bluuebunny/crossref_metadata_2025 huggingface dataset:
The HYPERMAQ dataset
Authors: Lavigne Héloïse , Dogliotti Ana , Doxaran David , Shen Fang , Castagna Alexandre , Beck Matthew , Vanhellemont Quinten , Sun Xuerong , Gossn Juan Ignacio , Pannimpullath Renosh , Sabbe Koen , Vansteenwegen Dieter , Ruddick Kevin
Published: June 2022

Abstract. Because of the large diversity of case 2 waters ranging from extremely absorbing to extremely scattering waters and the complexity of light transfer due to external terrestrial inputs, retrieving main biogeochemical parameters such as chlorophyll-a or suspended particulate matter concentration in these waters is still challenging. By providing optical and biogeochemical parameters for 180 sampling stations with turbidity and chlorophyll-a concentration ranging from 1 to 700 FNU and from 0.9 to 180 mg m-3 respectively, the HYPERMAQ dataset will contribute to a better description of marine optics in optically complex water bodies and can help the scientific community to develop algorithms. The HYPERMAQ dataset provides biogeochemical parameters (i.e. turbidity, pigment and chlorophyll-a concentration, suspended particulate matter), apparent optical properties (i.e. water reflectance from above water measurements) and inherent optical properties (i.e. absorption and attenuation coefficients) from six different study areas. These study areas include large estuaries (i.e. the Rio de la Plata in Argentina, the Yangtze Estuary in China and the Gironde Estuary in France), inland (i.e. the Spuikom in Belgium and Chascomùs lake in Argentina) and coastal waters (Belgium). The dataset is available from Lavigne et al. (2022),  https://doi.pangaea.de/10.1594/PANGAEA.944313.
Development and parameter estimation of snowmelt models using spatial snow-cover observations from MODIS
Authors: Gyawali Dhiraj Raj , Bárdossy András
Published: June 2022

Abstract. Given the importance of snow on different land and atmospheric processes, accurate representation of seasonal snow evolution, including distribution and melt volume, is highly imperative to any water resources development trajectories. The limitation of reliable snowmelt estimation in mountainous regions is, however, further exacerbated by data scarcity. This study attempts to develop relatively simple extended degree-day snow models driven by freely available snow-cover images. This approach offers relative simplicity and a plausible alternative to data-intensive models, as well as in situ measurements, and has a wide range of applicability, allowing for immediate verification with point measurements.
The methodology employs readily available MODIS composite images to calibrate the snowmelt models on spatial snow distribution in contrast to the traditional snow-water-equivalent-based calibration. The spatial distribution of snow-cover is simulated using different extended degree-day models with parameters calibrated against individual MODIS snow-cover images for cloud-free days or a set of images representing a period within the snow season. The study was carried out in Baden-Württemberg (Germany) and in Switzerland. The simulated snow-cover data show very good agreement with MODIS snow-cover distribution, and the calibrated parameters exhibit relative stability across the time domain. Furthermore, different thresholds that demarcate snow and no-snow pixels for both observed and simulated snow cover were analyzed to evaluate these thresholds' influence on the model performance and identified for the study regions.
The melt data from these calibrated snow models were used as standalone inputs to a modified Hydrologiska Byråns Vattenbalansavdelning (HBV) without the snow component in all the study catchments to assess the performance of the melt outputs in comparison to a calibrated standard HBV model. The results show an overall increase in Nash–Sutcliffe efficiency (NSE) performance and a reduction in uncertainty in terms of model performance. This can be attributed to the reduction in the number of parameters available for calibration in the modified HBV and an added reliability of the snow accumulation and melt processes inherent in the MODIS calibrated snow model output.
This paper highlights that the calibration using readily available images used in this method allows for a flexible regional calibration of snow-cover distribution in mountainous areas with reasonably accurate precipitation and temperature data and globally available inputs. Likewise, the study concludes that simpler specific alterations to processes contributing to snowmelt can contribute to reliably identify the snow distribution and bring about improvements in hydrological simulations, owing to better representation of the snow processes in snow-dominated regimes.
HMS Challenger and SMS Gazelle – their 19th century voyages compared
Authors: Gould William John
Published: June 2022

Abstract. This paper analyses the pioneering global voyages of HMS Challenger and SMS Gazelle in the 1870s – a time of rapid scientific advances and technological innovation. The voyage of Challenger has become well known as marking the start of the global-scale science of oceanography. The voyage of the Gazelle is much less well known despite the two voyages ending in the same year, 1876, and having similar geographical and scientific scope. Rather than focussing on the scientific achievements, the paper concentrates on how the expeditions were planned and executed, the lives and characters of the personnel involved and the underlying motivation behind the voyages. The paper presents the author’s translations of key elements of the Gazelle reports as a means of introducing the Gazelle expedition to an English-speaking readership.
Correlation between geochemical parameters and topography of geocovers of quartzitic relief at tropical area: study case in Serra da Canastra, Brazil
Authors: Nazar Thallita , Rodrigues Silvio , Santos Fabiana , Rodrigues Gelze
Published: June 2022

Geocovers contribute to the analysis of geomorphological processes that occur/occurred on the surface, serving as witnesses of these processes. Quartzitic regions tend to present incipient unconsolidated geocovers and are often characterized by rocky outcrops, even under humid tropical climates. The degree of weathering of geocovers and its relationship with the topography in these environments are still poorly understood. In this sense, the objective of this work is to analyze the relationship between topography and mineralogy of the clay fraction found in geocoverings developed on quartzitic relief, in a case study in Serra da Canastra, Chapadão do Diamante (ChD). We carried out a previous compartmentalization of the landscape into three main patterns, from which we selected three representative slopes for the survey of transects, from the interfluve to the valley floor. Thus, we selected nine geocoverage samples to perform the X-Ray Diffractometry (XRD) analysis, and analyzed the results using the exploratory multivariate technique of Principal Component Analysis (PCA). The results suggest a correlation between the identified minerals, their position on the slope and the characteristics of concavity and the presence of natural barriers. In the first transect, in very incipient geocoverings, minerals were found indicative of highly weathered environments and with poor drainage, such as Kaolinite and Illite, indicating greater permanence of water in the environment, due to small structural traps that allow the storage of products of quartzite weathering. In the second transect, the samples showed oxides and hydroxides of Fe and Al, which demonstrate the advanced degree of weathering in the area, which can constitute lateritic geocoverings, when in large quantities. The last transect, with deeper geocovers, in high slope, presented Goethite and Siderite, indicating a poorly drained environment, with water remaining longer in the system. This study revealed that mineralogical analyzes of materials from quartzite sample areas in a humid tropical environment may indicate that these areas refer to the management of the balance between the resistance of the quartzitic parent material and the intensity of weathering on the one hand, and the position and topographic shape of the slope can influence the weathering degrees of another.
Contribution of fluvial and marine sediment to the Senegal estuary (West Africa): a geochemical evaluation
Authors: Dramé Awa Bousso , Burningham Helene , Sall Moussa
Published: June 2022

Located at the doors of the Sahara Desert, the Senegal is an allogenic river originating in the Fouta Djallon (Guinea) in the Guinean subclimate (rainfall greater than 1000mm), crosses the Sudanian (900-1000mm), and Sahelo-Sudanian (500-900mm) influences before reaching the Atlantic Ocean under Sahelian (around 350mm) climate. This terminal section of the Senegal estuary is well known for its hydroclimatic variabilities, where the interaction between continental driving forces (ITCZ movements, harmattan winds, rainfalls) and Atlantic drivers (trade-winds, local wave climate conditions) influence the estuarine hydrodynamics. Results from geochemical analysis (grain size, elemental composition (XRF)) of the sediment cores collected during the flooding and dry seasons (August 2021 and February 2022) may give a better understanding of the alternating dominance of fluvial and marine hydrodynamics (including swells) dominance in the Senegal estuary over the recent period. Coupling this analysis with earth observation products may highlight the seasonality of the Langue Barbarie (sand spit) accretion/erosion cycles according to local variations such as bathymetry, wave climate variations, river discharges and human infrastructures.

 
Can we make tufa grow? Understanding the hydraulic conditions affecting tufa growth. 
Authors: Foley Antonia , Mao Luca
Published: June 2022

Anthropogenic and climatic events continue to affect river systems despite restoration action. Flooding events are increasing across the UK and placing additional pressure on Local Authorities to mitigate flood risks River restoration remains a key focus of conservation by the UK government, particularly as anthropogenic activities and the changing climate continue to degrade river systems at all scales. The increasing risk of flooding events across the country puts pressure on Local Authorities to mitigate flood. Flooding causes high degrees of sediment transport along the entire fluvial system and has negative ecological and chemical consequences. Under further threat are chalk streams, where the calcium concentration allows for tufa to deposit under varying hydraulic conditions. Chalk streams are heavily degraded by anthropogenic and human activities; however, their consistent flow from grounder aquifers provide ecological opportunities. Tufa naturally occurs within chalk stream environments and creates step barrages within the UK, providing hydraulic conditions such as degassed oxygen which provide ecological benefits and microhabitats. These barrages have been removed in some chalk streams such as the Upper Witham in Lincolnshire and encouraging their restoration may have hydraulic and ecological benefits.

There remains limited understanding of the physical factors controlling tufa deposition and no local understanding of the deposition rate within Lincolnshire. Consequently, the focus of this work is to explore the physical and chemical factors influencing tufa deposition and monitor its growth. The aim is to quantify the tufa deposition rate at Dunston Beck, Lincolnshire, and the role of flow velocity, flow depth and substrate on deposition rates. These aims will be met by measuring the tufa growth on the 14 sandstone and wooden plates that have been placed along a small reach of Dunston Beck that emulate different hydraulic conditions. The tufa growth will be measured using a handheld 3D scanning device monthly and samples of tufa grown on these plates will be taken and scanned using a Scanning Electron Microscope to categorise morphology and substrate. This is extremely important for classification of tufa as its categories can be caused by varying physical factors including flow rate. The results can be used to inform restoration practices as flow rates and microbial activity have a known relationship with tufa deposition. This work will inform the second phase of the Dunston Beck restoration and inform the Environment Agency with further information for restoring and classifying these sites.
Landscape Change due to Thousand Years of Iron Ore Production in the Erzberg Area (Styria, Austria)
Authors: Embleton-Hamann Christine , Premm Stefan
Published: June 2022

Iron ore has been mined in the Erzberg area for at least 900 years, possibly as long as 1500 years. This mining history can be divided into three periods of impact on the landscape. Due to the inefficiency of the early smelting techniques and the low production levels, the first period remained free of serious impacts. A huge demand for energy for ore smelting characterized the second period, resulting in supra-regional deforestation for charcoal production. The third period of mechanized surface mining is marked by the creation of large man-made landforms. In the Erzberg area, both historical documentation and modern recording of the mining activities are exceptionally good and provide an opportunity for i) a qualitative identification and description of the associated landscape changes and ii) a first attempt to quantify them. Qualitative analysis of the documents provided a detailed description of how distinct anthropogenic impacts and landforms have emerged, and identified the procedures that caused medieval supra-regional deforestation. A slope exposure opened along a creek allows interpretation of the geomorphic effects of the historical forest depletion. Quantification of the extent of deforestation was carried out for a forest area close to the mining site. The results allow a reconstruction of the condition of the forest at this site over two centuries. For quantification of the earth material moved by man in mechanized surface mining denudation rates for the Erzberg site were computed and compared with the sediment budget of a nearby river catchment. This comparison suggests that on the local scale man is two to three orders of magnitude more effective in transforming the landscape than geomorphic processes.
Morphological characterization of the cold-air pools of Abruzzo Region (Central Italy) and proposal for the creation of morphoclimatic sites 
Authors: Fazzini Massimiliano , Paglia Giorgio , Miccadei Enrico
Published: June 2022

Since the ‘90s, some climatologists and geomorphologists have focused attention on distinct areas characterized by extremely low temperatures, currently known as “cold-air pools.” They were recorded in specific synoptic conditions within karst plateaus, punctuated by sinkholes and other topographic depressions. Here, the interaction of climatic and morphologic features favors a strong nightly irradiance, especially when the ground is covered by snow, with considerable repercussions on the evolution of these morphoclimatic environments. Several new thermal gauges have been installed, sheltered from direct sun radiation, within the main European mountain ranges, particularly from the Pyrenees to the Alps, Apennines and Dinaric Alps, recording low temperatures comparable to those typical of high latitudes. In Central Apennines (Italy), within the main massifs of the Abruzzo Region, there are few monitored poljes (located at altitudes ranging between 1200 and 1600 m a.s.l.) characterized by these climatic conditions. During the winter advection of continental polar air, temperatures drop below -30°C. More in detail, at the Piani di Pezza (1460 m a.s.l.), the lowest official temperature in peninsular Italy was recorded on 15 February 2012, with a value of -37.4°C.

Nevertheless, it would be of fundamental importance to quantitatively define the morphological features at different spatial scales that allow these extreme thermal conditions recorded in the Abruzzo Region pools by comparison with other Apenninic or Alpine sites with similar morphological and climatic characteristics during well-defined synoptic situations. It would be desirable to propose these places as "morphoclimatic sites" since they increase the interest of tourists and meteophiles, as well as it currently happens with geosites and geomorphosites. A further purpose of this research is to contribute to the morphological characterization of the cold-air pools and confirm or refute the recent thermal trends calculated in the flat and hilly areas of Central Apennine as part of the studies aimed at a better understanding of climate change.

 

 
How human impacts on geomorphology echo through the centuries: explaining the declining flow capacity in Australia's most important river, the Murray.    
Authors: Rutherfurd Ian D. , Gower Thom , Grove James , Arrowsmith Christine , Vietz Geoff , Dyer Ben , Sims Alex
Published: June 2022

The River Murray is Australia’s largest and most important river.  It carries water for irrigation and city supply from the mountains in the east, semi-arid west.  The river crosses a series of low-angle alluvial fans (distributive fluvial systems) in its 1500 km path.  The Barmah Choke is a narrow section of the River Murray’s channel, formed by a Holocene river avulsion, that restricts flow capacity from the upper to lower Murray River.  The flow capacity of the Choke has declined nearly 20% since the 1980s, which imposes a constraint on regulated flows supplied down-valley, and is constraining economic development downstream.  Whilst there could be multiple geomorphic factors explaining the decline, we demonstrate that the most likely cause is a sheet of coarse sand shallowing the river, much of which originated from historical gold mining and catchment erosion in late 1800s.  The sheet of sand is reducing depth diversity, filling pools up to 5m deep, and degrading the ecological and cultural values of the river.  The whole length of the river through the Barmah Forest has shallowed over the last 30 years, aggrading by 1.9 m at the upstream end and 0.70 m in the most downstream section of the Choke (about 10% decrease in area).  The total volume of sand stored between Yarrawonga and Barmah is over 20 million m3, and the average total annual sand load transported into the 82km long Choke ranges between 130,000 m3 in a normal flow year to 500,000 m3 in a flood year (which translates into 2 – 9 cm of aggradation per year).  Surprisingly, overall, long-duration regulated irrigation flows have decreased the rate of sand transport through the Choke.  Decreasing downstream flow capacity across the Barmah Fan is a natural characteristic of this type of distributive fluvial system, but the sand sheet is accelerating the rate of decline.  Without intervention, conveyance through the Choke will inevitably continue to decline until the river avulses into a new channel.  A range of solutions are explored, but all are extremely expensive. 
Geoarchaeological approach of the middle Eure valley (Paris Basin, France): benchmarks for reconstructing both palaeoenvironments and human occupations during the Mid- and Late Holocene
Authors: Piau Théophile , Bétard François , Dugast Fabienne
Published: June 2022

Located in the western part of the Paris Basin (France), the Eure catchment is a rather unexplored area in the palaeoenvironmental, (geo)archaeological and historical field, especially in its median section. Actually, the latter status, which is predominantly agricultural, gives rise to very few spatial planning projects and as a result to very few preventive archaeological excavations. This area therefore provides an appropriate context for new considerations about technical approaches to be put into in an effective and relevant manner to overcome data gaps, whatever the period or the scientific field.

The poster will present the results of the investigations that have been carried out at different spatial scales with a geoarchaeological perspective: (i) cartographic and geomatics analysis to propose a first theoretical modelling of historical land-use; (ii) geomorphological mapping in order to underline the impacts of geomorphological dynamics on taphonomy and remains of archaeological settlement; (iii) geophysical surveys (Electrical Resistivity Tomography, Ground Penetrating Radar), percussion drilling for sedimentary cores and sedimentological analysis to obtain a 2D picture of the sediment structures of the palaeochannels, as well as to reconstruct the hydro-sedimentary dynamics of the Eure river close to archaeological remains; (iv) remote sensing using airborne technics by drone (photogrammetry, LiDAR, Infrared) and point cloud analysis to map microtopographic features of some (geo)archaeological key sectors.

The first results suggest a synchronous metamorphosis of the fluvial continuum that seems to take place during the Late Neolithic and Early Bronze Age. The Eure channels are disconnected from the main fluvial flow axis and progressively filled by detrital sedimentation, suggesting a significant soil erosion within the catchment at this time. On the other hand, peat sediments can be locally detected between the Bronze Age and the Early Middle Ages as a result of "site effects". Within the sub-watersheds of the right bank of the Eure, that are widely opened in the Tertiary series, a new and more recent phase of silty sedimentation has been identified from the Late Middle Ages onwards, probably linked to the growing soil erosion under the effect of large-scale upland-clearing. Despite their constraints, the investigative methods open up to new perspectives with a view to the integration of geomorphological and archaeological research in a programmatic but not necessarily preventive approach.

 
Glacial Lakes in the Chhombo Chhu Watershed (Sikkim Himalaya, India): Inventory, Classification, Evolution, and Potential GLOFs Assessment
Authors: Chowdhury Arindam , De Sunil Kumar , Sharma Milap Chand , Debnath Manasi
Published: June 2022

The Sikkim Himalaya, similar to other mountain regions, has lost considerable ice cover over the years owing to the changing climatic factors leading to enlargement of glacier-fed lakes, and thus posing a potential threat to downstream communities in the mountain and Tarai (foothills) region in case of breach anytime in the future. The Chhombo Chhu watershed (CCW) of Tista basin in the Sikkim Himalaya (~694.5 km2) is located in the transitional zone between the Greater Himalayan range with a Tethyan Sedimentary Sequence, is the storehouse of number of glacial lakes covering large areas, and volume. In order to evaluate the critical glacial lakes, we mapped the changes between 1975–2018 and assessed their dynamics based on manual analysis of medium to high-resolution optical images for the years 1975, 1989, 2000, 2010 and 2018, respectively and verified during field surveys. Results show that the number of lakes has increased from 62 to 98, and its total area expanded significantly by ~34.6 ± 5.4%, i.e., from 8.5 ± 0.2 km2 in 1975 to 11.4 ± 0.6 km2 by 2018, at an expansion rate of 0.8 ± 0.1% a−1. It is interesting to note that these lakes expanded faster during 2010–2018 (+1.18 ± 2.0% a–1), i.e. in the recent decade, compared to previous years such as +1.02 ± 1.1% a–1 in 1975–1988, +0.54 ± 1.3% a–1 in 1988–2000 and +0.20 ± 1.6% a–1 in 2000–2010. Lake outburst susceptibility result reveals that a total of twenty-seven potentially dangerous glacial lakes exist in the CCW; 5 have a status of ‘high’ outburst probability, 17 ‘medium’ and 5 ‘low’. Accelerating increasing long-term average annual trend of temperature (+0.283 °C a−1; 1975–2013) at 95% confidence level also supports the glacier area lost (–0.66 ± 0.1% a–1), and lake area enlargement trend (+0.80 ± 0.1% a–1) between 1975 and 2018, indicating heightened impact of climate change in the CCW of the Sikkim Himalaya.
Current soil problematics in the Tulum valley, related to climate change and anthropic use
Authors: Grígolo María Agostina , Rodríguez Aixa Inés , Lince Klinger Federico , Pittaluga Maria Alejandra
Published: June 2022

El Valle de Tulum está ubicado en la provincia de San Juan, en el Centro-Oeste de Argentina y tiene una población de 629.530 habitantes. Se encuentra en una zona de la Diagonal Árida Sudamericana. Sus habitantes han convertido el territorio en un oasis de riego, aprovechando las aguas superficiales del río San Juan a través de tres grandes obras como son los embalses de Ullúm, Punta Negra y Caracoles, más uno aún en construcción; y las aguas subterráneas de su amplio abanico aluvial.

Algunas prácticas antrópicas que en épocas pasadas contribuyeron al desarrollo de la región, como el drenaje de humedales, que amplían la frontera agrícola, hoy son el origen de suelos con severos problemas para habitar. En el siglo XIX, el valle se caracterizó por la presencia de cuerpos hidromórficos que lo ocuparon en su parte central, cerca del río San Juan. Este paleoambiente del Holoceno estaba formado por extensos humedales con agua permanente y un gran número de canales intercomunicados, así como por cauces de ríos abandonados. Los humedales desaparecieron por acciones de drenaje. Los nuevos suelos han permitido ampliar la frontera agrícola y proporcionar suelos orgánicos para la producción de alimentos.

In recent years, the region has experienced a serious water deficit, due to decreasing snow fall and high temperatures in the Andes Mountains, where the basins that supply water to the river, are located. (Pucheta, 2021). This condition unfavorably affected the agricultural soils caused by the action of anthropic drainage, which caused a large part of them to remain available for the real estate market.

In this new context, numerous problems have been detected and have been increasing with the water crisis due to climate change. For example, deformations and subsidence of the soil due to lower water tables, constructions on the river's paleochannels that are not visible to the naked eye because of anthropogenic changes in the landscape, which are evidenced through undulations and cracks in the streets and houses that can be detected by indirect geophysic consumption. As a result, there are dry vegetation areas and peat associated with old wetlands which are burnt during the summer, as well as salinization of the soil, among others. These problems have consequences, both for the environment, because it will not recover its original condition, and for the socio-economic dimension of the inhabitants, since the scarcity of irrigation water leads to the loss of agricultural and livestock production. Eventually, future scenarios that show serious difficulties in obtaining water for human consumption.
Identifying temporal and spatial denudation variations using in-situ terrestrial cosmogenic nuclides along vertical profiles on enrooted bedrock.
Authors: Raab Gerald
Published: June 2022

Tors, thus large residual rocks that are still enrooted in bedrock, adorn landscapes around the world. In recent years it became apparent, that tors are useful dipsticks that hold records of surface lowering rates of their surrounding surface. Here examples from the Sila Massif (Italy), Otago upland (New Zealand) and the Serra da Estrela (Protugal) are presented to provide a comprehensive overview of the capabilities and limitations of this new accessible archive.

The narrative provides details on the investigation technique, the modelling approach, formation patterns of tors and resulting surface denudation rates. The trademark of the “Tor Exhumation/Exposure Approach” is obtaining continuous in-situ denudation rate variations (not just averages) over thousands of years. In result, new comparisons with climate or vegetation changes and even topography controls can be derived by this approach.
Molards as proxies of permafrost degradation: investigating physical downscaled models 
Authors: Beck Calvin , Font Marianne , Conway Susan , Philippe Meven , Lagniel Emilie
Published: June 2022

Current climate change causes an increasing retreat of mountain permafrost. This retreat presents safety hazards due to more frequent slope instabilities. Thus assessing the state and evolution of permafrost is crucial. Unfortunately, mapping permafrost extent and retreat is not as simple as for other cryospheric landforms because permafrost is not directly detectable by remote sensing. However, in some mountain landslides, one can observe remnants of formerly ice-cemented blocks that degrade into cones of loose debris. These so-called molards imply the presence of an area of discontinuous permafrost at the level of the detachment zone.

To understand the processes that form molards we studied the degradation of the initial ice-cemented blocks by physical modeling. In nature, the height of these initial blocks ranges from 50 cm to up to 15 meters. For our experiments, it was, therefore, necessary to downscale the initial block to a more manageable cube size of 30 cm. These blocks are left to degrade under a controlled lab environment while being observed by a timelapse photogrammetric system as well as temperature and humidity sensors. The current experiments are investigating the effect of different sediment compositions, shape- and slope parameters on the decay and shape of the resulting molards. We find that especially the content of very fine sediment has a strong impact on the decay of the initial block due to its strong cohesion.

These initial results will be used to scale the experiment to the maximum size feasible in the lab: a 70 cm cube with a weight of up to 700 kg. The final goal is to create a numerical model based on the experimental findings, making it possible to distinguish molards from other similar landforms, such as hummocks or hummocky moraines. This knowledge can be used in the long term to identify and study these molards via remote sensing over a much larger area.
Total Carbon content assessed by UAS near-infrared imagery as a new fire severity metric
Authors: Wittenberg Lea , Hamzi Seham , Roberts Dar , Ichoku Charles , Shtober‐Zisu Nurit , Brook Anna
Published: June 2022

The ash produced by forest fires is a complex mixture of organic and inorganic particles with various properties. Ash and char are broad indicators for evaluating the impacts of fire on nutrient cycling and ecosystem recovery. Numerous studies suggested assessing fire severity by changes in ash characteristics. Traditional methods for fire severity are based on in situ observations, i.e. a visual approximation of changes in the forest floor and soil which are time-consuming and subjective. These measures primarily reflect the level of consumption of organic layers, the deposition of ash, particularly its depth and colour, and fire-induced changes in the soil. Numerous recent studies on fire severity suggested using remote sensing techniques combined with field observations via machine learning and spectral induces approaches to obtain practical tools for assessing the fire effects on ecosystems. While index thresholding can be easily implemented, its effectiveness over large areas is limited pattern coverage of forest type and fire regimes.

On the other hand, the machine learning algorithms allow multivariate classifications, but in the case of processing space-time series analysis, learning becomes complex and time-consuming. Therefore, there is no complete agreement on a quantitative index determining the severity metric. Given that wildfires play a significant role in controlling forest carbon storage and cycling, this study presents the potential of low-cost multispectral imagery across visible and near-infrared regions collected by the unmanned aerial systems to determine fire severity according to the colour and chemical properties of the vegetation ash. The use of multispectral imagery data might reduce impreciseness caused by manual colour matching and produce a vast and accurate spatial-temporal severity map. The suggested severity map is based on deep learning algorithms' spectral information used to evaluate chemical changes in fuels. These methods quantify total carbon content and assess the corresponding fire intensity required to form a particular residue. By designing three different learning algorithms (PLS-DA, ANN, and 1-D CNN) for two datasets (RGB images and Munsell colour versus UAS-based multispectral imagery) the multispectral prediction results show an excellent performance, which, therefore, shows that the deep network-based near-infrared remote sensing technology has a future potential to become an alternative and reliable fire severity monitoring method.
Magnitude and frequency of palaeofloods of the Duero River (Spain and Portugal) in the context of climate variability during the last 15 ka
Authors: Benito Gerardo , Greenbaum Noam , Medialdea Alicia , Calle Mikel , Sanchez-Moya Yolanda , Machado Maria , Corella Juan Pablo
Published: June 2022

The Duero River is one of the three major rivers in the Iberian Peninsula, draining a catchment area of 98,073 km2 (20% in Portugal and 80% in Spain) to the Atlantic Ocean. Extreme flooding in the western Duero River is associated with winter Atlantic fronts leading to some of the highest specific discharges to be found in European rivers. A paleoflood record in the Duero canyon, at the Spanish-Portuguese boundary, provides evidence of magnitude, frequency and timing of such extreme phenomena during the last 15 ka. Slackwater flood deposits (SWDs) are preserved in thick, high-standing benches in canyon expansions and tributary mouths. Fourteen high-resolution stratigraphic profiles were studied in two reaches, next to Bemposta and Saucelle dams, at the Arribes Natural Park. The paleoflood chronology was established using optically stimulated luminescence (OSL) and AMS radiocarbon dating. Flood discharge associated with each flood bed was estimated from hydraulic modelling (HEC-GeoRAS v.5).

The most complete record is found at the Duero-Tormes river junction (Bemposta reach), which comprises five inset SWD benches at elevations between 15 m and 25 m above river water level (arwl). The highest bench comprises six flood units within four sequences, dated to 13.8ka, 8.4ka, 2.4ka and post-2.4ka. At 23.5 m arwl, the second flood bench recorded 23 flood units organized into four sequences separated by well-developed paleosols, and dated to 11.6ka, 9.5ka, 4.4ka, 2.2ka and <0.5ka. The third inset bench (20 m arwl) comprises 19 flood units dated between 11.6ka and 10.5ka, whereas in the fourth inset bench (17.5 m arwl) 17 flood units were dated to 14.9ka, 12.6ka and 11.5ka. About 1 km downstream, a flood bench deposited at a channel expansion records 14 flood beds over the last 1.8ka with discharges >5000 m3/s.

The composite stratigraphic record comprises 62 floods over the last 15ka grouped into 10 flood phases (FP1 to FP10) with minimum discharges ranging between 4000 m3/s and 11,000 m3/s. The hydroclimatic analysis of the flood events, supported with historical flood analysis, shows a good temporal correlation between the occurrence of catastrophic floods and the existence of anomalous negative NAO index phase. The Duero’s palaeoflood record correlates in timing with flood episodes recorded in other Iberian rivers (e.g. Tagus, Guadiana) and lake sediments (e.g. Lake Sanabria), which highlights the impact of atmosphere-ocean hemispheric coupling conditions on extreme floods in the region. These findings suggest a response, at centennial scale, between climatic factors and the outcome variability in the magnitude and frequency of floods.
Micromorphological Insight into the Cave Sediments of Cadaval Cave, Tomar, Portugal.
Authors: Adewumi Opeyemi , Oosterbeek Luiz , Vallverdú i Poch Josep , Quinta-Ferreira Mário , Rosina Pierluigi , Pereira Telmo , Garcês Sara
Published: June 2022

Cadaval cave is located in a karstic canyon of the Nabão River, in the right margin of the Tagus River basin, municipality of Tomar, Centre of Portugal. The site encompasses a long stratigraphic sequence from present days to, at least, the Middle Palaeolithic. Major excavations were made during the 1980’s and restarted in 2019 under the scope of the FCT funded project - Moving tasks across shapes: the agro-pastoralists spread from and into the Alto Ribatejo (MTAS), (PTDC/EPH-ARQ/4356/2014).The Holocene sequence has three main sedimentary units: Layer E (without human occupation), Layer D (with Late early to Middle Neolithic necropolis) and Layer C (with a Late Neolithic necropolis). Because of the lack of detailed geoarchaeological studies, the process of deposition and modification of sedimentary layers remains in question, this being very important to better interpret natural vs human dynamics, including site formation processes. For instance, Layer E is supposed to correspond to an earlier Holocene stage (Greenlandian), a period in which other caves from the region have dwelling and funerary occupations. This can be related to the low demographic density at the time, but also to the roof collapse event, an idea reinforced by the presence of some Middle Neolithic burials on the top of some large slabs. Nevertheless, a better characterization of its formation and the degree of anthropic impact in the diagenetic process will allow for a clearer interpretation of this and other situations.The main objective of the first author`s ongoing PhD project is to characterize the Late Pleistocene and Holocene sedimentary processes and the site formation processes of the archaeological record in the basin of the Tagus River, namely assessing its anthropic component.  For this, a detailed geoarchaeological investigation is being carried out in several sites, including Cadaval cave, giving particular emphasis to the use of micromorphology.

Keywords: Micromorphology, Cave sediments, Neolithic, Stratigraphy, Holocene.
Late quaternary evolution of the continental shelf offshore Marzamemi (southern Sicily, Ionian Sea) and implications on the distribution of associated mesophotic bioconstructions
Authors: Varzi Andrea Giulia , Fallati Luca , Savini Alessandra , Bracchi Valentina Alice , Bazzicalupo Pietro , Rosso Antonietta , Sanfilippo Rossana , Bertolino Marco , Muzzupappa Maurizio , Basso Daniela
Published: June 2022

Coralligenous (C) bioconstructions include calcareous build-ups of biogenic origin that typify selected regions of the Mediterranean Sea. These peculiar habitats thrive from shallow waters (15-20 m of water depth (w.d.) up to the limit of the mesophotic zone, and they formed since the Holocene transgression. They are from few to tens of meters large, displaying variable lateral continuity and thickness. Peculiar C outcrops are present offshore Marzamemi (southeastern Sicily, Ionian Sea). Their extension and distribution across the shelf were investigated within the project CRESCIBLUREEF - Grown in the blue: new technologies for knowledge and conservation of Mediterranean reefs. We produced a new 17 km2 high-resolution bathymetric map using a R2-Sonic 2022 system, ground-truthed by ROV video inspections. From a geomorphological point of view, the shelf is typified by four distinct marine terraces. Climate change and tectonic uplift are the dominant forcing mechanisms responsible for the formation of long and narrow terraced landforms in a variety of geomorphic settings; and marine terraces are largely used to reconstruct the Quaternary glacial and interglacial climates. The coupling of documented uplift rate in this region (ca. 0.2 mm/yr since the Tyrrhenian time) and the evidence reported in literature for late Quaternary relative sea-level curves shows a good correlation between the distribution of C outcrops and local, short stasis of sea level transgression periods, culminated with the rapid Flandrian transgression. C outcrops are mainly spread over the first and last terraces at two specific depth ranges: from 36 to 42 m of w.d., and from 86 to 102 m of w.d., respectively. Settlement and growth were mainly favored by a low sedimentation regime. Indeed, lowstand stages were likely characterized by erosional forces. This is particularly noticeable in the middle of our study area, where we have a paleo-incision typified by peculiar erosional features we were able to map. The role of the inherited continental shelf landscape in creating favorable substrate for the settlement and growth of C during the Holocene is here investigated.
The role of groundwater in forming theatre-headed valleys in unconsolidated sediments and bedrock
Authors: Micallef Aaron
Published: June 2022

Groundwater has been implicated as an important geomorphic agent in valley development. In unconsolidated sand and gravel, field observations and numerical simulations have shown that groundwater can lead to the formation of theatre-headed valleys. However, the temporal scale at which these valleys form and the influence of geologic heterogeneities on valley evolution remain poorly constrained. In bedrock, the development of valleys by groundwater remains controversial, and other processes (e.g. plunge-pool erosion, megaflooding) have been proposed to explain such landforms.

Here I will present two case studies, from the Canterbury coastline of New Zealand (unconsolidated sediments) and the Maltese Islands (limestone), to address these knowledge gaps.

In the first case study (New Zealand), I integrate field observations, luminescence dating, multi-temporal UAV and satellite data, time-domain electromagnetic data and slope stability modelling to show that theatre-headed valley erosion by groundwater in sand and gravel is an episodic process that occurs once every 227 d on average, when rainfall intensities exceed 40 mm/d. Valleys can be elongated at rates of 30 m/d via the formation of alcoves and tunnels by groundwater seepage, followed by retrogressive slope failure due to undermining and a decrease in shear strength. Valley location is determined by the occurrence of hydraulically conductive zones, such as relict braided river channels, and sand lenses.

In the second case study (Maltese Islands), I combine field and remote sensing observations from Gnejna Valley with numerical modelling to demonstrate that groundwater seepage is the key driver of theatre-headed valley formation in jointed limestones over clays. Erosion takes place via widening of joints and fractures by fluid pressure and dissolution, and creeping of the underlying clay layer, both of which lead to slope failure at the valley head and its upslope retreat. The talus is removed by creep and sliding on the valley bed. The location and width of the valley are determined by the location of a master fault and the extent of the damage zone. An exponential decrease of seepage away from the master fault gives rise to a theatre-shaped head.
A new UNESCO Global Geopark at the southern Dead Sea, Jordan – first concepts and hazard monitoring
Authors: Al-Halbouni Djamil , AlRabayah Osama , Rüpke Lars
Published: June 2022

The Dead Sea area and its surroundings have suffered strong changes in the last decades, accompanied by a variety of natural hazards related to enhanced erosional processes, such as sinkholes, subsidence and flash floods. In this work we discuss the concepts and challenges of the establishment of a new UNESCO Global Geopark (UGGp) at the southeastern Dead Sea. The Geopark will thematically encompass the influence that the natural changes and related hazards have had on the local population, from geological, over historical up to recent times. The hydrogeology and geomorphology, i.e. the connection between erosion by water, dissolution of minerals and landscape evolution will be the main guiding theme that connects the Eastern Rim Highlands of Jordan with the Dead Sea rift valley through ephemeral wadis, vegetated springs areas and traditionally living communities. The creation of the UGGp is aimed at a holistic, sustainable development and management of the area by eco-tourism, and includes education on water resource management, hazard awareness and resilience, conservation as well as international geo- and bioscience research, especially on monitoring of Geohazards. The proposed territory contains a variety of geologic features from Cambrian (Umm Ishrin Sandstone), over Cretaceous (Kurnub, Ajlun and Belqa groups) up to the Quaternary deposits in alluvial fans, volcanic rocks (Neogene basalt), parts of the Lisan salt diapir and the recently exposed shoreline of the Dead Sea. Tectonically, the territory lies on the Arabian Peninsula, and is limited to the west by an active rift zone, the Dead Sea transform fault. The highlight and focus area of the Geopark lies near the SE shore of the DS, near Ghor Al-Haditha. It encompasses the active subsurface erosion zone, with a large variety of recent sinkholes and subsidence formations as well as a potpourri of mostly clayey-silt sediments consisting of a variety of precipitated evaporite minerals such as aragonite, gypsum, halite and detritic particles such as limestone, quartz and clay found all along the DS shore. Finally, a creation of such a space would be the forth in the Middle East, so an international reputation and visibility is guaranteed.
Late Quaternary large-scale folds in intracratonic central Amazonia evidenced from tectonic geomorphology
Authors: Rossetti Dilce , Vasconcelos Davi L. , Bezerra Francisco H. R. , Valeriano Marcio M. , Alves Fabio C. , Molina Eder C.
Published: June 2022

In intracratonic South America, the origin of neotectonic activity and its impact on large Amazonian rivers have been of continuous research interest, but the available evidence has been only for extensional structures. This investigation focuses on a megascale (~60,000 km2) domal relief from central Amazonia (the Juruá dome). The main goal was to verify the relationship of this anomalous relief with a growing fold and determine the origin of the stress field within the context of Andean uplift along with the westward movement of the South American plate. The approach applied here is unprecedented for the Amazon lowlands. This is because it combines evidence of tectonic adjustments of river systems using morphostructural and morphometric analyses from remote sensing imagery, integrated with subsurface data consisting of gravity and magnetic maps, seismic reflection, and well logs. The Juruá dome consists of a broad, rounded, and smooth, convex relief, with altitudes generally not exceeding 110 m developed into Pleistocene-Holocene deposits. The drainage over the dome is arranged concentrically into a broad annular pattern with localized anomalous segments in the Solimões River and various Amazonian tributaries. The results revealed that the Juruá dome evidence the growth of a broad anticline. Non-linear slightly convex χ-profiles of many rivers that cross or contour the dome evidence transient rivers, consistent with a development under growth fold. The fold modified the course of several rivers within the domal relief area, including the Juruá River, which is entrenched along NE-striking faults that released the stress along the fold axis. NE- and NW-striking normal and reverse faults with flower structure geometries are abundant in subsurface and suggest deformation from strike-slip tectonics. Gravity and magnetic data revealed that the fold and many of its associated faults are deep-rooted into basement rocks. The geomorphological and structural data are collectively compatible with a long-term NW-trending maximum horizontal compressive stress-field that is driving basin inversion. This neotectonic activity can be linked to far-field stresses from the pushes from the Andean orogeny and the movement of the South American plate against the North Andean and Nazca plates. Thus, this study can expand our knowledge on the impact of far-field stresses in intracratonic settings transmitted from collisional and constructional tectonic plates. Detecting active folded reliefs in central Amazonia is a new approach that can help characterize the extension and source of compressive far-field stresses in intracratonic northern South America.