features.  In this study London is used as a test case to evaluate, machine learning and rules-based approaches with opensource maps and LiDAR data to create more accurate representations (LOD2) of small-scale areas.  Machine learning is particularly well suited to the recognition of local repetitive features like building roofs and trees, while roads can be identified and mapped best using a faster rules-based approach.

In order to create a useful LOD2 representation, a user interface, processing rules manipulation and assumption editor have all been incorporated. Features like randomly assigning sub terrain features (basements) - using Monte-Carlo methods - and artificial sewage representation enable the user to grow these models from opensource data into useful model inputs. This project is aimed at local scale hydrological modelling, rainfall runoff analysis and other local planning applications.

 

The goal is to provide turn-key data processing for small scale modelling, which should help advance the installation of SuDs and other water management solutions, as well as having broader uses. The method is designed to enable fast and accurate representations of small-scale features (1 hectare to 1km2), with larger scale applications planned for future work.  This work forms part of the CAMELLIA project (Community Water Management for a Liveable London) and aims to provide useful tools for local scale modeller and possibly the larger scale industry/scientific user.
Short-term effects of biochar on soil CO2 efflux in boreal Scots pine forests
Authors: Zhu Xudan
Published: March 2020

The use of biochar as a soil amendment has been proposed to increase the carbon (C) sequestration in soils. However, a more rapid soil organic matter turnover after biochar application might reduce the effectiveness of biochar applications for C sequestration. Data on the effects of biochar on soil C turnover is particularly important in boreal forests where large quantities of forest harvest residues would be available as feedstock for biochar production. To better understand the effects of biochar on boreal forest soil, we established a split-plot experiment where two spruce biochar produced with different temperatures (500°C and 650°C) were applied at a rate of 1.0 kg m-2 and 0.5 kg m-2 in a young xeric Scots pine forest in southern Finland. Measurement of soil CO2 effluxes and microbial biomass were used to investigate changes in soil C dynamics. Biochar application increased the rate of soil CO2 efflux by 10.6% across all biochar treatments and significantly (P<0.05) in 1.0 kg m-2 treatments. Soil microbial biomass remained unchanged. Soil temperature was 0.1 to 0.5°C higher in the biochar-amended treatments. Further analysis revealed that when soil CO2 efflux was corrected for the changes in soil temperature and soil moisture, there were no significant differences between treatments. We conclude that increase in soil CO2 efflux was attributed to warmer soils at the initial stage after biochar application to the soil surface; changes in soil chemical properties did not have any detectable effect on soil respiration.
Anthropogenic iron deposition alters the ecosystem and carbon balance of the Indian Ocean over a centennial timescale
Authors: Pham Anh , Ito Takamitsu
Published: March 2020

Phytoplankton growth in the Indian Ocean is generally limited by macronutrients (nitrogen: N and phosphorus: P) in the north and by micronutrient (iron: Fe) in the south. Increasing anthropogenic atmospheric deposition of N and dissolved Fe (dFe) into the ocean can thus lead to significant responses from marine ecosystems in this ocean basin. Previous modeling studies investigated the impacts of anthropogenic nutrient deposition on the ocean, but their results are uncertain due to incomplete representations of Fe cycling. We use a state-of-the-art ocean ecosystem and Fe cycling model to evaluate the transient responses of ocean productivity and carbon uptake in the Indian Ocean, focusing on the centennial time scale. The model incorporates all major external sources and represents a complicated internal cycling process of Fe, thus showing significant improvements in reproducing observations. Sensitivity simulations show that after a century of anthropogenic deposition, increased dFe stimulates diatoms productivity in the southern Indian Ocean poleward of 50⁰S and the southeastern tropics. Diatoms production weakens in the south of the Arabian Sea due to the P limitation, and diatoms are outcompeted there by coccolithophores and picoplankton, which have a lower P demand. These changes in diatoms and coccolithophores productions alter the balance between the organic and carbonate pumps in the Indian Ocean, increasing the carbon uptake in the south of 50⁰S and the southeastern tropics while decreasing it in the Arabian Sea. Our results reveal the important role of ecosystem dynamics in controlling the sensitivity of carbon fluxes in the Indian Ocean under the impact of anthropogenic nutrient deposition over a centennial timescale.
Minerals as basis for functional materials
Authors: Amthauer Georg , Heuss-Aßbichler Soraya
Published: March 2020

Mineralogy deals with the structure and related physical and chemical properties of materials in the geo- and biosphere. The knowledge about these minerals and their specific properties is increasingly used in various technical, medical and environmental fields [1]. One of the most impressive examples is garnet, a mineral which usually occurs in magmatic and metamorphic rocks. On the one hand, its chemistry is closely related to the chemistry of the host rock and, more importantly, its crystal structure reflects the pressure and temperature conditions during its formation. On the other hand, garnet is an important material for technical issues, e.g. the well-known Yttrium Aluminum Garnet (YAG)-Laser, and it finds now new applications, e.g. in the field of energy storage. Even though the chemical composition varies considerably all garnets have in common the same crystal structure. Li-oxide garnet with the composition Li7La3Zr2O12 (LLZO) is an excellent example to demonstrate the application of mineralogical knowledge in material science. Recently, these garnets have been identified as a promising material in the field of energy storage, as they can be used as solid state electrolyte in Li-based all solid state battery concepts. In Li-ion batteries, solid electrolytes are considered to replace polymer based electrolytes, which have disadvantages e.g. they are highly inflammable.

The presentation of garnet stands as an example for numerous other mineral groups which build the basis for their application in material science, such as spinel, perovskite, zeolite, sphalerite, chalcopyrite, kesterite, argyrodite, etc. In our contribution some of these mineral groups and their importance as basis for functional materials will be presented.

[1] S.-Heuss-Aßbichler, G. Amthauer, M. John (Eds.). Highlights in Applied Mineralogy. Dr Gruyter Berlin/Boston 2017, 344 pp.
Improvements to melting snow behavior in an NWP bulk microphysics scheme
Authors: Iversen Emilie C. , Thompson Gregory , Nygaard Bjørn Egil
Published: March 2020

Snow falling into a melting layer will eventually consist of a fraction of meltwater and hence change its characteristics in terms of size, shape, density, fall speed and stickiness. Given that these characteristics contribute to determine the phase and amount of precipitation reaching the ground, precisely predicting such are important in order to obtain accurate weather forecasts for which society depends on. For example, in hydrological modelling precipitation phase at the surface is a first-order driver of hydrological processes in a water shed. Also, melting snow exerts a possible threat to critical infrastructure because the wet, sticky snow may adhere to the structures and form heavy ice sleeves.

Most widely used bulk microphysical parameterization schemes part of numerical weather prediction models represent only purely solid or liquid hydrometeors, and so melting particle characteristics are either ignored or represented by parent species with simple conditions for behavior in the melting layer. The Thompson microphysics scheme is explicitly developed for forecasting winter conditions in real-time as part of the WRF model, and to maintain computational performance, the introduction of additional prognostic variables is undesirable. This research aims at improving the Thompson scheme with respect to melting snow characteristics using a physically based approximation for the snowflake melted fraction, as well as a new definition of melting level and melting particle fall velocity. A real 3D WRF case is set up to compare with in-situ measurements of hydrometeor size and fall velocity from a disdrometer and a vertically pointing Doppler radar deployed during the Olympic Mountain Experiment (OLYMPEX). The modified microphysics scheme is able to replicate the bimodal distribution of fall speed – diameter relations typical of mixed precipitation seen in disdrometer data, as well as the non-linear increase in snow fall speed with melted fraction through the melting layer.
Relationship between aerosol concentration, relative humidity and atmospheric electric potential gradient in cities
Authors: Wright Matthew , Matthews James , Silva Hugo , Navasumrit Panida , Ruchirawat Mathuros , Shallcross Dudley
Published: March 2020

The vertical atmospheric potential gradient is particularly affected by high aerosol loading in cities as the air’s conductivity is reduced through aerosol attachment of free ions. The reduction of ion concentrations decreases the conductivity and, as the air-earth current remains constant, the potential difference increases. Aerosol size distributions can be affected by the relative humidity dependent on the aerosol hygroscopicity, if an aerosol is sufficiently hygroscopic, it will grow as humidity increases. As larger aerosols are, in principle, more prone to effectively scavenge ions, an increase in relative humidity may increase the size of hygroscopic aerosols, decrease ion concentrations and hence increased measured potential gradient. Measurements of atmospheric potential gradient in Lisbon, Portugal, demonstrated an increase in potential gradient associated with increasing relative humidity (in the range 60-90%), mainly for wind directions corresponding to marine air.

A JCI 131 field mill (Chilworth) and Maximet 500 (Gill) weather station were positioned on the roof of the University of Bristol School of Chemistry between May and September 2016. Particle number concentration was determined using a condensation particle counter (TSI 3010) with an upper limit of 10,000 particles cm-3. A dilution system was put in place to increase this range to 14,000 cm-3. The same field mill and weather station were used in Thailand. Measurements at 1 Hz (averaged to 1-minute samples) were taken on the roof of a 6-floor building, approximately 100 m from a busy toll road in Lak Si, northern Bangkok. Aerosol concentrations were taken with a Condensation Particle Counter (Grimm Aerosol Technik) at the same height. The measurement period began on March 8th 2018 after which there were 8 weeks of particle number count data.

In the Bristol measurement between 50% and 80% relative humidity, the median potential gradient increased, but above this it sharply decreases, which may be due to disturbed weather at the highest humidities. Initial analysis of the relationship between relative humidity and potential gradient in Bangkok shows a decrease in median potential gradient as relative humidity increases. This may be due to a large proportion of traffic related aerosol which could be less hygroscopic, but the potential for effects of disturbed weather and traffic to mask hygroscopic effects will be considered.
On the development of low cost, optimizable, 3D printed turbine flow meters for pipe and open channel applications
Authors: Butler Adrian , Rowan Tom , Colyer Alex
Published: March 2020

The work sets out a method and evaluates the accuracy of a 3D printed turbine flow meter for open channel and pipe flow; that can be optimised for different situations.  The motivation for this project was to create flow meters that are low cost and available to community groups and interested individuals, this work was conducted as part of the CAMELLIA project (Community Water Management for a Liveable London).  The flowmeters have been trialled in a number of locations by users with different skill sets and technical know-how.  Hall effect sensors have been coupled with consumer grade electronics to develop the most opensource system possible.  This work has taken advantage of recent advances in DLP printing, allowing for greater resolution at a lower cost than previous generations of 3D printers.  This is combined with work developed by the Open Prop software team, has enabled user customisable sensors to be built.  

The presented work aims to create an opensource, low cost and easy to use solution to some flow monitoring problems.  This paper details the lessons learnt and successes of this approach; it aims to create a basis for which further development and deployment of these sensors can be achieved.  
The Dynamic Vegetation Model HUMBOLDT (LSMbio) The role of biodiversity and nutrient limitation in driving ecosystem processes on a tropical altitudinal gradient
Authors: Dantas de Paula Mateus , Hickler Thomas
Published: March 2020

The HUMBOLDT-LSMbio component is an expansion of the LPJ-GUESS dynamic vegetation model , including local diversity of plant traits and an organic matter module representing the Nitrogen and Phosphorus cycles. In the new trait variation module the initial full range of possible traits is filtered along the altitudinal gradient with the aim to predict the trait distribution of communities observed in the field. The model was parameterized using local trait data per species collected by field campaigns along the whole altitudinal gradient, considering the leaf and wood economics spectrum and tissue nutrient concentrations, and locally measured N and P flux data, in which we were able to use deposition and weathering rates, as well as soil organic and mineral layer nutrient concentrations. In order to evaluate the model with regards to nutrient limitation, the simulation experiment was designed with the NUMEX nutrient manipulation experiment in mind, meaning that the reference nutrient limited community was compared to simulations in which N or/and P limitations were deactivated (i.e. plants could grow independent of their N or P demands being met). Results in NUMEX suggested that the removal of nutrient limitation would produce more biotically homogenous communites, and taller trees with higher productivity and more allocation to belowground biomass.

Our results indicate that including trait diversity and nutrient limitation provide a significant improvement in relation to ecosystem representation especially at higher elevations. Deactivation of nutrient limitation suggests reduced community trait differentiation along the elevation gradient (e.g. specific leaf area), and increased productivity (i.e. Carbon and NPP values). Deactivation of trait diversity impels plant survival at higher altitudes. Significant model improvements are expected in the future with further field trait measurements from the RESPECT subprojects, and the inclusion of other significant processes such as leaf herbivory, seed dispersal and of course the coupled model runs with LSMatmo and LSMhydro.
Flow-Py: Identifying protection forests and their effects on gravitational natural hazard processes on a regional scale
Authors: Neuhauser Michael , D’Amboise Christopher , Teich Michaela , Fischer Jan Thomas
Published: March 2020

Recently, strong wind storms have caused large-scale damages in Alpine mountain forests, leaving the underlying infrastructure exposed. These forests often provide protection against gravitational natural hazard processes such as avalanches, rockfall and soil slides. To manage these disturbed forests efficiently and effectively, it is important to know 1) which forest areas serve a protective function to the underlying infrastructure, 2) what is the actual protective effect of these forests on the hazard process, and 3) how one could improve this effect.

To define protective functions and to quantify the protective effects of forests, we created the Flow-Py model that identifies process areas of gravitational hazards, including avalanches, rockfall and debris slides. The model is written in Python to keep it easy adjustable. The run out routine of Flow-Py is based on the principles of energy conservation including frictional dissipation assuming simple coulomb friction, leading to constant travel-angle. Potential release areas and the corresponding travel angle have to be adapted for each type of gravitational mass movements. A important improvement, compared to similar models, is that it can handle mass movement in flat and uphill terrain. One major advantage of this model is its simplicity, resulting in a computationally inexpensive implementation, which allows for an application on a regional scale, covering large simulation areas. The adaptivity of the model further allows to consider existing infrastructure and to detect starting zones endangering the corresponding areas in a back-calculation step. Additionally, by adding forest cover to the simulations we can identify which forest area has a protective function and, based on information about forest structure, calculate the protective effect this forest provides to down slope infrastructure.

Flow-Py is a useful tool to identify forest areas that are important for hazard protection (protective function) and to quantify their protective effect. The model can be applied in protection forest management to prioritize measures in wind throw areas. Furthermore, it is possible to use this tool for analyzing the protective functions and effects of different forest extents and structural conditions, for example, caused by climate change or forest disturbances. In this work we elaborate the potential of Flow-Py by presenting an avalanche case study in the central alpine region of Austria (Gries/Vals, Tyrol, AT). For this case the simulation results indicate a process area affected by avalanches of ~65% with respect to the total area of ~ 195 km².
Modelling Regional Water and Energy balance in East Africa
Authors: Patil Sopan , Musau John , Marshall Michael
Published: March 2020

Effective modeling of surface water and energy balance is crucial in planning and management of regional resources. However, the heterogeneous and clumped vegetation structure controls the portioning of land surface water and energy fluxes, which leads to large variations of local radiative and hydrological processes. The aim of this study is to characterize the land surface heterogeneity in East Africa and examine the impact of the spatially and temporally varying vegetation parameters on energy and water balance in the region.  We used MODIS datasets on Leaf Area Index (LAI), Enhanced Vegetation Index (EVI) and albedo to derive time-varying vegetation parameters for the period 2001 – 2011 period at 0.05° resolution. These parameters were integrated with the Variable Infiltration Capacity (VIC) model to characterize the effects of varying vegetation properties on surface water and energy fluxes. A twin simulation was also carried based on seasonally averaged vegetation parameters to isolate the effects of time-varying and spatially heterogeneous parameters on the water and energy fluxes. The simulation results were compared to rigorously validated global datasets on evapotranspiration and sensible heat. Results showed that the time-varying and spatially heterogeneous vegetation parameters provided surface water and energy fluxes which were more consistent with the validation datasets. The simulated evapotranspiration matched reasonably well with the observed values particularly in areas characterized by sparse vegetation and which are more prone to human influence. The improvements were highly noticeable in grassland and savanna land cover types. However, due to intensive human activities in region which affect not only the lad cover but also the vegetation structure, there is need for characterization of the land cover parameters based on high resolution data which can better capture the land surface heterogeneity in the region.
Data pre-processing for ionosphere TEC retrieval based on DORIS observations
Authors: Zhang Shaocheng , Li Wei , Yin Fei , Gou Hongfei
Published: March 2020

 DORIS system aims to provide precise orbit determination of low earth orbit satellites, and the dual-frequencies on S1=2036.25 MHz and U2=401.25 MHz were used on DORIS signals. The ionosphere TEC retrieval on the signal path is possible based on DORIS dual-frequency observations.

Analysis results show that DORIS pseudo-ranges had noise with several kilometers level, hence only the carrier-phase observations could be utilized on TEC retrieval. Moreover, as the DORIS ground stations were thousands kilometers separated with each other, station differential cannot be guaranteed and the data preprocessing can only be done base on the un-difference observations before the TEC could be precisely determined.

In this research, a polynomial function was applied to model the DORIS phase observations, and minimal detectable biases (MDB) of less than one cycle wavelength was used as the index on the cycle-slip detection. And then the geometry free combination of S1 and U2 phase measurements were calculated for each DORIS LEO satellite passing arc. Finally, the unknown ambiguities bias on S1 and U2 geometry free observables were shifted to coincide with STEC calculated from the IGS GIM products.

Both the Jason-2 & 3 based DORIS observations were used for the validation, several simulated +5 and -1 cycle-slip events on both DORIS observation could be clearly detected and correctly repaired. And the calculated STEC on one satellite passing arc from the LEO satellite to station show well agreement with IGS STEC on continent area, and the differences on ocean areas could be used to prove that the IGS GIM products were less precise on those areas.
The use of sedimentary ancient DNA from lakes in tracing human-environment interactions in the Western Alps
Authors: Dulias Katharina , Knockaert Juliette , Giguet-Covex Charline , Walsh Kevin
Published: March 2020

Archaeologists working in high altitude-zones in the Alps where faunal remains were absent have until relatively recently, been reliant on palynology in order to infer the probable presence of pastured animals. The development of sedimentary ancient DNA (sedaDNA) analysis has changed this. We are now able, if taphonomic conditions permit, to identify the presence and absence of specific domesticated animals as well as changes in vegetation communities that were a consequence of pastoral activity. Over the past decade, lake sediment DNA has been used by an increasing number of studies to trace past agricultural activities, human presence and landscape changes.

More recently, lake sedaDNA sequencing has proven applicable to investigate the relative impact of human activities, such as transhumance pastoralism, on the vegetation in the catchment of lakes in the Western French Alps and the domestic species used at different time periods. Thus, providing a new outlook on the anthropogenic effect on alpine landscapes.

Our use of sedaDNA is one element in a project designed to elucidate the evolution of transhumance in the Western Alps. While the sequential isotope analyses from domesticated herbivore teeth facilitate our comprehension of seasonal pastoral mobility, the sedaDNA complements this work via its potential for inferring which pastures were frequented and the effect of livestock presence on these environments. This combined approach can demonstrate not only the existence of pastoral practises in the region, but also reconstruct the movement patterns as well as the direct impact of transhumance pastoralism in the Western Alps in a wide chronological and spatial frame.

With the application of advanced bioinformatic techniques, we combine previous data on past and present vegetation with our findings. The genetic data was obtained through the established method of metabarcoding, which is a relevant tool for reconstructing palaeoenvironments. Using the same approach with additional quantitative PCR analysis for mammalian sedaDNA offers even more detailed insights into the presence and possible abundance of domestic species in the lake catchment area.

This application can demonstrate the potential of sedaDNA in reconstructing palaeoenvironments and its relevance in conceptualising long-term ecosystem changes relating to human and non-human agencies.
Root architecture and hydrologic fluctuations explain spatiotemporal soil aggregation patterns
Authors: Ghezzehei Teamrat , Or Dani
Published: March 2020

Soil aggregation is a dynamic state involving numerous biophysical interactions that cannot be deduced from snapshots of soil aggregate sizes nor the state of bulk soil organic carbon (SOC) alone. Hydrophysical and  biogeochemical functions of soil aggregation are directly linked with dynamic nature of soil aggregation. At the local scale, aggregates are formed and around particulate organic debris and they evolve as undifferentiated biogeochemical hotspots. The rate of evolution varies with the life-stage of each hotspot (the remaining reserve of C and nutrients within the hotspot) as well as the physical environmental conditions (wetness and temperature). Thus, the macroscopic patterns of hotspot (aggregate) distributions reflect the interplay between the spatial/temporal patterns of C inputs and fluctuations of physical environmental conditions. Here, we show a modeling analysis of how these aggregation patterns vary across ranges of climatic and vegetation (root architecture) conditions. We utilize a model that considers the dynamic lifecycle of ensembles of multigenerational aggregates originating from polydisperse C inputs.
A Material Point Method for Glacier Calving
Authors: Gaume Johan , Gao Ming , Wolper Joshua , Luethi Martin P. , Vieli Andreas , Teran Joseph , Jiang Chenfanfu
Published: March 2020

Glaciers calving ice into the ocean is predicted to significantly contribute to sea-level rise and will thus influence future climate. Although numerous factors that induce glacier calving have been identified and studied, it is still extremely challenging to develop a unified and continuum computational framework that simulates ice fracture and glacier calving taking into account all important ingredients such as the interaction between ice and water, including buoyancy and melting, on complex and large scale geometry. This prevents scientists to precisely predict calving rates at the outlet of glaciers. Here, we propose to address this issue through numerical simulations of glacier calving based on the Material Point Method and finite strain elastoplasticity. A non-associative Cam-Clay model was developed to simulate the ice while the water is modeled as a nearly in-compressible fluid. First, simplified 2D simulations were performed to analyse the size of calved icebergs which were in good agreement with analytical solutions. The model reproduces not only the vertical glacier fracture observed in real calving events but also iceberg formation and tsunami-wave generation. Finally, 3D simulations of glacier calving were performed, taking into account opened crevasses on the top of the glacier. Although at a preliminary stage, and lacking experimental validation, we show the promise of our approach for modeling glacier calving, and more generally glacier and sea-ice dynamics.
Observing and modeling bedload sediment transport at the grain-scale
Authors: Deal Eric , Perron Taylor , Venditti Jeremy , Zhang Qiong , Benavides Santiago , Kamrin Ken
Published: March 2020

Empirical sediment transport models have common characteristics suggestive of the underlying physics, but mechanistic explanations for these characteristics are lacking due to an incomplete understanding of the fundamental physical mechanisms involved. Hydrodynamic interactions at the grain-scale are thought to be key, however, it is a major challenge to either observe or model these processes. In order to improve our understanding of grain-scale dynamics in sediment entrainment and transport we are studying the detailed mechanics of fluid-grain interactions using a combination of laboratory flume experiments, advanced numerical simulations, and granular mechanics theory. 

The flume experiments are conducted with an emphasis on exploring differences and similarities in the behaviour of glass spheres, a common theoretical tool, to naturally sourced river gravel. Using high-speed cameras coupled with computer-vision based particle tracking, we tracked the majority of grains in the grain bed and water column, with 130,000 glass sphere track paths longer than 10 particle diameters. In particular, we introduce a newly developed a machine learning based particle tracking of the natural grains, with 30,000 gravel track paths longer than 10 mean particle diameters. Fluid flow fields are also observed using particle image velocimetry (PIV). We present the comparison of our detailed observations of granular dynamics between spheres and natural gravel, with a focus on how grain shape impacts fluid-grain and grain-grain interactions.

Using a discrete-element plus Lattice-Boltzmann fluid method (LBM-DEM) we simulate a small portion of the laboratory flume with high temporal and spatial resolution. This method tracks discrete particles interacting with each other through contact laws while mechanically coupled to a dynamic interstitial fluid. We discuss the ability of our simulations to emulate our experiments, the benefits of which are twofold. First, where the simulations work well, we use them to observe grain-scale dynamics that would be difficult or impossible to measure in a laboratory setting or in the field. Second, we learn from situations in which the experiments and simulations diverge, leading to improvements in both the simulations and our understanding of how fluid-grain interactions influence sediment transport.
Integrating tree-ring and wine data from the Palatinate (Germany)
Authors: Konter Oliver , Esper Jan
Published: March 2020

Tree-ring growth of conifer trees originating from central European low mountain ranges often reveal indistinct growth-climate relationships. Temperature variations can play a crucial role, whereas water availability can also control the annual growth and become the main dominating factor. The low mountain range Pfälzerwald in the Palatinate region represents the largest contiguous forested area in Germany and features at its most eastern limitation a unique ecological setting due to its sandy soils and reduced water availability. In addition, its north-south orientation and associated lee-effects due to predominating westerlies together with altitudinal differences of more than 300 m lead to higher temperatures, lower precipitation amounts, and, as a forest management consequence, to a proportion of up to 80 % of pine trees. Despite these exceptional ecological and climatological prerequisites, calibrating tree-ring width data from 487 Pinus sylvestris core samples against regional meteorological stations (1950-2011) and gridded data (1901-2011) confirm alternating climate control mechanisms. Comparison with drought-related indices (scPDSI), combining precipitation and temperature, unfolds highest correlations with May-July conditions (r1901-2011=0.34, p<0.05), however, lacking temporal robustness in the early 20th century.

The vegetation outside the forested areas in the plain can be characterized as agricultural croplands with vineyards, representing one of the largest wine-growing regions in Germany. We collected and analyzed a 24 datasets of 57 consecutive years (1959-2015) of must sugar content, acidity, alcohol content, and sugar-free extracts in Riesling, Pinot Gris, Pinot Blanc, and Silvaner wines, originating from 15 wineries adjoining the forested area into the plain. Correlation of Riesling must sugar content against regional April-August temperature data reveals a highly significant signal (r1981-2015=0.73, p<0.01; high-pass filtered r=0.49, p<0.01). Sugar-free extract variations of Pinot Gris are significantly controlled by March-September precipitation (r2004-2014=0.76, p<0.01; high-pass filtered r=0.77, p<0.01).

In this low mountain range, tree-ring growth from conifers is not solely controlled by one climatic variable, though it is that combining tree-rings with must sugar content and sugar-free extract data from Riesling and Pinot Gris wine can further elucidate our understanding of longer-term climate variability in the Palatinate region.
The phoenix of beachrocks: Simultaneous breakdown and formation of an unusual facies on a high energy coastline (Mission Rocks Beach, South Africa)
Authors: Falkenroth Michaela , Green Andrew N. , Cooper J. Andrew G. , Hoffmann Gösta
Published: March 2020

Beachrocks are coastal sediments that are lithified through the precipitation of carbonate cements. It is widely acknowledged that lithofacies in beachrocks are variable and their interpretation is useful when using beachrock as a sea level indicator or when studying shoreline evolution over the centurial to millennial scales. Surprisingly however, the facies variability of beachrocks remains understudied as they are almost exclusively described as seaward dipping, slab-shaped outcrop forming in low energy dissipative beach environments. The Mission Rocks coastline of north-eastern South Africa is in stark contrast. Here the coast comprises an up to 3 m thick raised shore platform of beachrock, where a variety of sedimentological facies are observed. These comprise seaward-dipping planar bedded sandstones and conglomeratic units, often interbedded with bimodally-orientated trough cross bedded sandstones. In our study we aim to use sedimentological facies analysis, petrography and cathodoluminescence to unravel the deposition- and cementation processes of this beachrock facies.

In particular, an unusual beachrock breccia interposed amongst the breakdown remnants of the platform forms the basis of this paper. The breccia documents a cycle of simultaneous erosional breakdown and depositional buildup of the beachrock platform, a yet undescribed process for the development of beachrock.  Since it forms as a thin veneer (< 0.10 m), with a slightly thicker infill (≤ 0.5 m) amidst erosional hollows and gullies of the + 2 m high rocky platform, it raises into question the necessity of a thick sedimentary overburden, that is typically considered the requirement for beachrock cementation in the mixing zone.  Timing of beachrock formation is constrained by recent anthropogenic activities, as the underlaying platform was mined for building purposes during WWII and it is in these quarry slots and crack that the beachrock is found. While it is generally suspected that beachrocks may form at the centennial scale, evidence for this remains weak. Not only can the interpretation of this facies contribute to our understanding of the long term processes that form and break down beachrocks on high energetic coastlines, it provides insight into rapid beachrock formation and as such its utility as a sea level index point.
Building quantitative scenarios of irrigation under climatic and anthropogenic changes in the mediterranean area: application to Morocco
Authors: Younes Fakir , Michel Le Page , Lionel Jarlan , Aaron Boone , Brahim Berjamy , François Molle
Published: March 2020

In a context of major changes (climate, demography, economy, etc.), the Southern Mediterranean area faces serious challenges with intrinsically low, irregular and continuously decreasing water resources. A method for translating a narrative scenario of irrigation water requirements into a quantitative scenario is presented. At first, we propose to describe the Irrigation Water Requirements (IWR) of any area by a single equation. IWR depends on climate (ET0, Rainfall), crop development estimated from remote sensing time series (crop coefficient/NDVI relationships), and four efficiencies parameters. In a second part, a reference model of the crop coefficient monthly cycle ( ) is proposed by empirically relating to rainfall and NDVI. Three variations of the model are compared in order to make a projection until 2050 based on downscaled climate change scenarios. The reliability of the model depends on the representativeness of the calibration period: It is considered to be high at the beginning of the simulation (RMSE below 0.1), but it deteriorates as the calibrating period gets shorter compared to the objective period: r2= 0.5, RMSE = [0.1-0.14], stderr = [0.02-0.03] by 2050. An alternative scenario is built upon the reference by interpreting the narrative as bending points. Finally, the examination of irrigation water demand until 2050 suggests that the difference between the two climate scenarios is very small (<2%), while the two proposed agricultural scenarios are strongly contrasted both spatially and in their impact on water resources.
Nanostructure of biogenic aragonite: a study of otoliths and bivalve shells from a freshwater environment
Authors: Molnár Zsombor , Pekker Péter , Jakab Miklós , Dódony István , Vitál Zoltán , Pósfai Mihály
Published: March 2020

 There are numerous similarities between the otolith (an acellular calcium carbonate aggregate in the inner ears of fishes) and the shells of freshwater bivalves. Since both grow during a lifetime of the individuals, and show small increments or growth zones (in daily or subdaily periods), they are excellent time-keepers. By this capability they provide information about both the life history of the individuals and the geochemical evolution of their environments (Schulz-Mirbach et al., 2018; Cerrato, 2000). Changes of major and trace elements between the different growth zones have been studied thoroughly, but structural features, particularly those of otoliths, are not well known. We used scanning and scanning transmission electron microscopy (SEM and STEM) to study oriented ion-milled sections of an otolith and samples of Dreissena shells from Lake Balaton, a large, shallow lake in Hungary. SEM observations confirm that the growth zones within the otolith are built up of small increments, and they have a radially asymmetric appearance, whereas STEM images show that the small increments are terminated by tiny holes. Selected-area electron diffraction (SAED) patterns and HRTEM images show that the aragonite material of both samples is highly defective, with dense arrays of planar defects occurring in distinct areas, and grains joining along low-angle boundaries (around 1°). In addition, areas with multiple (double and triple) periodicities along the [110]* directions occur in both samples. Based on these preliminary observations, nanostructural features could provide important details about the growth of biogenic aragonite and the structural properties of distinct growth zones.

Cerrato R. M. (2000): What fish biologist should know about bivalve shells, Fisheries Research, 46, 39-49.

Schulz-Mirbach T., Ladich F., Plath M., Heß M. (2018): Enimgatic ear stones: what we know about the functional role and evolution of the fish otoliths, Biological Reviews, 94 (2), 457-482.

Acknowledgments: The research was supported by the ÚNKP-19-3 new national excellence program of the ministry for innovation and technology. 