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Colluvial landslides develop in loose Quaternary deposits, with deformation generally being progressive and crack development dominant in the sliding mass surface layer. With the Tanjiawan landslide in the Three Gorges Reservoir (China) as a case study, field investigations, deformation monitoring, and groundwater level monitoring data were integrated to analyze the landslide deformation characteristics and elucidate the influence of cracks on its deformation. We used numerical simulations, including the finite element and discrete element methods, for investigating the progressive deformation mechanism of rainfall-triggered landslides in the accumulation layer and predicting the failure process. The results indicated that crack formation instigated a preferential seepage channel in the shallow layer of the sliding mass, rainfall infiltration along cracks generated water pressure, and the landslide gradually morphed from a stable into a "step-like" progressive deformation state. Preferential flow inside the cracks effectively elevated the groundwater level within the landslide, and either the number or depth of cracks significantly affected the groundwater seepage field, thereby influencing slide stability. Geological conditions controlled the deformation and failure processes of each landslide section. The uplifted bedrock on the right side blocked the sliding process of the rear sliding mass, and the middle and front sliding masses moved faster but the sliding distance was shorter. The deformation trend is deformation, crack formation, preferential flow occurrence, crack extension, and deformation. The ultimate cause of failure was a steep rise in groundwater level following short duration heavy rainfall or long duration light rainfall. [ABSTRACT FROM AUTHOR]

Landslides are prominent geomorphological processes in active mountain belts hindering urban development and food production projects. Generally, heterogeneous geomorphological contexts are the most affected, particularly in the Mediterranean rim. On the other hand, landslides in homogenous contexts remain under-investigated. In such conditions, the monotony of certain causative factors may conceal the parameters controlling the landslide's magnitude and typological differences. In this paper, the frequency–size distribution of landslides was performed to investigate the effect of the main categories of the landslide causative factors to identify the key features connected to the magnitude of these gravitational processes. Results show that the main typological difference is related to the land use and lithological categories in a way that marls and cereal farming slopes promote small-size and hence shallow movements, while olive growing terrain for the land use and calcareous marls and colluvium for the lithological factor promote larger and deeper processes. Furthermore, the slope direction has also proved to be an influencing parameter on landslide typology, where slopes remaining in the shade during wet seasons (northern slopes) promote more shallow movements than those in the Sun. These findings show that even in monotonous contexts such as the foreland of the Rif chain (the Prerif), entities controlling the typological difference can be found and investigated, which improves our knowledge about the landslide hazard. [ABSTRACT FROM AUTHOR]

Soil erosion and the loss of soil organic carbon (SOC) pools are considered serious environmental problems in undulating landscapes on loess covers, accompanied in some areas, such as south Poland, by the physical degradation of chernozemic soils. The aim of the present study was to identify the scale and reasons for spatial variation of the SOC pools in the intensely cultivated Luvic Phaeozems in one of the unique patches of chernozemic soils in Poland. This study, carried out in a soil catena located in the undulating Carpathian Foreland in south-east Poland, has demonstrated that the SOC pools can greatly differ on a very small scale, even in relatively less differentiated landscapes and in soils classified into the same group. The scale and reasons for the differentiation of the SOC pools depend on the method (depth) of calculation. The spatial differences were smaller and were mainly related to the SOC concentrations and the bulk density of the topsoil horizons, when calculated for depths of 0–30 cm and 0–50 cm. On the other hand, the SOC pools calculated for the 0–100 cm soil layer differed most significantly between the profiles in the catena, representing a continuous growing trend from the uppermost towards the lowermost part of the catena, and were clearly related to the total thickness of the humus horizon(s). The latter findings confirm that sheet erosion has a major impact on the spatial variation of SOC pools in an agricultural landscape. However, soil morphology and the distribution of SOC across the soil profiles suggest additional influences from historical pedogenesis and modern farming technology. The presence of black, thick and humus-rich chernic horizons in all soils across the catena indicates that modern farming must not degrade the soils, but, on the contrary, it can help in the restoration of even neo-formation of chernozemic soils (Phaeozems), if oriented towards the conservation of humus content, soil structure, and biological activity. [ABSTRACT FROM AUTHOR]

This comprehensive study explores the Upper Pleistocene geological history of Mallorca, employing a multidisciplinary approach that integrates previous findings with new insights. The research spans various coastal regions, focusing on four distinct study areas characterized by different geomorphological and structural contexts. The first structural context, exemplified by Port des Canonge, showcases a fold and thrust sedimentary succession, resulting in prominent cliffs with Jurassic and Triassic formations. The second context, observed in Caloscamps, features smoother reliefs and notable terrestrial sediment input. Meanwhile, the third context, represented by Punta de s'Avançada and Punta de n'Amer, exhibits cliffs carved on Upper Miocene tabular units devoid of terrestrial sediment input. The main objective is to provide a comprehensive understanding of the geological and sedimentological characteristics of the Upper Pleistocene units across the Mallorca coastal regions by investigating different study areas located along the west, north-west, north-east, and east coasts, in distinct geomorphological and geological contexts using sedimentological methodologies: stratigraphic analysis, X-ray diffraction analysis, microscopic techniques, and assessment of sediment color. Additionally, Optically Stimulated Luminescence (OSL) dating techniques are employed, providing a precise temporal framework spanning Marine Isotope Stage 6 (MIS 6) to Marine Isotope Stage 3 (MIS 3). The findings reveal the complex interplay of environmental factors, climatic variations, and geological evolution across Mallorca. Colluvial deposits and paleosols reflect climatic shifts. Alluvial fans and aeolianites highlight periods of intense sediment transport and deposition linked to climate fluctuations. Finally, to provide a comprehensive overview of the outcrops present on the island, a stratigraphic correlation of the mentioned areas was conducted. In conclusion, the study enhances our comprehension of the regional coastal dynamics, geological composition, and environmental history, providing invaluable contributions to the broader understanding of Pleistocene deposits. [ABSTRACT FROM AUTHOR]

This review paper delves into the geological history of Mallorca, focusing on the Middle to Late Pleistocene period and its impact on the landscape and climate of the island. The Quaternary, particularly, the Last Interglacial, represents a relatively short timeframe on the global chronological scale, yet it is notable for its climatic instability and complex alternation of glacial and interglacial phases, leading to fluctuations in sea levels. During the last interglacial, millennial-scale fluctuations, known as Dansgaard–Oeschger and Heinrich events, occurred. Aeolianites are thought to have formed during periods of sparse vegetation cover and abundant sediment availability from the sea bed or platform (Heinrich events), while colluvial deposits and paleosols are believed to represent periods of reduced sediment supply and enhanced pedogenesis (Dansgaard–Oeschger events). These different deposits reflect climatic shifts and sea-level changes, offering insights into the environmental history of the island. Fossil evidence, including Strombus bubonius (currently known as Thetystrombus lauts) or "Senegalese hosts," reveals past warm climatic fluctuations, particularly during the Last Interglacial. Myotragus balearicus exemplifies evolutionary adaptation and isolation on the island, offering a unique perspective on its paleontological legacy. The integration of stratigraphic characteristics and literature research on Optically Stimulated Luminescence (OSL) dating techniques provides a comprehensive temporal framework, spanning from Marine Isotope Stage 6 (MIS 6) to Marine Isotope Stage 2 (MIS 2), enabling the precise dating of geological events and a stratigraphic correlation. [ABSTRACT FROM AUTHOR]

Quantitative disaster risk studies for slow-moving rotational and translational landslides in small regions (e.g., cities and watersheds) are very scarce. The limitations of risk modeling associated with these hazards include (i) the lack of data for physical modeling, (ii) methodological restrictions on estimating landslide intensity with statistical models and determining the temporal probability of landslides, and (iii) the absence of characterizations of the physical vulnerability of exposed assets. The present study combines and updates different methodologies to overcome these limitations for quantitative landslide disaster risk estimation, creating a novel methodological approach that was applied in a pilot study in Tegucigalpa city, Honduras. Tegucigalpa, the capital city of Honduras, has the highest number of recorded landslides in the country. In a previous study, landslides were found to be mainly concentrated in areas with colluvium and residual soils. As an input for the disaster risk assessment, this study generated landslide risk vulnerability functions based on empirical data. The application of the proposed methodology allowed us to estimate the average annual loss (AAL) caused by landslides in the study area—a key disaster risk metric that is lacking in other landslide disaster risk studies—enabling comparisons with disaster risk estimates associated with other hazards. In particular, the AAL value obtained for the study region was USD 7.26 million. [ABSTRACT FROM AUTHOR]

A detailed assessment of heavy metal concentration has been done through a regional geochemical survey near an industrial area in the outskirts of Raipur City. The multi‐metal analysis was carried out through detailed sampling of stream sediments and slope wash samples. All heavy metals like Cobalt (Co), Chromium (Cr), Copper (Cu), Nickel (Ni), Lead (Pb), and Arsenic (As) are found to present at higher concentrations than their permissible limits. The maximum concentration of heavy metals in descending order of occurrences for Cr, Pb, Cu, Co, Ni, and As were 213, 68, 55, 54, 45, and 35, ppm, respectively. The weathering of the carbonate rocks present in the area is found to be the source of a few metals like Ni, Cr, and Cu. Other metals like Co, Pb, and As are observed at higher concentrations near the industrial areas in the northwestern part. The chemical effluents released from the steel industries are believed to be the prime source of these metals, which also confirmed through field validation. This study emphasizes the significance of the geochemical database generated by National Geochemical Mapping (NGCM) for social and environmental goals. [ABSTRACT FROM AUTHOR]

On July 27, 2023, at approximately 04:00, a debris flow, with an estimated volume of 25,000 m3, struck Lanhua Village in the southern part of Shuicheng District, Guizhou Province, China. This event led to the burial and damage of 15 houses in Lanhua Village. Remarkably, residents successfully observed this debris flow 30 min before its peak arrival, enabling sufficient time for evacuation prior to the onset of this fatal geological disaster. To elucidate the evolutionary process of the Lanhua Village debris flow, a detailed field survey was conducted utilizing unmanned aerial vehicle (UAV) technology. The findings suggest that extreme heavy rainfall served as the primary trigger for the debris flow. Landslides, comprising residual slope deposits at the top of the slope and induced by rainfall, resulted in the obstruction of Highway X244 and the blockage of culverts beneath the road. These blockages contributed to the formation of a peak cross-basin flood, exceeding 7 m3/s, which acted as the driving force initiating the debris flow. The thick layer of colluvial deposits covering the slope surface, with approximately 23,000 m3 of material mobilized by flood erosion, constituted the primary source contributing to the rapid expansion and movement of the debris flow. The topography, characterized by steep upper slopes and gentler lower slopes, was a contributing factor to the debris flow deposits spreading into residential areas, resulting in disaster. The event in Lanhua Village exemplifies a "landslide-blockage-flood diversion-erosion-debris flow" disaster chain. [ABSTRACT FROM AUTHOR]

It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall. Based on the systematic analysis of the change law of reservoir water level, rainfall and displacements of reservoir colluvium landslide, this paper proposes the compound hydrodynamic action of rainfall and reservoir water as the unload-load parameter, and the landslide displacement as the unload-load response parameter. Based on this, a physical prediction model of the compound hydrodynamic unload-load response ratio of reservoir colluvium landslide was established, and the quantitative relationship between the compound hydrodynamic unload-load response ratio and its stability evolution was in-depth analyzed and determined. On the basis of the above research, taking Shuping landslide, a typical hydrodynamic pressure landslide as an example, the unload-load response ratio model is used to systematically evaluate and predict the stability evolution law and the change trend of the landslide under compound hydrodynamic action. The prediction result shows that the variation law of the compound hydrodynamic unload-load response ratio is consistent with the dynamic evolution law of its stability. Therefore, the above studies show that the compound hydrodynamic unload-load response ratio parameter is an effective displacement dynamic evaluation parameter for reservoir colluvium landslides, so it can be used in the prediction of the reservoir colluvium landslides. [ABSTRACT FROM AUTHOR]

Unsaturated soils with bimodal pore structures, such as many residual and colluvial soils, are widespread in nature. Bimodal pore structures can noticeably influence their soil–water retention behaviour. Estimating the bimodal soil–water retention curve (SWRC) accurately has become critical in both theoretical research and engineering practice. In this paper, a novel equation to simulate the bimodal SWRC of unsaturated soils is proposed. The proposed bimodal SWRC equation not only provides higher simulation accuracy for bimodal SWRCs compared to other equations, but it also shows good agreement with experimental data from different types of soils. Moreover, the relationships between bimodal SWRC variables (i.e., air entry value, inflection point, and slopes at transition zone) and the best fitting parameters are presented. Finally, a practical approach is developed to estimate the bimodal relative permeability of unsaturated soils based on the proposed bimodal SWRC equation. The results are convincingly demonstrated that there is good agreement between the predicted and measured relative permeability coefficients of unsaturated soils in the literature. [ABSTRACT FROM AUTHOR]

The occurrence of debris flow events in small-scale watersheds with dense vegetation in mountainous areas that result in significant loss of life and missing individuals challenges our understanding and expertise in investigating and preventing these disasters. This has raised concerns about the occurrence of large debris flow disasters from small watersheds. This study focused on a catastrophic debris flow that took place in Longtou Gully (0.45 km2) in Tianquan County, Ya'an City on 25 September 2021, which resulted in 14 deaths and missing individuals. Through comprehensive field investigations, high-precision remote sensing data analyses, and numerical simulations, we analyzed the triggering mechanisms and dynamic processes of this event. Our results indicate that the convergence hollow at the channel head exhibited higher hydraulic conditions during rainfall compared to gentle slopes and convex terrains, leading to the instability of colluvial soil due to the expansion of the saturated zone near the soil–bedrock interface. The entrainment of material eroded from the channel resulted in an approximately 4.7 times increase in volume, and the channel scarp with a height of about 200 m amplified the destructive power of the debris flow. We emphasize the need to take seriously the possibility of catastrophic debris flows in small-scale watersheds, with colluvial deposits in hollows at the channel head under vegetation cover that serve as precursor material sources, and the presence of channel scarps formed by changes in the incision rate of the main river, which is common in the small watershed on both sides. This study provides insights for risk assessment of debris flows in small-scale catchments with dense vegetation cover in mountainous areas, highlighting the importance of vigilance in addressing disasters in small-scale catchments, particularly in regions with increasing human–environment conflicts. [ABSTRACT FROM AUTHOR]

Collapsing erosion is a unique phenomenon commonly observed on the granite residue hillslopes in the tropical and subtropical regions of southern China, characterized by its abrupt occurrence and significant erosion volumes. However, the impacts of soil crust conditions on the erosion of colluvial deposits with granite residual soils have only been studied to a limited extent. To address this issue, this study investigates the impacts of three soil crust conditions (i.e., without crust, 10-minute crust, and 20-minute crust) on gully morphology, rainfall infiltration, and runoff and sediment yield during slope erosion of colluvial deposits with granite residues (classified as Acrisols) in Yudu County, Ganzhou City, Jiangxi Province, China, using simulated rainfall tests and photographic methods. The results showed that as the strength of the soil crust increased, the capacity of moisture infiltration and the width and depth of the gully as well as the sediment concentration and yield ratio decreased; at the same time, the runoff ratio increased. The sediment yield in the without-crust test was found to be 1.24 and 1.43 times higher than that observed in the 10-minute crust and 20-minute crust tests, respectively. These results indicate that soil crusts can effectively prevent slope erosion and moisture infiltration, while providing valuable insights for the management of soil erosion in natural environments. [ABSTRACT FROM AUTHOR]

Palaeoclimatic and palaeoenvironmental proxy data are presented for the Late Quaternary based on mineralogical, geochemical and palynological analysis of a palaeosoil-sediment section in the lower Kürtün Valley (Samsun region, Northern Türkiye). The geochronology along the section is established based on OSL and radiocarbon dating. The base of the palaeosoil-sediment section consists of a palaeo-terrace fill of the Kürtün Creek dated to 108 ± 9 ka, corresponding to the last interglacial period (MIS5c). After this warm and humid period, the last ice age began. Sea level dropped and the Kürtün Stream deepened its bed. Fluvial terrace deposits were covered with colluvial materials and a palaeosoil sequence formed. The bottommost part of the palaeosoil formation carries the fingerprints of a dry climate of 68 ± 9 ka ago (MIS4). The middle part of the section coincides with MIS2 (28,959 cal BP) and is characterized by humid conditions with arid pulses accompanied by the occurrences of calcrete nodules. The palaeosoil-sediment section ends with the records of MIS1 (8381 cal BP), corresponding to warmer and more humid conditions. This study emphasizes the importance of palaeosoil-calcrete formation in the lower Kürtün Valley for explaining climate changes from MIS5c to MIS1. The results are compatible with studies conducted in the Eastern Mediterranean. High-resolution multi-proxy studies are recommended to better understand the connection between local climates and global climate phenomena in the Late Quaternary. [ABSTRACT FROM AUTHOR]

Preferential flow plays a vital role in infiltration processes in structured soil. However, knowledge of preferential flow in colluvial deposits of Benggang remains limited. In this study, three typical colluvial deposits with different formation times were selected. The formation times of colluvial deposits A, B and C increased in sequence. Water infiltration in colluvial soil was visualized through Brilliant Blue dye experiments (a total of 90 photos from the dyed soil profiles). The dye morphological characteristics of preferential flow were analysed, and the influencing factors were explored. The dye morphological parameters confirmed the occurrence of preferential flow in the colluvial deposits. The dye coverage of colluvial deposit A was the greatest (61.12%), followed by colluvial deposits B (50.41%) and C (46.81%). The matrix flow depth, preferential flow fraction and length index of colluvial deposits A and B were greater than those of colluvial deposit C. Preferential flow was more notable in colluvial deposits A and B than in colluvial deposit C. The migration process of dyed water varied spatially. There were more preferential flow paths at a 10 cm horizontal width. In addition to the bulk density and saturated hydraulic conductivity, the soil particle composition, especially the gravel content (r = 0.740), was closely related to the observed dye coverage. According to the principal component analysis results, the soil particle composition imposed the greatest influence on the formation of preferential flow in the colluvial deposits, with a contribution of 45.24%. The results provide a theoretical reference for explaining the mechanism of soil infiltration processes and a systematic basis for the treatment of colluvial deposits. [ABSTRACT FROM AUTHOR]

Exploration in the mining sector results in the accumulation of extensive databases encompassing diverse geochemical datasets. The efficient processing of this multivariate data necessitates the application of advanced Python data analysis tools. Such an approach is essential for the extraction of criteria that will inform and optimize future exploration and mining operations. In this study, we utilize the Python language to explore the database of Aura Energy Company established within the uranium exploration project in the regions of Oued El Foula and Aïn Sder, where a total of 1065 drilling wells have been executed. The uranium deposit in Oued El Foula and Aïn Sder is of a surficial type and results from alteration and erosion of granites. Overall, economic concentrations of uranium are near the surface (with a depth of less than 10 m) and hosted in unconsolidated rock (mainly in colluviums) and igneous rocks (mainly granites). The uranium deposit exhibits an economic association with vanadium and thorium. The granites in the regions of Oued El Foula and Aïn Sder form from the melt at the upper continental crust. In addition, these granites show enrichment in LILE and depletion in HFSE which is a characteristic of alkaline granites resulting from wet melting and evolved melt. [ABSTRACT FROM AUTHOR]

Earthquakes are one of the natural disasters that cause great losses of life and property. As a result of earthquakes, significant transformations occur in the space due to population losses and collapse of the buildings. The February 6 Kahramanmaraş-centered earthquakes are considered to be the disaster of the century. In this context, the aim of the research is to reveal the impact of the earthquakes that occurred on February 6 on the city of Kahramanmaraş. Therefore, observations were conducted during field studies, maps were derived using GIS and mid-photo images were used in the study. The extent to which 86 neighborhoods in Dulkadiroğlu and Onikişubat district centers were affected by the earthquakes was determined. While determining the effects of earthquakes on neighborhoods, observations made in field studies and population data obtained from TUIK were used and the population changes in the neighborhoods after the earthquakes were revealed. The concentration of buildings was determined with Maxar satellite data, and buildings collapsed after the earthquakes were added to the study with intermediate photo images. According to the result map obtained from field studies, neighborhood population change rates and satellite images, the impact on the neighborhoods was determined as highly, moderately, and slightly affected. Of the 86 neighborhoods, 16 were slightly, 12 were moderately, and 58 were heavily affected by the earthquakes. In the research area, areas corresponding to alluvial and colluvial lands that are not suitable for settlement in terms of ground, Şazibey, Hayrullah and İsmet Paşa neighborhoods, where population density is high and vertical construction is observed, were more affected by the earthquakes. On the other hand, Ahır Mountain and the surrounding areas, where sandstones and mudstones from the Eocene period are located, were less affected. Likewise, despite the highrise buildings, the fact that the buildings were new and built in areas more suitable for settlement in terms of ground ensured that Cumhuriyet, Beş Nisan and Hürriyet neighborhoods were less affected by the earthquakes. Since this research reveals the extent to which neighborhoods are affected by earthquakes, it can be a guide in the steps to be taken in the city to be rebuilt. [ABSTRACT FROM AUTHOR]

Heterogeneous rock masses that include rhythmic alternations of marl, shale, marly limestone, sandstone, siltstone, and argillite, such as Flysch, are particularly prone to generating colluvial deposits on gentle slopes, which are often subject to failures triggered by heavy rainfall. Flysch-derived colluvial soils are made up of highly heterogeneous sediments ranging from clayey loam to rock fragments, and they have been studied more rarely than homogeneous soils. In this work, we present a geotechnical and hydraulic characterisation performed both in situ and in the laboratory on flysch-derived colluvial soils that were involved in a channelised landslide in the pre-alpine area of the Friuli Venezia Giulia region (NE Italy). The investigated soils were characterised by the average values of the grain size composition of about 25% gravel, 20% sand, 30% silt, and 25% clay. The loamy matrix presented low-to-medium values of the liquid and plastic limits, as well as of the plasticity index (LL = 40%, PL = 23%, and PI = 17%, respectively). The values of the peak friction angle for natural intact samples were 33° < ϕ'p < 38°, whereas the residual friction angle fell to 23–24° at great depths and high vertical stresses, for a prevailing silty–clayey matrix. Variable head permeability tests were performed both in situ and in the laboratory, showing that the values of the vertical and horizontal permeability were very close and in the range 1 × 10−4–1 × 10−6 m/s. The soil permeability measured in the field was generally higher than the hydraulic conductivity calculated on laboratory samples. The proposed geotechnical and hydrological characterisation of flysch-derived colluvial soils can be of fundamental importance before the use of more thorough analyses/models aimed at forecasting the possible occurrence of slope failures and evaluating the related landslide hazard. The reported geotechnical and hydraulic parameters of flysch-derived colluvial materials can represent a useful reference for rainfall infiltration modelling and slope stability analyses of colluvial covers that are subject to intense and/or prolonged precipitation. However, when facing engineering problems involving colluvial soils, particularly those coming from flysch rock masses, the intrinsic variability in their grain size composition, consistency, and plasticity characteristics is a key feature and attention should be paid to the proper assumption of the corresponding geotechnical and hydraulic parameters. [ABSTRACT FROM AUTHOR]

In the practice of gold mining industry, hazardous waste known as tailings is produced during the ore extraction process. These tailings are typically stored in a dam structure called a Tailings Storage Facility (TSF). The planning and construction of a TSF are critical considerations, as the failure of a TSF can have substantial environmental impacts, pose risks to human safety, and result in industrial losses. Therefore, strict control is necessary in the development of TSFs to minimize the potential negative consequences. This research focuses on the transport of contaminants within a TSF, specifically examining the concentration of chloride contaminants and conducting particle movement analysis. The study utilizes modeling through the GeoStudio SEEP/W program to simulate groundwater flow profiles and the GeoStudio CTRAN/W program to understand contaminant movement over a 100-year period. GeoStudio modeling employs 10 materials: impermeable clay soil, filter sandy soil, transition gravel rock, three mine waste types (Fine, Rockfill, and Rockfill with fine), hard rock bedrock layer, in-situ soil representing the original layer, landslide with colluvial soil, and the tailings itself. Back analysis is employed to iterate model parameters and ensure modeling accuracy against field data, including comparisons with water quality test results and readings from vibrating wire piezometer (VWP) instrumentation. The contaminant transport is influenced by advection-dispersion processes and tends to concentrate within the TSF boundary toward the dam toe over a 100-year timeframe. The analysis emphasizes the influence of advection in contaminant transport and underscores the importance of particle position relative to the groundwater level, with Particle Tracking Analysis shows significant movement within the groundwater flow area. This research provides crucial insights into the dynamics of contaminant concentration, informing better decision-making in TSF planning and management. The findings underscore the imperative of strict control measures to minimize environmental impacts and human safety risks associated with TSFs, thereby advancing knowledge in gold mining waste management. [ABSTRACT FROM AUTHOR]

A debris slide and subsequent fire on September 18, 2018, destroyed a bank building and damaged property in Warrensville, North Carolina. The slide pushed a propane tank and an electrical generator against the bank. In that collision, an electrical arc caused the propane to explode, which produced a fireball. Employees in the bank narrowly escaped with minor injuries, and slide debris buried part of an unoccupied drive-through lane. North Carolina Geological Survey geologists responded to a request from the Ashe County Emergency Manager and investigated the slide area to assess slope stability for public safety. Aided by uncrewed aerial system imagery, we documented slope and debris slide features and geologic materials and constructed a geologic cross section through the 1,400 m2 debris slide. We concluded that record above-normal precipitation followed by rainfall from the remnants of Hurricane Florence during September 15-18, 2018, induced the slide, and that geologic conditions and hillside modifications over prior decades had predisposed the slope to failure. Colluvial deposits derived from sheared amphibolite bedrock, and curved trees within and adjacent to the 2018 slide indicated preexisting marginally stable hillslope conditions. The 2018 slide included the area of a 2000 slide that involved a cut slope constructed during earlier site development. Stability analyses showed that the described conditions led to an unstable slope at the time of the 2018 slide. A septic leach field involved in the 2018 slide was damaged; however, it is uncertain if it was a causal factor in the slide. [ABSTRACT FROM AUTHOR]

The objective of this study is to assess the impact of utilizing a BW (Buttress wall) to control the deflection of a diaphragm wall in colluvial soil conditions in Vietnam. The physical and mechanical properties of the colluvial layers are evaluated using data closely monitored during a specific project, serving as validation for 3D numerical simulations utilizing the Hardening Soil Model. The analysis results closely match the field monitoring data, which has tested the accuracy of the simulation model. This forms the basis for further investigations into the dimensional parameters of BW walls, including length, thickness, and spacing between them. The results obtained from the parametric study demonstrate that altering the wall length and spacing between BW walls significantly limits the deflection of the diaphragm wall, while changes in thickness have a negligible effect. Through the 3D numerical simulations, a linear relationship between the maximum wall deflection and parameters such as wall length and spacing between BW walls has been established. [ABSTRACT FROM AUTHOR]

Soil erosion and the loss of soil organic carbon (SOC) pools are considered serious environmental problems in undulating landscapes on loess covers, accompanied in some areas, such as south Poland, by the physical degradation of chernozemic soils. The aim of the present study was to identify the scale and reasons for spatial variation of the SOC pools in the intensely cultivated Luvic Phaeozems in one of the unique patches of chernozemic soils in Poland. This study, carried out in a soil catena located in the undulating Carpathian Foreland in south-east Poland, has demonstrated that the SOC pools can greatly differ on a very small scale, even in relatively less differentiated landscapes and in soils classified into the same group. The scale and reasons for the differentiation of the SOC pools depend on the method (depth) of calculation. The spatial differences were smaller and were mainly related to the SOC concentrations and the bulk density of the topsoil horizons, when calculated for depths of 0–30 cm and 0–50 cm. On the other hand, the SOC pools calculated for the 0–100 cm soil layer differed most significantly between the profiles in the catena, representing a continuous growing trend from the uppermost towards the lowermost part of the catena, and were clearly related to the total thickness of the humus horizon(s). The latter findings confirm that sheet erosion has a major impact on the spatial variation of SOC pools in an agricultural landscape. However, soil morphology and the distribution of SOC across the soil profiles suggest additional influences from historical pedogenesis and modern farming technology. The presence of black, thick and humus-rich chernic horizons in all soils across the catena indicates that modern farming must not degrade the soils, but, on the contrary, it can help in the restoration of even neo-formation of chernozemic soils (Phaeozems), if oriented towards the conservation of humus content, soil structure, and biological activity.

Accurate data mapping and visualization are of crucial importance for the detection and monitoring of slope morphodynamics, including erosion processes and studying small erosional landforms (rills and gullies). The purpose of the current research is to examine how the flight geometry of unmanned aerial systems (UASs) could affect the accuracy of photogrammetric processing products, concerning small erosion landforms that are a result of slope wash and temporary small streams formed by rain. In October 2021, three UAS flights with a different geometry were carried out in a hilly to a low-mountain area with an average altitude of about 650 m where erosion processes are observed. UAS imagery processing was carried out using structure-from-motion (SfM) photogrammetry. High-resolution products such as photogrammetric-based point clouds, digital surface models (DSMs) and orthophotos were generated. The obtained data were compared and evaluated by the root mean square error (RMSE), length measurement, cloud-to-cloud comparison, and 3D spatial GIS analysis of DSMs. The results show small differences between the considered photogrammetric products generated by nadir-viewing and oblique-viewing (45°—single strip and 60°—cross strips) geometry. The complex analysis of the obtained photogrammetric products gives an advantage to the 60°—cross strips imagery, in studying erosional terrains with slow slope morphodynamics. [ABSTRACT FROM AUTHOR]

An investigation of the Magdalenian occupation at Étiolles-Les Coudray (France) was conducted using geophysical methods. Based on ground-penetrating radar (GPR), electrical resistivity tomography (ERT), electromagnetic induction (EMI), and stratigraphic information, we present a reconstruction of the main sediment interfaces carrying the Magdalenian occupation. Étiolles-Les Coudray is one of the most important open-air campsites in the Paris Basin, where consecutive settlements distributed along the Hauldres stream were preserved by silts. The geoarchaeological goals were, in particular, the reconstruction of the ancient environment in which hunter–gatherers settled, providing spatialized known stratigraphies able to find an echo in the Seine Valley. Moreover, a focus on the capability of geophysical methods to detect archaeological features is also presented and discussed. We observed that the major reflections in the GPR records were generated from interfaces that have grain size variation: (1) the bottom of the Holocene colluvium and (2) the bottom of the upper Late Glacial silt. EMI and ERT show a very clear horizon associated with the upper Late Glacial silt, in some places even more clearly defined than with GPR. We confirmed the presence of a channel along the slope, placed under Locus 1, and a second channel of the same type globally following the paleotopography of Locus 2. We created a thickness map of the "beige sandy silt" and hypothesized a high probability of good preservation conditions of Magdalenian evidence. Finally, the detection of several localized diffraction hyperbolas in the GPR record offers the possibility to obtain the ground truth of the geophysical results in the near future and verify the nature (archaeological or geological) of these features. [ABSTRACT FROM AUTHOR]

This work investigates the rainfall infiltration process within homogeneous and stratified colluvial deposits caused by short (1–3 h) and intense (40–90 mm/h) rainfall, using both analytical and numerical infiltration modelling. The findings of the investigation demonstrate that the classic Green–Ampt model can be employed effectively to study homogeneous colluvial covers with permeability equal to or lower than kw = 10−5 m/s and that are subject to a 1 h rainfall with intensity I ≥ 45–50 mm/h. In these circumstances, a top-down saturation front forms within the colluvial deposit, leading to the saturation of a 70–100 cm-thick layer. This critical condition occurs every 5–10 years in the mountain area of the Friuli Venezia Giulia Region (NE Italy), which corresponds to a lower return period of critical hydrologic events when compared with other mountain basins in the Alps due to the higher initial degree of saturation characterising colluvial covers in this area (70–95%). When analysing stratified colluvial covers, the Dagan–Bresler approximate model, as well as the numerical modelling, emphasised the strong influence that abrupt variations in the permeability of the various soil layers have on the infiltration process at depth. In particular, the presence of a top organic soil horizon that is rich in macro-pores and is characterised by a higher permeability (k = 10−4 m/s) actually reduces the possibility of surficial ponding, which is the basic condition of the "piston" models. The highly permeable top soil allows for a rapid downward infiltration up to contact with the underlying colluvial material, which is less permeable (k = 10−5 m/s). Therefore, a perched water table forms starting from the organic soil–colluvium interface, originating pore–water overpressures within the colluvial deposit, with maximum values in the order of 5–10 kPa. [ABSTRACT FROM AUTHOR]

Predicting the hydrological response of watersheds to climate disturbances requires a detailed understanding of the processes connecting hillslopes and streams. Using a network of soil moisture and temperature sensors, electrical resistivity tomography monitoring, and a weather station we assess the above and below‐ground processes driving the hydrological response of a hillslope during snowmelt and summer monsoon. The transect covers bedrock and vegetation gradients, with a steep upper part characterized by shallow bedrock, and gentle lower part underlain by colluvium. The main vegetation cover is conifers on the upper, and grass and veratrum on the lower part. Combined with a simplified hydrological model, we show that the thin soil layer of the steep slope acts as a preferential flow path, leading to mostly shallow lateral flow, interrupted by vertical flow, mostly at tree locations, and likely facilitated by flow along fractures and roots. Vertical flow and upstream‐driven groundwater dynamics are prevailing at the colluvium, presenting a very different hydrological behavior compared to the upper part. These results show that subsurface structure and features have a strong control on the hydrological response of a hillslope and that those can create considerably varying hydrological dynamics across small spatial scales. Key Points: Vegetation, bedrock, and topographic characteristics define hydrological dynamicsShallow lateral flow characterizes steep, shallow bedrockVertical up and downward flow prevails at gentle slope underlain by colluvium [ABSTRACT FROM AUTHOR]

The erosion of rocky coasts contributes to global cycles of elements over geological times and also constitutes a major hazard that may potentially increase in the future. Yet, it remains a challenge to quantify rocky coast retreat rates over millennia; a time span that encompasses the stochasticity of the processes involved. Specifically, there are no available methods that can be used to quantify slow coastal erosion (< 1 cm yr-1) averaged over millennia. Here, we use the 10Be concentration in colluvium, corresponding to the by-product of aerial rocky coast erosion, to quantify the local coastal retreat rate averaged over millennia. We test this approach along the Mediterranean coast of the Eastern Pyrenees (n=8) and the desert coast in Southern Peru (n=3). We observe a consistent relationship between the inferred erosion rates, the geomorphic and climatic contexts. The retreat rates are similar, 0.3–0.5 mm yr-1 for five samples taken on the Mediterranean coast, whereas one sample located on a cape and two samples from a vegetated colluvium have a lower rate of ~0.1 mm yr-1. The coastal retreat rate of the drier Peruvian coast is slower at 0.05 mm yr-1. Although the integration periods of these erosion rates may encompass pre-Holocene times, during which the sea-level and thus the retreat rate were much lower, we conclude here that the associated bias on the inferred retreat rate is less than 80 %. We anticipate that this new method of quantifying slow rocky coastal erosion will fill a major gap in the coastal erosion database and improve our understanding of both coastal erosion factors and hazards. [ABSTRACT FROM AUTHOR]

In 2011, in the Aleksandrov quarry (Kursk oblast, Russia), the Ryshkovo pedolithocomplex of the Mikulino (Eemian) Interglacial (MIS-5e) was studied. It includes three to four soil profiles separated by humified pedosediments. The lower soil is an eroded gray forest soil, the two middle soils ones are meadow soils at the bottom of the ravine and a soddy-podzolic soil on the paleoslope, and the upper soil is an underdeveloped soil with elements of forest pedogenesis. Morphological, physicochemical, and microbiomorphic studies of the pedolithocomplexes on the slope and in the bottom of the buried coastal ravine filled with colluvial and alluvial–colluvial sediments made it possible to reconstruct at least three pedogenic and four morpholithogenic stages in MIS-5e, which significantly detailed the event history of the interglacial. In the profile of the Ryshkovo pedolithocomplex, the buried humus horizon of the lower gray forest soil is clearly visible reflecting warmer climatic conditions of the first half of the last completed interglacial in comparison with its second half. Soil formation in trans-accumulative landscapes was repeatedly interrupted by erosion–accumulation processes, which reflects the instability (rhythmicity) of the climatic situation during the Mikulino interglacial and correlates well with detailed records from other geological archives. [ABSTRACT FROM AUTHOR]

Talus, as the product of movement and accumulation along the slope after the cracking of cliffs or steep rock walls, is a common landform in the mountain periglacial environment. Significant thermal anomalies within talus have been widely reported to be a result of cooling effects. During the cold season, the increased temperature difference between talus and the ambient environment strengthens the intensity of convection (vertical flows) and transforms into upward advection (lateral flows) and exhausts the internal warm current. During the warm season, heat is concentrated on the surface of the talus, and the internal dominant cold current moves downward along the slope by advection. The principle of the proactive cooling effects of talus has been widely utilized in railway construction within permafrost regions as embankments to alleviate degradation of the underlying permafrost. However, limited model studies have examined the cooling effects of blocky debris in nature, and in situ observations are rare. Therefore, it will be important to increase observations and develop process‐based models that couple heat conduction, convection/advection, water transfer processes, and even the latent heat of phase change. This will help to better understand the extent of the cooling effects and its impact on the thermal regime of permafrost. [ABSTRACT FROM AUTHOR]

The infilling rate of hollows is one of the primary factors affecting the recurrence interval of shallow landslides. Although many studies have focused on colluvium in hollows under various regional settings, few have directly estimated the infilling rates from radiocarbon dating and airborne LIDAR digital elevation models (DEMs) in shallow landslide scars. In this work, we analysed the radiocarbon dates of charcoal in the colluvium in the granitic mountains of Hiroshima and Hofu, where heavy rainfall has caused multiple shallow landslides in recent years. A total of 27 samples were collected from landslide scars in seven hollows, and the infilling rates were inferred from the calibrated radiocarbon ages and pre‐landslide depth of the samples estimated from the DEMs before the landslide event. Topographic parameters including local slope gradient and size of the source area were also measured using the DEMs. Our findings showed that the calibrated radiocarbon ages of colluvium in hollows ranged from about 350 to 1700 cal BP, and the infilling rates ranged from about 0.2 ± 0.2 to 5.4 ± 0.9 mm/y. In the two hollows with limited human impacts, the infilling rates were relatively low, and there is a trend of increase with increasing source‐area size and topographic curvature. In contrast, infilling rates were very high at two hollows with intensive human impacts where active surface erosion occurred from the 17th to the early 20th century. Three hollows located around the ruins of a medieval castle near the drainage divides of the source area also had relatively high infilling rates. For the hollows with intensive human impacts, the infilling rates were not controlled by topographic attributes such as source‐area size and curvature. [ABSTRACT FROM AUTHOR]

Anthropogenic activity changes the processes of erosion on slopes. The deforestation process is connected with the deposition of material at the foot of the slope. During this process, macro-charcoals from anthropogenic-induced fires are trapped in the sediments. This paper provides an analysis of charcoal counts and sediment characteristics and is supported by historical data analysis. During this study, a discrepancy between radiocarbon dating and historical data was revealed; a probable explanation is presented.

In tropical and subtropical zones, sandy colluviums composed of soil aggregates are highly significant for the understanding of depositional processes in the natural realm. The formation processes of soil aggregates–colluviums (pedosediments in other climate zones) are poorly defined. Deeper knowledge on the origin of soil aggregates–colluviums from low‐density or high‐density overland flows is essential for improved understanding of colluviums found in modern, Quaternary and ancient stratigraphic records. The understanding of depositional processes of soil aggregates–colluviums has been integrated into this study by combining macrostratigraphy and microstratigraphy and laboratory experimental techniques. The actualism principle was applied using a sedimentological description of a modern soil aggregates–colluvium deposit generated by overland flows. In addition, physical experiments were performed to simulate the natural sedimentation processes of overland flows composed of various sediment concentrations. The results indicate the maximum grain size (granules and pebbles) of the soil aggregates–colluvium beds originating from high competence overland flows involving large volumes of local rainfall (storms). Overland flows are responsible for laminated beds of soil aggregates–colluviums; however, the laminations are heterogeneous sequences compared to those of low‐density flows, which have homogeneous sequences. The microstratigraphy of the natural, modern soil aggregates–colluviums shows varied structures in overland flow laminations, implying several types of flow density. The internal organization of the laminae suggests that the accretion of the colluvium deposit occurred through high‐density flows and high to low‐transitional density flows. Low‐density flows were less frequent and may constitute either single or more diluted tail flows. Finally, overland flow can generate facies with similar end members to mass movements, being distinguished only by bed thickness. Linking field observations with experimental results, as in the present study, leads to deeper understanding of overland flow sedimentation processes, especially in tropical and subtropical zones. [ABSTRACT FROM AUTHOR]

Regional geochemical mapping was carried out in Bilaspur and Korba Districts of Chhattisgarh, and stream sediments/slope wash, soil, and water samples were analyzed for concentration of heavy metals. The study contributes to understanding heavy metals contamination of sediments, soils, and water due to anthropogenic activity, mainly in agriculture-based rural areas. The study reveals that high geochemical anomalies observed for heavy metals like Ni, Cr, As, and Zn in sediments and soil samples are due to the extensive uses of phosphatic fertilizer and soil amendments in the form of poultry and swine manure. Water quality assessment of major streams in the study areas shows that the water is suitable for domestic and agricultural uses. Correlation analysis reveals that the chemical weathering of rockforming minerals doesn’t control the surface water chemistry of the study area and is also an anthropogenic source of sodium in water. This study also shows the importance of the country’s geochemical mapping database, which will have much broader applications than conventional mineral exploration and geological mapping. [ABSTRACT FROM AUTHOR]

Fluvial and colluvial deposits of Late Holocene age in South-Central Ontario catchments have provided few 14C dates, most by conventional methods registering century-old ages. Other young deposits, dated by conventional and accelerator mass spectrometry radiocarbon (AMS 14C), have yielded bomb-affected post-1950 ages over variable time limits. Attempts to date the base of Ah and lower-in-section soil horizons, in Early to Late Holocene stream terrace deposits, have yielded atomic bomb effects. Comparing bomb contamination in Late Holocene fluvial deposits, using both conventional and AMS methods, identifies a mix of bomb-affected beds juxtaposed with dated beds, the latter yielding ages with narrow standard deviations. Colluvial deposits overlying key glacial sections in the Rouge Catchment, while rare, yield bracketed AMS ages for an Ahbk horizon that refines weathering times relative to previously obtained conventional 14C dates. Bomb-affected sediment appears variably distributed within floodplain soils and in the ground soil of a colluvial section. Mass wasted deposits, with AMS 14C ages spread over the last few centuries, appear related to Little Ice Age (LIA) changes in climate, corroborated by pollen records. Further, these AMS-14C dated beds calibrate weathering of secondary Fe-Al oxihydroxides over the first half a millennium of weathering time. [ABSTRACT FROM AUTHOR]

There are now 101 radiocarbon dates from the long Paleolithic and post-Paleolithic culture-stratigraphic sequence in El Mirón Cave, Cantabrian Spain. Here we report on two dates on bone from two different humans whose remains were found in disturbed surface sediments in the cave vestibule rear and that confirm the existence of burials in addition to previously reported residential occupations in the vestibule front pertaining to the Chalcolithic and early Bronze Age periods (ca. 5500–3500 cal BP). In another attempt to resolve problems of stratigraphic incoherence of dates from the early Magdalenian periods in the vestibule rear, six new assays on faunal remains from Levels 119, 117, 114, 108, and 106 were run at Queen's University in Belfast. There continue to be date inversions in the Lower Magdalenian range of levels that may be explained by a combination of intensive anthropic and rodent activity, major rock fall, slope wash and gravity-caused object movements, as well as possible problems in following some thin levels during excavations over a large area and across many years of work in the cave vestibule interior, particularly in the absence of any layers that are culturally sterile or even poor. Nonetheless, the coherent age of the Initial Magdalenian is fully confirmed by a new date from Level 21 in the vestibule front at ca. 22,000–20,500 cal BP), as is the general age range of the Lower Magdalenian (ca. 20,500–18,000 cal BP). [ABSTRACT FROM AUTHOR]

Water pathways and water contamination in mixed land‐use catchments are complex to understand. Runoff‐generating sources can be numerous and water pathways modified by anthropogenic elements. Monitoring surveys considering geochemical and microbial parameters, are often carried out on such catchment, but are often simple in terms of studied parameters. Nonetheless, they can be helpful to identify the specific signatures of the main runoff‐generating sources and estimate their contribution to total runoff at the outlet of mixed land‐use catchments. Based on a monthly biogeochemical monitoring program conducted between 2017 and 2019 in the Ratier catchment (19.8 km2) near Lyon (France), a step‐by‐step approach was developed to: (1) identify the main runoff‐generating sources using a perceptual model of the Ratier catchment, (2) identify the respective biogeochemical signatures of each source using this biogeochemical dataset and hydro‐meteorological indicators and (3) estimate their contribution to the stream total runoff using an End‐Member Mixing Analysis method. We identified three main runoff‐generating sources outside of rainy periods: a colluvium aquifer, a fractured gneiss aquifer and a saprolite layer. The monitored geochemical datasets were found divided into three groups matching these sources. Contributions of these sources were estimated based on representative tracer concentrations. Microbial parameters showed a homogeneous agricultural and anthropogenic contamination among the catchment surface water, but also deeper into the fractured gneiss groundwater. This approach showed the potential of using simple monitoring datasets to identify runoff‐generating sources and estimate their contribution to total runoff. [ABSTRACT FROM AUTHOR]

Soil formation in Mediterranean periglacial karst landscapes remains poorly understood as the interplay between local and allochthonous sources of parent materials, and mineral alteration and pedogenesis, as dominant post‐depositional processes, depends on a variety of climatic and environmental factors. Herein, we investigate the balance between erosion and aeolian dust accretion in the formation of an alpine soil profile in the periglacial zone of Mount Olympus in Greece. We applied a wide range of analytical methods to 23 samples, from a soil profile developed in a glaciokarstic plateau, from colluvial sediment horizons interbedded in postglacial scree slopes of different maturity and formation age and from modern Sahara dust samples deposited on the snowpack. Colluvial sediment horizons exhibit high concentrations of carbonate gravel and calcite‐rich sand and represent the local erosion products. The soil B horizon developed on the glaciokarstic plateau, contains high amounts of fine earth and is rich in quartz, mica, plagioclase, clays and Fe–Ti oxides. Based on physical and textural characteristics, the soil profile is partitioned in a surficial weathered Bw and an illuvial Bt horizon that overlies the local regolith composed of fragmented glacial till and slope wash deposits. Radiogenic isotope systematics, textural and mineralogical analysis show that the contribution of aeolian (Sahara and locally sourced) dust to the development of the soil B horizon ranges between 50% and 65%. Cryoturbation results in fine earth translocation from Bw to the Bt horizon, whereas weak pedogenetic modifications of detrital (aeolian and bedrock‐derived) minerals result in magnetic mineral weathering and secondary clay formation. Our findings reveal that aeolian dust accretion from Saharan and lcal sources is the dominant process in providing alpine soil parent material and that cryoturbation, weak pedogenesis and clay mineral alteration occur within the Mediterranean periglacial zone of Mount Olympus. [ABSTRACT FROM AUTHOR]

Soil erosion in loess landscapes results in soil organic carbon (SOC) redistribution and storage in SOC pools. Understanding the SOC dynamics is important because changes in the SOC stocks may have impacts on global climate change. However, the topographic‐related patterns controlling SOC storage are not well understood. Closed depressions are natural landforms in loess landscapes and preserve buried Holocene soils and SOC‐rich colluvia resulting from soil erosion and are SOC pools. The aim of this study was to quantify the impact of natural closed depressions on SOC storage in the loess landscape of the Nałęczów Plateau. Buried Holocene soils and colluvial sediments infilling five representative closed depressions were documented and the SOC stocks were calculated. Using GIS analysis SOC from all closed depressions was calculated and mapped. Between 13.5 and 229.78 Mg of SOC are in the entire soil profiles of the studied closed depressions, 10%–21% of the SOC stock is in the topsoils. The SOC stock in all closed depressions of the study area reaches 172.09–265.19 Mg ha−1 and in the soil cover outside the closed depressions is 51.20–105.40 Mg ha−1. SOC from closed depressions varies spatially and increases the SOC stock at regional scale by 0.1–90 Mg ha−1. For about 21% of the study area, the SOC from closed depressions increases the SOC stock in the agricultural landscape by more than 10% (up to 60%). This study highlights the importance of closed depressions for SOC storage and provides a better understanding of its spatial distribution at the regional scale. [ABSTRACT FROM AUTHOR]

Probabilistic models to inform landslide early warning systems often rely on rainfall totals observed during past events with landslides. However, these models are generally developed for broad regions using large catalogs, with dozens, hundreds, or even thousands of landslide occurrences. This study evaluates strategies for training landslide forecasting models with a scanty record of landslide-triggering events, which is a typical limitation in remote, sparsely populated regions. We evaluate 136 statistical models trained on a precipitation dataset with five landslide-triggering precipitation events recorded near Sitka, Alaska, USA, as well as > 6000 d of non-triggering rainfall (2002–2020). We also conduct extensive statistical evaluation for three primary purposes: (1) to select the best-fitting models, (2) to evaluate performance of the preferred models, and (3) to select and evaluate warning thresholds. We use Akaike, Bayesian, and leave-one-out information criteria to compare the 136 models, which are trained on different cumulative precipitation variables at time intervals ranging from 1 h to 2 weeks, using both frequentist and Bayesian methods to estimate the daily probability and intensity of potential landslide occurrence (logistic regression and Poisson regression). We evaluate the best-fit models using leave-one-out validation as well as by testing a subset of the data. Despite this sparse landslide inventory, we find that probabilistic models can effectively distinguish days with landslides from days without slide activity. Our statistical analyses show that 3 h precipitation totals are the best predictor of elevated landslide hazard, and adding antecedent precipitation (days to weeks) did not improve model performance. This relatively short timescale of precipitation combined with the limited role of antecedent conditions likely reflects the rapid draining of porous colluvial soils on the very steep hillslopes around Sitka. Although frequentist and Bayesian inferences produce similar estimates of landslide hazard, they do have different implications for use and interpretation: frequentist models are familiar and easy to implement, but Bayesian models capture the rare-events problem more explicitly and allow for better understanding of parameter uncertainty given the available data. We use the resulting estimates of daily landslide probability to establish two decision boundaries that define three levels of warning. With these decision boundaries, the frequentist logistic regression model incorporates National Weather Service quantitative precipitation forecasts into a real-time landslide early warning "dashboard" system (https://sitkalandslide.org/ , last access: 9 October 2023). This dashboard provides accessible and data-driven situational awareness for community members and emergency managers. [ABSTRACT FROM AUTHOR]

In-channel storage of both fine sediment and sediment-bound phosphorus has been recognized as potentially large contributors to respective watershed loads, yet they are rarely quantified in the field. In this field-based study, we quantified and characterized in-channel fine sediment and total phosphorus (TP) storage within a third-order stream. We hypothesized storage to be significant within the context of watershed-scale sediment and TP loads and that storage trends are influenced by channel characteristics and hydraulics. In May 2015, the volume of stored in-channel sediment was estimated within a 13.5 km stretch of Walnut Creek, an alluvial stream draining an agriculturally dominated watershed in Jasper County, Iowa, USA. Storage volume was estimated in-field through a series of 240 transects which were stratified across reaches of the varying channel and hydraulic conditions (e.g., sinuosity, stream power). Overall storage volume was broken down into feature classes (e.g., point bars) based on in-channel depositional processes. Following in-field quantification, feature class sediment samples were collected and analyzed for physical properties (e.g., bulk density) and TP concentration. Physical and chemical analyses, coupled with in-field volume estimation, allowed for watershed-scale masses of in-channel sediment and TP to be calculated and then placed within the context of respective annual loads. Sediment and TP were estimated to be stored at ~2.7 Mg m-1 and 0.7 kg m-1, respectively. Sinuous reaches exhibited significantly greater sediment storage volume (p < 0.001) and depth (p < 0.001) versus straight reaches. Reach sinuosity exhibited a significant positive correlation (p = 0.03) with storage mass and represented the most effective storage predictor. The majority of storage mass (72%) was represented by colluvial material accumulations at the streambank toe. Loose bed sediment was the second greatest contributor to storage mass (18%), with the remaining feature classes (e.g., bars) representing a combined ~10%. Sediment storage mass was ~3.25 times greater than the watershed suspended sediment load for 2015. The TP mass was found to be nearly equal to the respective watershed load for 2015. In-channel sediment and TP storage masses within Walnut Creek were found to be significant in comparison to respective annual loads, and thus storage is expected to play a significant role in respective watershed routing, loading, and the overall budgets of these parameters. Though challenging, quantification of in-channel fine sediment and TP storage is necessary to relate source contributions (e.g., streambank erosion) to watershed loads and is critical to account for interannual sediment and TP export. [ABSTRACT FROM AUTHOR]

Landslides are caused by rainfall as one of the main factors. In order to study the effect of rainfall on the physical and mechanical parameters of landslides, a physical model of the colluvium landslide is created in laboratory conditions with silty clay, river sand, and gravel, taking Shuping landslide in the Three Gorges Reservoir area as the prototype. The artificial rainfall is applied to the accumulation model, which is steady for 60 h, and then the gravel soil is taken out along the different elevations of the colluvium for the permeability test and direct shear test, and the evolution law of changes in porosity, the permeability coefficient, and the shear strength parameters along the elevation are studied. Combined with XRF and NMR tests, the spatial variation of the permeability coefficient and shear strength parameters is discussed from the perspective of chemical elements, minerals content, and porosity, and the stability analysis of a colluvium landslide is carried out considering the influence of parameters along the elevation. The results show that under the action of rainfall seepage, the fine particles of clay are transported from upslope to downslope, resulting in more and more fine particles of clay at the toe slope. The original pores are gradually filled, the cementation between particles is stronger, the corresponding cohesion is increased, and the permeability coefficient is reduced. Due to the loss of fine particles at the upslope, the relative content of coarse particles increases, leading to an increase in the internal friction angle. The variability of the slope's physical and mechanical parameters is a result of the spatial transport of clay particles in the colluvium caused by the rainfall seepage above. Specifically, the permeability coefficient and internal friction angle from upslope to downslope decrease linearly under the action of rainfall, but the law of the cohesion increases linearly. The upslope's permeability coefficient and internal friction angle decrease by 11% and 8% compared to those of the downslope, while the cohesion increases by 168%. The results of FLAC3D numerical calculation of Shuping landslide show that the maximum deformation in the X direction of 145 m and 175 m water level increases by 12% and 42%, and the safety factor decreases by 0.63% and 5% under the combined action of rainfall and the reservoir water level, that is, when considering the variation of parameters along the elevation of the landslide. The research findings provide a better understanding of the spatial parameters in similar colluvium bodies under rainfall action. [ABSTRACT FROM AUTHOR]

This article aims to refine the description of the artefacts and the geomorphological, geological, pedological and chronological (optically stimulated luminescence (OSL) analyses of sedimentary deposits) characterisation of the Rincão I site (southeastern Brazil) to contribute to the understanding of early human–environment interactions. The archaeological site occupation took place on hillslopes truncated by the Mogi‐Guaçu River's lateral (~1200 m) and vertical (~5 m) movements during the Late Quaternary, in an area where in situ bedrock outcrops are uncommon. This geological context favoured human groups simultaneously having access to the resources provided by the alluvial plain and hillslopes. Here we describe how about three hundred lithic artefacts are associated with soils that originated from sandy colluvium with OSL ages between 20.3 and 5.5 thousand years. These ages are consistent with the local palaeopedological and geomorphological contexts of landscape changes, and partly controversial from the perspective of models currently in vogue for the human occupation of southeastern Brazil. The vestiges of past human presence amid the hillslope sandy colluvium deposits include: 1) a set of flakes and formal artefacts (one stemmed point and three convex artefacts) made of sandstone obtained from hillslopes near (<10 km) the site; and 2) predominant detritus and flakes of quartz and flint obtained mostly from the adjacent (<1.5 km) alluvial plain, linked to flaking sequences other than those of the formal artefacts. Only quartz artefacts were found in the lower levels of the site stratigraphy, whereas in the intermediate and upper levels quartz, flint and sandstone artefacts were found, suggesting that there were changes in the raw materials used for flaking over time. The formal artefacts from the site have technological attributes like the ones observed in assemblages associated with a previously known lithic industry (Rioclarense), but a different pattern of choice of raw materials. This suggests that technical standards underwent a process of adaptation to the environmental particularities surrounding the Rincão I site. [ABSTRACT FROM AUTHOR]

Archeological and geoscientific research in loess landscapes remains challenging due to erosional discordances and the relocation of sediments by fluvial erosion and slope wash. The Lower Rhine Embayment (LRE) can serve as a blueprint for archeological and paleoenvironmental research in loess landscapes of Central Europe. The accumulation of wind-blown dust; paleosols developed therein; and the archeological artifacts preserved in loess, colluvial or alluvial sediments are evidence of the Pleistocene and Holocene dynamics of the landscape. Geomorphologic processes in different and specific relief positions must be considered different processes that transform and relocate sediments and archeological remains. Besides aeolian accumulation, erosion and deflation have also transformed the landscape of the LRE. These include fluvial slope wash, gully formation, colluviation, and periglacial processes such as solifluction, cryoturbation and the formation of ice wedge pseudomorphs. In addition, other post-depositional processes, including weathering and soil formation, modify the sedimentary record. In light of the landscape evolution from more hilly landscapes to the flat, agriculturally used terrain we see today, we highlight the relevance and importance of different geomorphological and soil processes including their impacts and challenges for archeological and geoscientific studies. Kurzfassung: Archäologische und geowissenschaftliche Forschung ist in Lösslandschaften aufgrund von Erosionsdiskordanzen und der Verlagerung von Sedimenten durch fluviale Erosion bis heute eine Herausforderung. Die Niederrheinische Bucht kann als Blaupause für die archäologische und paläoökologische Forschung in mitteleuropäischen Lösslandschaften dienen. Die Akkumulation von Staub, darin entwickelte Paläoböden sowie archäologische Artefakte, welche im Löss und den korrelaten Sedimenten wie Kolluvien und Auenlehmen erhalten geblieben sind, liefern wichtige Hinweise für die pleistozäne und holozäne Landschaftsdynamik. All diese Indizien können helfen, die Paläoumweltbedingungen früherer Siedlungen zu verstehen. Die verschiedenen geomorphologischen Prozesse und deren spezifische Reliefposition müssen berücksichtigt werden, da Lösssedimente und darin enthaltene archäologische Artefakte durch diese Prozesse umgewandelt und verlagert werden können. Neben der äolischen Akkumulation haben auch Erosion und Deflation die Landschaft der Niederrheinischen Bucht verändert. Dies sind insbesondere fluviale Hangabspülungen, Erosionsgullies , Kolluvien und periglaziale Prozesse wie Solifluktion, Kryoturbation und die Bildung von Eiskeilpseudomorphosen. Darüber hinaus führen Prozesse nach der Ablagerung, einschließlich Verwitterung und Bodenbildung, zu Veränderungen in den Sedimentarchiven. Vor dem Hintergrund der Landschaftsentwicklung von vorwiegend hügeligen Landschaften hin zum flachen, landwirtschaftlich genutzten Gelände, wie wir es heute vorfinden, beleuchten wir die Relevanz und Bedeutung verschiedener geomorphologischer und bodenkundlicher Prozesse sowie deren Auswirkungen und Herausforderungen für archäologische und geowissenschaftliche Untersuchungen und Studien. [ABSTRACT FROM AUTHOR]

The Lago del Capraro doline (Salento peninsula, southern Italy), a valuable Mediterranean Temporary Pond (MTP), has been investigated aiming to define its geomorphological features and to collect data about the local hydraulic regime. At the bottom of the Lago del Capraro doline, in fact, a small temporary pond appears soon after major precipitation events as that one of autumn 2013. The morphological survey shows that this solution doline is placed on a karst plain surface stretching at about 70 m of altitude; the doline has an elliptical shape with the major axis 130 m long whereas the length of the minor axis is about 100 m. It shows a flat bottom, placed at about 65 m above m.s.l., due to the presence of a colluvial sandy clays filling, bordered by steep limestone slopes about 5 m high. Geophysical surveys and a cone dynamic penetrometer test allowed a detailed geological model to be realized. In particular, ERT and seismic refraction models revealed the geometry and the thickness of doline filling deposits as well as the preferential infiltration zones of surface waters. Interestingly, the cone penetrometer test reveals that resistance decreases downward in the filling lower part, most likely because of the active solution process at the doline bottom. The results of this study suggest an increase of surface water infiltration at doline bottom in the next future so that the development of a pond will be an increasingly rare event, partly compensated by the clustering of rainy periods during autumn months as expected in the future by climate models. [ABSTRACT FROM AUTHOR]

Slow-moving, chronically destructive landslides are projected to grow in number globally in response to precipitation increases from climate change, and land disturbances from wildfire, mining and construction. In the Cincinnati and northern Kentucky metropolitan area, USA, landslides develop in colluvium that covers the steep slopes along the Ohio River and its tributaries. Here we quantify elevation changes in a slow-moving colluvial landslide over 14 years using county-wide lidar, uncrewed aerial vehicle (UAV) structure-from-motion (SfM) surveys and a UAV lidar survey. Because the technology and quality differ between surveys, the challenge was to calculate a threshold of detectable change for each survey combination. We introduce two methods; the first uses propagated elevation difference errors and the second back-calculates the individual survey errors. Thresholds of detection range from ±0.05 to ±0.20 m. Record rainfall in 2011 produced the largest vertical changes. Since then, the landslide toe has continued to deform, and the landslide has doubled its width by extending into a previously undisturbed slope. Although this study presents a technique to utilize older datasets in combination with modern surveys to monitor slow-moving landslides, it is broadly applicable to other studies where topographic data of differing quality are available. [ABSTRACT FROM AUTHOR]

During the Assyrian rule over Northern Mesopotamia (present-day northern Iraq), complex systems of canals were built to increase the surface of cultivable land and improve the movement of people and goods across the irrigated waterscape of the hinterland of Nineveh and other major urban centres, with the aim of granting socio-economic prosperity to the empire. Nevertheless, supra-regional political instability eventually led to the rapid downfall of the Assyrian state during the late seventh century BCE, causing the swift abandonment of the canal systems. In this study, we examine the post-abandonment formation processes of the natural and anthropogenic infillings of three portions of King Sennacherib's Khinis canal system (705–681 BCE, northwestern Kurdistan Region of Iraq) through means of archaeological, sedimentological and micromorphological analyses. We identify water lain sediments, desiccation features, colluvial gravel intake and pastoral occupation layers, anchoring the deposit to radiometric dating and contextualising it against the known regional climatic history. The interpretation of pedostratigraphic evidence highlights subsequent phases of use, abandonment, and repurposing of the canals, reflecting shifts in land-use from agriculture to pastoralism and dynamic adaptation and resilience of the local ancient communities in response to Late-Holocene climate changes and geopolitical events. [ABSTRACT FROM AUTHOR]

Yedoma ice complex sediments with large syngenetic ice wedges (IW) are usually observed in outcrops in river valleys on permafrost plains and on sea coasts and lake shores in the north of Siberia, Alaska, and Canada. Less frequently, they occur in mountainous and foothill regions of East Siberia, for example, in the Upper Kolyma Upland and in river valleys of the Eastern Sayan Range and the Anabar Plateau, as well as in Alaska and Yukon. The author's materials on gravelly Yedoma with IWs in the intermountain basins, on mountain slopes, and on sea coasts and lake shores are presented. The obtained data allow a conclusion that gravelly Yedoma has mainly alluvial, lacustrine, and colluvial origins with an insignificant participation of aeolian processes. Occurrence of the late Pleistocene gravelly deposits with large syngenetic IWs confirms a hypothesis of polygenetic origin of Yedoma. [ABSTRACT FROM AUTHOR]

Probabilistic models to inform landslide early warning systems often rely on rainfall totals observed during past events with landslides. However, these models are generally developed for broad regions using large catalogs, with dozens, hundreds, or even thousands of landslide occurrences. This study evaluates strategies for training landslide forecasting models with a scanty record of landslide-triggering events, which is a typical limitation in remote, sparsely populated regions. We train and evaluate 136 statistical models with a rainfall dataset with five landslide-triggering rainfall events recorded near Sitka, Alaska, USA, as well as >6,000 days of non-triggering rainfall (2002–2020). We use Akaike, Bayesian, and leave-one-out information criteria to compare models trained on cumulative precipitation at timescales ranging from 1 hour to 2 weeks, using both frequentist and Bayesian methods to estimate the daily probability and intensity of potential landslide occurrence (logistic regression and Poisson regression). We evaluate the best-fit models using leave-one-out validation as well as with testing a subset of the data. Despite this sparse landslide inventory, we find that probabilistic models can effectively distinguish days with landslides from days without. Although frequentist and Bayesian inference produce similar estimates of landslide hazard, they do have different implications for use and interpretation: frequentist models are familiar and easy to implement, but Bayesian models capture the rare-events problem more explicitly and allow for better understanding of parameter uncertainty given the available data. Three-hour precipitation totals are the best predictor of elevated landslide hazard, and adding antecedent precipitation (days to weeks) did not improve model performance. This relatively short timescale combined with the limited role of antecedent conditions reflects the rapid draining of porous colluvial soils on very steep hillslopes around Sitka. We use the resulting estimates of daily landslide probability to establish two decision boundaries for three levels of warning. With these decision boundaries, the frequentist logistic regression model incorporates National Weather Service quantitative precipitation forecasts into a real-time landslide early warning "dashboard" system (sitkalandslide.org). This dashboard provides accessible and data-driven situational awareness for community members and emergency managers. [ABSTRACT FROM AUTHOR]

Establishing an accurate and dependable displacement prediction model is essential to building an early warning system for landslide hazards. This study proposes an adaptive hybrid machine learning model for forecasting the step-like displacements of reservoir colluvial landslides. Firstly, candidate factors are determined based on the landslide deformation response. Then, the cumulative displacement and candidate factors are decomposed using the optimized variational mode decomposition algorithm. Second, the sensitivity analysis of the gray wolf optimizer-based kernel extreme learning machine (GWO-KELM) models to each factor component is analyzed using the PAWN method. Then, the factors are optimized based on the analysis results. Third, based on the optimized factors, GWO-KELM models of different displacement components are established and integrated to predict the cumulative displacement. The Baishuihe landslide was taken as an example. The raw data of its three monitoring sites were employed to verify the performance of the proposed model. The results indicate that the model can decompose the cumulative displacement and factors with the adaptively determined parameters. In addition, the model performed well over a three-year prediction of the landslide displacement. [ABSTRACT FROM AUTHOR]

In the literature, mainly particle-size distribution (PSD) analyses in the soil catenas, of e.g., moraine and riverine landscapes were discussed. Analysis and comparison of PSD in moraine (ML) and ice-dammed lakes (ID-LL) landscapes were not studied. Since the landscape of ice-dammed lakes origin has diversified relief and is under intensive agricultural use, the aspects of erosion are of great importance. The changes in PSD were studied in 14 soil catenas (toposequences) of eroding soils at the upper slope (US) as well as colluvial soils at the middle (MS) and lower (LS) slopes and in the depressions (D). The PSD of the fine fractions (<2 mm) was analysed according to the hydrometer method. In order to describe the effect of agricultural use on the variability of PSD in soil surface horizons, sedimentological and granulometric indices were calculated. In the studied moraine landscape, the content of coarse silt fraction was increasing in the catenal sequence from 9.7% in the US to 17.7% in the D. Similar relationships were revealed for the fine silt content. Significant differences were found between the average contents of coarse and fine silt fractions at the US as well as the LS and the D. However, such a relation was not found in the soil catena in the ice-dammed lake landscape. Eroded and colluvial soil materials were very poorly sorted with a standard deviation index of 2.65–3.69. Humus horizons of analysed soils had very fine, fine skewed PSD, mesokurtic and platykurtic distribution (ML), symmetrical, fine skewed and platykurtic distribution (I-DLL). The cluster analysis enabled the separation of two groups of soils: one group in the moraine landscape and the other in the ice-dammed lakes landscape. The PSD in studied soils was similar only among the soils within one type of landscape. [ABSTRACT FROM AUTHOR]

The south-eastern Gorny Altai is one of the most hazardous seismogenic area in the north of Central Asia. We present a synthesis of field, 230Th-U geochronological, mineralogical and geochemical data collected on seven Quaternary travertines. All travertines occur within the zones of active faults that border the Chuya and Kurai intermontane basins. Travertine cement mainly comprises calcite (with minor amounts of aragonite), which cements alluvial, alluvial fan, and colluvial deposits. The results of 230Th-U dating suggest that deposition of the travertines was triggered by large paleoearthquakes in the last eight thousand years. Several stages of travertine formation with ages 9–11 ka BP correspond to the known period of strong paleoseismicity in the region (8–16 ka BP). The 123 ka BP travertine resulted from a slip triggered by the Middle Pleistocene deglaciation, while that of 400 ka BP represents seismic motions likely associated with the main Cenozoic orogenic phase. All travertine forming events fall within warm and wet climatic phases (interglacials). Large earthquakes activated faults and caused a rapid rise along them of ambient-temperature bicarbonate groundwater, which was previously sealed in deep-seated Upper Neoproterozoic–Paleozoic limestone-dolostone aquifers. Rapid CO2 degassing of the spring water was the most important control of calcite or aragonite precipitation. Such travertines represent an important tool for paleoseismological research in seismically active regions. [ABSTRACT FROM AUTHOR]