bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosolids Incorporation in Mediterranean Soils Increase Phosphate Adsorption
Authors: Freiberg Yaniv , Fine Pinchas , Borisover Michael , Baram Shahar
Published: March 2021

Contradictory data exists on the impact of biosolids incorporation on ortho-phosphate (IP) binding to arid and semi-arid Mediterranean soils. We used two mature organic amendments (OA) with low IP solubility to study the effect of OAs addition on the IP adsorption parameters of Mediterranean soils. Seven soils, encompassing a wide range of mechanical, chemical and mineralogical properties, were mixed with a biosolids compost (DSC) at 9:1 ratio (w/w dry weight basis). The soils and mixtures were either incubated for seven years under constant temperature (30℃) and moisture content (80% of 30 kPa tension) or were unincubated. IP adsorption parameters were also measured in not-incubated soil DSC mixtures at 97:3 ratio. In all the soils, DSC addition significantly increased the IP adsorption capacities (by Langmuir's model) from 126 to 397 mg IP kg-1 in the soils to 254 through 669 mg IP kg-1 in the soil-DSC-mixtures. The increased capacities were accompanied by a significant decrease in the adsorption affinities, from values of 0.12 to 1.02 L kg-1 in the soils to 0.05 and 0.25 L kg-1 in the mixtures. Biosolids addition at 97:3 ratio had a similar effect on the IP adsorption parameters as the 9:1 ratio. These two IP adsorption parameters continued to change along the incubation. The other OA tested was a municipal solid waste compost (MSWC), which was mixed with two montmorillonitic soils at 97:3 ratio (soil:OA), one with high lime and low Al/Fe-oxides contents and the other with low lime and high Al/Fe-oxides content. OA addition increased the IP adsorption capacity in the lime-rich soil, while it did not affect the other. Overall, our results show that the solid matrix of the two OA's used by us embodied IP adsorption sites, most likely through metal bridging with Ca2+, which increases the total adsorption capacity of the soil-OA mixture. Concomitantly, DOM from the OAs competes with IP on adsorption sites reducing the soil's adsorption capacity. The magnitude of each one of these two processes depends on the soil and the added OA characteristic and will determine the overall change in the soil's capability to retain IP after biosolids incorporation.

 
Satellite-based analysis of CO and Fires in the Arctic
Authors: Karppinen Tomi , Sundström Anu-Maija , Lindqvist Hannakaisa , Tamminen Johanna
Published: March 2021

Climate change is proceeding fastest in the Arctic region. While human-induced emissions of long-lived greenhouse gases are the main driving factor of global warming, short-lived climate forcers or pollutants emitted from the forest fires are also playing an important role, especially in the Arctic. Forest fire emissions also affect local air quality and photochemical processes in the atmosphere. For example, CO contributes to the formation of tropospheric ozone and affects the abundance of greenhouse gases such as methane and CO2.

During past years Arctic summers have been warmer and drier elevating the risk for extensive forest fire episodes. Satellite observations show, that during the past three summers (2018-2020) fire detections in Arctic, especially in Arctic Siberia have increased considerably, affecting also local emissions of CO. This work focuses on studying CO concentration and its variation at high latitudes and in the Arctic using satellite and ground-based observations. Satellite observations of CO from TROPOMI are analyzed for the 2018-2020 (NH) summer months. To assess the satellite retrieved columns the satellite measurements are compared to ground-based remote sensing measurements at Sodankylä. Also, ground-based in-situ measurements are used to see how the total column changes mirror the ground level concentrations. The fire characteristics are analyzed using observations from MODIS instruments onboard Aqua and Terra. Fire effects on seasonal cycle and interannual variability of CO concentrations at Arctic high latitudes are analyzed.
Soil erosion and its prevention measures during the construction period of underground engineering: a case study in the city Shanghai, China
Authors: Tang Hongliang
Published: March 2021

Abstract: As a huge metropolis, the highly intensive development and utilization of underground space in Shanghai has become the distinct trend of urban construction. Combined research among more than 100 industrial and civil construction projects in the city finds that soil erosion during the construction of underground works accounts for a significant proportion (50%~60%) of the totality of soil erosion or degradation. In order to further promote the precise management and control of water and soil conservation in the procedure of construction engineering projects, this paper analyzes the relationship between foundation pit supporting measures and water and soil conservation results in typical underground engineering examples. Through summing up the high frequency risk points of water and soil loss caused by underground engineering of housing construction projects in Shanghai, several positive methods for preventing and controlling water and soil erosion could be contributed correspondingly for the future work, such as pretreatment of the drilling caving of bored piles, and making full use of the soil produced by underground excavation.

Key words: underground engineering; risk analysis; water and soil conservation measures
Fluid inclusion 40Ar/39Ar geochronology of andalusite from syn-tectonic quartz veins: perspectives on dating regional deformation and metamorphism events
Authors: Xiao Ming , Jiang Ying-De , Qiu Hua-Ning , Zhao Guo-Chun
Published: March 2021

A long-lasting orogenic process often generates vast complexity of deformation and metamorphism. Understanding the time scales of these processes is essential for the reconstruction of the finite architecture of a fossil orogenic belt, which, nevertheless, is not always straightforward. This is because multiple episodes of tectonic events would lead to multiple growth periods of accessory minerals and deformation of rock-forming minerals, which brings challenges for conventional dating methods such as U–Pb, K/Ar, and 40Ar/39Ar step-heating. Fortunately, the emplacement of syn-tectonic quartz veins witness the deformation process and potentially, the associated metamorphism. They, therefore, have the potential to provide vital age information for regional crustal evolution. These veins, especially those in metapelitic terranes, usually contain andalusite, a fluid inclusion bearing K-poor pure aluminosilicate, which stands a good chance for directly dating syn-tectonic veining events by the fluid inclusion 40Ar/39Ar stepwise crushing technique.

Combined with detailed petro-structural investigation, this study applies the fluid inclusion 40Ar/39Ar geochronology, for the first time, on andalusite minerals in syn-tectonic quartz veins from the Chinese Altai Orogenic Belt, Central Asia, to explore a new way for dating deformation and metamorphism. 40Ar/39Ar stepwise crushing on three andalusite samples yielded well-defined Early Permain ages of 282–274 Ma. These ages are consistent with previously published emplacement ages of regional syn-tectonic leucosome/pegmatite/granite veins and metamorphic ages for local and region schist/gneiss from the same metamorphic series. These results collectively suggest that the fluid inclusion 40Ar/39Ar geochronology of andalusite in syn-tectonic quartz veins has the potential to constrain the timing of fluid-present deformation and potentially contemporaneous metamorphism. This work, therefore, provides a novel way for the age constraints of regional tectonic-thermal evolution of metapelitic terranes in general.

Acknowledgements

This project was supported by the Guangdong Basic and Applied Basic Research Foundation (No. 2019A1515012190), the International Partnership Program of Chinese Academy of Sciences (No. 132744KYSB20190039) and the Projects funded by China Postdoctoral Science Foundation (No. 2019M663133). A Guangdong Special Support Program to Y.D. Jiang is also acknowledged.
State evolution laws and earthquake nucleation
Authors: Viesca Robert
Published: March 2021

In models of faults as elastic continua with a frictional interface, earthquake nucleation is the initiation of a propagating dynamic fault rupture nucleated by a localized slip instability. A mechanism capturing both the weakening process leading to nucleation as well as fault healing between events, is a slip rate- and state-dependent friction, with so-called direct effect and evolution effects [Dieterich, JGR 1979; Ruina, JGR 1983]. While the constitutive representation of the direct effect is theoretically supported [e.g., Nakatani, JGR 2001; Rice et al., JMPS 2001], that of the evolution effect remains empirical and a number of state-evolution laws have been proposed to fit lab rock friction data [Ruina, JGR 1983; Kato and Tullis, GRL 2001; Bar-Sinai et al., GRL 2012; Nagata et al., JGR 2012]. These laws may share a common linearization about steady-state, such that a linear stability analysis of steady, uniform sliding yields a single critical wavelength for unstable growth of perturbations [Rice and Ruina, JAM 1983]. However, the laws’ differences are apparent at later, non-linear stages of instability development.

Previously, we showed that instability development under aging-law state evolution could be understood in terms of dynamical systems [Viesca, PR-E 2016, PRS-A 2016]: the non-linear acceleration of slip occurs as the attraction of a fault’s slip rate to a fixed point, corresponding to slip rate diverging with a fixed spatial distribution and rate of acceleration. Here we show that this framework can also be applied to understand slip instability development under all commonly used evolution laws, including the so-called slip and Nagata laws. To do so, we develop an intermediate state evolution law that transitions between the slip and aging laws with the adjustment of a single parameter. We show that, to within a variable transformation, the intermediate law is equivalent to the Nagata law and that fixed-point blow-up solutions exist for any value of the transition parameter. We assess these fixed-points’ stability via a linear stability analysis and provide an explanation for previously observed behavior in numerical solutions for slip rate and state evolution under various evolution laws [Ampuero and Rubin, JGR 2008; Kame et al., 2013; Bar-Sinai et al., PR-E 2013; Bhattacharya and Rubin, JGR 2014].
Near Real-Time Flood Impact Analysis on Road Networks
Authors: Kwant Martijn , de Groen Frederique , van Marle Margreet , Haag Arjen , Haaksma Herman
Published: March 2021

Traditional flood risk studies often focus on direct economic impact, such as property damage or agricultural loss. However, the impact of floods is not limited to these direct damages. In fact societal costs and/or cascading effects are often much higher than the direct impact of floods. Cascading effects, such as access to healthcare and infrastructure accessibility are vital components for efficient emergency response management. This requires methodologies to quickly analyze the impact of large-scale floods on infrastructure networks.

 

In this case study, the use of satellite-based flood maps are examined in combination with network criticality in the Mandalay region in central Myanmar. This region was severely affected by flooding after heavy monsoon rains in 2019. Many regions in the world are affected by this type of floods every year, resulting in large scale evacuations and limited access to health care. During these type of events, the transportation network is a crucial part for emergency response, as it is used for the delivery of goods, evacuation and deployment of emergency hospitals.

 

The core of this study is a methodology to assess near real-time flood extents based on Sentinel-1 satellite imagery and the impact on network criticality. These tools were used to analyze the redundancy of the infrastructure network and quantify cascading impacts of flood hazards such as road accessibility and access to medical services. The methodology shows potential for operational use by linking with flood early warning systems (e.g. Delft-FEWS) enabling impact-based forecasting.
Using open source & low cost rain gauges to support debris flow real-time monitoring in Lima, Peru
Authors: Arestegui Miguel , Ordoñez Miluska , Cisneros Abel , Madueño Giorgio , Almeida Cinthia , Aliaga Vannia , Quispe Nelson , Millán Carlos , Lavado Waldo , Huaman Samuel , Phillips Jeremy
Published: March 2021

Debris flow, locally known as huaycos, impact the east part of the metropolitan city of Lima, capital of Peru. However, after many extreme events such as the one related to the 2017 “Coastal Niño” or the one in 1987, there is a lack of historical data and sufficiently accurate monitoring systems.

 

The fact that this area is densely populated presents obvious challenges, from social and physical perspectives, but also some opportunities. We present our experience using open source & low cost rain gauges on previously unmonitored microwatershed, as part of a broader watershed-level monitoring system enhancement by SENAMHI (National Meteorological and Hydrological Service). We also present our experience on linking monitoring systems, debris flow modelling and community based risk management towards developing operational EWS.
Variation characteristics of temperature and precipitation on the northern slopes of the Himalaya region from 1979 to 2018
Authors: Han Yizhe , Ma Yaoming , Wang Zhongyan , Ma Weiqiang
Published: March 2021

The northern slopes of Himalaya (NSH) have the highest average elevation in the world. It is difficult to assess how climate change has affected this region because only a few observations are available from the high terrain and harsh environment. This study investigates the long-term characteristics of temperature and precipitation in the NSH. Further, the association of these variations with atmospheric circulation patterns is also investigated. Our results indicated that the warming trend in this region is almost 1.5 times that of the TP region, 2 times that of China, and 3.5 times that of the world. Additionally, the warming rate of the NSH is more obvious than other regions in the Himalayas, which shows that different regions of the Himalayas have different sensitivity to climate change. Although the warming trend in the NSH region does not show obvious seasonal differences like the TP, the temperature increase rate in autumn and winter is still higher than that in spring and summer. The abrupt change point for the temperature increase in summer was about 5 years later than that in other seasons, indicating that the NSH region is more sensitive to climate warming in cooler seasons, which is similar to the western and northwestern Himalaya. Furthermore, the Southern Oscillation Index (SOI) displays significant relationships with the temperature in the NSH, meanwhile, the North Atlantic Oscillation index (NAO) and Western Pacific Subtropical High Intensity Index (WPI) also exist some correlations with seasonal temperature change. This indicating that the atmospheric circulation would also have affected the temperature increase in this region, especially in summer and winter. The changes in precipitation are only affected by the SOI during the monsoon season (June to September), indicating that ENSO influences precipitation changes through water vapor transmission. In contrast, the precipitation in the TP is correlated with NAO, SOI and WPI, which indicating the precipitation of the TP might be affected by multiple circulation systems.

 

 
(Paleo)climate science for the 21st century
Authors: Cobb Kim M.
Published: March 2021

Records of past climate trends, variability, and extremes hold key insights into Earth’s changing climate, yet their full potential will remain untapped without a concerted effort to surmount several critical challenges, some time-sensitive.  In a century defined by accelerating climate change and human disturbance, the climate archive itself is at grave risk given that i) many paleoclimate records end in the late 20th century, with no concerted effort to extend them to the present-day, and ii) many paleoclimate archives are disappearing under pressure from climate change and/or human disturbance. Second, many paleoclimate records are comprised of oxygen isotopes, yet the coordinated, multi-scale observational and modeling infrastructures required to unravel the mechanisms governing water isotope variability are as yet underdeveloped. This dramatic oversight exists despite development of technologies that avoid costly analysis via mass spectrometers, and despite the fact that water isotopes may very well be one of the most powerful diagnostic tracers of a changing global water cycle. Lastly, in part owing to the aforementioned deficiencies, paleoclimate data assimilation efforts remain fraught with large uncertainties, despite their promise in constraining many of the most uncertain aspects of future climate impacts, including the evolution of extreme events and hydrological trends and variability. Climate science for the 21st century requires deep investments in the full integration of paleoclimate data and approaches into frameworks for climate risk and hazard assessments. In this sense, it is not surprising that paleoclimate scientists have played a key role in the communication of climate change science to decision-makers and the general public alike. Their understanding of the Earth system also equips them to contribute valuable insights to teams comprised of researchers, practitioners, and  decision-makers charged with leveraging science to inform solutions, in service to society. It’s time to recognize that all climate scientists study climate of the past, and all paleoclimate scientists have insights that are relevant to our climate future.
Effects of extreme events on the morphology of submarine channels: the case of the Elliot hazard cascade
Authors: Tilston Michael , Shugar Dan H. , Clare Michael , Heijnen Maarten , Acikalin Sanem , Cartigny Matthieu , Talling Peter , Parsons Daniel , Lintern Gwyn , Stacey Cooper , Hubbard Stephen , Hage Sophie , Bell Daniel , Clark John Hughes , Giesbrecht Ian , Jackson Jenifer , Menounos Brian
Published: March 2021

Submarine systems where the canyon head is directly connected to the river mouth arguably provide the best setting for in situ studies of turbidity currents since the sediment supply propelling them arrive in periodic pulses linked to fluvial freshet events. Consequently, the frequency of, and similarity between, the turbidity currents flowing through these systems make it easier for their channel morphology to evolve towards a state of dynamic equilibrium. Therefore, if an extreme event occurs that dramatically alters the system’s sediment supply, it is reasonable to assume that submarine channels will undergo a period of rapid adjustment. This is the present scenario occurring in Bute Inlet following the recent Elliot Creek hazard cascade. Bute Inlet is one of the most actively monitored sites for turbidity currents in the world, and the extensive historical dataset that has been amassed at this site along with the rare Elliot Creek event provides the unique opportunity to study the impacts of extreme allogenic forcing mechanisms on the morphodynamics of submarine channels.

Preliminary measurements indicate that the turbidity in Elliot Creek has increased by ~40x compared to pre-slide measurements, and oceanographic measurements within a few days of the event show very high turbidity in ocean bottom water to a distance of almost 70 km from the delta. While the bathymetric survey since the landslide is so far constrained to the proximal region of the inlet, early results show that channel morphology was rapidly altered. Specifically, the submarine channel fed by Southgate River, which supplied water and sediment from the landslide and glacial outburst flood, was lowered by about 3m across the width of the channel bed. Conversely, the morphology of the channel fed by Homathko River has remained static between the 2020 and 2021 surveys. Below the confluence of these two submarine channels, the cyclic steps that once dominated the bed morphology appear to have been largely infilled by a 1-2m thick drape of sediment along the inner half of the channel bend, whereas the outer banks have laterally eroded by upwards of 50m at some points. This trend of channel widening and lateral migration appear to be propagating down the system. Importantly, the nature of the slide suggests that sediment delivery will remain elevated with respect to background conditions for decades into the future, suggesting that the submarine channel may be in the process of adapting to an entirely new flow regime rather than reacting to a singular extreme flow event.
Terrestrial overview of a landslide-tsunami-flood cascade at Elliot Creek, British Columbia 
Authors: Geertsema Marten , Menounous Brian , Shugar Dan , Millard Tom , Ward Brent , Ekstrom Göran , Clague John , Lynett Patrick , Carrivick Jonathan , Friele Pierre , Schaeffer Andrew , Donatti Davide , Stead Doug , Jackson Jennifer , Higman Bretwood , Dai Chunli , Brillon Camille , Heathfield Derek , Bullard Gemma , Giesbrecht Ian , Hughes Katie , Jacquemart Mylène
Published: March 2021

On 28 November 2020, some 18 Mm3 of quartz diorite detached from a steep rock face at the head of Elliot Creek in the southern Coast Mountains of British Columbia. The rock mass fragmented as it descended 1000 m and flowed across a debris-covered glacier. The rock avalanche was recorded on local and distant seismometers, with long-period amplitudes equivalent to a M 4.9 earthquake. Local seismic stations detected several earthquakes of magnitude <2.4 over the minutes and hours preceding the slide, though no causative relationship is yet suggested. Pre-slide optical and radar remote sensing data indicated some slope deformation leading up to failure. More than half of the rock debris entered a 0.6 km2  lake, where it generated a 115 m displacement wave that overtopped the moraine at the far end of the lake. We estimate that some 13.5 Mm3 of water left the lake from the combined impact of the landslide as well as erosion of the dam. The water that left the lake was channelized along Elliot Creek, scouring the valley more than 40 m in some places over a distance of 10 km before depositing debris on a 2 km2 fan in the Southgate River valley. Debris temporarily dammed the river, and turbid water continued down the Southgate River to Bute Inlet, where it produced a 70 km turbidity current and altered turbidity and water chemistry in the inlet for weeks. The landslide followed a century of rapid glacier retreat and thinning that exposed a growing lake basin. The outburst flood extended the damage of the landslide far beyond the limit of the landslide, destroying forest and impacting salmon spawning and rearing habitat. We expect more cascading impacts from landslides in the glacierized mountains of British Columbia as glaciers continue to retreat, exposing water bodies below steep slopes while simultaneously removing buttressing support.
Spring-summer 2020 aerosol pollution in Moscow metropolitan area
Authors: Kasimov Nikolay , Popovicheva Olga , Vlasov Dmitry , Chichaeva Marina , Larionova Anastasia
Published: March 2021

Reduction of urban emissions following the response to COVID-19 pandemic has provided the unique possibility for assessment of the aerosol pollution in the metropolitan area with the highest population density in Russia. According to observation data obtained from the aerosol research station of Meteorological Observatory of Lomonosov Moscow State University, the strict control measures and social lockdowns initiated in spring 2020 in Moscow megacity have had a notable decreasing of PM2.5, black carbon (BC), and PM10-bound potentially toxic elements (PTEs) concentrations. The average concentration of PM2.5 and BC has decreased by 42% and 75%, respectively, in comparison to the following period of economical restoration in summer 2020. A city traffic decrease led to a gentle dynamics of a BC diurnal trend due to a reduced energy load in the morning hours. Changes in the enterprises operating regime affected the redistribution of emissions intensities from working days to weekends. During the period of recovery of economic activity in the summer of 2020, the emission intensity has increased and the direction of BC sources has changed. Furthermore, these factors resulted in substantial increase in the pollution levels for the most of PTEs during the period of economical restoration. For instance, Ba, Sn, K, Cu, Bi, B, Mo, As, Sb, and Pb concentrations emitted from vehicles and industrial sources were increased by 42–167%. Levels of PTEs originated from construction and demolition processes (Sr, Mg, and Ca by 175%, 21%, and 19%, respectively), road dust and soil particles resuspension (Zr, P, Mn, and Fe, by 76%, 51%, 49% and 46%, respectively) also experienced the significant growth. Real-time measurements of short-term changes in the atmosphere aerosol pollution with a rapid extreme fall and subsequent restoration of economic activity allows a better understanding of the processes taking place in the system of economy-society-environment of large cities.
Comparison of local kinematic rupture joint inversion approaches for tsunami early warning: Examples of the 2017-2020 Mw > 6.3 East Aegean earthquakes
Authors: Metz Malte , Isken Marius , Wang Rongjiang , Dahm Torsten , Özener Haluk , Chousianitis Konstantinos , Lorito Stefano , Romano Fabrizio
Published: March 2021

The fast inversion of reliable centroid moment tensor and kinematic rupture parameters of earthquakes occurring near coastal margins is a key for the assessment of the tsunamigenic potential and early tsunami warning (TEW). In recent years, more and more multi-channel seismic and geodetic online station networks have been built-up to improve the TEW, for instance the GNSS and strong motion networks in Italy, Greece, and Turkey, additionally to the broadband seismological monitoring. Inclusion of such data for the fast kinematic source inversion can improve the resolution and robustness of its’ solutions. However, methods have to be further developed and tested to fully exploit the potential of such rich joint dataset.

In this frame, we compare and test two in-house developed, kinematic / dynamic rupture inversion methods which are based on completely different approaches. The IDS (Iterative Deconvolution and Stacking, Zhang et al., 2014) combines an iterative seismic network inversion with back projection techniques to retrieve subfault source time functions. The pseudo dynamic rupture model (Dahm et al., in review) links the rupture front propagation estimate based on the Eikonal equation with the dislocation derived from a boundary element method to model dislocation snapshots. We used the latter in both a fast rupture estimate and a fully probabilistic source inversion.

We use some Mw > 6.3 earthquakes that occurred in the coastal range of the Aegean Sea as an example for comparison: the Mw 6.3 Lesbos earthquake (12 June 2017), the Mw 6.6 Bodrum earthquake (20 July 2017), and the recent Mw 7.0 earthquake which occurred at Samos on 30 October 2020. The latter earthquake and the resulting tsunami caused fatalities and severe damage at the shorelines of Samos and around the city of Izmir, Turkey.
The fast estimates are based on only little data and/or prior information obtained from the regional seismicity catalogue and available active fault information. The large number of seismic (broadband, strong motion) and geodetic (high-rate GNSS) stations in local and regional distance from the earthquake with good azimuthal coverage jointly inverted with InSAR data allows for robust inversion results. These, and other solutions, are used as a reference for the comparison of our fast source estimates.
Preliminary results of the slip distribution and the source time function are in good agreement with modelling results from other authors.

We present our insights into the kinematics of the chosen earthquakes investigated by means of joint inversions. Finally, the accuracy of our first fast source estimates, which could be of potential use in tsunami early warning, will be discussed.
Connectivity of floodplains in Germany – which floodplain extent is relevant?
Authors: Natho Stephanie
Published: March 2021

Floodplains are transitional ecosystems, rich in biodiversity, endangered and adapted to inundation by floods. Flood magnitude, hydrologic connectivity and elevation define the extent of an active floodplain. In past centuries, active floodplains in Germany were reduced by up to 90% of their original size – in terms of the area that is statistically inundated at least once every 100 years. But, does this area reflect the area relevant for floodplain ecosystems and for evaluating their functioning and the services they provide? Analyzing two scenarios of Flood Hazard Maps (FHM), a German-wide comparison including 78 rivers was carried out to quantify the extent of floods with statistical occurrence intervals of 5 to 25 years, so-called ‘frequent floods’ (T-frequent), and intervals of 100 years, or ‘medium floods’ (T-medium), as well as selected characteristics. The comparison was carried out on the river (basin) level, and based on hydrological catchments. By additionally analyzing measured discharges of relevant gauges from the past 20 years, real inundation was quantified. As a result, even in exceptional wet years these ‘frequent floods’ occur for a few days per year or not at all. The extent of the two FHM scenarios differs for most areas: Only at 13% of gauging units was the T-frequent inundation extent similar to that of T-medium. Furthermore, within T-medium the land use of arable land doubles and that of urban areas more than doubles, showing how disconnected the T-medium floodplain is in many parts. On the other hand, 25% of grasslands are Natura 2000 meadows occurring within the borders of T-frequent but only 6% are Natura 2000 meadows outside these borders, indicating the effect of connectivity and thus inundation, making these habitats valuable in terms of biodiversity mainly in T-frequent. This study provides evidence that, especially for regulatory services like water purification, water retention and climate mitigation, T-frequent might be more suitable for consideration. With more frequent flooding, less intensively used areas are connected more often, holding back water, nutrients and sediments – in addition to comparatively more areas relevant for nature conservation. For flood protection and also as a refuge for flora and fauna and for connection of habitats, of course the extent of disastrous 100-yr floods are important.
Detecting future changes of short-term rainfall characteristics in the mountainous regions of Slovakia
Authors: Földes Gabriel , Labat Marija Mihaela , Kohnová Silvia , Kandera Miroslav
Published: March 2021

The study focuses on future changes in short-term rainfall characteristics. The analysis was performed for the mountainous regions in the northern part of Slovakia at 10 selected climatological stations. The rainfall data are simulated by Community Land Model Scenario which represents the future climate change.  The Community Land Model Scenario is a multidisciplinary project between scientists and several working groups mainly in the USA. The model includes impacts of changes in vegetation on the climate. The scenario has semi- pessimistic characteristics with a predicted global temperature increase by 2.9°C by the 2100. The analysis was performed for five rainfall durations (60, 120, 180, 240 and 1440 minutes) for the historical (1961-2020) and for the future (2071-2100) periods.  The detection of the future changes in short-term rainfall characteristics was made by several methods; for the seasonal changes the Burn´s vector was used, for the trend testing the data the Mann-Kendall test was applied. Results provide information how climate change impacts the short-term rainfall intensities in the mountainous regions of Slovakia.
Gradient Boosting Machine for Phosphorus Removal Prediction in Multi-Soil-Layering (MSL) system operated in a rural area 
Authors: Sbahi Sofyan , Ouazzani Naaila , Lahrouni Abderrahmane , Hejjaj Abdessamed , Mandi Laila
Published: March 2021

The quality of effluents from wastewater treatment plants still challenging especially in underprivileged rural areas where water resources are mostly affected by pollution, depletion and excessive exploitation. Thus, the prediction of phosphorus removal is one of the most important tasks in the management of wastewater effluent. Predictive model accuracy is crucial for safe reuse of treated water for public health and the environment. However, linear models that use a high dimensional dataset may be unable to build accurate and interpretable models. To address this complexity, the current study evaluates the effect of hydraulic retention time (HRT) on the removal of orthophosphates (PO4–P) and total phosphorus (TP) by the multi-soil-layering (MSL) eco-friendly technology. In addition, it attempts to predict this removal from domestic wastewater using a combined approach based on feature selection technique and gradient boosting machine algorithm (GBM). Sixteen physicochemical and bacterial indicators were monitored for a one-year period. The results show that the HRT impact significantly (p < 0.01) the removal of phosphorus content by the MSL system. The HRT, pH, PO4–P and TP were suggested relevant for predicting the removal of TP, while HRT and PO4–P were sufficient for predicting the removal rate of PO4–P. The analysis of accuracy using the validation dataset demonstrates that GBM models have high credibility as they achieve an R² > 0.92, while the analysis of sensitivity reveals that the HRT was the most important factor affecting phosphorus removal in the MSL system. In addition, the modeling results show that the GBM model has proven to be useful for predicting pollutant removal in the MSL technology and investigating its behavior.

 
Climate Simulations to Carbon Neutral with Improved Minimal Complexity Earth Simulator 
Authors: Chen Jiewei , Cui Huijuan , Xu Yangyang
Published: March 2021

The Paris Agreement stated a goal to keep global warming to well below 2℃, preferably to  1.5 C above preindustrial levels. To further ensure the implementation of the Paris Agreement, recently, many countries have proposed to achieve carbon neutral between 2050-2070. In this study, we produce a set of carbon neutral scenarios and examined their climate responses using the minimal complexity earth simulator (MiCES). First of all, parameter sensitivity analysis is applied to optimize the parameters for the model using a multi-parameter sensitivity analysis method and output measurement method, which turns out that the 7 parameters related to heat and carbon transferred are most sensitive among all 37 parameters. Uncertainties of the key parameters are further constrained by observed emission and temperature within their uncertainty range, providing reference bounds of parameters with 95% confidence intervals. Then we design ideal emission scenarios with China’s carbon emission peak at 2024,2027,2030 and carbon neutral in 2050,2055,2060,2065,2070 and extrapolated to world’s emission. With improved key parameters’ value, we simulated  climate responses to carbon neutral scenarios. We found that the Paris goal of limiting temperature increase to 1.5 °C above pre-industrial levels will require either negative carbon emission or all greenhouse gases neutral during this century, and the carbon neutral before 2060 proposed by Chinese government will contribute to limiting global temperature increase with the 2 °C level.
Release and sedimentation behaviors of biochar colloids in soil solutions
Authors: Fang Jing
Published: March 2021

The release of biochar colloids considerably affects the stability of biochar in environment. Currently, information on the release behavior and suspension stability of biochar colloids in real soil solutions is scarce. In this study, 20 soils were collected from different districts in China and the release behavior of biochar colloids and their suspension stability in soil solutions were systematically examined. The results showed that both pyrolysis temperature and biomass source had important effects on the formation of biochar colloids in soil solutions. The formation amount of biochar colloids from low pyrolysis temperatures (400 ℃) (average amount of 9.33–16.41 mg/g) were significantly higher than those from high pyrolysis temperatures (700 ℃) (average amount of less than 2 mg/g). The formation amount of wheat straw-derived biochar colloids were higher than those of rice straw-derived biochar colloids probably due to the higher O/C ratio in wheat-straw biochar. Further, biochar colloidal formation amount was negatively correlated with comprehensive effect of dissolved organic carbon, Fe and Al in soil solutions. The sedimentation curve of biochar colloids in soil solutions is well described by an exponential model and demonstrated high suspension stability. Around 40% of the biochar colloids were maintained in the suspension at the final sedimentation equilibrium. The settling efficiency of biochar colloids was positively correlated with comprehensive effect of the ionic strength and K, Ca, Na, and Mg contents in soil solutions. Our findings help promote a deeper understanding of biochar loss and stability in the soil-water environment.
Formation of dry granular fronts and watery tails indebris flows
Authors: Meng Xiannan , Johnson Chris , Gray Nico
Published: March 2021

Dry granular fronts and watery tails often develop in debris flows, but their formation mechanisms are still poorly understood. Dry bouldery debris flow fronts are often attributed to particle-size segregation, but idealized experimental mixtures of fluid and mono-disperse grains also exhibit the formation of dry fronts. This motivates the development of a new depth-averaged model that treats grain-water mixtures as a buoyancy and Darcy drag coupled multiphase medium. This system is able to describe the temporal and spatial evolution of the grain and water depths as well as the associated grain and water depth-averaged velocities. It considers the layered development of the flow and incorporates a shear velocity profile into the model, instead of the standard plug flow assumption that is employed by almost all debris-flow models. By revisiting Davies' moving bed flume experiments, it is shown that, in the under-saturated region, shear results in the surface layer of dry grains moving faster than the bulk and they are preferentially transported to the flow front to develop a dry snout. Conversely, in the over-saturated region, the flow thickness is sufficiently small that the water friction is stronger than the friction acting on the grains. As a result, the surface grains can move faster than the water and leave it behind. This novel theory provides a rational framework that describes the complete longitudinal profile of debris flows from the dry granular front to the pure watery tail without the need to consider particle-size segregation.
Nonlinear internal wave generation over the Yermak Plateau 
Authors: Urbancic Gabin , Lamb Kevin , Fer Ilker , Padman Laurie
Published: March 2021

North of the critical latitude (78.4), internal waves of the M2 tidal frequency can no longer freely propagate, and the energy conversion from the barotropic to the internal tides vanishes. Near the continental slopes around the Arctic Ocean, internal wave energy is enhanced and comparable to values at mid-latitudes (Rippeth et al. 2015, Levine et al. 1985). Observations on the northern flank of the Yermak Plateau (YP) has characterized the region as one of enhanced internal wave activity and nonlinear internal waves have been observed (Czipott et al. 1991, Padman and Dillon 1991).

The YP is a bathymetry feature stretching out into the Fram Strait north-west of Svalbard. The YP plays a prominent role in the Arctic’s heat balance due to its interaction with the West-Spitsbergen current which is a main contributor to the heat transport into the Arctic Ocean. Nonlinear waves generated over the YP are a significant energy source for mixing and can therefore modulate and force exchange processes.

To study the nonlinear internal wave generation mechanisms over the YP, we used a high resolution, nonlinear, non-hydrostatic model. We found that nonlinear internal waves are forced not by the M2 but the K1 tide which has been observed to have significant variability over the YP (Padman et al. 1992). Barotropic, diurnal shelf waves generated on the eastern side of the YP propagates counter-clockwise, amplifying the cross-slope currents. This amplification is the necessary condition for nonlinear internal wave generation over the YP.
 Land-atmosphere coupling in operational NCUM forecasts during the 2020 monsoon season
Authors: Barton Emma , Taylor Chris , Jayakumar A. , Mitra Ashis , Arulalan T.
Published: March 2021

The onset, persistence and variability of summer monsoon rainfall impacts over a billion people. Advance knowledge is critical for agricultural planning and hazard mitigation, yet forecasting remains a challenge. Sources of error that have been identified in forecast models include the representation of the land surface and subsequent coupling with the boundary layer and convection. This study presents an analysis of land-atmosphere coupling in the operational Indian 4km convective scale regional model configuration of the Unified Model (NCUM-R), used by NCMRWF to provide daily forecasts. An earlier study (Barton et al, QJRMS 2019) analysed the coupling in this model for a single forecast when research aircraft observations were available. It revealed rapidly evolving biases in the monsoon trough linked to errors in the representation of soil moisture. Our current work aims to understand whether this behavior is typical of the monsoon season. This matters because the trough is an important dynamical feature and a key driver of regional rainfall. Here we provide a more comprehensive analysis by assessing the impact of initial soil moisture state on a full season of operational three day forecasts. NCUM-R output is evaluated by comparison to ERA5 reanalysis (atmospheric temperature and pressure) and satellite observations from AMSR2 (land surface temperature) and SMAP (soil moisture).  Correlations between surface and atmospheric variables in the model are computed using linear regression. Our results suggest that systematic biases in the evolution of atmospheric temperature and pressure over three days are indeed linked to errors in the initial soil moisture state. These biases likely impact rainfall predictions derived from the forecasts throughout the monsoon season. This work highlights the importance for realistic soil moisture initialisation in high resolution operational forecasts.
Typical debris-flow barrier dams and associated outburst floods in the southeastern Tibet
Authors: Hu Kaiheng , Zhang Xiaopeng , Wei Li
Published: March 2021

Large-magnitude debris flows up to a volume of 1.0 million m3 happen frequently in the southeastern margin of Tibetan plateau due to rapid rock uplift, high relief and abundant rainfall. These flows with high bulk density can easily block main rivers. Such debris-flow barrier dams fail very quickly, resulting in outburst floods and intensive sed-iment transport. We collect data of four recent large-scale debris-flow damming events at Peilong, Yigong, Tianmo and Sedongpu catch-ments, and examine the process of riverbank erosion and sediment transportation under dam narrowing and outburst flooding. More than 10% of debris mass was delivered downstream when the dams breached. It is concluded that debris flow is main erosion way in this area, and the very high erosion rate play a key role on river morpholo-gy in southeast Tibet.
Comparison of two flood forecasting approaches over High Atlas Mountains basins in Morocco
Authors: El Mahdi El Khalki , Tramblay Yves , Amengual Arnau , Homar Victor , Romero Romualdo , Saidi Mohammed El Mehdi , Alaouri Meriem
Published: March 2021

This study aims to compare flood forecasting approaches adapted to the context of Morocco, for two catchments (Rheraya and Ourika) located in the High Atlas Mountains. We evaluated the performances of flash-flood forecasts using two approaches; one relying on event-based hydrological modelling, and the second, a generalized least squares regression model linking event rainfall, antecedent soil moisture and runoff. The meteorological forecasts considered were provided by the AROME (Application of Research to Operations at Mesoscale), ALADIN (Aire Limited Dynamic Adaptation International Development) and WRF (Weather Research and Forecasting) models. For both approaches, three soil moisture data sources (in-situ measurements, ESA-CCI remote sensing data and ERA5 reanalysis) were compared to estimate the initial soil wetness conditions before flood events. Results showed that the AROME and WRF models better simulate precipitation amounts than ALADIN, mostly due to their better ability to reproduce convective events. The comparison between the two flood forecasting approaches showed that the regression model outperforms the hydrological model-based approach, due to fewer calibration parameters and a better robustness. The best results were obtained with the combination of the WRF forecasts with antecedent soil moisture from ERA5. This type of approach needs to be tested in other basins of North Africa where data are available, in order to develop flood forecasting in these regions, which are strongly vulnerable to flash floods.
The Late Holocene forest fire history in continuous permafrost zone of Central Siberia
Authors: Novenko Elena , Mazei Natalia , Kupryanov Dmitry , Prokushkin Anatoly
Published: March 2021

Understanding the long-term fire history of larch forests in the permafrost zone of Central Siberia is essential for an assessment of the possible responses and feedbacks of forest ecosystems to climate change. The multi-proxy record from the area of the Evenkian field station of the Sukachev Institute of Forest SB RAS, located in the middle part of the Lower Tunguska river basin provides important new data on the fire frequency, vegetation changes and paludification dynamics in the Central Evenkia over the last 3.5 ka BP. The new results of radiocarbon dating, loss on ignition, plant macrofossil and macro charcoal analyses from a sediment core taken in the waterlogged larch forest (N 64°09'56.1" E 100°31'43.9") are presented.

The obtained data have shown that fires were an important factor in the evolution of forest ecosystems in this continuous permafrost regions and acted as a trigger for the paludification process in the study area. The reconstruction of fire frequency demonstrated that the fire return period in the warm epochs of the late Holocene (3.6-2.7 ka BP, 1.5-0.7 ka BP, including the Medieval Climate Anomaly) varied from 115 to 150 years, and increased to 275-300 years during the periods of cooling (2.7-1.5 ka BP; the Little Ice Age, 0.7-0.15 ka BP). We suggested that the shorter and possibly colder summers during the cold epochs led to a decreased evaporation and a rise of ground moisture in many habitats, which was unfavorable for the occurrence and extension of forest fires. During the last 200 years the frequency of forest fires in the study area increased significantly, the fire return period reduced to a minimum value for the entire period under consideration (i.e. the last 3.5 ka BP) and reached 80 years. The fire free interval revealed from the macro charcoal analyses for the last 200 years is close to the average fire free interval reconstructed by dendrochronological data from the study area for the same period. The low human impact on forest ecosystems due to remote location of study area from settlements and mining regions suggests the natural causes of these fires.

This work was supported by the Russian Science Foundation, project № 20-17-00043.