bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical modeling of seismically-induced slope displacements: a comparison between 2D and 3D finite difference models and Newmark-Displacements
Authors: Domej Gisela , Bourdeau Céline
Published: March 2020

The majority of numerical landslide models are designed in 2D. In particular, models based on finite difference methods (FDM) are time-consuming and – as a result – in most cases also cost-intensive. 3D models, therefore, increase the processing time significantly. Another contributing factor to long processing times in the context of modeling of seismically-induced displacements is the fact that mesh grid increments must be small due to the necessity of correct wave propagation through the material. The larger the frequency range of the applied seismic signal should be, the smaller has to be the mesh grid increment. 3D models are, however, considered as more realistic.

In this work, we present a comprehensive study on numerical 2D and 3D models of the Diezma Landslide, Southern Spain. The Landslide is represented in its shape as it appeared at the time of the main rupture on 18th of March in four model layouts: (1) a simplified model in 3D that outlines the landslide body with planar triangular tiles, (2) a longitudinal cross section through this simplified 3D model representing the simplified 2D model, (3) a smooth model in 3D that envelops the landslide body according to the main topographic features, and (4) a longitudinal cross section through this smooth 3D model representing the smooth 2D model.

On both the simplified and the smooth 2D models, a series of 11 seismic scenarios was applied as SV-waves assuming a source sufficiently far for vertical incidence at the model bottoms in order to produce horizontal shear inside the landslide body with respect to the underlying bedrock. All 11 signals are characterized by different frequency contents, Arias Intensities from 0.1 to 1 m/s, moment magnitudes from 5.0 to 7.0 and peak ground accelerations from 0.8 to 1.2 m/s², and therefore correspond to scenarios that represent the local seismicity in Southern Spain.
Because of time-related limitations, only four of these signals were respectively applied to the simplified and smooth 3D model. Newmark-Displacements were calculated using all 11 signals with the classic Newmark-Method that approximates the landslide body in 2D by a rigid block on an inclined plane, and with Newmark’s Empirical Law as spatial information covering the landslide area across the slope in regular intervals.

We present a systematic comparison of all models and obtained displacements, showing that the Newmark-Methods deliver very similar results to the maximum displacements obtained by FDM. Moreover, we discuss on a particular example that – although seeming more accurate in the layout – smooth models lead not necessarily to realistic results.
Exploration of resources in permanently shadowed lunar polar regions
Authors: Horanyi Mihaly , Bernardoni Edwin , Kempf Sascha , Sternovsky Zoltan , Szalay Jamey
Published: March 2020

Our understanding of the lunar dust exosphere is based on  NASA’s Lunar Atmosphere and Dust Environment Explorer. Its findings provide a unique opportunity to map the composition of the lunar surface from orbit and identify regions that are rich in volatiles, providing opportunities for future in situ resource utilization (ISRU), which is a key element in establishing human habitats on the Moon. The expected availability of water ice, and other volatiles, in Permanently Shadowed Regions (PSR) makes the lunar poles of prime interest. However, the relative strength of the various sources, sinks, and transport mechanisms of water into and out of PSRs remain largely unknown. The quantitative characterization of the temporal and spatial variability of the influx of IDPs to the polar regions of the Moon is critical to the understanding the evolution of volatiles in PSRs. A dust instrument onboard a polar orbiting lunar spacecraft could make fundamental measurements to assess the availability and accessibility of water ice in PSRs. Water is thought to be continually delivered to the Moon through geological timescales by water-bearing comets and asteroids and produced continuously in situ by the impacts of solar wind protons of oxygen-rich minerals on the surface. IDPs are an unlikely source of water due to their long UV exposure in the inner solar system, but their high-speed impacts can mobilize secondary ejecta dust particles, atoms and molecules, some with high-enough speed to escape the Moon. Other surface processes that can lead to mobilization, transport and loss of water molecules and other volatiles include solar heating, photochemical processes, and solar wind sputtering. Since the efficiency of these are reduced in PSRs, dust impacts remain the dominant process to dictate the evolution of volatiles in PSRs.
The continually present dust ejecta cloud was observed by LADEE/LDEX. A more capable dust instrument, in addition to the size and speed of an impacting particle, can also measure the composition of secondary ejecta particles, resulting in a surface composition map with a spatial resolution comparable to the height of the spacecraft.
This talk will describe the available instrumentation, its testing and calibration using the SSERVI /IMPACT dust accelerator  facility at the University of Colorado, Boulder, and conclude with the recognition that a polar-orbiting spacecraft could directly sample lunar ejecta, providing the critical link between IDP bombardment and the evolution of water ice in PSRs.
Effect of soil pH, compost amendment and plant genotype on the accumulation of target elements in phytoremediation and phytomining research in shoots of Phalaris arundinacea
Authors: Moschner Christin , Schwabe Ringo , Wiche Oliver
Published: March 2020

Phytomining is a phytoassisted technique for the extraction of economically valuable elements from soils and offers a promising chance to improve the supply of critical raw materials such as germanium (Ge) and rare earth elements (REEs). The efficiency of phytoextraction depends on numerous soil-associated and plant-associated factors (e.g. concentrations of target elements in potentially plant available soil fractions, rhizosphere processes and uptake mechanisms of plants). The aim of this study was to evaluate the effect of different soil properties (pH, compost amendment) on the mobility of selected target elements for phytoremediation (As, Pb, Cd, Zn) and phytomining (Ge, REEs) in soil and accumulation in shoots of different genotypes and populations of Phalaris arundinacea. In a field experiment we cultivated 10 different genotypes and populations of Phalaris arundinacea on four different substrates with similar element concentrations but different pH-values (pH 6.6 – 7.8) and levels of compost amendment (5l /m2 compost or without compost). On each of the substrates, we cultivated Phalaris arundinacea (genotypes) with two replicates on plots 4 m2 each and installed suction cups to collect soil solution. After harvest concentrations of Ge, REEs, P, Fe, Mn, Zn, Pb, As and Cd in shoots and soil solution were determined with ICP-MS. Compared to the slight alkaline soil, acidic soil conditions significantly increased shoot concentrations of Fe, Mn, As, Cd, Pb and REEs. Under acidic soil conditions addition of compost further increased the concentrations of all investigated target elements in shoots of P. arundinacea except of As. In soil solution only concentrations of Fe and Mn significantly increased due to the compost amendment, while concentrations of P, Ge, REEs, Cd and Pb decreased. Shoot concentrations of all investigated elements, particularly REEs, showed remarkable differences among the genotypes and population and this responds of the plants was in turn influenced by substrate properties suggesting phenotypic plasticity during element acquisition in the rhizosphere. In future experiments the heritability of these traits will be rigorously tested in order to establish optimized seed material. We conclude that amendment of soil with compost seems to be a sustainable approach to enhance the uptake of plant nutrients and REEs into shoots of Phalaris arundinacea. However, the role of plant genetics and consequently processes during element acquisition in the rhizosphere and uptake remain field of further research but if proven this would have major implications for the optimization of phytoextraction techniques.
UAV- and SfM-related techniques applied to volcano-tectonics for virtual outcrops construction and geoscience communication. Examples from the North Volcanic Zone, Iceland
Authors: Pasquaré Mariotto Federico , Tibaldi Alessandro
Published: March 2020

UAV- and SfM-related techniques applied to volcano-tectonics for virtual outcrops construction and geoscience communication. Examples from the North Volcanic Zone, Iceland

 Authors: Federico Pasquaré Mariotto1, Alessandro Tibaldi2,3

 

1Insubria University, Department of Human and Innovation Sciences                     2University of Milan-Bicocca, Department of Earth and Environmental Science, Milan, Italy 3CRUST- Interuniversity Center for 3D Seismotectonics with Territorial Applications, Italy

 

Iceland offers an unparalleled chance to observe the most powerful natural phenomena related to the combination of tectonic and magmatic forces, such as active rifting, volcanic eruptions, sub-volcanic intrusions. We have focused on a number of geosites which are found in the Northern Volcanic Zone (NVZ) of Iceland; here, the following volcano-tectonic features can be observed: i) the Theystareykir  Fissure Swarm (ThFS), an active rift system with a central volcano, several major faults and numerous eruptive fissures; ii) the Krafla Fissure Swarm (KFS), another major rift system marked by the presence of monogenetic cones, dip-slip faults, eruptive fissures, extension fractures and the active Krafla volcano.

In order to showcase a few, outstanding examples of the above, we have made use of UAVs integrated by the Structure-from-Motion (SfM) Photogrammetry. As is well known, the combination of UAV-digital image collection and SfM techniques has been increasingly applied to geological and environmental research. We have applied this approach to the collection of high-definition images and with the purpose of constructing 3-D models, which may be considered “Virtual Outcrops (VO)”.

We highlight that such 3-D models can be navigated in immersive Virtual Reality mode, and hence can be a key tool not only for research purposes: in fact, this is a novel, cutting-edge approach which is suitable for improving geosite popularization and geoscience communication, allowing for the engagement of a wider audience, including potential end-users from the younger generation.

 

 
Water-related synergists and antagonists in the SDGnexus Network
Authors: Weeser Björn , Breuer Lutz
Published: March 2020

 SDGs related to land use, food provision, and energy production.
What we talk about when we talk about seasonality?
Authors: Kwiecien Ola
Published: March 2020

The concept of seasonal changes is traditionally understood as a consecutive follow-up of four seasons, spring, summer, autumn, and winter (in the mid-latitudes); or wet/ dry season alteration (in low latitudes). Intuitively, the term ‘seasonality’ usually refers to temperature or moisture gradients throughout a year. These gradients determine the composition and dynamics of natural ecosystems and agricultural strategies; as such seasonality is a key parameter when describing modern and past climatic and environmental conditions. Consequently, changes in seasonality are often called for as the ultimate driving force of observed changes, but there is more to them than meets the eye. Most importantly there is an essential and often overlooked aspect of external, orbitally-driven seasonality, and internal, regional-to-local responses to these changes.

What does ‘increased’ or ‘decreased’ seasonality actually mean? Can we quantify this change? And is the amplitude all that matters? What about temporal distribution? Does temperature and precipitation always respond symmetrically and harmonically? My contribution is aimed at raising awareness, caution and precision when referring to seasonality changes. Come to my poster and let’s discuss it!
Storage/Release of Geologic Carbon Influenced Pleistocene Glacial/Interglacial Atmospheric pCO2 Cycles
Authors: Stott Lowell , Shao Jun , Harazin Kathleen , Davy Bryan , Pecher Ingo , Coffin Richard , Reiss Ludovic , Suckale Jenny
Published: March 2020

For over 100 years scientists have puzzled over the mechanisms responsible for the repeated climate changes known as Ice Ages. A breakthrough was achieved when ice cores and marine archives revealed that the Ice Ages were paced at 100kyr intervals in alignment with Earth’s eccentricity cycle for the past million years. A second breakthrough was achieved when ice core records revealed that the Ice Ages were accompanied by ~80-90ppm variations in atmospheric pCO2. But after decades of research the mechanisms responsible for those atmospheric pCO2 variations remains an open and unresolved puzzle.

Here we present new findings that challenge the long-standing paradigm that geologic processes that regulate carbon exchange between the Earth’s interior and exterior act too slowly to have influenced the ocean and atmosphere carbon budgets on glacial time scales. The evidence includes large Δ14C excursions found in biogenic sediments in each of the Ocean basins at the last glacial termination. These excursions point to a sustained release of 14C-dead carbon spanning several thousand years.  In the Atlantic, Pacific and Indian Ocean the excursions are found near seafloor deformation features, including pockmarks that are indicative of gas-rich fluid release from sub-surface reservoirs. In the eastern equatorial Pacific, the Δ14C excursions are associated with enhanced hydrothermal metal concentrations including Fe, and Z that point to a hydrothermal source. Our ongoing research seeks to identify the storage and release mechanisms that operate on these carbon reservoirs on glacial time scales and to put constraints on the amount of carbon released at the last glacial termination. While the amount of carbon released from these geologic sources remains an open question for now, it is clear that geologic processes have affected changes in the global carbon budget on glacial time scales.
Character, spatial and temporal variation of turbidity currents on a source-to-sink scale.
Authors: Heerema Kate , Talling Peter , Cartigny Matthieu , Lintern Gwyn , Stacey Cooper , Enkin Randy , Hage Sophie , McGhee Claire , Chen Ye , Parsons Dan , Simmons Steve , Clare Mike
Published: March 2020

Seafloor avalanches of sediment called turbidity currents are one of the principle mechanisms for moving sediments across our planet. However, turbidity currents are notoriously difficult to monitor directly in action, and we still mainly depend on their sedimentary deposits as well as physical and numerical models to understand their temporal and spatial evolution. In recent years, multiple studies have successfully made direct measurements within active turbidity currents at multiple sites along their pathway. However, these direct measurements are often limited to the upper reaches of submarine systems, only cover relatively short (few months to a couple of years) time scales, or have very few measurement stations (<3). To capture the full range of turbidity current types and recurrence times we need to combine direct monitoring with longer-term archives in sedimentary deposits. Here we present an unusual data set that extends from the submarine channel on the delta, to the final deposits in the deep basin. The dataset combines short-term (< 1 year) direct measurements of flows with long-term sediment deposits (dating back to about 100 years). This combination of data types allows us to understand turbidity current frequencies, runouts, heights and characteristics along an entire submarine system.  

We analyse data from Bute Inlet, which is a fjord in British Colombia, Canada. The entire turbidity current system stretches out for 80 km, with an incised submarine channel extending for 45 km. 46 Cores have been collected between 2015 and 2018. Simultaneously, direct measurements of the currents have been obtained in 2016 and 2018 using Acoustic Doppler Current Profilers (ADCPs) in the submarine channel.

Our objective is two-fold. First, we look at flow frequency over time and space. Visual logs of the sediment cores, as well as sediment accumulation rates for a selection of cores, are used to infer flow frequencies. We then use the ADCP data to understand more frequent and recent flows at 6 places along the channel. These ADCP measurements are used to infer frequencies which are not necessarily recorded in the deposits, and give additional insights into current-day activity. This allows us to reconstruct the change in frequency over space and time.

Second, we consider the variation in turbidity current character to understand how flows evolve along the channel. Facies determination and grain size data are used to infer turbidity current character. Cores along the channel, on terraces and in the deep basin are used to understand the spatial variation. Finally, comparison of deposits and monitoring (ADCP) data shows how submarine flows are recorded by their deposits.
The opposing factors controlling change in warming related future flood extremes
Authors: Sharma Ashish
Published: March 2020

It is well accepted that warmer temperatures lead to greater moisture holding capacity for the atmosphere, resulting in bigger downpours, creating larger design precipitation intensities and possibly less secure flood infrastructure. It is also known that higher temperatures increase evaporation rates and hence dry soils quicker than before. This presentation discusses the role each of these controls plays in natural and urbanised catchments. It is shown that one of these two tends to dominate depending on a range of factors, including catchment attributes, as well as how extreme the design problem is. This presentation uses examples from four urban catchments spread across three continents as well as over 200 natural catchments representing various climatic zones in Australia to form its conclusions.
Application of Data Assimilation and Ensemble Kalman Filter for Flood Forecast in Tamsui River, Taiwan
Authors: Hsu Ming-hsi , Fu Jin-Cheng , Tsao Ming-Chun , Kimura Nobuaki
Published: March 2020

Typhoon is the most frequent natural disaster that causes widespread damage during summer and autumn in Taiwan. On average, each year the island suffers four typhoons, which result in disastrous flash floods and losses in a short time because of steep terrains and intense rainfall. The Tamsui River Basin is located in northern Taiwan about 2,726 square kilometers and inhabited by eight million people. During flooding events, the emergency managers rely on accurate flood forecasting to take proper actions for damage reductions. The flood forecasting and warning system based on hydraulic models play an important role in flood risk management. This study first establishes river stage routing model based on dynamic wave theory. Then, both the real-time observed river stages and the least squares method are used to adjust the model currently flow conditions as the data assimilation. Finally, The Ensemble Kalman Filter method carries out the data correction with the computation of minimum error-covariance between the model prediction and the observation. The simulation results found the root-mean-square error of forecasted river stage using the data assimilation at the gauged stations of Taipei Bridge and Tudi-Gong-Bi for 1-3 hours lead time is 0.862m, 0.892m, 0.903m, and 0.281m, 0.326m, 0.345m, respectively. When the Ensemble Kalmen Filter is added in the model, the root-mean-square error reduces to 0.191m, 0.375m, 0.612m, and 0.062m, 0.090m, 0.145m at described gauged stations. It is found that the data assimilation and the Ensemble Kalmen Filter give reliable forecast water stages with a small root-mean-square error which successfully corrects the forecasted river stage at each time step of the flood routing process. The results reveal that the integrated model gains a better accuracy of the water-stage profiles with probabilistic uncertainties. The model provides reliable forecasts of the water-stage profiles for 1–3 hours lead time along the Tamsui River for specific locations in emergency response for flood risk management.
Status on Chinese Space Geodesy Networks and their Applications
Authors: Wang Xiaoya , Zhang Zhongping , Shu Fengchun , Wang Guangli , Xi Kewei
Published: March 2020

Chinese space geodetic networks were established in 1990s. The first SLR station in china was setup by Shanghai Astronomical Observatory (SHAO) in 1975 and now there are 7 SLR stations on operation in china. The observation accuracy has been improved from 1m to 8mm and the observation range has been extended from 1000km to 3600km for artificial satellites, 385000km for Lunar Range. The orbit determination accuracy has also been enhanced from several hectometer to 1-2 cm. And the products of SLR Terrestrial Reference Frame (TRF) and EOP is similar with that of other ILRS ACs and CCs. Currently 4 VLBI stations, including Seshan25, Kunming, Urumqi and Tianma65, participate in the IVS observing program. The total number of observing days was increased significantly in the past years. Shanghai VLBI correlator has been operational for the IVS data correlation since 2015. In addition to regular geodesy, we are also actively involved in the UT1 measurements and densification of the ICRF. We obtained first fringes between the two VGOS antennas at Shanghai in July 2019. A few more VGOS antennas will be built by collaborating with our partners in China or abroad. SHAO has provided the VLBI products such as POS+EOP to IVS. The first GPS station in China was setup in 1992 by JPL under the agreement between CAS and NASA, and now there are over 2000 GNSS stations running by CAS, China Earthquake Administration, Chinese Academy of Surveying & Mapping, China Meteorological Administration, Ministry of Education of the people’s Republic of China, Company and their subdivisions. From the ownership of Chinese GNSS network, we could see the comprehensive applications such as regional TRF densification, EOP measurement, meteorological service, earthquake displacement, ionospheric modelling, crustal movement monitoring, PNT and so on. The first DORIS station was set up in Wuhan in 2003 and now there are 2 DORIS sites in China. Chinese space geodetic networks and their application will be further developed in future.
Modeling Direct Economic Loss of Residential Building Contents Induced by River Flood and Storm Surge: A Case Study on Typhoon Rammasun in Haikou City of China
Authors: Zhang Haixia , Yu Lu , Fang Weihua
Published: March 2020

Typhoon often brings heavy rainfall, floods and storm surges to estuaries and may cause devastating disaster loss, especially in the downstream coastal urban areas, so a timely modeling of disaster loss is of great importance to emergency management. However, the complexity of interaction between river flood and storm surge imposes great challenges to the simulation of coastal flood in urban cities. At the same time, the local characteristics of building contents such as their types, values and vulnerabilities in different cities may also vary greatly. Haikou city, located in Hainan Island of China, was flooded due to the cascading effects of the upstream flood from Nandu River basin and the strong storm surge caused by strong winds of typhoon Rammasun during July 18 to 20, 2014.

In this study, firstly, the water from Nandu River was simulated with hydrological model and one-dimensional hydraulic model, and the coastal storm surge was modeled with a numerical surge model. The outputs of these models were used as the boundary conditions of two-dimensional hydraulic model, coupled with SWMM to reflect urban surface flow. Based on the above models, the maximum flood depth in Haikou city were derived. The inundation depth of Nandu River Estuary and riverside area is about 4 meters, while it of urban areas is relatively shallow. Secondly, the boundary of all the buildings in Haikou city and their geographic distribution were collected, and the values of contents were estimated building by building based on questionnaire survey data. Finally, based on the vulnerability curves developed in the past study, the direct economic loss of residential building contents were estimated. The results can provide a firm basis for the prediction of future loss before TC landing.
Sub-seasonal prediction of rainfall over the South China Sea and its surrounding areas during spring-summer transitional season
Authors: Li Qingquan , Wang Juanhuai , Yang Song , Wang Fang , Wu Jie , Hu Yamin
Published: March 2020

        The sub-seasonal characteristics and prediction of rainfall over the South China Sea and surrounding areas during spring-summer transitional season (April-May-June) are investigated using a full set of hindcasts generated by the Dynamic Extended Range Forecast operational system version 2.0 (DERF2.0) of Beijing Climate Center, China Meteorological Administration. The onset and development of Asian summer monsoon and the seasonal migration of rain belt over East Asia can be well depicted by the model hindcasts at various leads. However, there exist considerable differences between model results and observations, and model biases depend not only on lead time, but also on the stage of monsoon evolution. In general, forecast skill drops with increasing lead time, but rises again after lead time becomes longer than 30 days, possibly associated with the effect of slowly-varying forcing or atmospheric variability. An abrupt turning point of bias development appears around mid-May, when bias growths of wind and precipitation exhibit significant changes over the northwestern Pacific and South Asia, especially over the Bay of Bengal and the South China Sea. This abrupt bias change is reasonably captured by the first two modes of multivariate empirical orthogonal function analysis, which reveals several important features associated with the bias change. This analysis may provide useful information for further improving model performance in sub-seasonal rainfall prediction.
Sensitivity of ensemble forecast verification to model bias
Authors: Wang Jingzhuo , Chen Jing , Du Jun
Published: March 2020

        This study demonstrates how model bias can adversely affect the quality assessment of an ensemble prediction system (EPS) by verification metrics. A regional EPS [Global and Regional Assimilation and Prediction Enhanced System-Regional Ensemble Prediction System (GRAPES-REPS)] was verified over a period of one month over China. Three variables (500-hPa and 2-m temperatures, and 250-hPa wind) are selected to represent "strong" and "weak" bias situations. Ensemble spread and probabilistic forecasts are compared before and after a bias correction. The results show that the conclusions drawn from ensemble verification about the EPS are dramatically different with or without model bias. This is true for both ensemble spread and probabilistic forecasts. The GRAPES-REPS is severely underdispersive before the bias correction but becomes calibrated afterward, although the improvement in the spread' spatial structure is much less; the spread-skill relation is also improved. The probabilities become much sharper and almost perfectly reliable after the bias is removed. Therefore, it is necessary to remove forecast biases before an EPS can be accurately evaluated since an EPS deals only with random error but not systematic error. Only when an EPS has no or little forecast bias, can ensemble verification metrics reliably reveal the true quality of an EPS without removing forecast bias first. An implication is that EPS developers should not be expected to introduce methods to dramatically increase ensemble spread (either by perturbation method or statistical calibration) to achieve reliability. Instead, the preferred solution is to reduce model bias through prediction system developments and to focus on the quality of spread (not the quantity of spread). Forecast products should also be produced from the debiased but not the raw ensemble.
Archetypal analysis of Southern Hemisphere extreme circulation events
Authors: Risbey James , Monselesan Didier
Published: March 2020

Archetypal analysis of Southern Hemisphere extreme circulation events

This work conducts an archetypal analysis (AA) of midtropospheric flow
in the Southern Hemisphere.  The analysis identifies the archetypical
extreme flow states and compares them with the leading modes of
variability from Principal Component Analysis (PCA) methods.  In
particular, we examine long-lived extreme circulation patterns and
events from both AA and PCA, together with their synoptic signatures
and surface impacts.  The long-lived circulation types are efficient at
generating surface temperature extremes and exhibit long period
variability.  Case studies of documented surface extreme events show
that they correspond clearly to the midtropospheric flow archetypes.

 
Climatology and trends of Dissolved Organic Carbon in coastal waters off Sarawak, Borneo
Authors: Sanwlani Nivedita , Martin Patrick , Cherukuru Nagur , Muller Moritz , Evans Christopher
Published: March 2020

South-East Asian peatlands are a globally significant carbon store. Rivers draining these peatlands have some of the highest dissolved organic carbon (DOC) concentrations in the world and account for up to 10% of the global land-to-ocean carbon flux, thus representing an important input to the marine carbon cycle. The release of DOC from peatlands is a natural process, yet the rapid and extensive transformation of these peatlands for agriculture over the past two decades is thought to have increased fluvial carbon losses significantly. However, not only do we lack a firm understanding of the fate of this terrigenous DOC in tropical seas, the distribution and long-term variability in DOC have never been studied at large scales in SE Asia. We will present the seasonal climatology (2002-2018) of spatial distribution patterns of DOC concentrations and optical properties (absorption coefficients, spectral slope) of colored dissolved organic matter (CDOM) for coastal waters of Sarawak, Malaysian Borneo derived using a regionally tailored semi-analytical inversion model from MODIS Aqua. Our results reveal substantial inputs of DOC from Sarawak rivers DOC close to shore exceeds 125 µM, and CDOM across the study region shows predominantly terrigenous spectral signatures. DOC concentrations were higher during the rainier northeast monsoon than during the drier south-west monsoon. Our data suggest that long-term increases in DOC concentration have occurred across parts of our study region from 2002–2018, which has implications for the aquatic light regime and coastal biogeochemistry[PM5]. These results will be discussed in the context of past anthropogenic disturbance to coastal peatlands.
Assessment of Water Footprint for Koshi River Basin (KRB), Nepal
Authors: Singh Raj Deva , Ghimire Kumar , Pandey Ashish
Published: March 2020

Nepal is an agrarian country and almost one-third of Gross Domestic Product (GDP) is dependent on agricultural sector. Koshi river basin is the largest basin in the country and serves large share on agricultural production. Like another country, Nepalese agriculture holds largest water use in agriculture. In this context, it is necessary to reduce water use pressure. In this study, water footprint of different crop (rice, maize, wheat, millet, sugarcane, potato and barley) have been estimated for the year 2005 -2014 to get the average water footprint of crop production during study period. CROPWAT model, developed by Food and Agriculture Organization (FAO 2010b).

For the computation of the green and blue water footprints, estimated values of ET (the output of CROPWAT model) and yield (derived from statistical data) are utilised. Blue and green water footprint are computed for different districts (16 districts within KRB) / for KRB in different years (10 years from 2005 to 2014) and crops (considered 7 local crops). The water footprint of crops production for any district or basin represents the average of WF production of seven crops in the respective district or basin.

The study provides a picture of green and blue water use in crop production in the field and reduction in the water footprint of crop production by selecting suitable crops at different places in the field. The Crop, that has lower water footprint, can be intensified at that location and the crops, having higher water footprint, can be discontinued for production or measure for water saving technique needs to be implemented reducing evapotranspiration. The water footprint of agriculture crop production can be reduced by increasing the yield of the crops. Some measures like use of an improved variety of seed, fertilizer, mechanized farming and soil moisture conservation technology may also be used to increase the crop yields.

The crop harvested areas include both rainfed as well as irrigated land. Agricultural land occupies 22% of the study area, out of which 94% areas are rainfed whereas remaining 6% areas are under irrigation. The study shows 98% of total water use in crop production is due to green water use (received from rainfall) and remaining 2 % is due to blue water use received from irrigation (surface and ground water as source). Potato has 22% blue water proportion and contributes 85% share to the total blue water use in the basin. Maize and rice together hold 77% share of total water use in crops production. The average annual water footprint of crop production in KRB is 1248 cubic meter/ton having the variation of 9% during the period of 2005-2014. Sunsari, Dhankuta districts have lower water footprint of crop production. The coefficient of variation of water footprint of millet crop production is lower as compared to those of other crops considered for study whereas sugarcane has a higher variation of water footprint for its production.
Characterizing the groundwater flow pathways and recharge sources of a desert inter-dune aquifer system by geophysical approaches and multiple isotopes (B, H and O)
Authors: Zhang Xiaolang , Luo Xin , Jiao Jiu Jimmy
Published: March 2020

Studies of groundwater hydrodynamics are rare in desert aquifer system due to its remote location, sparse population, low effort input, and limited field data, but necessary and vital for water security and environment protection. Hydro-meteorological conditions, subsurface electrical resistivity structure, and the chemical and isotopic (11B/10B, 2H/H, and 18O/16O) compositions of groundwater and lake water in a desert inter-dune aquifer system were systematically investigated in order to delineate the origins and processes of groundwater flow. It was found that (1) two possible recharge mechanisms are possible to recharge the shallow sand dune aquifer, namely intensive rainfall infiltration and moisture-heat coupled transport; (2) the electrical resistivity tomography data show that salt lake water intrudes the ambient aquifer and interacts with fresh groundwater. The emergences of uptake of boron and increase of δ11B in salt groundwater further stress the intrusion of salt lake water. (3) Dissolution of 10B in fresh groundwater leads to a shift of the δ11B value from positive to negative along the flow path. Fresh groundwater streamlines originate from one place with high δ11B value in solution to another place with low δ11B value. Further referring to much high δ11B value in local rainwater, it is suggested that the shallow lakeshore groundwater is probably recharged by local rainfall; (4) Combining with the flow field of lakeshore groundwater and, hydrogen and oxygen isotopic characteristics of groundwater and lake water, the desert lake water is considered to be mainly sustained by shallow lacustrine groundwater discharge.
Long-term Pressure Evolutions due to Geologic Heterogeneities during CO2 Injection
Authors: Kim Taehee
Published: March 2020

In general, the characterization of the heterogeneity in a reservoir is considered to be important in the exploration and selection of CO2 storage formation, but it is not clear how the heterogeneity affects the evolution of the pore pressure. In particular, long-term changes in the pore pressure when most of the storage candidates are bounded by faults or bedrock, such as Korea, have been rarely examined. Many literature related to results of studies and international CCS standardization indicate that the heterogeneity of storage formation should be identified, but it is still unclear to what extent the precision or resolution of the investigation is required at the selection or design stage. The heterogeneity of sedimentary layers can be divided into two categories in terms of geographic statistics. At this time, the criteria of the classification is statistical stationarity. From a geological point of view, the statistical stationarity may be consistent with the sedimentary environment. In other words, it can be assumed that strata deposited at the same place, at similar times, and in similar circumstances have similar hydrogeological properties, despite of some detailed differences. In this case, the heterogeneity refers to “detailed differences” and the homogeneity refers to statistical parameters such as means or variances of physical properties and spatial auto-covariance. On the other hand, the nonstationary heterogeneity refers to a case where there is no statistical homogeneity, due to differences in geological structures such as faults and differences in strata such as sandstone and mudstone. In this study, the numerical sensitivity analysis was used to investigate the effect of each heterogeneity on the pressure buildup. The nonstationary heterogeneity applied in this study is a vertical structure that completely penetrates the storage formation. The results of ten models with the stationary heterogeneity showed almost similar pressure changes in the macroscale, although there were some pore pressure differences at the injection well between each of models. The pressure difference at the injection well between each model was dependent on the bulk permeability within a certain distance (200m in this study) near the injection wells, not on the average permeability of the whole system. In other words, when the injection well is installed at a point having a relatively high permeability, some additional increase in pressure due to the heterogeneity rarely occurs. However, lowering the permeability due to nonstationary heterogeneity can causes the global pressure rise in the storage formation, results were very similar to those of the case with closed boundary condition when the heterogeneity reduced the permeability to 10-4 times or less of the permeability in the storage formation.
Global Heritage Stone Resource - Activities in Germany
Authors: Ehling Angela
Published: March 2020

The „International Union of Geological Sciences” (IUGS) enacted an initiative at the 33. World Congress in Oslo 2008 with the title “Global Heritage Stone Resource “ (GHSR). Aim of this initiative is to increase the perception and estimation of natural stones in the architectonic heritage in particular and in the geoheritage context in general. That includes to emphasize the need to protect dimension stone quarries as well as to avoid the replacements with inappropriate stones at cultural heritage sites.
Germany with its federal structures took part in this initative only since 2018. A national working group, consisting of geologists as well as representatives of the dimension stone industry and the preservation of monuments, has been founded. Besides some public information first activity was the compilation of a national list with natural stones which should be nominated for a GHSR-certification. Meanwhile members of our national group work actively with the Heritage Stone Subcommission, two stones have been nominated for certification and a book about the natural stones at UNESCO-Sites in Germany is underway and will be published within the new series “Natural Stones and World Heritage” in 2021. The activities of the German working group go ahead with the longer lasting activities of the network “stones in the city”. The aim of both is to focus on the natural stones as a natural, unique and sustainable building material, which is shaping cultural landscapes.  Even the declaration of the “stone of the year” in Germany since 10 years refers to their use as building material. Thus, all these initiatives can be combined and may focus on that stones which are worth to be a Global Heritage Stone.
Crustal density structure of the Antarctic continent from constrained 3-D gravity inversion
Authors: Ji Fei , Zhang Qiao
Published: March 2020

Crustal density is a fundamental physical parameter that helps to reveal its composition and structure, and is also significantly related to the tectonic evolution and geodynamics. Based on the latest Bouguer gravity anomalies and the constrains of 3-D shear velocity model and surface heat flow data, the 3-D gravity inversion method, incorporating deep weight function, has been used to obtain the refined density structure over the Antarctic continent. Our results show that the density anomalies changes from -0.25 g/cm3 to 0.20 g/cm3. Due to the multi-phase extensional tectonics in Mesozoic and Cenozoic, the low density anomalies dominates in the West Antarctica, while the East Antarctica is characterized by high values of density anomalies. By comparing with the variations of effective elastic thickness, the inverted density structure correlates well with the lithospheric integrated strength. According to the mechanical strength and inverted density structure in the West Antarctic Rift System (WARS), our analysis found that except for the local area affected by the Cenozoic extension and magmatic activity, the crustal thermal structure in the WARS tends to be normal under the effect of heat dissipation. Finally, the low density anomalies features in West Antarctica extend to beneath the Transantarcitc Mountains (TAMs), however, we hypothesize that a single rift mechanism seems not be used to explain the entire TAMs range.
Measuring gravity changes for decades
Authors: Van Camp Michel , de Viron Olivier , Meurers Bruno , Francis Olivier
Published: March 2020

Being sensitive to any phenomena associated with mass transfer, terrestrial gravimetry allows the monitoring of many phenomena at the 10-10 g level (1 nm/s²) such as Earth tides, groundwater content, tectonic deformation, or volcanic activity. This sensitivity is richness, but also a source of problems because data interpretation requires separating the signatures from the different sources, including possible measurement artefacts associated with high precision. Separating the signal from a given source requires a thorough knowledge of both the instrument and the phenomena.

At the Membach geophysical laboratory, Belgium, the same superconducting gravimeter has monitored gravity continuously for more than 24 years. Together with 300 repeated absolute gravity measurements and environmental monitoring, this has allowed us to reach an unprecedented metrological knowledge of the instrument and of its sensitivity to hydrological and geophysical signals.

Separation is possible whenever the phenomena exhibit distinct time/frequency signatures, such as (pseudo)periodic phenomena or long-term processes, so that the signatures from other sources average out by stacking. For example, when performing repeated gravity measurements to evidence slow tectonic deformation, the easiest way to mitigate hydrological effects is to accumulate measurements for many years, at the same epoch of the year: the impact of seasonal variations is then minimized, and the interannual variations cancel out. Using 10 repeated absolute gravity campaigns at the same epoch of the year, we showed that the gravity rate of change uncertainty reaches on average 3–4 nm/s²/yr. Concurrently, using superconducting gravimeter time series longer than 10 years, we also investigated the time variations of tidal parameters.

It is also possible to separate phenomena by observing them by both gravity and some other techniques, with a different transfer function. By using 11 year-long times series from the gravimeter and soil moisture probes, and by stacking the observations, we measured directly the groundwater mass loss by evapotranspiration in the forest above the laboratory of Membach. Always with a precision better than 1 nm/s² (<=> 2.5 mm of water), we also monitored ground partial saturation dynamics and combining the gravity data with a weather radar allowed measuring convective precipitation at a scale of up to 1 km².

Extracting and interpreting those elusive signals could only by achieved throughout multi-instrumentation, multi-disciplinary collaborative studies, and 25 years of hard work.
Impacts of crab burrow on exchange of inorganic and organic carbon across the interface of water column and sediments in salt marshes
Authors: Xiao Kai , Li Hailong , Wilson Alicia , Santos Isaac , Tamborski Joseph
Published: March 2020

Abundant crab burrows in salt marshes can act as preferential water flow conduits for solute exchange by perforating muddy sediments, yet the impact of crab burrows on modulating carbon sequestration potential are not well understood. The field observations to assess how crab burrows drive carbon exchange over time scales of minutes to weeks along an intertidal marsh transect in North Inlet, South Carolina were conducted. The field analysis found that (1) continuous pore water exchange between the crab burrows and the surrounding soil matrix occurs because of tidally driven hydraulic gradients; (2) the burrow CO2 concentrations is higher than on the marsh surface because of respiration. The average gas-phase CO2 concentration in the crab burrows was approximately six times greater than ambient air. The lab analysis found that the concentrations of DIC and DOC in crab burrow porewater were lower than porewaters in the surrounding soil matrix. The porewater δ13C-DIC signatures in the crab burrows were heavier than those in the soil matrix, reflecting a mixture with seawater.

Crab burrows can influence carbon export by three pathways: gas phase CO2 release from burrows caused by the irrigation of surface water, hydraulic gradient-driven porewater exchange (PEX) and concentration gradient-driven passive diffusion transport (PDT). Among these pathways, PEX showed the dominance of the crab burrow-induced carbon export, which is at least an order of magnitude higher than the others. Crab burrow-induced carbon export from the whole intertidal transect was calculated as the sum of CO2 release and the dissolved carbon loss by PEX and PDT transport from the surrounding soil matrix to the crab burrow. The estimated C export was extrapolated to US East Coast salt marshes, which was nearly equivalent to riverine DIC flux, half of salt marsh DIC exports. These new insights underline the ecological roles of crab burrows in salt marsh carbon budgets, especially the importance of porewater exchange between crab burrows and the surrounding soil matrix.