Entire Slope Research Articles

Centennial scale temporal responses of soil magnetic susceptibility and spatial variation to human cultivation on hillslopes in Northeast China

Soil loss is a significant environmental issue that causes soil degradation and threatens national food security in the black soil region of Northeast China. The magnetic susceptibility (MS) technique is a promising method for evaluating soil loss and estimating soil redistribution. In this study, undisturbed soil samples were selected from four typical black soil cropland slopes with 110a, 60a, 30a, and 20a cultivated durations at 10 cm intervals from the surface to a depth of 50 cm to measure soil MS. Based on measurable magnetic indexes, a quantitative relationship between MS and cultivation duration was constructed. The results indicated that: (1) The MS showed an approximate trend, namely 110a < 60a < 20a < 30a < 0a, the longer the sloping land was cultivated, the smaller the MS. (2) The reduction rate of χlf on the surface and underlying soil ranged from 1.57 to 3.27 and was also enhanced in the topsoil. (3) The relative difference value of MS among cultivation durations were greater at the lower slope than at the upper and middle slopes for all selected slopes; however, all positions became nearly constant after 50a of cultivation; (4) MS values substantially correlated in power function with cultivation duration on the entire slope and on three slope positions with r2 values from 0.50 to 0.86 and root mean square error values from 0.21 to 0.41. Soil MS in croplands varied with cultivation duration and was directly proportional to the increase in cultivation duration, which was used to establish soil redistribution and erosion patterns. The results of this study demonstrate that MS is a credible index for quantifying soil loss during continuous tillage at the centennial scale.

Multi-Factor Analysis on the Stability of High Slopes in Open-Pit Mines

During the production of open-pit mines, the stability of slopes can be affected by various factors such as structural surfaces, production blasting vibrations, and mining areas. In this study, the researchers focused on the slope of the open-pit mine at Yinshan and employed UAV mapping technology to conduct an on-site geological engineering investigation. Information on the yield, trace length, spacing, and density of the structural surface of the south slope was obtained. The researchers also carried out vibration blasting tests in combination with the production blasting activities in the mine to determine the blasting vibration attenuation law and whether the blasting vibration speed met safety specifications. Additionally, numerical simulation methods were used to examine the influence of the mining area on the stability of the current slope and the designed excavation slope. The slope stability was evaluated using the limit equilibrium method, and the researchers separately discussed the influence of self-weight load and self-weight load plus blasting vibration force on the stability of the high slope of the open pit. The results showed the following: (1) The rock mass structural plane in the south slope of the mining area was mainly dominated by a medium-large dip structural plane, and three faults and joint fissures in the investigation area combined to form cutting and sliding surfaces in the rock mass that were prone to collapse and sliding. (2) The maximum blasting vibration speed met safety requirements. (3) There was no large range of plastic zone damage in the entire slope, and the overall stability of the slope was good. (4) The present slope was relatively stable when considering only self-weight stress and the blasting vibration force. However, there was a certain risk of instability in the design of the excavation slope.

Cropland-to-shrubland conversion reduces soil water storage and contributes little to soil carbon sequestration in a dryland area

The conversion of croplands to shrublands is a common approach used to control soil erosion in the drylands of the Loess Plateau in China and affects the soil, water, and carbon cycles. Knowledge of the soil water content (SWC) and soil organic carbon (SOC) content in response to land-use change is essential for optimizing revegetation strategies and improving ecosystem services. This study investigated the distribution characteristics of the SWC and SOC content for the 0–500 cm soil layer in 11 croplands and 39 shrublands planted on a former cropland over 50 years ago. The coupled and trade-off relationship between soil water consumption and carbon fixation in the shrubland soil was also analyzed. The results showed that the SOC content and SWC of the shrublands and croplands varied with soil depth, but their distribution patterns were similar under both land-use types. Planting shrubs on slopes reduced the SWC but did not significantly enhance the SOC content, indicating that cropland-to-shrubland conversion results in excessive soil water depletion without increasing carbon fixation in the soil. Additionally, both the SOC content and SWC of the shrublands varied significantly with slope positions (p < 0.05) and showed intermediate coordination levels across the entire slope. Moreover, the SOC content provided higher benefits than SWC, where the foot slope showing a relatively higher coupling coordination degree and a lower trade-off than other slope positions. These results suggest that shrubs provide a limited contribution to improve SOC stocks in the drylands of the Loess Plateau and that reductions in deep soil water under cropland-to-shrubland conversion require consideration when planning future ecological restoration measures. To improve ecosystem services (carbon sequestration and soil conservation) without compromising water resources in the drylands of the Loess Plateau or similar regions worldwide, it is necessary to fully consider the slope position and the trade-off between the SWC and SOC content.

Quaternary sedimentary processes on the Bahamas: From platform to abyss

Understanding the interaction between sediment production on and export from shallow-water areas of platforms and slopes is primordial when assessing sedimentary processes on a carbonate-platform scale. In this manuscript we explore variations in facies, sediment export, sediment deposition and reorganisation, hydroacoustic- and small-scale sedimentary structures, but also assess the variability in current systems as observed during the Quaternary for the north-facing margin of Little Bahama Bank (LBB) and compare those characteristics with features observed on other slopes surrounding LBB and Great Bahama Bank (GBB).Over the past decade, the northern margin of LBB was explored during a series of oceanographic cruises of the CARAMBAR project, which included the collection of 24.270 km2 of bathymetry data, 6.398 km of very high-resolution seismic profiles, and 42 cores covering water depths ranging from 177 m to 4873 m. This study evaluates the results obtained from the analysis of sediment cores retrieved in the Great Abaco Canyon area (GAC), located between the lower northern LBB slope, which is connected to the abyssal plain. The analysis of the shallower parts of the LBB slope relies on earlier studies and are complementary to our data, and allow for a detailed analysis of the sedimentary processes acting along the entire LBB slope.The data reveal that Quaternary sediment distribution differs when moving from the north-eastern to the north-western LBB slope. The entire LBB slope is dissected by numerous canyons. Gravity processes enriched in coarse platform components occur infrequently and are concentrated within lobes in the east. Only coarse-grained rich bank facies can concentrate coarse grains on this margin. The western LBB slope is mostly influenced by fine-grained platform export and current circulation. The deeper GAC area is dominated by pelagic sediments that are supplied from the canyon sides and through tributaries. The sediment composition confirms that pelagic sediment production and current movements determine the sediment-deposition and redistribution processes at this site.The comparison with other Bahamian slopes demonstrates that a leeward position agrees with high sedimentation rates on the slopes resulting in specific morphologic structures, such as gullies and sediment waves, related to fine-grained sediment export, whereas platform-derived coarse-grained facies are deposited downstream in larger structures, such as canyons, that are not affected by the main wind direction. Slope angle could also have an impact on grain-size export, as it appears that coarse-grained deposits are frequent on steep slopes like those bordering the Exuma Sound basin.

СТІЙКІСТЬ ҐРУНТОВИХ СПОРУД З УРАХУВАННЯМ ПРОСТОРОВОГО ЕФЕКТУ

Problems of stability of soil structures and the development of landslides, including the Black Sea coast, pose a significant danger to the population and existing buildings and structures. The development of landslides and landslide-prone slopes requires careful and detailed study, the results of which should be the basis for the implementation of measures for engineering protection of territories, taken into account in the design and construction of new facilities. When calculating the stability of slopes, there is a difference in the calculated values of the coefficients of stability in two-dimensional and three-dimensional problem statements. Analysis of the research indicates the need to take into account the influence of topographic conditions of the entire slope when calculating it in two-dimensional schemes within the designated areas. Determination of the coefficient of stability can be carried out by both analytical and graph-analytical methods. In most cases, the calculation of the stability of slopes and escarpment and the determination of the coefficient of stability is performed for two-dimensional sections constructed on lines that coincide with the most probable direction of shift of the shear body. The most common methods used in calculating the stability of slopes in a two-dimensional problem statement are the most used because of their simplicity, but these methods are based on the acceptance of some assumptions described above. Based on the analysis of a number of works on two-dimensional and three-dimensional modeling of soil slopes, it is shown that the assessment of the stability of landslides is a complex, responsible and poorly studied task. Performing calculations of soil slopes in the three-dimensional formulation of the problem gives results close to reality, in contrast to the results obtained by conventional and common engineering methods for two-dimensional schemes. This is due to the fact that the three-dimensional formulation of the problem takes into account the combination of engineering and geological conditions of the entire slope. Three-dimensional modeling of soil slopes also allows taking into account factors that have a significant impact on stability, which cannot be taken into account in two-dimensional modeling (features of topography, the presence of trimming slopes, ravines, point structures, etc.).

The distribution of soil C and N along the slope is regulated by vegetation type on the Loess Plateau

Soil carbon (C) and nitrogen (N) dynamics significantly contribute to greenhouse gas emissions from terrestrial ecosystems. However, uncertainty exists regarding the distribution of soil C and N along slopes of various vegetation types. To examine differences in soil C and N on the slope, this study selected three vegetation restoration types of grasslands (Artemisia sacrorum and Artemisia capillaris), shrublands (Caragana korshinskii) and forestlands (Robinia pseudoacacia) with five slope positions (top, upper, middle, lower, and foot). The results showed that the distribution of soil C and N were regulated by the vegetation type. Soil C and N stocks in grasslands and shrublands increased from the top to the foot slope, but this pattern was not observed in forestlands. The lowest coefficients of variation (CVs) of soil C and N along the slope were observed in the shrublands, with the highest soil C (17.0 Mg ha−1) and N (1.9 Mg ha−1) stocks on the entire slope. The primary factors influencing soil C and N distribution along the slope differed depending on the vegetation type. The primary factors influencing soil C and N in grassland slopes were pH and belowground biomass C/N, while those in shrublands and forestlands were pH, litter biomass C/N, and soil inorganic N (NH4+ and NO3–). Moreover, variations in mineral-associated organic C and mineral-associated organic N dominated the soil C and N dynamics. This study showed that vegetation types regulated the distribution of soil C and N throughout the slope. The shrublands were the optimal vegetation type on the entire slope, which can help in boosting soil C and N stocks in Central Loess Plateau.

Assessing flank instability of Stromboli volcano (Italy) by reappraising the 30 December 2002 tsunamigenic landslides

Bearing in mind the destructive potential of tsunamis induced by volcanic landslides, the tsunamigenic event occurring at Stromboli volcano in Italy on 30 December 2002 has been re-examined here, by means of visible images and slope stability analysis. This was one of the few examples in the world of a flank collapse occurring at a volcano that was directly observed. We present the results of stability analyses, together with a sequence of photos collected from a helicopter a few minutes before the collapse. The result of this study is that the sequence of landslides triggering the 2002 Stromboli tsunami can be defined as the final stage of a lateral magma intrusion that exerted a high thrust at high altitude, destabilizing the entire slope. This study allows a more complete understanding of the event that took place on Stromboli on 30 December 2002. Furthermore, the approach used here, if appropriately modified, can be used in other contexts, contributing to the understanding of the condition that leads to tsunamigenic landslides.

Along-slope bottom currents driven by dissipation of internal tides in the northeastern South China Sea

Recent mooring observations on the continental slope on the east side of the Dongsha Island in the northeastern South China Sea (SCS) showed that an along-slope bottom current can be generated when internal tides obliquely incident to the slope are dissipated near the seafloor. In this study, new mooring data collected on the south side of the Dongsha Island are used to explore the universality of internal wave driven the bottom currents and test the ability of the previous theory in estimating the along-slope current. The data show strong near-bottom energy dissipation due to the critical reflection of diurnal internal tides on the continental slope, with a time-mean depth-integrated dissipation rate of ~4.8×10-3 W/m2. Because of the obliquely incident of diurnal internal tides to the slope, near-bottom dissipation of internal tides generates a southwestward along-slope current, with the maximum velocity exceeding 6 cm/s. By comparing the observations, the previous theory for internal wave induced mean flows developed by Thorpe (1999) shows a good ability to estimate the along-slope bottom current velocity. Based on the theory, as well as modelled energy dissipation on the entire continental slope in the northeastern SCS, a map is obtained to quantitatively describe the along-slope bottom flow caused by internal tide breaking on the slope.

Liquefaction-induced flow-like landslides: the case of Valarties (Spain)

This paper examines a flowslide involving a glacial deposit of low-plasticity silty sand triggered by a karstic spring after a rainfall period. The work aims at explaining the triggering, propagation and kinematics of flow-like landslides in a unique framework. In particular, a material point method open-source code, able to solve coupled hydro-mechanical problems for saturated/unsaturated soils, was developed. Laboratory and field experiments revealed a liquefaction potential of the mobilised material. To simulate such potential, a recent liquefaction model (Ta-Ger), validated so far at a laboratory scale, was selected, extended to unsaturated conditions, implemented and calibrated. The analysis indicates a complex behaviour of the moving mass and explains the mechanisms developing sequentially in the flowslide. The impact of the upper unstable soil mass against the soil at lower elevations is a key phenomenon to generalise soil liquefaction in the entire slope. Patterns of soil velocity and displacements are far from being a uniform flow of liquefied material. The model developed is a powerful tool to interpret flowslides involving a saturated and unsaturated soil profile. The paper includes sensitivity analyses and discusses the discrepancies observed in the run-up of the flowslide climbing on the opposite slope of the valley.

Experimental and Numerical Study on Progressive Collapse Analysis of a Glulam Frame Structure: I. Side Column Exposed to Fire

This paper presents experimental and numerical investigations on progressive collapse behavior of a two-story glulam frame when the side column is exposed to ISO834 standard fire. The collapse mechanism initiated by fire is identified. The experimental results show that the progressive collapse of a glulam frame could be described for three stages, namely bending effect stage, catenary effect stage and failure stage, respectively. These stages are discussed in detail to understand the structural behavior before and during collapse. It is demonstrated that the entire frame slopes towards the side of the heated column, and the “overturning” collapse occurs eventually. The catenary effect of beams is the main reason for the progressive collapse of the frame. In addition, a finite element model of a glulam frame is established to simulate the progressive collapse behavior. The effects of axial loads on the columns are summarized. The numerical simulation results agree well with the experimental results, which could verify the effectiveness and practicability of finite element simulation. Furthermore, the progressive collapse resistance of the frame in practical design were proposed.

Parametric Design and Field Behavior of Earthen Structures

The stability of earthen structures is governed by field uncertainties arising from material properties, environment loading, and slope geometry. This research devised a systematic approach to capture the effects of field uncertainties on the stability of natural and manmade slopes. New design charts were developed by incrementally changing slope geometry and randomly generating shear strength parameters. Subset simulation was used to determine the safe range of soil properties for various slopes. The charts were applied to three published case studies with distinct triggering mechanisms resulting from complex field settings. All of the investigated slopes were found to be stable (factor of safety (FOS) &gt; 1.0) under the reported geometry and shear strength parameters while assuming no water table. The effects of soil properties’ variation and environmental conditions on fluctuating water table were captured through history matching. Results indicated three distinct failure mechanisms: foundation settlement of a glacial moraine till (Vernon, British Columbia) due to an increased pore water pressure during construction of the compacted fill (FOS = 1.45 without berms and 2.24 with berms); instability in the natural cut (FOS = 0.98) comprising layered glacio-lacustrine clays (Labret, Saskatchewan) due to saturation of the entire slope resulting from a long duration rainfall; and collapse of a compacted fill (FOS = 0.98) on a glacial moraine till (Hamelin Creek, Alberta) due to soil saturation arising from thawing of a frozen layer in the slope. This validation illustrates that the new approach fully captures environmental loading (resulting in water table variation in the slope) and partly captures construction practice and site geology via soil properties.

Theoretical and numerical analysis of flexural toppling failure in soft-hard interbedded anti-dip rock slopes

Soft-hard interbedded structures are commonly found in anti-dip rock slopes and endow the slopes with special properties. In this work, a simple two-beam model was first used to discuss the possible failure modes of rock layers with different lithology. The exact failure sequence of rock layers depends on their tensile strengths, elastic moduli, and thicknesses. Then, based on the deformation compatibility of rock layers, a novel theoretical method called the DCM for assessing the stability of soft-hard interbedded anti-dip rock slopes was proposed. A centrifuge test and a numerical model were used to verify the feasibility of the DCM. The calculated critical g-level of 47 g for the centrifuge model and a safety factor of 0.96 for the numerical model agree well with the results of the centrifuge test (45 g) and numerical simulation (0.98). Moreover, the traditional limit equilibrium method (LEM) was also adopted to explore these two models. The calculated results of 68 g and 1.79 using the traditional LEM were found to be much larger than the validated values, with deviations of more than 50%. This finding implies that the traditional LEM is not suitable for assessing the stability of soft-hard interbedded anti-dip rock slopes. In addition, the failure evolution of toppling failure in soft-hard interbedded anti-dip rock slopes was investigated using numerical modelling. The results show that the soft and hard rock layers do not fail at the same time; the rock layers of one type of lithology are destabilized first, then the other rock layers begin to fail until the entire slope undergoes flexural toppling.

ОЦІНКА СТІЙКОСТІ ДІЛЯНКИ СХИЛУ ОДЕСЬКОГО УЗБЕРЕЖЖЯ

Currently, there is a reduction in sites convenient for the construction of facilities. In this regard, the question of the development of new territories that were previously considered unsuitable or economically unprofitable for construction is increasingly being raised. Very often it is necessary to build buildings and structures on or near slopes. The development of landslide and landslide-prone slopes requires a comprehensive study, the results of which should be used in the selection of measures for the engineering protection of territories, as well as design and construction on slopes. The main task of engineers, when performing design and survey work in landslide-prone areas, is to assess the stability of the slope and the magnitude of the landslide pressure. The article calculates the stability of the landslide-prone slope of the Odessa coast for the purpose of further construction development. The slope in question is located on the Franzysky Boulevard, in the area of the Chkalov resort. The site features are in complex engineering and geological conditions (loess soils, collapsing properties of soils, several water-bearing layers). It has been established that deep block landslides of extrusion occurred earlier in this area. After landslide control measures consisting in construction of marine cost protection and drainage structures, an increase in slope stability was observed. Despite the measures taken, there is a beach erosion with partial destruction of coast protection structures, which can lead to increased abrasion and negatively affect the stability of the entire slope. Slope stability calculations are performed in two-dimensional and three-dimensional formulation. According to the flat schemes, calculations were performed in the Slide software package using Bishop and Janbu methods. The slope stability assessment in a three-dimensional formulation was performed by the finite element method using the Midas GTS NX calculation program and consists of determining the stress-strain state of the soil mass and the stability margin factor. Based on the calculation results obtained, the slope stability is assessed and options for landslide control (retaining) structures are proposed.

Numerical Simulation of Slope Stability during Underground Excavation Using the Lagrange Element Strength Reduction Method

In this study, the Lagrange element strength reduction method is used to explore slope stability and as an evaluation method of underground mining of end-slope coal in a rock-stability analysis. A numerical analysis model is established herein using the geological conditions for mining in a coordinated open pit with an underground mining area of the Anjialing Open-Pit Mine and Underground No. 2 Mine. Additionally, the evolution law of slope stability in open-pit end-slope mining is studied using the proposed numerical simulation method. According to our findings, the steps show obvious horizontal movement and deformation under the influence of underground mining disturbances. Taking the horizontal displacement at the slope tops of the steps as the deformation index, the entire disturbed slope is divided into four regions: upper, middle-upper, middle-lower, and lower steps. When a step is fully affected by underground mining, its subsidence value first increases rapidly and then slowly. An exponential function is used to reflect the change rule in the step-subsidence value as the working face advances. In the underground mining process, the critical sliding surface of the slope develops along the soft rock or coal seam, showing an L-shaped or a W (double L)-shaped broken line. As the working face advances, the initial position of the sliding mass is unchanged while the cutting position alternately changes up and down in the weak plane. The safety factor suddenly drops when the advancing distance exceeds a certain value.

A computationally efficient SPH framework for unsaturated soils and its application to predicting the entire rainfall-induced slope failure process

The first and fully validated smoothed particle hydrodynamics (SPH) model is presented to tackle coupled flow–deformation problems in unsaturated porous media that undergo large deformation and post-failure behaviour. Unlike the commonly adopted double-layer SPH framework for saturated soils, this paper presents a three-phase single-layer SPH model capable of predicting anisotropic seepage flows through porous media and their complete time-dependent transition from unsaturated to saturated states, as well as their influence on the mechanical behaviour of the porous media and vice versa. The mathematical framework is developed based on Biot's mixture theory and discretised using the authors’ recently developed novel SPH approximation scheme for the second derivatives of a field quantity. The soil is modelled using a suction-dependent elastoplastic constitutive model, expressed in terms of effective stress and suction. In addition, an adaptive two-timescale scheme is proposed for the first time to address existing challenges in solving coupled-flow large-deformation problems that involve a significant difference in the timescale required for the solid and fluid phases. The capability of the proposed SPH model was demonstrated through fundamental consolidation tests and a large-scale rainfall-induced slope failure experiment. Very good agreements with theoretical solutions and experimental results are achieved, suggesting that the proposed SPH model can be readily extended to solve a wide range of large-scale geotechnical applications involving coupled unsaturated seepage–deformation problems.

Effects of material migration on the spatial distribution of topsoil moisture at the slope scale

Soil moisture is strongly spatially variable and scale dependent, but there is a lack of research focusing on factors that link soil actual evaporation to the spatial distribution of topsoil moisture at the slope scale. External factors (e.g., meteorological) have similar effects across entire slopes; hence, this paper instead explores the internal factors controlling differential soil actual evaporation. We consider the effects of historical rainfall on soil erosion, and adopt a combined approach encompassing slope investigations, a slope rainfall simulation experiment, slope erosion analyzed by 3D laser terrain scanning, and evaporation experiments. Along the runoff direction, we show that the relative topsoil clay content increases, but slope surface deformation and failure lead to a decrease in the relative content of clay in deposits located on the lower of slope. The original thickness of slope surface decreases in the upper part of the slope, due to particle migration, while the slope surface relatively far away from the upper part of the slope tends to be thicker, due to the accumulation of slope deposits. The actual evaporation of the topsoil relatively far from the upper part of the slope is significantly weaker (63%–72% probability), which may be related to the high clay content, dense soil structure, and high content of clay minerals. The topsoil evaporation also tends to weaken as overburden thickness increases. Here, we suggest that marked differences in the original thickness of the slope surface and in the properties of the topsoil caused by the migration and deposition of soil particles under successive years of rainfall erosion, are important factors controlling differences in topsoil actual evaporation in different parts of the slope. This understanding lays the foundation for the analysis of hydrological processes in different parts of a slope, which is crucial for the study of shallow slope mechanical behavior.

Opak Fault Strand Delineation Using Merapi Slope Shifted Indicator

Abstract After the Yogya earthquake occurred on May 27, 2006, the opinions of experts split into two groups regarding location of responsible fault to earthquake shacking; (1), First group argues that Opak Fault displacement caused the earthquake. Where fault line is commonly known runs along Opak River, striking from Parangtritis Beach to Prambanan. (2) Second group of experts stated at deferent opinion, that another fault displacement triggered the earthquake shock. Where is located at the East side of the Opak River about 10 Km. On the other-hand, this paper proposes an idea to unravel Opak Fault position by understanding, that main active fault movement underlying Bantul region has been influencing continuum mechanical process, onto Merapi Sediments surface since the early periods of continuing Merapi materials sedimentation. It should has been reflected to the surface landform at above the fault strand. Further, indicates to morphotectonic feature as an en echelon slope shifted alignment. Thus, it can be the way to assist in defining attribute of main fault (PDZ) areas by using its en echelon indicator of shifting slope alignment. This paper also presents the results of determining Opak fault line location by using Digital Elevation Model (DEM-NAS) to generate custom shading in approaching landform features. With a further doing specific landscapes observations over the entire of Young Merapi deposits. There are other challenges to alternate identification of buried basin faults fill, by doing carefully identifications in morphotectonic aspects over the entire South Slope Merapi flank. It traces from Kepurun village at about elevation 400 m towards Parangtritis at 25 m of elevation. Independent field morphotectonic data sets of such scarp, terraces, water springs alignment and active cracks are encountered in the vicinity of Merapi sediments slope shifted, particularly in Tirtomartani Jetis village Kalasan. Identification of such structures obtained from morphotectonic analysis results are regarded as reliable indicator of faults, which is efficiently can be found in field. Key word: Opak Fault, Morphotectonic, Slope Shifted, Delineation.

TrophicCS: Spatialized trophic data of the Celtic Sea continental shelf food web.

Understanding the dynamics of species interactions for food (prey-predator, competition for resources) and the functioning of trophic networks (dependence on trophic pathways, food chain flows, etc.) has become a thriving ecological research field in recent decades. This empirical knowledge is then used to develop population and ecosystem modeling approaches to support ecosystem-based management. The TrophicCS data set offers spatialized trophic information on a large spatial scale (the entire Celtic Sea continental shelf and upper slope) for a wide range of species. It combines ingested prey (gut content analysis) and a more integrated indicator of food sources (stable isotope analysis). A total of 1337 samples of large epifaunal invertebrates (bivalve mollusks and decapod crustaceans), zooplankton, fish, and cephalopods, corresponding to 111 taxa (94% determined at the species level), were collected and analyzed for stable isotope analysis of their carbon and nitrogen content. Samples were collected between 2014 and 2016, mostly during the month of November and between 57 and 516 m depth. Sample size varied between taxa (from 1 to 52), with 98 taxa having at least three samples. The gut contents of 1027 fish belonging to 10 commercially important species: black anglerfish (Lophius budegassa), white anglerfish (Lophius piscatorius), blue whiting (Micromesistius poutassou), cod (Gadus morhua), haddock (Melanogrammus aeglefinus), hake (Merluccius merluccius), megrim (Lepidorhombus whiffiagonis), plaice (Pleuronectes platessa), sole (Solea solea), and whiting (Merlangius merlangus) were analyzed. Sampling occurred in November 2014 and 2015. The gut content data set contains the occurrence of prey in gut, identified to the lowest taxonomic level possible. No prey were assigned for 274 empty gut contents. To consider potential ontogenetic diet changes, a large size range was sampled for each species. The TrophicCS data set was used to improve understanding of trophic relationships and ecosystem functioning in the Celtic Sea. Data are released under a CC-BY-NC-SA license, and please cite this paper when reusing the data.

PROPERTIES OF SOILS ALONG A TOPOSEQUENCE UNDERLAIN BY COARSE GRAINED GRANITE GNEISS IN IFE AREA SOUTH WEST NIGERIA

Research has shown that soil profiles are influenced by five separate, yet interacting factors: parent material, climate, topography, organisms and time which give soil profiles their distinctive character. Topography however, plays a major role in the variation of soil properties and nutrient distribution along a non-uniform agricultural landscape. This study was conducted to investigate the effects of topography on chemical properties of soil underlain by coarse grained granite gneiss at the teaching and research farm of Obafemi Awolowo University Ile Ife. Three profile pits was established at different physiographic positions along a toposequence (upper, middle and lower positions) were considered for this study. A total of eleven (11) samples were collected for routine laboratory analysis from the established horizons. The results revealed that the clay content increased with increase in profile depth while sand content decreases. Organic matter content was relatively low 0.2 – 1.35%, a result of continuous cultivation in the area. The values of available P (1.29 – 5.40ppm) showed that it is inadequate for crop production. The pH, exchangeable cations and exchangeable acidity values fluctuate across the pedons under investigation. The correlation between slope position and chemical properties showed that no singular property consistently showed the same level of significance on the entire slope.&#x0D; For effective management of the soils, organic inputs and usage of vegetal cover such as planting of cowpea and other crawling plants of economic importance should be adopted to assist in improving the organic matter content, conservation management practices should also be employed to prevent rapid soil degradation across the topography.

The State of the Art and New Insight into Combined Finite–Discrete Element Modelling of the Entire Rock Slope Failure Process

The stability of rock slopes is of significance, as even the slightest slope failure can result in damage to infrastructure and catastrophes for human beings. Thus, this article focuses on the review of the current techniques available for rock slope stability analysis. The rock slope stability techniques can be classified as conventional methods and numerical methods. The advantages and limitations of the conventional method are briefly reviewed. The numerical methods mainly included three types, i.e., continuum methods, discontinuum methods, and the combined/hybrid continuum–discontinuum methods. This article pays more attention to the last type. The combined/hybrid finite–discrete element method (FDEM), which might be the most widely used continuum–discontinuum method, is introduced and we illustrated its abilities in modelling the entire rock slope failure process. The fundamental principles of FDEM, i.e., the contact interaction of the discrete bodies and the transition from continuum to discontinuum, are introduced in detail. The abilities of the FDEM in modelling the rock slope failure process are calibrated by modelling the entire typical rock slope failure process. Then, the application of the FDEM in the analysis of slope stability is introduced and discussed. Finally, the authors give insight into the GPGUP-parallelized FDEM modelling of the high rock slope failure process by the implementation of the strength reduction method (SRM). It is concluded that the FDEM can effectively model the entire rock slope failure process, even without the implantation of any slope modes, and the GPGUP-parallelized FDEM is a promising tool in the study and application of rock slope stabilities.