bluuebunny/crossref_metadata_2025 huggingface dataset:
Dolines as microhabitat relief feature and their importance for Eurasian lynx (Lynx lynx) ecology
Authors: Čonč Špela , Oliveira Teresa , Breg Valjavec Mateja , Krofel Miha
Published: June 2022

Automatic methods for detecting and delineating relief features allow remote and low-cost mapping, which has an outstanding potential for large-scale spatial analysis and calculation of morphometric characteristics of karst depressions in remote, forested and hard to cross areas. Besides geomorphology, detection methods can be also useful for wildlife ecology and similar research. We applied a filled-DTM (digital terrain model) method using LiDAR (Light Detection and Ranging) data to automatically detect dolines and other karst depressions in a rugged terrain of the Dinaric Mountains, Slovenia. For the dolines we calculated basic morphometric and morphological characteristics such as surface area, diameter, depth, slope, ruggedness and others.
To demonstrate its applicability for wildlife research, we applied it 1) in a preliminary study (Menišija plateau and Logatec-Begunje plain test area, NW Dinaric Mountains) in combination with GPS-telemetry data to assess the selection of these features by the Eurasian lynx (Lynx lynx) and 2) to analyse what characteristic are typical for those dolines where lynx killed ungulates (whole Dinaric Mountains of Slovenia).
In preliminary study we found that lynx selected for habitats in the vicinity of karst depressions, among which they preferentially used larger karst depressions. Lynx also regularly killed ungulate prey near these features. For whole Dinaric Mountains 202 kill sites were identified, among which 32.2% (n=65) were located inside dolines or in their close vicinity. Analysing the characteristics of those dolines where lynx kill sites were identified, we found that also these dolines were larger than mean and median surface area, depth, and diameter of all dolines in the Dinaric Mountains. The median with standard error of surface area of the dolines where the lynx caught its prey is 1,141.4 ± 703.2 m2, has diameter of 38.8 ± 11.3 m, and is 5.2 ± 1.9 m deep. The maximum slope in these dolines ranges from 20.4 to 56.3°, which could indicate the formation of smaller walls, rocky outcrops and karren fields. Morphometric and morphological characteristics of dolines could influence success of lynx hunting.
Habitat selection for karst depressions and high proportion of killed ungulate inside or in close vicinity of dolines illustrate that karstic features could play an important role in the ecology of lynx

Key words: Karst depressions, GIS, LiDAR, geomorphology, Eurasian lynx (Lynx lynx), kill sites, microhabitat characteristics, Dinaric mountains, telemetry, spatial ecology
Application of density analysis for quantitative assessment of the geoheritage and its implementation in the Courel Mountains UNESCO Global Geopark (Spain)
Authors: Ballesteros Daniel ,   Workingroup for the geosite inventory of Courel Mountains UGGp
Published: June 2022

Inventories of geosites and their quantitative assessments constitute solid and efficient tools to conduct geoconservation and geotourism actions towards suitable management. The criteria addressed for listing and evaluating geosites vary widely according to the target, subject, value and work scale of the inventory, as well as different ways of understanding geoheritage. All this complicates the display and understanding of the geoheritage and its grade of implementation in a UNESCO Global Geopark (UGGp).

The objective of our work is to apply density functions to display graphically the numerical assessments of the geosite inventory of the Courel Mountains UGGp (Spain) and the degree of implementation of the geoheritage in its local development. The inventory focuses on tourism and educational uses and involves five main quantitative indexes (environmental value, scientific value, geoconservation, potential use, real use); in detail, the potential use results from four secondary indexes (visitability, promotion, local services & leisure, other interests). The density curves were performed for each selected index projected on an X-axis that ranges from “very low” to “very high” values.

The natural value density curve shows an expected approximately normal distribution. The scientific value function has two maxima at “middle-high” and “low” value, and the geoconservation index corresponds to a normal distribution in which the mean is located at high-very high values. The highest abundance of the potential and real uses curves fit the low score; in the same way, the modes of the secondary indexes range from the “very low” to “medium” values. The density curves reveal the occurrence of well-preserved geosites with a variable natural interest and scientific knowledge. Many geosites required additional scientific studies. The low potential use suggests the implementation of the geosites into the UGGp development should be encouraged through the promotion of geosites, the improvement of their visitability (mainly accessibility and viewing), and the provision of new local services and outdoor activities in their surroundings by local enterprises.

In conclusion, density functions constitute a useful tool to display visually and make easier interpretations of the geosite quantitative assessment. The density curves also represent the global state of the local geoheritage and its implementation in the performance of the UGGp.
Evaluating Landuse Changes due to Anthropogenic Activities in Highly Urbanized Flood Plain of Prayagraj city, Uttar Pradesh India
Authors: Raje Mukta
Published: June 2022

Evaluation of Changes in landuse due to anthropogenic activities in highly urbanized flood plain of Prayagraj city, Uttar Pradesh, India

                                                                                                                  Dr Mukta Raje – Associate Professor , SPG college Mihrawan,  Jaunpur, Uttar Pradesh , India

 

 

Urban settlement along the river Ganga with in Prayagraj city is prevalent since ancient time. Present scenario,both natural landscape as well as cultural settlement are the consequence of centuries long anthropogenic activities. Present study aims to understand the trend in landuse changes from 2000 to 2020 in this highly urbanized flood plain and its relation to geomorphology and anthropogenic activities. The  study adopts a relatively new approach to identify site specific condition for characterizing the landuse changes over a certain region of Ganga Yamuna Doab. The study indicates the best possible landuse conditions for better management and reduction in geo hydrological risk by suggested preventive measures. The research also indicates many landuse variations caused by socio-economic changes.

 
Assessing exposure changes to landsliding in Lisbon Metropolitan Area
Authors: Melo Raquel , Zêzere José Luís , Oliveira Sérgio C. , Garcia Ricardo A. C. , Oliveira Sandra
Published: June 2022

The Lisbon Metropolitan Area (LMA) is a Portuguese administrative region that encompasses 18 municipalities and is characterized by a high risk of landsliding as a consequence of the high susceptibility and exposure of people and assets. Therefore, this work aimed to assess the evolution of exposure levels to landsliding in each municipality of LMA, based on three timesteps (1995, 2011 and 2018), through the following summarized steps: 1) Landslide susceptibility modelling for LMA using an inventory that contains 1268 landslides, mostly rotational and translational slides; 2) Assessment of the relationship between the number of existing buildings and the urban area represented in the official land use map in 2011; 3) Assessment of the population exposed to landslides in 2011 (using Census data) within and outside the urban areas, based on the dasymetric distribution approach; 4) Backward and forward projection of population exposure to landsliding in the years of 1995 and 2018, for which official land use maps are available. Projections are based on relations found in 2) and 3). Overall, the results show that population exposure to landsliding has increased over time in LMA, but differently depending on the municipality considered. The relations found allow to estimate future population and assets exposure based on scenarios of urban expansion and population growth.

S.C. Oliveira was financed by the Portuguese Foundation for Science and Technology, I.P., under the framework of the project BeSafeSlide Landslide Early Warning soft technology prototype to improve community resilience and adaptation to environmental change (PTDC/GES-AMB/30052/2017). Ricardo A. C. Garcia was financed by the project Riskcoast - Development of tools to prevent and manage geological risks on the coast linked to climate change (SOE3/P4/EO868, Interreg Sudoe). CEG Research Unit UID/GEO/00295/2019.
The heterogeneity of the hydromorphological responses of a small peri-urban river to the urbanization of its basin
Authors: de milleville lucile , gob frederic , lespez laurent , tales evelyne
Published: June 2022

For several millennia, large growing cities, like Paris in France, had transformed and ultimately altered the hydro-bio-morphological functioning of rivers that flow through them and drain their peri-urban neighborhoods. Consequently, those rivers, particularly the smaller ones, were completely disregarded, considered as part of the sewer system or feared because of the risk of flooding. Nowadays, the way these urban and peri-urban rivers are seen by the local populations and river managers are changing because of the European politics of ecological restauration of rivers coupled to the increasing demand of nature in the city. Within the Parisian metropolis territory more and more streams regain a place in the urban project, generally through projects of ecological restoration. Unfortunately, these restoration projects are often difficult to build and not always efficient because of the very strong urban constraints but also because of the lack of knowledge on the functioning of these small rivers. If the hydrological changes, the modifications in sedimentary dynamics, and in-bed geometry consequent to urbanization have been well described, the general heterogeneity of river responses makes it difficult to understand the whole picture of the river system and therefore to plan its restoration.

In this study of a small peri-urban river from the Parisian agglomeration, the river Morbras, we propose on one hand, to characterize the longitudinal geomorphological variations in the channel and identify river responses of urbanization and, on the other hand, to reconstruct the hydro-morphological trajectory that led to this present situation and explain the heterogeneity.

The Morbras is a gravel bed river, 17.7km long, 6.4m wide, with a slope of 0.5%. Our results showed an average incision of 0.5m (locally over 1m), an average widening of nearly 1m (locally over 3m), and heterogeneous distribution of riffle-pool sequences. Systematic analysis of within-channel forms revealed high morphological diversity, the absence of a linear relationship between the rate of urbanization and incision/erosion, and the absence of longitudinal changes in response to urbanization. This may be explained by the history of the river and by its successive transformations that accompanied the multiphase transition of the catchment from fully rural to highly populated peri-urban. In particular direct intervention in the bed, initially for the creation of ponds, later for the installation of mills and more recently river management for flood mitigation or even old style river restoration.
Volcanic geomorphosites assessment in North Lisbon region
Authors: Costa Fernando , Alves Silva António , Fonseco Madalena
Published: June 2022

The main goal of this work is to present the first systematic inventory and scientific assessment of the geomorphosites related with the Lisbon Volcanic Complex (CVL). This geologic unit of the Upper Cretaceous, Campanian (70 to 72,6+/- 3,1 Ma) (Ferreira e Macedo, 1979), is an heritage of magmatic activity related to North Atlantic opening. The CVL covers about 150 km2 of the 9 North Lisbon region municipalities. Basalt represent 70% of the rocks of the CVL, showing the predominance of an effusive activity and a subaerial volcanism. This geological complex feature also includes other types of volcanic rocks, such as rhyolite or trachyte, or even some interspersed sedimentary rocks.

The most visible impacts on the landscape of the volcanic activity on North Lisbon region are a few traces of cones, large extensions of lava flows and pyroclastic materials, and local structures such as chimneys, necks, dykes and sills. Volcanic cones are heavily eroded however their dominant elevation remains partly preserved by compact basaltic chimneys or necks.

Some of major cones, by their panoramic views, coupled to some particular lavic features, as columnar disjunction in hexagonal prisms, are the most relevant volcanic geotouristic attractions of the North Lisbon region, by its scientific, cultural/historical, scenic/aesthetic and social/economic values, due to human perception of geomorphological landforms and processes.

A selection, fundamental description, scientific assessment and mapping of main geomorphosites, will be carried out, as a contribution to publicize the single volcanic region in Continental Portugal, in order to reduce its vulnerability, preserving this geoheritage from destructive anthropic actions. In addition, it will be suggested geotrails between geomorphosites and will be proposed instructive-educational panels, to inform about the natural processes and mechanisms that originated these volcanic landscapes.

The geomorphosites, with a recognized scientific and didactic values, include single places and areas, where volcanic rocks and structures encompasses a considerable extension, and also panoramic viewpoints, particularly the dominants volcanic cones from where a great variety of regional landforms can be observed. Also additional values, namely cultural material or immaterial and religious features, are coupled to some of these geomorphosites, particularly to the dominant landforms.

Key words: Volcanic landforms, geomorphosites assessment, landscape conservation, North Lisbon region, Portugal
Chronology and dynamics of fluvial style transformation in theYounger Dryas – Holocene transition (lower San River, SEPoland)
Authors: Gębica Piotr , Michno2, Anna , Sobucki Mateusz , Wacnik Agnieszka , Superson Sławomir
Published: June 2022

Reconstruction of fluvial style changes in the San River in the Subcarpathian Basins is based on
geomorphological and sedimentological analyses. The time control of alluvial fills and temporal
changes in the river channel are derived from radiocarbon and optically stimulated luminescence
dating combined with independent pollen-based biochronostratigraphy. The results showed that the
alluvial plain of the braided (BR) or braided-meandering (BR-M?) river was abandoned before
12,800 cal BP. Large meanders (LM) were cut off in the older part of the Younger Dryas (YD; ca.
12,600 cal BP), and in the younger part of this period (ca. 12,450 cal BP). The small meanders (SM)
developed at the end of the YD and were abandoned at the onset of the Preboreal (PB; ca.11,550
cal BP). The erosion phase at the YD-PB transition, reported from many valleys in Central Europe,
was not confirmed in the study area. The full cycle of San River channel transformation (BR (BRM?)->
LM->SM); was estimated to be approximately 1200 years. According to the palynological data,
open pine forests with birch that survived from the end of the Allerød dominated the landscape of
the river valley during the YD cooling and did not undergo major changes during the warming in the
early PB. Therefore, we assume that the influence of vegetation changes in the San River channel
pattern transformation was nonsignificant. The location of the studied palaeochannels in the
floodbasin filled with silty clayey deposits may have influenced the formation of relatively narrow
and deep channels, than that of much the wider and shallower meanders from the YD, situated
several kilometres downstream of the surveyed sites.
Morphological and hydraulic response of the braided-wandering river to human intervention (the case study of the Belá River, Slovak Carpathians)
Authors: Kidová Anna , Radecki-Pawlik Artur , Rusnák Miloš , Plesiński Karol
Published: June 2022

The contribution evaluates the impact of river training works designed to address problems associated with flooding on the braided-wandering Belá River in Slovakian Carpathians. This impact was investigated after the flood event in July 2018 on 11 river reaches where the river engineering and management intervention was applied. We analyzed its impact by spatio-temporal variations in river morphology (12 channel parameters) and changes in cross-section and hydraulic parameters (flow velocity, shear stress, stream power, W/D ratio) between pre- and post-flood management periods. The research hypotheses related to decreasing geodiversity in managed river reaches, a rapid increase in flow velocity during an extreme flood in river reaches where there is no sufficient floodplain inundation due to artificially high banks built by river training works, and increasing erosive force in the channel zone thanks to river management intervention were confirmed. The intervention in the braidplain area of the Belá River resulted in an undesirable simplification of the river pattern, loss of geomorphic diversity, loss of channel–floodplain connectivity, and disturbance and restraint of hydromorphological continuity. Identification of main conflicts of the Belá River management is important for clarifying the different approaches of stakeholders in the study area and aims to provide an objective illustration of their consequences. The presented analyses could help in future management issues as well as in the more critical decision-making process in vulnerable and rare braided river systems on the present when we are losing so many natural rivers by human decisions. This research was supported by the Science Grant Agency (VEGA) of the Ministry of Education of the Slovak Republic and the Slovak Academy of Sciences (02/0086/21).
Weirs effects on the sediment continuity of two lowland rivers (Orne et Vire rivers, France) : implications for river restoration.
Authors: Rollet Anne-Julia , Reulier Romain , Fantino Guillaume , Dufour Simon , Glais Arthur
Published: June 2022

In the search for good ecological status of watercourses, the restoration of sediment transport is today the subject of particular attention. The removal of transverse structures (weirs, dams) is often advocated, even though the real effect of small weirs on the transport of the bed load has not been demonstrated in all types of context (particularly medium and low energy rivers). This paper will present the results of a study on two highly anthropised rivers in Normandy (Vire and Orne Rivers, N-W France) to (I) document the real effect of weirs on the dynamics of coarse sediment transfers (> coarse gravel), (II) quantify the morphological effect of this interruption on the morphology/granularity of the channel, and (III) discuss the relevance of the removal of these structures for the restoration of sediment continuity in these systems. To this end, an annual sediment tracing system (848 RFID tracers) was set up in 2017 upstream of 6 structures of different types (micro-power stations, weirs, breached weirs) as well as on two recently restored sites in order to test different configurations. These tracers were placed in transects perpendicular to the flow, at different levels in the reservoirs in order to understand in detail the contribution of the water bodies and the structures as such in the modification of the mobility of coarse sediments. This monitoring was completed by measurements of morphological parameters (granulometry and geometry) upstream and downstream of these structures as well as by bathymetric measurements in the reservoirs in order to determine their filling levels. We were thus able to highlight the existence of coarse sediment mobility between structures despite modest powers (< 30 W.m²) as well as the significant effect of the hydraulic slowing of the reservoirs on the mobility of coarse sediments, regardless of the size of the structure considered. Since 2017, no tracer has been able to pass unrestored structures, which leads us to believe that these structures really affect sediment dynamics. Nevertheless, this sediment load interruption does not seem to induce any morphological adjustment downstream. These results thus question the interest of structure removal operations for the physical restoration of rivers in which the importance of solid flow seems to be a secondary control factor.
On the evolutionary patterns of the large river deltas. Examples from Danube delta and other deltaic systems
Authors: Vespremeanu-Stroe Alfred , Berbecariu Alexandru , Zăinescu Florin , Tătui Florin , Preoteasa Luminița , Anthony Edward
Published: June 2022

Large river deltas are the among the most dynamic and complex natural systems, with a  complicated evolution which explain the relative small number of deltas which formation has been fully understood (reconstructed). However, deltas evolution is governed by a series of laws and patterns starting from their formation to the present. The aim of this study is to define the specific growth models of the Danube Delta and to discuss them in association with the other deltas of the world which share similar patterns of evolution. Thus, 7 evolutionary patterns have been identified in the Danube Delta as follows: (i) starting the deltaic units formation (as a bayhead delta around 7500 BP) before the sea-level stabilization, (ii) the preference of delta development into the deeper sectors (of the Danube bay), (iii) the river mouths of the open-coast lobes get a policyclic evolution, (iv) open-coast lobes are asymmetric and share the same evolution, (v) deltaic lobes have large (multi-secular) periods of decay despite the short-time triggering events (i.e. avulsions, sediment reduction), (vi) neotectonic subsidence reshaped the southern delta, (vii) the land-use controls the sediments discharge and impose the rhythms of delta development. Although each delta has its own particularities, certain patterns that are found in the evolution of the Danube Delta have also been found in other deltas, apparently different from the morphological point of view. The specific cases of the large Asian deltas (e.g.: Changjiang, Mekong, Godavari, Krishna, Red River) and many other from around the world (Mississippi, Rhone, Po, Kuban, Rioni) are discussed in relation with different evolutionary patterns identified for Danube. A special attention is paid to the role of human influence (via deforestation, agricultural practices, river damming and channeling) on delta formation and evolution during different historical periods, from Neolithic to modern times.
Assessment of current and future soil erosion risk in Romania
Authors: Patriche Cristian Valeriu , Bogdan Rosca , Pirnau Radu Gabriel , Vasiliniuc Ionut
Published: June 2022

Our study attempts to estimate current and future rill and interrill soil erosion in Romania using RUSLE model in GIS environment. We used the 25 x 25 m resolution EUDEM to derive terrain slope, while the SAGA GIS software was used to derive the slope and slope length (LS) factor. The rainfall erosivity (R) factor was extracted from RUSLE2015 European soil erosion model.  For the computation of the crop and crop management (C) factor we used detailed crop information for arable lands for the year 2021. Soil erodibility (K) factor was computed in four different manners. Therefore, four spatial models of soil erosion were achieved and the optimum one was selected by correlations of estimated erosion with measured erosion values for several locations throughout the country. To estimate the possible future changes in soil erosion rates due to climate change, we extracted monthly rainfall data from CHESLA database for the Romanian territory for two climate change scenarios (RCP 4.5 and 8.5) and two time periods (2014-2060 and 2061-2080) and computed the modified Fournier index. A statistical relationship between rainfall erosivity and the current modified Fournier index was computed and then applied to future Fournier index values in order to estimate future rainfall erosivity values. Our results show that rainfall erosivity is likely to enhance during the 2041-2060 period, especially in the western, south-western and eastern part of the country, causing a corresponding increase in soil erosion rates with 1-2 t ha-1 yr-1 on average. During the 2061-2080 period, rainfall erosivity is likely to decrease in the central and eastern Romania.
Late Quaternary Evolution of an Iconic Braided Stream: Dating the Alluvial Fill of the Platte River, Nebraska, USA
Authors: Hanson Paul R. , Reinier Clayton , Joeckel Robert , Bruihler Jacob , Young Aaron
Published: June 2022

Despite the prominence of the Platte River in the literature on fluvial sedimentology, its alluvial history has not been well documented. We have studied the Platte’s alluvial fill to understand how the river system responded to climate changes over the last glacial-interglacial cycle. Geoprobe cores from multiple locations along the river’s valley in Nebraska demonstrate that the fill is dominated by sand and gravelly sand, and that deposits of silty clay through silty sand are minor components. We also generated an alluvial chronology using luminescence dating methods on sand samples collected from depths of up to 15 m below the present floodplain. Our results demonstrate that sediments dating to Oxygen Isotope Stages 2 and 3 lie at depths of 2–15 m below the present floodplain, and that portions of the upper 5–8 m of the alluvial fill dates to the Holocene. We hypothesize that: (1) the Platte River aggraded during the late Pleistocene, and (2) the upper portions of these Pleistocene sediments were reworked as the river locally entrenched into those older sediments during the Holocene. Late Pleistocene valley aggradation was likely related to increases in sediment availability in the Rocky Mountain headwaters, as well as sediment influx from local landscapes in Nebraska. 
Geodiversity and Geoheritage value of balanced and pedestal rocks in South America
Authors: Rabassa Jorge , Ollier Cliff , Ladeira Francisco
Published: June 2022

ABSTRACT

According to the Glossary of Geology “a balanced rock is a large rock resting more or less precariously on its base formed by weathering and erosion in place.” Popular usage extends a bit further, so balanced rocks come in many forms and have many names, quite apart from specific local names.

According to the Glossary of Geology a pedestal rock is “an isolated residual or erosional mass of rock supported by or balanced on a pedestal. The term is also applied to the entire feature.”

To the layman balanced rocks are amongst the most spectacular and intriguing of landforms, with a scientific and social significance much greater than their scarcity might suggest. Several quite different processes can produce balanced rocks, including differential erosion, surface weathering, deep weathering and stripping, induced tensional fracture, and marine erosion. Many attract tourists so have commercial as well as aesthetic and cultural value, and so feature in Geoheritage and Geotourism issues. Problems of balanced rocks include vandalism and the relatively modern practice of artificial rock stacking.

Most people are intrigued by balanced rocks, in which a huge rock appears to be balanced on underlying rocks, and often wonder “How did that rock get up there”.  They may acquire legends, and mythical explanations of their origin. People may come from far away to see them, and some develop a lucrative tourist trade. This may grow until management issues arise. Here we provide a scientific explanation of how balancing rocks are formed, and also discuss some of the management and social problems that they may create.

Spectacular examples of balanced rocks are frequently found in different environments in South America, particularly in cratonic areas, and some of them are presented in this paper.

 
Subglacial carbonate deposits - a new source for studying the presence of glaciers in a glaciokarstic environment
Authors: Zorn Matija , Lipar Matej , Ferk Mateja , Cof Klemen , Čretnik Janko
Published: June 2022

Subglacial carbonate deposits have been exposed on the lee sides of small protuberances on a bare polished and striated limestone bedrock surface in the immediate vicinity of the disappearing small glaciers in the south-eastern Alps (N Slovenia and NE Italy). The uranium-thorium dating of these carbonates indicates that they were deposited during the Last Glacial Maximum (LGM) and Younger Dryas (YD). The small glaciers in the Slovenian Alps (i.e., the Triglav and Skuta glaciers) are generally considered relicts of the Little Ice Age that were not continuously present due to the warm Holocene Climatic Optimum (HCO). If these glaciers had completely melted during the HCO, the the subglacial carbonates of the LGM and YD would have been exposed to frost weathering and would have had little chance of being preserved to the present day. While it has been postulated that subglacial carbonates are not very resistant to such weathering, no direct data have been available to date. Therefore, the objective of our study was to determine the rate of freeze-thaw weathering of subglacial carbonate deposits. Freeze-thaw analysis was performed in a controlled freeze-thaw chamber under dry and wet conditions. Preliminary results after 56 freeze-thaw cycles indicate an average mass loss of 2.13%. According to the high-altitude meteorological station adjacent to the Triglav Glacier, there is an average of 19 freeze and thaw cycles per year when there is no snow cover, indicating an average mass loss of 0.73% per year and a total mass loss in about 2000 years. These laboratory results suggest that the subglacial carbonates would likely have weathered in the absence of glaciers during the HCO and thus can be considered indicative of the recently exposed ice- or glacier-free surface for the first time since their deposition.
Landscape analysis based on soil color in the windward slope of the Baturité Massif, northeastern Brazil
Authors: Silva Neto Jose Osmar , Freitas Soares Larisse , Pinto Vidal de Oliveira Vládia , Sabrina Vidal de Souza Anna
Published: June 2022

The Baturité Massif is located in northern Ceará state (Northeast Brazil) and is the most humid mountain range of the state, with an average annual rainfall of 1500mm. The predominant lithostratigraphic unities are composed of gneisses, schists, quartzites, amphibolites, and other calcium-silicate rocks. The mountainous relief reaches 800-900 m a.s.l on the central region of the massif, which stands out by steep and winding slopes in contrast with vast flattened surfaces of 100 - 200 meters a.s.l. Based on previous studies in the area, this research aimed to analyze the correlation between the coloration of the Lixisols - the most common type of soil in the region, and the changes in size and density of the vegetation, featuring a tropical evergreen forest at the highest altitudes and a tropical semideciduous forest at low altitudes. In order to identify variations in soil color, a morphopedological analysis was carried out through toposequence in the municipality of Pacoti, located at the windward slope of the Baturité massif. Samples were collected in 6 soil profiles, with altitudes ranging from 300 to 950 meters. The determination of coloration was executed with the wet samples, using the Munsell chart and from the collected values, the soil redness index (RI) was calculated using the following equation: RI= ((10- M) × C)/V; M = hue (7.5R = 0; 10R = 1; 2.5YR = 2; 5YR = 3; 7.5YR = 4; 10YR = 5; 2.5YR = 6); V = value; C = chroma. Profile 1 (960 meters) presented low-density vegetation of arboreous size, with low RI on both superficial and sub superficial soil horizons. At intermediate altitudes (>400m and <600m), the soil profiles 2, 5 and M, presented vegetation in a climax state with low RI values on superficial horizons but high RI values on sub superficial horizons. On the other hand, at the lower altitude region (<400m), soil profiles 3 and 4 presented quite the opposite, with high RI values on the superficial horizons and low RI values at the sub superficial ones, the vegetation in this area was shrubby and with a high density of individuals. Thus, it is assumed that there is a direct correlation between reddening indexes, topography, and state of vegetational development of the landscape
Glacial evolution of La Seara Valley (Courel Mountains, NW Spain) based on 36Cl Cosmic-Ray Exposure dating
Authors: González Díaz Benjamín , Pérez-Alberti Augusto , Ruiz-Fernández Jesús , Rinterknecht Vincent , Rodríguez-Rodríguez Laura , García-Hernández Cristina , Team Aster
Published: June 2022

The glacial history of the Iberian Peninsula, both glacial landforms and associated deposits, as well as the geochronology framework of the successive glacial stages within the Last Glaciation (LG), is now better understood. In turn, there is a growing body of evidence on glacial stages prior to LG. The increased use of absolute dating techniques has made these advances possible. However, some issues should be addressed to fully understand the extent and significance of past glacial processes in the Iberian Mountains. Those areas that were marginally affected by the ice during the LG (that is, located in low or moderate altitude sectors) remain unexamined in depth, with few geochronological contributions. These are more distant areas and often far from the main research focus. Moreover, the finding of glacial evidence (generally scarcer) is hindered by a dense vegetation cover. This is the case of A Seara Valley (Courel Mountains), located in the NW edge of the Iberian Peninsula, where several boulders and erosion surfaces of glacial origin were sampled for 36Cl Cosmic-Ray Exposure (CRE) dating. Nine samples were collected during the spring2019 fieldwork campaign. Additionally, the paleoglacier was reconstructed and the associated landforms were mapped. Sampling strategy was challenging because only few moraines are well-preserved, and suitable boulders for CRE dating are scarce due to the predominant outcropping of slates. Only one moraine ridge was located at the bottom of A Seara Valley (1113 m a.s.l.), in which seven samples were collected. It is a polygenic moraine, dismantled by postglacial processes. Besides, the discrepant ages obtained in some boulders show that they were probably covered by sediments. The oldest geochronological data indicates that, at least, the glacier connected with this moraine at 21 ka (MIS-2). Additionally, two samples were collected on a glacial polished threshold located in an intermediate sector of the valley, at 1243 m a.s.l. Here, the result of 19 ka points to an accelerated retreat of this glacier to its headwater (as in other glaciated areas of NW Spain), i.e., a very quick deglaciation process.

 

Acknowledgments:

Benjamín González Díaz appreciates the support of the Spanish FPU program (reference: FPU19/06583). This contribution studies the research topics addressed in the project FUO-19-112 (Courel Mountains UNESCO Global Geopark; Ribeira Sacra-Courel Local Action Group, LEADER Program of the European Union).
Buried by lake sediments, revealed by deflation: the MSA of Makgadikgadi, central southern Africa
Authors: Thomas David , Burrough Sallie L. , Coulson Sheila , Mothulatshipi Sarah , Nash David J. , Staurset Sigrid
Published: June 2022

Central southern Africa is often viewed as an archaeological void, especially when compared to the continent’s heavily researched coastal regions. This is in part due to its geomorphological context: the Kalahari basin is a flat depositional void with few archaeological sites due to limited traditionally-favoured preservation contexts. Yet recently, the Kalahari’s Makgadikgadi mega-palaeolake basin has been controversially proposed, through DNA research, as the ‘ancestral homeland’ of modern humans, prior to MSA dispersal c130k yr ago, with only small residual populations remaining thereafter (Chan et al., 2019), despite the absence of supporting archaeological data.

Rather than being archaeologically-sterile, we provide new data from four field seasons that demonstrate the richness (hundreds) of MSA sites in the Makgadikgadi basin, their unique context on the palaeolake floor, and the significance of geomorphological processes in explaining their location, high preservation quality, and modern exposure at the surface. Six sites have been excavated, including extensive undisturbed silcrete MSA lithic spreads. One can be dated to within 81-68 ka, another occurred after 57ka, both resting on, and then buried by, OSL-dated palaeolake sediments derived from high lake stands. Human use of the basin floor occurring during low, or seasonally dry, phase of the basin’s complex hydrological history. Sites are being exposed at the surface of today’s dry basin through processes of aeolian deflation, removing ancient lake sediments from one of Africa’s major atmospheric dust sources.

Our work shows that without a clear understanding of Makgadikgadi’s geomorphological history, and of the processes operating in the system, it is difficult to appropriately explain the preservation and quality of the MSA sites in the basin. Our work shows a more complex environmental dynamic, and likely a more complex early human history, that previous research has suggested.

Reference: Chan EKF et al 2019 ‘Human origins in a southern African palaeo-wetland and first migrations’. Nature 575, 185-189
Downstream fining of bar sediments in a meandering river: variations and influence of lateral inputs in the upper Odra River
Authors: Vaverka Lukáš , Holušová Adriana , Poledniková Zuzana , Galia Tomáš
Published: June 2022

From a general point of view, river sediment is gradually fining the downstream direction, which is mainly a product of abrasion and selective transport. Downstream fining is not constant, and certain disturbances, such as sediment supply from tributaries or erosion connected with lateral and vertical shifts in the channel, can abruptly change sediment size. The main goal of this case study is to analyse discontinuities in the downstream fining of sediment size and link these variations with possible sources, i.e., lateral inputs. We focussed on the 75-km-long Odra (Oder) River reach in Czechia. The Odra is a relatively preserved meandering river with dominant gravel sediments. The supply of sediments is realised from two contrast geologically distinct mountain ranges, namely the Nízký Jeseník Mts. (generally offals and slates) in the Bohemian Massif and the Moravskoslezské Beskydy Mts. (flysch-based) in the Outer Western Carpathians. Analysis of the surface layer of 15 gravel bars was performed by the Wolman method, by which we randomly measured 100 clasts on each gravel bar. Additionally, we collected subsurface samples for sieving analysis. In the composition of the subsurface samples, there were dominant gravels and sandy gravels. Only four sites were muddy sandy gravels, which may be caused by the predominant slow flow in that part of the Odra River reach. The data of the coarse-grained material (≥ 2 mm) from the surface layer showed downstream fining only in the approx. first third of the river reach (27 km). The downstream part of the reach did not show significant fining, but rather a gradual increase in grain size of the surface bar layers. The most apparent fluctuation in grain size showed the 25th and 75th percentiles (14 - 29 mm and 25 - 42 mm, respectively), while the median indicated lesser variations. The discontinuity in fining can generally be linked to the influence of tributaries that carry coarse gravel from mountainous areas, but in this case the samples near tributaries do not show abrupt changes in sediment calibre. It is reasonable to assume that the coarse sediment was supplied to the river by lateral erosion of alluvial deposits in active meander bends, as indicated by the presence of coarse gravels in the architecture of the eroded alluvium.
Virtual velocity of fluvial sediment using mine tailings as a tracer in a gravel-sand bed river in the Ozark Highlands (USA)
Authors: Pavlowsky Robert , Lecce Scott
Published: June 2022

Mine tailings released to the environment by historical lead mining were used as tracers to assess bed sediment dispersal rates in Big River (2,500 km2) in the Ozark Highlands of southeast Missouri, USA.  Large quantities of dolomitic sand and fine gravel particles were released to the main channel at known source points between 1900 and 1935.  High resolution channel bed sediment sampling was used to quantify downstream patterns of sediment storage, grain size distributions, tailings abundance by grain counting, and geochemical signatures of finer particles.  As expected, tailings particles are sorted longitudinally according to particle size with finer sediments being dispersed farther downstream. Maximum virtual velocities of sediment transport decreased with grain size in the following order: 490 m/yr, 1-2 mm; 400 m/yr, 2-4 mm; 330 m/yr, 4-8 mm; and 230 m/yr, 8-16 mm.  Average velocities are typically half those of the maximum values. These results suggest that gravel budgets and sediment waves in the main channel may be more sensitive to local variations in sediment storage and reworking than by delivery of sediment from upstream tributaries.
Assessment of Increased Debris Flow Hazard After Wildfires: Lessons from the Dalaman Fire, Eastern Mediterranean, Turkey
Authors: Gorum Tolga , Yildiz Cihan , Ozcan Orkan , Comert Resul , Yetemen Omer
Published: June 2022

Wildfires have a long history in the Mediterranean and Atlantic coastal regions, and such devastating events are anticipated to increase in parallel with changing climatic conditions. Wildfires play an important role in short-term ecological and geomorphological changes, as they can instantly affect vegetation, soil properties, and drainage properties. In comparison to unburned conditions, wildfire alters the erosional response of hillslopes, increasing the potential for runoff and sediment flux, as reported in many studies. Specifically, wildfire-affected steep hillslopes can promote the initiation of debris flows which may cause substantial sediment delivery and increase hazard levels for society and infrastructure downstream of burned areas.

In this study, we report the erosional response of hillslopes and spatial probability debris flows after the July 10, 2019, Dalaman, Göcek (Muğla) wildfire, which was effective in a total of 15 km2 forested area. We used different ground and remote sensing methods covering two years of field observation and measurements from shortly after the event. In our study, in which we compared the results obtained by conventional field-based assessments with Unmanned Aerial Vehicle (UAV) measurements, we quantified that the erosion is localized spatially in the middle and upper parts of the basins and led to an average erosion rate of more than 10 mm in two years. In addition, we revealed that the susceptibility of the debris flows after the fire has increased significantly, primarily concentrated in the far north of the fire-affected hillslope sections. We concluded that the spatial probability of debris-flow events and their runouts would increase their impacts by significantly affecting the excavation of hillslope materials, mainly boosted by salvage logging after the event. Moreover, our preliminary findings show that accurate estimates of the magnitude of post-wildfire debris flow and erosion potential are essential to comprehend immediate hazards as well as long-term geomorphic changes.

This study has been produced benefiting from the 2232 International Fellowship for Outstanding Researchers Program of the Scientific and Technological Research Council of Turkey (TUBITAK) through grant 118C329. The financial support received from TUBITAK does not mean that the content of the publication is approved in a scientific sense by TUBITAK.
The role of extreme events and human activities in the transformation of the Himalayan river corridor (Darjeeling Himalayas, India)
Authors: Prokop Pawel
Published: June 2022

River corridor dynamics reflect nature-human interactions with respect to geomorphic process and form or ecological function and structure. The aim of this study was to investigate the role of extreme rainfall, flooding and anthropogenic impacts in the transformation of the Himalayan river corridor. The research was conducted in the mountain part of the Teesta River with catchment of about 8000 km2 located in the Sikkim-Darjeeling Himalayas. The Teesta River originates from the glaciers in the northern Sikkim. Cutting schists and gneisses through the Darjeeling Himalayas the river flows into the Brahmaputra as its largest right-bank tributary in India and Bangladesh. The annual rainfall in the Darjeeling Himalayas ranges from 2000 to 4000 mm and monthly discharge of the Teesta River ranges from 150 to 1500 m3/s during the winter and monsoon seasons, respectively. On 3-5 October 1968, heavy rains of over 750 mm caused an extreme discharge of 17,000 m3/s and triggered extensive landslides. The water level rose by over 20 m, the highest level for any river in India in the last 70 years. The extreme flooding caused aggradation of the riverbed to 5-7 m. Between 1999 and 2016 four high dams were constructed in the mountain part of the Teesta catchment. The planned construction of further dams means that the catchment would have one of the highest average dam densities in the world.

The analysis focused on 28 km long and 600 wide river corridor with two high dams between the Rangit tributary and the Teesta outlet from the Darjeeling Himalayas. The active channel and land use were mapped using Corona program, SPOT and GoogleEarth satellite imagery every 5 years between 1965 and 2010. For hydrological analyses, daily rainfall from Kalimpong station, annual maximum and minimum water levels as well as discharges from two gauge stations located at the beginning and end of the Teesta corridor were used. The data were supplemented by own observations and measurements of profiles across the river at water gauge locations.

The results indicate that before the construction of the dams, specific stream power above 300 W/m2, capable of transforming the channel, was observed at the outlet of the Teesta from the Himalayas once every four years. The enlargement of the active channel after the 1968 flood, which took several years, was similar to its permanent enlargement as a result of the construction of two dams after 2010. The greatest landslide activity was the result of high rainfall and floods, while the creation of reservoirs contributed only marginally to landslide activation. Forest, which dominates the land use pattern in the Teesta corridor (72% in 1965), decreased by 10% up to 2020 as a result of extreme flooding, development of built-up areas and water inundation after reservoirs creation.