bluuebunny/crossref_metadata_2025 huggingface dataset:
Geoarchaeology of the alluvial plain deposits at Entrecampos, Lisboa: first insights for a stratigraphic reconstruction 
Authors: Almeida Luís , Zambaldi Maurizio , Gameiro Cristina , Leónidas João , Antunes Nelson , Nogueira Natacha , Neto Nuno
Published: June 2022

In the framework of a preventive archaeological excavation at the Unidade de Execução de Entrecampos - Parcela A (UEE-PA) in central Lisbon, Portugal, a sedimentary succession preserving evidence ranging from Prehistory to the 20th century was unearthed. In order to better understand the site stratigraphy, two trenches (N-S/E-W) of about 40 m long and 5.50 m deep were opened in February 2022 by mechanical means allowing us to identify a sedimentary succession ranging from the Miocene bedrock to Holocene deposits.  Considering the importance of this stratification and its almost unique state of preservation for the city, we decided to follow a broad geoarchaeological approach, including geomorphological, sedimentological and lithic techno-typological analyses, as well as radiocarbon and OSL dating. Here we present some preliminary data, while further microstratigraphic analysis and physical-chemical and mineralogical characterisation of the deposits (grain size analyses, pH and organic matter content, XRD of clays) are ongoing. The alluvial plain deposits at the UEE-PA at Entrecampos are framed in the upper basin of the Ribeira de Alcântara valley and are related to a branch of the hydrographic drainage network of the Lumiar and Campo Grande plateau, on the right bank of the Tagus River close to its Atlantic mouth; their geomorphological expression is evident in the smooth base profile and the quite large deposits resulting from the erosion and transport of tertiary bedrock softest formations. The infill and incision are presumably in accordance with the Quaternary fluvial model of the Lower Tagus River sedimentary record. At the site, the depositional dynamics consist of aggradation related to a high dynamic discharge recorded at the base of the alluvial deposits, with a progressive reduction of the transport flux capacity to the top, resulting in turn in a silty loam floodplain deposit. The latter preserves a consistent number of lithic artefacts at its base (Palaeolithic and/or Mesolithic), pointing to a late Pleistocene or early Holocene chronology. This situation suggests the occurrence of  subsequent intermittent depositions that marked the initial stage of the suspended watercourse load, followed by the activation of soil formation processes which slightly affected the underlying sandy deposits as well. Further investigation will provide an absolute chronology for the main depositional events and will therefore help to reach a better understanding of the local paleoenvironmental and geoarchaeological contexts during the Quaternary in a central area in Lisbon city.
Prediction of Rainfall Induced Landslides Using Machine Learning Models along Highway-Bandipora to Gurez Road, J&K, India
Authors: Nanda Dr. Aadil Manzoor , Ahmed Prof. Pervez , Kanth Prof. Tasawoor Ahmad
Published: June 2022

The present study endeavours to explore the efficacy of machine learning models in landslide predictions triggered by extreme rainfall events along Highway from Bandipora to Gurez, J&K, India. Random Forest (RF) and Logistic Regression (LR) Models were employed on account of their technical utility and logical procedure to transform the decision making into a series of algorithm steps that eventually culminate in low variance and minimum bias. The crux of these models was to find the optimal parameters for targeted feature i.e. landslide prediction. Hyper-parameter tuning was used to optimize the performance of the respective models. These models were evaluated for accuracy using the receiver operating characteristics, area under the curve (ROC-AUC) and false negative rate (FNR). When antecedent rainfall data is incorporated in the prediction models, both (LR and RF) performed better with an AUC of 0.825 and 0.843 respectively. The results reveal a positive correlation between antecedent precipitation and landslide occurrence rather than between single-day landslide and rainfall events. In case of FNR, LR and RF improved to14.32% and 15.92% respectively, when antecedent rainfall was included in the analysis. Comparing the two models, LR model’s performance is well within the acceptable limits of FNR and therefore could be preferred for landslide prediction and early warning over RF. LR model’s incorrect prediction rate is 8.48% without including antecedent precipitation data and 5.84% including antecedent precipitation data. Our study calls for wider use of Machinery Learning Models for developing early warning systems of landslides.

Keywords: -Rainfall Triggered; Machine Learning Models; Area Under Curve; False Negative Rate.
State of rock glaciers in the Rushan Range of Tajikistan, Western Pamir
Authors: Ma Qiqi , Oguchi Takashi
Published: June 2022

Rock glaciers are climatically more resistant than glaciers and contain valuable water volume equivalents. Rock glaciers are widespread in the Rushan Range of Tajikistan, Western Pamir, but have not been systematically investigated, and thus their climatical significance versus glaciers is unknown. Here we present the first systematic assessment of active and inactive rock glaciers of Rushan, based on the combination of SAR interferometry from Sentinel 1 and optical images from Google Earth, totaling more than 600 landforms with an area coverage of ~160 km2. Supported by ArcGIS, we extracted and calculated morphometric parameters of these rock glaciers, found that the distribution of rock glaciers in the western Rushan is significantly different from those located in the eastern part, and analyzed the lowest altitudinal limit for the presence of permafrost in Rushan Range from active rock glacier locations. This study provides an important dataset for understanding the sustainability of rock glaciers in Western Pamir. 
Advances in Nummerical dating for Reconstructing Coastal Environments from the German North Sea Coast and the Mediterranean Coast of Sardinia 
Authors: Frechen Manfred
Published: June 2022

Optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) methods using quartz and potassium-rich feldspar, respectively, have been successfully applied to deposits from a variety of different sedimentary environments to determine the time elapsed since the last exposure to sunlight. Coastal sediments including aeolian and shallow marine deposits have been proved to be excellent material for dating, because they fullfill the basic luminescence dating assumptions such as sufficient bleaching/zeroing prior to deposition. Furthermore, in combination with radiocarbon dating robust and reliable chronological frameworks have been provided.

In this paper, we present two luminescence dating case studies. The first one is about a sediment core including Holocene sediments from the German North Sea Coast, previously studied by Zhang et al. (2014) and extended by a sediment core from an inland barrier spit at Eiderstedt peninsula. The lithostratigraphic, sedimentological and chronological investigations yielded the following interpretation: The uppermost 1-2 meter of the sediments are of terrestrial origin and deposited after the construction of dykes along the coast during the 11th century. These results are in agreement with sedimentological and chronological results from two further localities in the vicinity of the key location. More than 20 m of shallow marine sediments are exposed including a marker horizon rich in shells and shell fragments giving evidence for the rapid Holocene sea-level rise and the arrival of the “sea” at around 8,300 Years BP at the locality under study. Wadden sediments, mud and sand flats sediments and beach wall or barriere spit sediments are typical for the Holocene sequence. A hiatus is found for the time period between 13,000 and 8,300 years BP. Last glacial deposits up to a depth of at least 70 m consist mainly of (reworked) aeolian and fluvial sediments.

The sediment successions along the coast of Sardinia provide important information about the Late Pleistocene – Holocene sea-level changes and sea-level elevations. However, the chronological results of different dating methods, such as OSL, IRSL, electron-spin resonance, radiocarbon, uranium/thorium and amino acid racemisation are not sound and have been a matter of debate for many years. We will discuss the reliability of the different dating methods and present new radiocarbon and luminescence dates as the second case study.

 

Zhang, J., Grube, A., Tsukamoto, S., Frechen, M. (2014): OSL and 14C chronologies of a Holocene sedimentary record (Garding-2 core) from the German North Sea coast.- Boreas, 43: 856-868.
Assessing sediment connectivity on agricultural hillslopes using sediment transport modeling and network analysis
Authors: Perez John Edward , Poeppl Ronald , Turnbull Laura , Wainwright John
Published: June 2022

Fine sediment input into river systems is an environmental challenge of increasing significance due to accelerating soil-erosion rates in agricultural catchment systems. Along with erosion, sediment transport within cultivated hillslopes determines the amount of material that can be delivered into river channels in such systems. To effectively manage this problem, it is necessary to identify sediment sources, sinks, and the pattern of linkages within and between different landscape compartments along sediment pathways. Sediment connectivity is an emerging concept that can help to address on- and off-site effects of soil erosion by describing the efficiency of fine sediment transfer through these different zones. Field assessments and process-based modeling has been typically used in quantitative soil erosion and connectivity investigations. However, a major advance in recent years has been the adoption of network analysis as an approach to quantify sediment connectivity. The aim of this study is to assess sediment connectivity in selected agricultural hillslopes of the Fugnitz Catchment (Austria) by combining sediment transport modeling and network analysis. Sediment transport was dynamically simulated using the process-based MAHLERAN model (Wainwright et al., 2008). Simulated results were then translated into an adjacency matrix and its corresponding network graph – composed of nodes and links that represent individual geomorphic units and the fluxes between them as connected through runoff and sediment pathways. Structural properties of the generated network were finally quantified using network-analysis tools in MATLAB. The results show different patterns of sediment pathways which exhibit greater propensity to deliver sediments. These insights can be used to designate connectivity hotspots where interventions may be targeted to mitigate on- and off-site impacts of soil erosion.
Detecting differential surface uplift at the orogen scale by topography and river network features: the Southern Apennines case study (Italy)
Authors: Valente Ettore , Cerrone Ciro , Ascione Alessandra
Published: June 2022

The growth of a mountain chain results from a complex interplay between endogenous and exogenous processes. The former depends on the geodynamic setting and cause the uplift of the orogenic wedge whereas the latter tend to erode the uplifted topography. Surface uplift may act at uneven temporal and spatial scale and reconstructing its distribution through space and time may provide fundamental data to unravel either the future tendency of geomorphic processes (e.g., increased erosion in uplifted areas) or to identify areas affected by active tectonics. In this study, we adopted a morphotectonic approach to unravel the spatial distribution of surface uplift in active orogens, such as the southern Apennines of Italy. Features of the topography (e.g., maximum, mean and minimum elevation maps, relief maps and swath profile) and the river network (e.g., river long profile and chi-long profile, Ksn index, chi index map) have been derived through ArcGis and Matlab softwares. The combined analysis of all indexes allows recognising a locus of enhanced surface uplift that moves from NE (the Bradanic foredeep) to the SW (the outer sector of the orogenic wedge). Surface uplift do not extend towards the inner sector of the orogenic wedge and its spatial distribution roughly follow the main divide. Furthermore, a natural tendency of the main divide to shift towards the NE has been also identified, that is consistent with the uneven spatial distribution of vertical motions. To quantify differences in surface uplift between the foredeep-outer chain and the inner chain, we analysed published data about MIS5 paleoshorelines. These data also confirmed the uneven distribution of surface uplift at the orogen scale, thus confirming that the adopted morphotectonic approach may be considered a powerful tool to constrain the spatial distribution of vertical motions.
Natural and mining legacies in Nalón river floodplain deposits (NW Iberian Peninsula)
Authors: Menendez-Duarte Rosana , Vazquez-Tarrio Daniel , Fernandez-Iglesias Elena , Tomillo Pelayo , Suarez-Ruiz Isabel , Rodriguez-Valdes Eduardo , Medialdea Alicia
Published: June 2022

Nalón River is one of the most important rivers draining the Northern watershed of Cantabrian Mountains (NW Iberian Peninsula). This drainage basin was subject to an intense coal mining activity during the 19th and 20th centuries. The resulting products of this mining activity (mainly those derived from coal washing) have been incorporated into the stratigraphic sequence of floodplains. This makes Nalón river a unique opportunity to study accretion rates in floodplains and to investigate the rate of sand sediment propagation and dispersion in gravel-bed rivers (two processes whose study is complex and elusive), as well as to study the spread of coal residues and other contaminants in the fluvial environment.
With these aims, we accomplished a stratigraphic survey of floodpain deposits in the lower alluvial plain of Nalón river. We identified a total number of 17 stratigraphic levels in a 3-m thick floodplain sequence. Some of these levels correspond to low-energy deposits (fine sand), while others correspond to high-stage flood deposits (very coarse sand and gravel), with abundant   sediment structures such as parallel lamination, cross-bedding and ripples. Samples taken from the floodplain sequence were prepared for grain-size analysis, organic petrography determinations (16 samples) and geochemical analysis (24 samples). Geochemical analysis measures the total concentrations for 63 elements by inductively coupled plasma-mass spectrometry (ICP-MS). ?). Additionally, we took 7 samples for luminescence (OSL) dating and one (small wood pieces) for 14C.
Coal is very abundant throughout the stratigraphic section, which suggests that sedimentation was simultaneous with the development of intensive mining that has developed in the last 150 years. On the other hand, there are several dams upstream the study section, the oldest one built in 1952. These dams have undoubtedly interrupted sediment continuity, so mining-derived sediments might not have represented a significant contribution to floodplain deposits after dam construction. However, the upper levels of the stratigraphic section contain abundant coal particles, which suggests that these levels pre-date dams (1952) or that the upper levels incorporated material derived from riverbed and bank erosion.
The objectives of this study are twofold: 1) to  analyse coal and  their associated  contaminants incorporated into fluvial sediments in the Nalón river; and 2) to reconstruct the sedimentary history of the alluvial plain, while exploring the use of coal and geochemical data as sediment markers.
Climatic Influence of chemical weathering on the particle size distribution of the slope soil layers in granitic bedrock areas
Authors: Oguchi Chiaki , Nakamura Konomi , Wakatsuki Tsuyoshi
Published: June 2022

Granitic rocks tend to turn into sandy sediment, grus, through weathering, which makes them prone to collapse even on relatively gentle slopes. Such weathering of rocks is broadly classified into chemical weathering and physical weathering, with chemical weathering dominant in warmer regions and physical weathering dominant in colder regions. Many weathering indices have already been proposed for chemical weathering, and it is possible to estimate the chemical weathering process by using these indices. However, it has not been clearly stated how the weathering process affects the properties of the weathering product, the sediment. Therefore, in this study, we examined the characteristics and regional characteristics of weathering of the soil layer, the collapse reserve material, by examining the relationship between grain size composition, the simplest physical property of the soil, and chemical weathering index values. The samples studied were weathered granite and granodiorite collected near the slip surfaces of slopes where slope failures have occurred in the past in several areas with different climates in Japan. First, each weathering index of CIA (Chemical Index of Alteration, Nesbitt and Young, 1982) and the Si/Al ratio (Marbut, 1935) were calculated based on chemical composition values. The percentage of clay and silt is analyzed and calculated by using Wentworth's (1922) scale. The relationship between CIA values and the clay-silt ratio is positive and proportional. A negative proportional relationship was obtained between Si/Al ratio and the clay-silt ratio. The relatively cold region is more affected by physical weathering than other regions, due to the smaller difference in chemical weathering index values between the surface soil and base rock and the higher percentage of coarse-grained weathering products.

 
Geomorphology and tsunamigenesis of blocky MTDs on collisional tectonic settings: Insights from Southwest Iberia and the Hikurangi Margin (New Zealand)
Authors: Gamboa Davide , Omira Rachid , Terrinha Pedro , Barnes Phil , Davidson Sam
Published: June 2022

Submarine mass-movements are a major hazard on continental margins, particularly on collisional tectonic settings where recurrent earthquakes may trigger catastrophic collapses. Associated mass-transport deposits (MTDs) are typically heterogeneous, often characterised by a mixture of allochthonous slope lithologies transported to the abyssal depths, being further mixed with autochthonous basin sediments. Examples of such complex MTDs on thrust-controlled slopes are the North Gorringe Avalanche on the flank of the Gorringe Ridge, located on the Southwest Iberian Margin (NE Atlantic), and the Ruatoria MTD on the Hikurangi Subduction Margin, offshore New Zealand. Both MTDs present morphological similarities, such as a large evacuation area with significant height differences (between 2500 m to 3000 m for both cases), numerous blocky debris still observable on the seafloor despite the post-collapse burial and marked deformation of basin sediments over large areas. With a volume of circa 4500 Km3 and covering 9850 km2, the Ruatoria is particularly impressive and comprises one of the largest MTDs in the world. A geomorphological analysis is complemented by models to assess the tsunamigenesis of such impressive collapses and the hazards for margins across the oceans where they occur.

This work is supported by FCT project MAGICLAND (ref: PTDC/CTA-GEO/30381/2017)
Reducing water related risks in the Lower Danube through Nature Based Solution implementation
Authors: Scrieciu Albert , Rotaru Sabin , Giordano Raffaele , Pagano Alessandro
Published: June 2022

The Lower Danube wetlands, one of the most important European wetland ecosystem, lost nearly 80% of its surface over the last century due to river dredging, land reclamation and flood control. Anthropic interventions along the Danube river water course, such as construction of the hydropower plants Iron Gates I and Iron Gates II and alterations along its banks, have generated high bank erosion processes as well as riverbed changes with negative impact on navigation. The negative effects induced by anthropic interventions coupled with climate change impact have intensified the flooding and drought events.

We propose a wetland restoration project in the Lower Danube by designing a Nature Based Solution (NBS) for dealing with flood risk. Our research is focused on the Dabuleni-Potelu-Corabia (DPC) enclosure, a land reclamation area dammed in 1965 against catastrophic floods, having a safety reserve height of 1 meter. This area along with other Lower Danube stretches have been heavily impacted by the catastrophic flood of 2006 and their resilience to such events is even more weaken by less destructive but more frequent floods. We propose different scenarios for the restoration of the DPC enclosure based on a hydraulic model of the catastrophic flood from 2006. Furthermore, we explore the potential of implementing this NBS discussing the generated benefits and co-benefits and describe the different steps to develop a Natural Assurance Scheme for the Lower Danube.
Glaciers and Palaeoclimatic Reconstructions in the Changme Khangpu Basin, Eastern Himalayas, INDIA
Authors: Debnath Manasi , Sharma Milap Chand , Syiemlieh Hiambok Jones , Chowdhury Arindam
Published: June 2022

Climate reconstructions from the Third Pole show that climate change is not uniform, but tends to exhibit a consistent pattern with changes at the regional scale over the Himalayan axis than elsewhere. To find out the answers related to the questions about the past climate in the Changme Khangpu Basin (CKB), an important region of Eastern Himalayas, the palaeoclimate research has been carried out using the proxy of glacier dynamicity. CKB covering an area of 767.8 km2 and climatically this part mainly controlled by the Indian Summer Monsoon (ISM), limited penetration of Western Disturbances and North-East Monsoon. To reach the objective, the study has opted for geomorphic feature analysis, sedimentological analysis, and associated with geochronological methods using the Accelerator Mass Spectrometry 14C dating and Schmidt Hammer rebound value dating methods to place the glacier variability and associated climate changes over time. In addition, glacier geomorphology has been used to reconstruct the equilibrium line altitude shifts and associated temperature departures. The three valleys such as Changme Khangpu (CK), Khong Kyong Kangse (KKK) and Katao have shown consistency in glacier advances and climatic shifts in different time periods. It has been estimated that the CK valley Phase-II glacier advance was initiated by the peak in ISM and enhanced by the transition climatic phase between MIS 3 (i.e. prior to 32 ka calBP) and MIS 2. The KKK Phase-I glacier advance was related to the CK Phase-II advance. In addition, the post-glacial (between 14.29 to 3.5 ka calBP) relatable climatic phases in the CK valley and Katao valley also have been identified.

 

Keywords: Changme Khangpu Basin; Eastern Himalayas; Palaeoclimate; Glaciers, 14C AMS dating; Schmidt Hammer rebound value.
Spatial aspects of tree ring-based reconstruction of past landslides behaviour: where to sample?
Authors: Šilhán Karel
Published: June 2022

Knowledge of the spatial distribution of landslides is essential for forestry, landscape planning or hazard assessment. In fact, dendrogeomorphic approaches are a useful tool to construct past landslide behaviour due to the known location of the sampled trees. The position of trees on the landslide surface can influence the detection of spatial patterns of landslide reactivation and significantly affect the amount and intensity of recorded landslide signals within a series of tree rings. This is due to the presence of different morphological zones with different movement mechanisms that generate landslide bodies. In this study, data from 1030 tree-ring series originating from 515 trees occupying ten different complex landslide sites in the Outer Western Carpathians were used to test the spatial distribution of landslide signals during reactivation events and to investigate the specific influence of six different landslide morphological zones on tree growth, with the aim of revealing the most valuable sites for future sampling at the landslide surface. Spatial patterns of landslide reactivation were tested using the Moran index. Signals from tree rings generally do not tend to cluster spatially. Thus, the analysis of spatial patterns can be used as a very stringent condition for verifying landslide events in the case of a limited number of tree-ring signals. Moreover, this analysis is only suitable for block-type landslides (not for flow-type landslides). Furthermore, this research presents a general model of the influence of movement mechanism on tree growth in the different morphological zones forming complex landslide areas. Finally, recommendations for future sampling strategies regarding tree location within specific morphological zones are made based on the results obtained. In general, trees on subhorizontal landslide blocks or in the plastic shallow movement zone should be preferred as opposed to trees on steep landslide sections or in the source zone, which should be avoided.
The development of the periglacial dune fields within the central part of the European Sand Belt – insights from the pattern analysis
Authors: Łopuch Michał , Jary Zdzisław , Sokołowski Robert , Moska Piotr , Zieliński Paweł , Skurzyński Jacek , Krawczyk Marcin , Raczyk Jerzy , Mroczek Przemysław , Poręba Grzegorz , Szymak Agnieszka , Tudyka Konrad
Published: June 2022

The age of aeolian deposits and duration of conditions favorable for aeolian processes within the European Sand Belt (ESB) are still debated. Nowadays combined 14C and OSL data are proper tools to establish the chronology of ESB dunes. However, both methods have significant limitations. They can be used only in existing outcrops limiting spatial coverage of results and making them not reliable for whole dune fields. The second issue is that the oldest dune sediments can be already reworked during dune migration. Finally, the measurement error of OSL data is too high to determine the constructional time of dune fields. To overcome these limitations, we used LiDAR data to examine the pattern properties of 31 dune fields located within the central part of ESB. Dune field pattern is recognized as a self-organizing system, where pattern evolution is a function of constructional time. This is reflected by increasing dune spacing and crest length, a decrease in defect density, and an overall reduction in the statistical variance of these parameters as the pattern matures. Curves describing the relationship between these parameters and constructional time were already established.

Results of the pattern analyses show that studied dune fields represent a wide range of spatial patterns, from irregular parabolic dune fields through a variety of transitional types to well-developed and regular patterns of large transverse dunes. The study confirms that periglacial dune fields undergo the same self-organization of pattern as dune fields located in hot and temperate areas. Regardless of the specific periglacial conditions, the temporal relationship between crest length, spacing, and defect density is preserved. Calculated constructional time for dune fields ranges between 1.2-4.2 ka for defect density, 0.3-5.9 ka for crest length, and 2.2-6.8 ka for spacing, indicating high spatial and temporal variability in the development of dune fields and a lack of zonation regarding to ice-sheet retreat. The coexistence of a few dune fields characterized by different degrees of pattern maturity in close vicinity suggests that the evolution of these dune fields was individual for each site and driven mainly by local events leading to the release of sand, such as subsequent incision of rivers, lowering of groundwater table, forest fires or human-induced deforestation. 

Presented results were obtained with the support of Polish National Science Centre, contracts number 2018/30/E/ST10/00616 and 2021/41/N/ST10/00350.
Hydromorphological characterization, assessment and monitoring in ephemeral streams: a case study in NE Iberian Peninsula.
Authors: Ollero Alfredo , Ibisate Askoa , Ballarín Daniel , García Jesús Horacio , Gimeno Marcos , Gómez-Gutiérrez Álvaro , Martínez-Segura Marcos , Moral Rubén , Ortiz Josu , Hermoso Yilena , Sanmartín Sergio , Vásconez Marco David
Published: June 2022

Ephemeral streams are an important reality in the Mediterranean area, constituting more than 50% of the channel network in the eastern region of the Iberian Peninsula. The northernmost cases are located in the semi-arid areas of the Ebro basin. Among the 592 cases registered (under the CCAMICEM project) in the Ebro basin, the Rambla de Cariñena stands out for its representativeness and dimensions.

With a basin area of 330 km2, it drains the northern piedmont of Sierra de Algairén (Iberian Mountain Range). It is a temporary river in its headwaters and upper course (Frasno River), which becomes ephemeral (Rambla) in its middle and lower courses, where it forms a large gravel bed river morphology, until it disappears without flowing into any river. In the past, there are references, as well as geomorphological evidence, that it had surface flow, but intensive vineyard agriculture and the global change recorded in the last 50 years have transformed it in ephemeral.

Recent years have showed relevant flash-floods, such as in the springs of 2008, 2015 and 2018. Its geomorphological dynamics is very interesting, with a highly sinuous meander, formation and destruction of gravel bars in each flood, and some incipient signs of incision. The Rambla de Cariñena constitutes a remarkable case for analyzing climate and global change in this type of fluvial course, as it has been worked on in the CCAMICEM project.

In this project, different characterization, assessment and monitoring works have been carried out in recent years, applying river survey techniques such as field reconnaissance, analysis and geomorphological mapping using drone flights, and radioelectric tomography to observe the depth of the alluvium. The evolutionary dynamics of the Rambla de Cariñena has also been explained through a multi-temporal analysis using aerial images and LiDAR PNOA data with a density of 0.5-4 points/m² to model the current channel. And the IHG hydrogeomorphological index has been applied to observe its impacts and assess its ecological status.

All this work has result in a database which is a base to follow the evolution of these streams in the future, as well as a pilot research for these river typologies in the Ebro basin and the identification of symptoms linked to climate change.

Key words: river survey techniques, flash flood, channel dynamics, IHG index, Rambla de Cariñena
Suspended sediment budget in the Bananal Plain tropical wetlands, Araguaia River basin, Central Brazil
Authors: Cremon Edipo , dos Santos Daniel Araujo Ramos , Pereira Gabriel
Published: June 2022

One of the most notable examples of tropical savannah plains affected by seasonal flooding in South America is the Bananal Plain along the Araguaia River. The Bananal Plain represents one of the last natural refugia for the diverse fauna of the Cerrado biome. The transport of suspended sediments (TSS) along the Araguaia River and, particularly, in the Bananal Plain area is not yet fully understood. In this work the TSS between two hydro-sedimentometric stations of the Bananal Plain along the Araguaia River was analyzed. In addition to in situ data, estimates from empirical models for satellite images were compiled to produce a 30-year (1984-2014) time series of suspended sediment concentration. Non-parametric statistics were applied to examine the temporal trend of monthly and annual TSS by Seasonal Mann-Kendall and Mann-Kendall tests, respectively. A 14% loss of wash load is estimated downstream of the Bananal Plain (at the Conceição do Araguaia hydro-sedimentometric station) compared to upstream (Aruanã station). In this area, an average of 0.65 Mt∙year-1 of suspended sediment is deposited along the river. The results indicate that there was no statistically significant increase or decrease in the annual TSS in the time period analyzed, however there is a tendency for the wash load to decrease for the dry months upstream of the Bananal Plain.
Distribution of shallow landslides in tropical mountains based on time-series of high-resolution satellite data and UAV surveys: a case study of Eje Cafetero, Andes, Colombia
Authors: Tomczyk Aleksandra , Ewertowski Marek
Published: June 2022

Modern landscape dynamics in many tropical mountains is affected by changes in land cover and variations in climatic conditions. For example, large differences in elevation and aspect increase general tendencies of changes in temperature and precipitation. Moreover, human activities related to agriculture, transport, mining, and settlements can impact local hydrological conditions but also directly transform mountain relief. These external drivers can lead to the intensification of geomorphological processes, including an increase in the number of shallow landslides, which in some cases can threaten human life and infrastructure.  

This study combined field-based and remote sensing data to map the distribution of landslides in a landscape representing a tropical mountain environment strongly affected by human presence. Study area includes four sites in Andes, Colombia in departments of Caldas and Risaralda: Salamina, Santuario, Santa Rosa de Cabal, Florida. Time series of high-resolution satellite imagery (Ikonos, WorldView, Pleiades) from 2000/2003, 2013/2014, 2019/2020 were used to identify the location of landslides and develop a spatial database. Remote mapping was verified during the fieldworks in 2017, 2018, and 2019. In addition, very detailed UAV data were generated for selected landslides to obtain their geomorphological characteristics. In the last step, frequency ratio modelling was used to investigate the relationship between topographical and land cover factors and landslides distribution.

In total, we mapped more than 900 small landslides characterised by an area from 102 m2 to 104 m2. Most of the landslides were located in cultivated landscape (pastures, farms, plantations) or along local roads. Our results indicated four potential scenarios of landslide activities: (1) intensification of landslide processes and increase in the landslide area; (2) active landslide, but stable in terms of dimensions (2) activation of new landslides; (3) deactivation and vegetation succession. Most of the activation of new landslides and intensification of existing ones were related to direct human terrain modification, mainly developing new roads or repairing existing ones.

The research was funded by the Polish National Science Centre, Poland (Project number 2015/19/D/ST10/00251)
Modeling feedbacks between lithologic contrasts, erosion, and sediment production in layered landscapes
Authors: Guryan Grace , Johnson Joel , Gasparini Nicole
Published: June 2022

This work explores how feedbacks between erodibility contrasts and sediment production influence the evolution of mountain rivers incising through layered rocks. Mountain rivers are key drivers of landscape response to climatic and tectonic forcing. Transient perturbations from changes in climate or tectonics are reflected in the profiles of bedrock rivers, but these signals can be challenging to unravel in lithologically complex settings. In layered rocks in particular, contrasts in erodibility cause erosion rates to vary through space and time, complicating landscape response to external forcing. Recent studies have used the detachment-limited stream power incision model to illustrate the complex variations in erosion rates that arise in layered rocks (Forte et al. 2016, Perne et al. 2017). However, these studies do not capture the effect of sediment cover on channel evolution. We use the Stream Power with Alluvium Conservation and Entrainment (SPACE) model (Shobe et al. 2017) to explore how sediment cover influences landscape evolution and modulates the topographic expression of erodibility contrasts in mixed bedrock-alluvial rivers incising through horizontally layered rocks.

Lithology influences channel evolution by setting the substrate erodibility and by producing coarse sediment. Motivated by the layered strata of the Guadalupe Mountains in Texas and New Mexico, USA, this study uses the SPACE model to simulate how relative differences in sediment grain size influence long-term landscape evolution. The influence of sediment particle size is tested by varying both the particle settling velocity and the erodibility of the alluvial layer across model runs. While the SPACE model does not resolve individual grains, varying these two parameters allows us to test the relative effects of finer vs. coarser sediment. We simulate river evolution through alternating layers of hard and soft rock over million-year timescales, with a constant uplift rate of 1 mm/year. We find that compared to the detachment-limited case, model runs with sediment cover have systematically higher channel steepness values in soft rock layers and lower channel steepness values in hard rock layers. As the relative sediment particle size is increased, the contrast in steepness between the two rock types decreases. We also find that model runs with relatively coarser sediment reach a steady average elevation more quickly than model runs with finer sediment, suggesting that sediment size exerts a strong control on landscape adjustment times. We also analyze how erosion rates across the entire model grid and sediment flux at the watershed outlet vary through time as hard and soft layers are exposed in different proportions. This work illustrates how strongly sediment cover influences channel evolution in mountains with layered stratigraphy, and demonstrates the importance of taking lithology and sediment cover into account when interpreting channel profiles.
Inventory, outcrop characterization and numerical assessement for a field class and geoconservation purpose on the Leba EN280 road (Huíla Plateau, SW Angola)
Authors: Ramos Anabela , Lopes Fernando C.
Published: June 2022

The studied area is located in the Serra da Leba, Humpata Plateau, the most central and elevated sector of the great Huila Plateau (southwest of Angola). Here a thick volcano-sedimentary sequence of Proterozoic age emerges, known as Chela Group, unconformably overlies Eburnean and pre-Eburnean granitoids. This sequence is covered in disconformity by the Leba Formation, consisting of clay, cherts and black dolomitic limestones with stromatolites.

In the area, in particular on the Leba EN280 road, outcrops have been inventoried and characterized which by its geological content can be defined as geosites: 1) Small quarry of clay in Humpata Plateau; 2) Old lime oven of Leba; 3) Viewpoint of Serra da Leba; 4) Slope of the first curve of the Leba Road; 5) Slope of the third loop of the Leba Road; 6) Reverse fault in granitoid rock; 7) Dolerites curve; 8) Ductile simple shear zone. The high scientific, didactic and aesthetic value of these outcrops justifies their integration in a geo-educational itinerary, contributing to the enhancement and awareness of the Serra da Leba's geological heritage, for its promotion and scientific and educational dissemination. A quantitative assessement of the selected sites to be classified as geosites that must be preserved (integration in a geoconservation strategy) will be purpose.
Ephemeral rivers, geomorfphological evolution and mapping. A case study in NE Iberian Peninsula
Authors: Ibisate Askoa , García J. Horacio , Ollero Alfredo , Ortiz Josu , Gómez-Gutierrez Alvaro , Sáenz de Olazagoitia Ana
Published: June 2022

Ephemeral rivers (IRES – Intermittent Rivers and Ephemeral Streams) differ from perennial rivers in that they do not have a base flow, therefore, when direct flow stop, they dry up. This condition is spatially accentuated in the ephemeral streams of arid and semi-arid environments (SAES – Semi-arid Ephemeral Streams). Much of the East of the Iberian Peninsula has a climate and lithological conditions that favour the presence of SAES.

The hydrogeomorphological dynamics of these rivers are controlled by flash-floods, with marked rises inflow, short delay times, and on numerous occasions, a significant sediment load. These characteristics that define them, added to the urban development of recent decades, mean that SAES is not usually part of restoration plans. In addition to the technical-administrative “forgetting”, there is scarce appreciation and lack of social sensitivity towards the SAES.

In this project (CCAMICEM Project from Spanish Research National Plan) we focus on the cartographic development of ephemeral rivers with the aim of knowing the geomorphological evolution of several reaches, and between different dates, as a geoindicator of global change using historical and UAVs images. A diachronic geomorphological mapping has been carried out in six reaches distributed throughout the Ebro River Basin (Tudela, Reajo, Alpartir, Cariñena, Sosa and Seco). The timeframe covers 65 years, from 1956-57 (American Flight B) to 2021 through images taken with an unmanned aerial vehicle (UAV). As intermediate years, images were taken from the mid-1980s, and the latest official orthoimage available (2017). The official images belong to the National Geographic Institute (IGN). An altimetric correction has been made in the first two images.

The categories identified have been active channel, main channel and secondary channel, sediment bars (which can be vegetated, scant vegetated and non-active paleo-bars), the deposits coming from bank failures or tributaries, rocky areas, exhumed old sediment areas, and consolidated or unconsolidated granular bed. The categories were mapped at different scales according to the quality of the image, that is, from a scale ≤1/300 of the UAV to another scale ≤1/1000 of the American Flight B. The results achieved are allowing geomorphological changes and basin processes to be related to global change.
Sediment sources, sediment dis-connectivity and rates of denudation and land-to-sea solute and sedimentary fluxes in selected Mediterranean catchment systems in eastern Spain
Authors: Beylich Achim A. , Laute Katja
Published: June 2022

The Pou Roig-Quisi and Mascarat catchments in eastern Spain (Calpe) are located as neighbouring catchment systems in a Mediterranean, mostly mountainous and anthropogenically modified environment. The catchments drain directly into the Mediterranean sea. The selected study areas are characterized by a mild Mediterranean climate with a mean annual air temperature of ca. 18°C and a mean annual precipitation sum around 400 mm (measured slightly above sea level). During the coldest months (January, February) frost and snow can occur in the highest elevations although the mountain ranges are situated close to the coast. In contrast, maximum summer temperatures (July, August) can easily exceed 30°C and south-facing hillslopes and rockwalls are exposed to high solar radiation. The lithology in the area is clearly dominated by marine limestones. Elevation ranges from sea level up to 1126 m a.s.l. Geomorphological processes include chemical and mechanical weathering, rock falls, debris flows, splash and slope wash, fluvial erosion, and fluvial solute, suspended sediment and bedload transport.

This ongoing GFL research is focussed on sediment sources, sediment (dis-)connectivity, spatiotemporal variability and rates of contemporary denudational processes and land-to-sea solute and sedimentary fluxes. Our work includes detailed field and remotely sensed geomorphological mapping and computing of morphometric catchment parameters combined with the extended statistical analysis of high-resolution meteorological and rock temperature data and the observation and monitoring of sediment-transfer, runoff and fluvial transport events. In the field, we are using a combination of different observation, monitoring and sampling techniques, including different tracer techniques and sediment traps in stream channels, remote time-laps cameras, and event-based high-resolution field monitoring combined with frequent water and sediment samplings. Sediment connectivity is significantly reduced by extended terraced areas within the catchment systems. Sediment transfers, the intermittent runoff, and fluvial transport and land-to-ocean fluxes are almost entirely controlled by pluvial events. High runoff during extreme rainfall events forms a relevant hazard particularly in the lowest parts of the catchment systems. Mechanical fluvial denudation shows a higher spatiotemporal variability than chemical denudation. Altogether, drainage-basin wide chemical denudation dominates over drainage-basin wide mechanical fluvial denudation which is explained by partly limited sediment availability, long-term sediment storage at defined locations, and by the predominant marine limestones found in the catchment areas.
Sediment Connectivity: Punctuated Anthropogenic Sediment Production and Dynamic Sediment Delivery Ratios
Authors: James Allan
Published: June 2022

Forecasting fluvial sediment yields involves several assumptions about catchment dynamics that should be explicitly realized. For example, sediment delivery ratios (SDR), the ratio of sediment yield to sediment production (Y/P), are often assumed constant and used to translate upland sediment production to downstream deliveries or estimate yields from erosion models.  Constant SDR values may be lumped basin-wide or applied in distributed grids or sub-catchment response units. The assumption of constant SDRs, however, tacitly subsumes an assumption of approximately constant sediment production rates averaged over time. Yet, SDRs may vary substantially and systematically over time in response to changing land-use, climate, or other factors that govern sediment production. With human disturbances, it’s common to have a punctuated sediment production followed by a systematic peak and decline of yields as the legacy sediment is translated downstream through time. 

            Hydraulic mining in California is an extreme case of punctuated sediment production where massive amounts of hydraulic mining sediment (HMS) were produced between 1853 and 1884 and then abruptly stopped. This research used geomorphic change detection and DEM differencing in two small, mountain catchments in the mining districts to document sediment production, initial storage, and recent storage of HMS. Total sediment production from mining in the two catchments was 41.3 and 23.5 106m3, which was used to compute SDRs for the various periods. Average sediment yields were calculated from the changes in storage between periods. Changes in sediment yields show the dynamics of SDRs through time. Initial SDRs were high in the late 19th century but increased further as cumulative deliveries increased. On a catchment scale, the two basins had SDRs of 62 and 70% in 1884 when mining ceased, but this had increased to 88 and 84% by 2014 as the cumulative yields increased. Lateral connectivity played an important role in changing yields as easily eroded sediment became less accessible, but yields also decreased in response to channel gradient declines and bed armoring. Longitudinal connectivity was also important within the catchments through the emergence of bedrock gorges that trapped large pockets of sediment for some periods. The dynamics of delivery ratios calls for a knowledge of the history of geomorphic changes in catchments in order to recognize systematic changes in sediment production.