Journal articles on the topic 'DEM Soil'
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Michalopoulou, Maria, Nikolaos Depountis, Konstantinos Nikolakopoulos, and Vasileios Boumpoulis. "The Significance of Digital Elevation Models in the Calculation of LS Factor and Soil Erosion." Land 11, no. 9 (September 16, 2022): 1592. http://dx.doi.org/10.3390/land11091592.
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This study focuses on the role of topography in soil erosion modelling by examining the impact of topographic data from various sources on the calculation of the slope length and slope steepness factor (LS). For this purpose, the Pinios dam drainage basin in the Ilia Regional Unit, Western Greece, was selected as a pilot area of this study. Specifically, six Digital Elevation Models (DEM) from four different sources with various resolutions (5, 30, and 90 m) were compared with ground control point (GCP) values to assess their relative vertical accuracy. These DEM were acquired for the calculation of the LS factor by using two different equations. Then the calculated LS factors were implemented in the RUSLE model for the estimation of soil loss. The current study includes a comparative analysis of the elevation, the slopes, the LS factor, and the soil loss. The results showed that the 5 m resolution DEM had the best vertical accuracy, and thus it is considered to be the most suitable DEM for soil erosion modelling. Moreover, the comparison of the DEM elevation values showed high similarity, in contrast to the slope values. In addition, the comparative assessment of the LS and soil loss values calculated from each DEM with the two LS equations revealed a great divergence. It is noticeable that both LS and soil loss results presented higher values for slopes greater than 20°. It is concluded that the comparison of the LS values calculated with the two examined approaches and the use of different DEM with various resolutions and different sources does not change consistently with the increase of DEM grid size and accuracy. Thus, it is very significant in soil erosion modelling to use an LS equation that imports thresholds in its formula to avoid overestimation in soil loss calculations.
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Aouichaty, Nabil, Yassine Bouslihim, Said Hilali, Abdeljalil Zouhri, and Yahya Koulali. "Influence of DEM resolution on the RUSLE model: Case of abandoned quarries in Settat province (Morocco)." E3S Web of Conferences 314 (2021): 04004. http://dx.doi.org/10.1051/e3sconf/202131404004.
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Topographic slope information is one of the critical variables, which governs soil erosion. This topographic slope can be derived from the Digital Elevation Model (DEM). Significant discrepancies are found in the estimation of soil erosion using different DEMs of different resolutions. In the present study, the Revised Universal Soil Loss Equation (RUSLE) was used for soils in the Settat province (Morocco) to assess the risk of water erosion caused by abandoned quarries. The soil erosion rate was divided into five classes to illustrate the erosion rate variability using two DEMs (30m and 90m). The impact of topography on erosion was determined by calculating the value of the LS factors. In this case, the values obtained vary between 0 - 120.623 for ASTER DEM (30m) and 0 - 10.225 for DEM SRTM (90m). The results also show that most quarries have a soil loss rate that varies between 0 t/ha/year and 8.1 t/ha/year for ASTER DEM (30 m). However, for DEM SRTM (90 m), the soil loss rate is zero. This suggests that RUSLE model users should use high-resolution input data for a close representation of reality and capture the maximum results with reasonable accuracy.
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Wu, Jiaxiong, Yanhua Shen, Shudi Yang, and Zhipeng Feng. "Simulation of Track-Soft Soil Interactions Using a Discrete Element Method." Applied Sciences 12, no. 5 (February 28, 2022): 2524. http://dx.doi.org/10.3390/app12052524.
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With the development of unmanned tracked vehicles, soil model predictions of soft terrains are becoming more essential. In order to accurately simulate the interaction characteristics between soil particles and the track, soil modeling with a discrete element method (DEM) is proposed. Volume-based scaled-up modeling of DEM soil particles and the calibration of DEM input parameters were investigated as a feasible approach to realizing many particle calculations. Calibration of DEM input parameters can solve the distortions between actual and DEM particle sizes. Cohesion and friction parameters of the scaled-up soil particle model were recalibrated by the shape accumulated through the virtual design of the experiment. Soil DEM particles were scaled up to 1 mm spherical particles, and recalibrated DEM parameter values were used to match the actual accumulated soil shape. Three calibrated scaled-up soil models were used for the shear stress–displacement DEM simulation of a track segment, and the mean absolute percentage error (MAPE) was less than 11% compared with the actual shear stress–displacement test. The parameter value of soil traction performance empirical model of a tracked vehicle is modified according to the soil shear stress–displacement DEM simulation. Comparative analysis was performed for travel test results of a tracked vehicle; the relative error of the soil traction prediction results to actuals was less than 16.8%. This showed that the volume-based particle scaling technique is an effective DEM for the mechanical simulation of soil.
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Drover, D. R., C. R. Jackson, M. Bitew, and E. Du. "Effects of DEM scale on the spatial distribution of the TOPMODEL topographic wetness index and its correlations to watershed characteristics." Hydrology and Earth System Sciences Discussions 12, no. 11 (November 12, 2015): 11817–46. http://dx.doi.org/10.5194/hessd-12-11817-2015.
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Abstract. Topographic wetness indices (TWIs) calculated from digital elevation models (DEMs) are meant to predict relative landscape wetness and should have predictive power for soil and vegetation attributes. While previous researchers have shown cumulative TWI distributions shift to larger values as DEM resolution decreases, there has been little work assessing how DEM scales affect TWI spatial distributions and correlations with soil and vegetation properties. We explored how various DEM resolutions (2, 5, 10, 20, 30, and 50 m) subsampled from high definition LiDAR altered the spatial distribution of TWI values and the correlations of these values with soil characteristics determined from point samples, Natural Resources Conservation Service (NRCS) soil units, depths to groundwater, and managed vegetation distributions within a first order basin in the Upper Southeastern Coastal Plain with moderate slopes, flat valleys, and several wetlands. Point-scale soil characteristics were determined by laboratory analysis of point samples collected from riparian transects and hillslope grids. DEM scale affected the spatial distribution of TWI values in ways that affect our interpretation of landscape processes. At the finest DEM resolutions, valleys disappeared as TWI values were driven by local microtopography and not basin position. Spatial distribution of TWI values most closely matched the spatial distribution of soils, depth to groundwater, and vegetation stands for the 10, 20, and 30 m resolutions. DEM resolution affected the shape and direction of relationships between soil nitrogen and carbon contents and TWI values, but TWI values provided poor prediction of soil chemistry at all resolutions.
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Newton, Paul C. D., Gregor W. Yeates, and Des J. Ross. "Response of soil nematode fauna to naturally elevated CO2 levels influenced by soil pattern." Nematology 1, no. 3 (1999): 285–93. http://dx.doi.org/10.1163/156854199508289.
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Abstract As experimental elevation of CO2 in short-term experiments may produce organic matter with decomposition characteristics different from those produced under long-term equilibrated conditions, we sampled the soil nematode fauna near a natural CO2 vent in Northland, New Zealand. Various indices of the nematode fauna showed significant effects, with all being significantly correlated with soil pH, microbial carbon and atmospheric CO2 across the 33 sampling points. There was a general decrease in nematode abundance and diversity, but an increase in dominance and proportion of bacterial-feeding nematodes with increasing atmospheric CO2 concentration. However, when the nematode data from gley and organic soils present at the site were differentiated most of the significant correlations were with soil microbial carbon; they were positive in the organic soil but negative in the gley soil. That these responses can be related to soil carbon and to microbial carbon demonstrates that any general response to long-term CO2 enrichment represents an integration of specific responses by the soil biota in the various soils present. Die Reaktion der Bodennematodenfauna auf durch Bodenbedingungen beeinflusste naturlich erhohte CO2-Werte - Da eine experimentelle Erhohung von CO2 in Kurzzeitversuchen organisches Material erzeugen konnte, das andere Zersetzungseigenschaften hat als das unter ausgeglichenen Langzeitbedingungen entstehende, haben wir die Nematodenfauna in Bodenproben aus der Nahe eines naturlichen CO2-Austrittes in Northland, Neuseeland untersucht. Bei mehreren Kennzeichen der Nematodenfauna zeigten sich deutliche Wirkungen, die alle signifikant korreliert waren mit dem Boden-pH, dem mikrobiellen Kohlenstoff und dem atmospharischen CO2, und zwar quer durch alle 33 Entnahmestellen. Mit steigender Konzentration des atmospharischen CO2 trat eine allgemeine Abnahme der Haufigkeit und der Verschiedenartigkeit der Nematoden ein, aber eine Zunahme der Vorherrschaft und des Anteils bakterienfressender Nematoden. Wenn aber die Nematodenwerte von an einer Entnahmestelle vorhandenen Gley- und organischen Boden vergleichen wurden, bestanden die meisten der signifikanten Beziehungen mit dem mikrobiellen Kohlenstoff. Sie waren positiv im organischen Boden und negativ im Gleyboden. Die Tatsache, dass diese Reaktionen zum Bodenkohlenstoff und dem mikrobiellen Kohlenstoff in Beziehung gebracht werden konnen zeigt, dass jede allgemeine Reaktion auf eine langfristige Anreicherung von CO2 eine Integration spezischer Reaktionen durch die in den verschiedenen Boden vorhandenen biotischen Faktoren darstellt.
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Lin, Chunxiu, Chang Xia, Zhen Liu, and Cuiying Zhou. "A Comprehensive Correlation Study of Structured Soils in Coastal Area of South China about Structural Characteristics." Journal of Marine Science and Engineering 10, no. 4 (April 6, 2022): 508. http://dx.doi.org/10.3390/jmse10040508.
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Granite residual soil is a common engineering material, and its mechanical properties are of great importance to engineering safety. This kind of soil presents obvious structural characteristics, and many researchers have emphasized the significance of its structural features. According to previous experiments, from a macroscopic perspective, many researchers have investigated the structural relationship between undisturbed and remolded soils, but few studies have considered it in the mesoscopic aspect. Adopting DEM (a mesomechanical simulation method), we can study how the structure affects the mechanical process between undisturbed and remolded soil. Therefore, this paper combines DEM with laboratory tests to study the structural characteristic correlation between undisturbed and remolded soil. The results indicate that a weak cohesion effect exists in undisturbed soil, and the damage of weak cohesion elements accompanies the failure process. Weak cohesion elements in undisturbed soil cause inhomogeneities in deformation, stress state, and damage accumulation, which ultimately causes differences in strength curves. This paper explains the mechanism of the structural effect on mechanical evolution from a mesomechanical perspective. The DEM simulation method proposed in this paper can be applied to structured soils and better guide engineering practice.
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Zhou, Hao, Tienan Zhou, Xuezhen Wang, Lian Hu, Shengsheng Wang, Xiwen Luo, and Jiangtao Ji. "Determination of Discrete Element Modelling Parameters of a Paddy Soil with a High Moisture Content (>40%)." Agriculture 12, no. 12 (November 24, 2022): 2000. http://dx.doi.org/10.3390/agriculture12122000.
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Discrete element modelling (DEM) parameters are of great importance for the accurate prediction of soil properties and disturbance. This study aimed to provide an efficient method for accurately determining the DEM parameters of a paddy soil with a high moisture content (45.66%). The DEM parameters of the paddy soil modelled using the Hertz–Mindlin with JKR contact model were determined by using the Plackett–Burman (PB), steepest ascent, and central composite tests. The accuracies of the developed DEM models were evaluated using actual slumping tests. Based on the PB test, the surface energy of soil, coefficients of soil–soil rolling friction, and coefficients of soil–steel static friction exerted larger influences on the overall relative error (δZH). The optimization results showed that to achieve a minimum δZH (5.96%), the surface energy of soil, the coefficients of soil–soil rolling friction, and the coefficients of soil–steel static friction should be 0.808 J m−2, 0.11, and 0.6, respectively. The optimized DEM model had an overall relative error of 7.27% with a coefficient of variation of 1.32%, indicating that the DEM parameters of the calibrated paddy soil had good accuracy.
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Chidi, Chhabi Lal, Wei Zhao, Suresh Chaudhary, Donghong Xiong, and Yanhong Wu. "Sensitivity Assessment of Spatial Resolution Difference in DEM for Soil Erosion Estimation Based on UAV Observations: An Experiment on Agriculture Terraces in the Middle Hill of Nepal." ISPRS International Journal of Geo-Information 10, no. 1 (January 13, 2021): 28. http://dx.doi.org/10.3390/ijgi10010028.
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Soil erosion in the agricultural area of a hill slope is a fundamental issue for crop productivity and environmental sustainability. Building terrace is a very popular way to control soil erosion, and accurate assessment of the soil erosion rate is important for sustainable agriculture and environmental management. Currently, many soil erosion estimations are mainly based on the freely available medium or coarse resolution digital elevation model (DEM) data that neglect micro topographic modification of the agriculture terraces. The development of unmanned aerial vehicle (UAV) technology enables the development of high-resolution (centimeter level) DEM to present accurate topographic features. To demonstrate the sensitivity of soil erosion estimates to DEM resolution at this high-resolution level, this study tries to evaluate soil erosion estimation in the Middle Hill agriculture terraces in Nepal based on UAV derived high-resolution (5 × 5 cm) DEM data and make a comparative study for the estimates by using the DEM data aggregated into different spatial resolutions (5 × 5 cm to 10 × 10 m). Firstly, slope gradient, slope length, and topographic factors were calculated at different resolutions. Then, the revised universal soil loss estimation (RUSLE) model was applied to estimate soil erosion rates with the derived LS factor at different resolutions. The results indicated that there was higher change rate in slope gradient, slope length, LS factor, and soil erosion rate when using DEM data with resolution from 5 × 5 cm to 2 × 2 m than using coarser DEM data. A power trend line was effectively used to present the relationship between soil erosion rate and DEM resolution. The findings indicated that soil erosion estimates are highly sensitive to DEM resolution (from 5 × 5 cm to 2 × 2 m), and the changes become relatively stable from 2 × 2 m. The use of DEM data with pixel size larger than 2 × 2 m cannot detect the micro topography. With the insights about the influencing mechanism of DEM resolution on soil erosion estimates, this study provides important suggestions for appropriate DEM data selection that should be investigated first for accurate soil erosion estimation.
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Feng, De Cheng, Wen Xin Zuo, and Peng Cao. "The Prospect and Review of DEM Model Using in Saturated and Unsaturated Soil." Applied Mechanics and Materials 105-107 (September 2011): 1371–75. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1371.
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The saturated and unsaturated soil were widely studied by many researchers nowadays. With the development of calculation mechanics and computer, the discrete element method (DEM), as a powerful technique, has been implemented in saturated soil mechanics. This paper review the development of DEM and its application in saturated soil research. Meanwhile, it also prospect the application of DEM in unsaturated soil research. Besides, it also raised some problems that might be met in the real practice and it also tried to put forward some reasonable methods to solve these problems. In the end, this paper put forward a new DEM contact model based on the surface energy to analysis unsaturated soil.
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Nguyen, Hoang Bao Khoi, Md Mizanur Rahman, and Md Rajibul Karim. "An Investigation of Instability on Constant Shear Drained (CSD) Path under the CSSM Framework: A DEM Study." Geosciences 12, no. 12 (December 6, 2022): 449. http://dx.doi.org/10.3390/geosciences12120449.
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Soil liquefaction or instability, one of the most catastrophic phenomena, has attracted significant research attention in recent years. The main cause of soil liquefaction or instability is the reduction in the effective stress in the soil due to the build-up of pore water pressure. Such a phenomenon has often been thought to be related to the undrained shearing of saturated or nearly saturated sandy soils. Notwithstanding, many researchers also reported soil instability under a drained condition due to the reduction in lateral stress. This condition is often referred to as the constant shear drained (CSD) condition, and it is not uncommon in nature, especially in a soil slope. Even though several catastrophic dam failures have been attributed to CSD failure, the failure mechanisms in CSD conditions are not well understood, e.g., how the volumetric strain or effective stress changes at the triggering of flow deformation. Researchers often consider the soil fabric to be one of the contributors to soil behaviour and use this parameter to explain the failure mechanism of soil. However, the soil fabric is difficult to measure in conventional laboratory tests. Due to that reason, a numerical approach capable of capturing the soil fabric, the discrete element method (DEM), is used to investigate the CSD shearing mechanism. A series of simulations on 3D assemblies of ellipsoid particles was conducted. The DEM specimens exhibited instability behaviour when the effective stress paths nearly reached the critical state line. It can be clearly observed that the axial and volumetric strains changed suddenly when the stress states were close to the critical state line. Alongside these micromechanical observations, the study also presents deeper insights into soil behaviour by relating the macro-observations to the micromechanical aspect of the soil.
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Costa, Elias Mendes, Alessandro Samuel-Rosa, and Lúcia Helena Cunha dos Anjos. "Digital elevation model quality on digital soil mapping prediction accuracy." Ciência e Agrotecnologia 42, no. 6 (December 2018): 608–22. http://dx.doi.org/10.1590/1413-70542018426027418.
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ABSTRACT Digital elevation models (DEM) used in digital soil mapping (DSM) are commonly selected based on measures and indicators (quality criteria) that are thought to reflect how well a given DEM represents the terrain surface. The hypothesis is that the more accurate a DEM, the more accurate will be the DSM predictions. The objective of this study was to assess different criteria to identify the DEM that delivers the most accurate DSM predictions. A set of 10 criteria were used to evaluate the quality of nine DEMs constructed with different data sources, processing routines and three resolutions (5, 20, and 30 m). Multinomial logistic regression models were calibrated using 157 soil observations and terrain attributes derived from each DEM. Soil class predictions were validated using leave-one-out cross-validation. Results showed that, for each resolution, the quality criteria are useful to identify the DEM that more accurately represents the terrain surface. However, for all three resolutions, the most accurate DEM did not produce the most accurate DSM predictions. With the 20-m resolution DEMs, DSM predictions were five percentage points less accurate when using the more accurate DEM. The 5-m resolution was the most accurate DEM overall and resulted in DSM predictions with 44% accuracy; this value was equal to that obtained with two coarser resolution, lower accuracy DEMs. Thus, identifying the truly best DEM for DSM requires assessment of the accuracy of DSM predictions using some form of external validation, because not necessarily the most accurate DEM will produce the best DSM predictions.
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Rui, Rui, Frits van Tol, Xiao-Long Xia, Suzanne van Eekelen, Gang Hu, and Yuan-you Xia. "Evolution of soil arching; 2D DEM simulations." Computers and Geotechnics 73 (March 2016): 199–209. http://dx.doi.org/10.1016/j.compgeo.2015.12.006.
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Case, Bradley S., Fan-Rui Meng, and Paul A. Arp. "Digital elevation modelling of soil type and drainage within small forested catchments." Canadian Journal of Soil Science 85, no. 1 (February 1, 2005): 127–37. http://dx.doi.org/10.4141/s04-008.
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This paper deals with predicting flow accumulation, drainage class, and soil and vegetation type within small headwater catchments (<20 ha) of two contrasting forested areas in northern New Brunswick, Canada, based on digital elevation modelling. A digital elevation model (DEM), with a point sampling resolution of about 75 m, was used to derive local flow accumulation and slope gradients. These calculations were then compared with direct field mapping of flow accumulation and slope gradients, involving on-site tracking of watershed boundaries, ridges, hummocks, depressions, gullies, and stream channels. In general, the resulting DEM-derived and field-assessed flow accumulation values did not differ statistically from each other. Subsequently, these values were analyzed as potential predictors for soil wetness, drainage, and soil and vegetation type as determined for 77 small forest plots, all scattered throughout the catchments at locations of increasing flow accumulation. In this analysis, the field-assessed flow accumulation values were found to be better predictors than the DEM-derived values . It is suggested that the DEM-derived predictions would be much enhanced by an increased DEM resolution, and that this increase would lead to particularly reliable estimates for local soil wetness, drainage, and soil and vegetation type in catchments with low substrate permeability. Key words: Flow accumulation, soil wetness index, soil taxonomic units, soil drainage, soil permeability, digital elevation model
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Graziani, Alessandro, Claudio Rossini, and Tatiana Rotonda. "Characterization and DEM Modeling of Shear Zones at a Large Dam Foundation." International Journal of Geomechanics 12, no. 6 (December 2012): 648–64. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0000220.
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Wang, Z., B. Ma, G. Yang, and M. Ziegler. "Investigation progress of geogrid-soil interaction using DEM." IOP Conference Series: Materials Science and Engineering 1260, no. 1 (October 1, 2022): 012042. http://dx.doi.org/10.1088/1757-899x/1260/1/012042.
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Abstract The discrete element modeling, which has particular advantages of capturing detailed insights into the geogrid–soil interaction, provides a new perspective to study the geogrid reinforcement mechanism especially at a microscopic scale. To summarize the current investigation achievements, discrete element modeling of geogrid and soil as well as their interaction under different testing conditions were reviewed in this paper. The DEM investigations provide not only qualitative visualization of the geogrid–soil interaction but also quantitative response of the geogrid and its surrounding soil. Such investigation achievements provide researchers helpful hints for the design of geogrid reinforced soil structures.
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Bui, Elisabeth N., Andrew Loughhead, and Robert Corner. "Extracting soil-landscape rules from previous soil surveys." Soil Research 37, no. 3 (1999): 495. http://dx.doi.org/10.1071/s98047.
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Where map legends and map unit definitions reflect the mental models used by soil surveyors to map soils in the past, the association between soil map units and other environmental spatial data can be re-modelled to infer formal survey rules. These rules then can be used to guide subsequent re-interpretations of spatial information for the same area or for another area judged to be similar. Classification trees and Bayesian statistical modelling were used to extract soil mapping rules from an existing map using the Toowoomba area in south-eastern Queensland, Australia, as a case study. In the Toowoomba map area, regional soil-landscape rules could be extracted by combining geology and DEM-derived attributes. The two approaches achieved comparable success.
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Chashchin, Aleksey, Iraida Samofalova, and Natalya Mudrykh. "The use of morphometric indicators of the relief for soil mapping of around plants in the conditions of the middle taiga in the northern part of the Perm region." InterCarto. InterGIS 27, no. 4 (2021): 162–74. http://dx.doi.org/10.35595/2414-9179-2021-4-27-162-174.
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The digital elevation model (DEM) matrix allows to reveal the relationship of the soil cover with morphometric parameters. Therefore, in the absence of the possibility of a large-scale field survey of soils, for territories with a high degree of erosion hazard, the data on the relief make it possible to carry out predictive large-scale soil maps. The aim of the work is to create a cartographic model of the soil cover of agricultural land based on the extrapolation of the results of DEM processing and to compare it with the existing large-scale soil map in similar natural conditions. The object of research is the territory of LLC “Selskoe” located in the Solikamsk urban district of the Perm region. Agricultural land use belongs to the northernmost agricultural lands in the region. The total area of research was 429 hectares of arable land. The plot includes 8 fields. For soil mapping, a digital elevation model ALOS 30 and a large-scale soil map of the key site were used, which characterizes part of the land use of the subsidiary farm “Voskhod”. Using the results of the classification of the relief according to the GIS SAGA TPI based landform classification algorithm as a contour base and the existing soil map of the key site, a soil map of LLC “Selskoe” was made by the extrapolation method. The steepness of the slopes and the topographic moisture index were used as auxiliary data. In conditions of complex relief, a clear dependence of the location of soils on relief elements has been established. By extrapolating data from a large-scale soil survey, 10 soil cartographic units were identified. According to the relief elements, podzolic, sod-podzolic, bog-podzolic and alluvial soils were identified. In terms of granulometric composition, light soils prevail, a small area is occupied by medium loamy soils.
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Mohamed, Mohamed Ali. "Classification of Landforms for Digital Soil Mapping in Urban Areas Using LiDAR Data Derived Terrain Attributes: A Case Study from Berlin, Germany." Land 9, no. 9 (September 9, 2020): 319. http://dx.doi.org/10.3390/land9090319.
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In this study, a knowledge-based fuzzy classification method was used to classify possible soil-landforms in urban areas based on analysis of morphometric parameters (terrain attributes) derived from digital elevation models (DEMs). A case study in the city area of Berlin was used to compare two different resolution DEMs in terms of their potential to find a specific relationship between landforms, soil types and the suitability of these DEMs for soil mapping. Almost all the topographic parameters were obtained from high-resolution light detection and ranging (LiDAR)-DEM (1 m) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)-DEM (30 m), which were used as thresholds for the classification of landforms in the selected study area with a total area of about 39.40 km2. The accuracy of both classifications was evaluated by comparing ground point samples as ground truth data with the classification results. The LiDAR-DEM based classification has shown promising results for classification of landforms into geomorphological (sub)categories in urban areas. This is indicated by an acceptable overall accuracy of 93%. While the classification based on ASTER-DEM showed an accuracy of 70%. The coarser ASTER-DEM based classification requires additional and more detailed information directly related to soil-forming factors to extract geomorphological parameters. The importance of using LiDAR-DEM classification was particularly evident when classifying landforms that have narrow spatial extent such as embankments and channel banks or when determining the general accuracy of landform boundaries such as crests and flat lands. However, this LiDAR-DEM classification has shown that there are categories of landforms that received a large proportion of the misclassifications such as terraced land and steep embankments in other parts of the study area due to the increased distance from the major rivers and the complex nature of these landforms. In contrast, the results of the ASTER-DEM based classification have shown that the ASTER-DEM cannot deal with small-scale spatial variation of soil and landforms due to the increasing human impacts on landscapes in urban areas. The application of the approach used to extract terrain parameters from the LiDAR-DEM and their use in classification of landforms has shown that it can support soil surveys that require a lot of time and resources for traditional soil mapping.
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Gholaminejad, Ahmadreza, Ahmad Mahboubi, and Ali Noorzad. "Combined DEM-FDM modelling of encased stone column." E3S Web of Conferences 92 (2019): 16012. http://dx.doi.org/10.1051/e3sconf/20199216012.
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Combination of the continuum-based numerical methods and the discrete element method (DEM) could be a powerful way of simulating complex problems. This approach benefits from the capabilities of both methods. The main feature of the discrete element method is that the soil grains are considered as individual particles without need to impose any behaviour law in modelling the medium. The limitation of this method is, however, its high computational demand. In continuum based methods, on the other hand, it is impossible to trace micro scale phenomena. According to these facts, combining continuum and discrete methods is an optimal way in approaching geotechnical problems which deal with granular soils. In this approach, the coarse grain zone (medium) is modelled using DEM and the surrounding media are modelled using the continuum methods. Stone columns that are widely used for improving and/or increasing the strength of weak soils could be modelled using this type of coupled simulation. The Coarse aggregates present in the stone column make it appropriate for the coupled modelling. In this paper, the ordinary and encased stone columns have been simulated by combining 2D DEM and finite difference method (FDM). Clump technique was employed to achieve the interlocking of aggregate particles in DEM, and the surrounding cohesive soil was modelled using FDM. The obtained results were validated by the reported experimental results in the literature, indicating that the coupled DEM-FDM method is a robust way to simulate stone columns.
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Dobos, Endre, B. Norman, and B. Worstell. "The Use of DEM and Satellite Data for Regional Scale Soil Databases." Agrokémia és Talajtan 51, no. 1-2 (March 1, 2002): 263–72. http://dx.doi.org/10.1556/agrokem.51.2002.1-2.31.
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New, quantitative methods and data sources for characterizing small scale soil resources have been demonstrated. AVHRR and coarse spatial resolution DEM were designed for mapping large areas of the world quickly and cost effectively. The method combines digital elevation data, “ground truth” information, including the soil taxonomic class for measured soil locations, and a time series of satellite images to form a digital soil database. The results show that using ancillary information such as AVHRR data and DEM derivatives from the national to continental level surveys is among the most promising tools for geographers and soil surveyors. The AVHRR data is often used for land cover studies but its usefulness in soil studies has not yet been proven. This study is a representative example of the usefulness of AVHRR data in characterizing the soil-forming environment and delineating soil patterns, particularly when integrated with other data for describing the soil landscape, such as the DEM, slope, curvature and PDD. The predictive power of AVHRR and similar low spatial resolution satellite data sources could be further improved with the development of soil sensitive filters. Mention should be made of the potential improvement of the products derived from these data sources with the use of better quality data provided by satellites that have been launched recently. Neither the AVHRR nor the DEM-derivatives show high correlation with the soil classes, but both represent a great portion of the environmental variability. In general, the more uncorrelated information is extracted from DEM and AVHRR, the better explanation of the spatial soil variability is achieved with an integrated use of them. The images of AVHRR time series show a relatively low correlation, thus each of the new dates adds much potential information on the soils. The studies also highlighted the great help of surface vegetation in soil remote sensing, as indicated by the high R² value of Band 1 and NDVI. The importance of the short-term weather history of the study area was also demonstrated. Terrain information and terrain variables were primarily developed for large scale local studies. Small scale mapping of large regions presents different issues, like over-generalization and over-smoothing of the soil information. The terrain features with smaller extents are dissolved into a larger neighborhood. As a smoother terrain map is created, a lot of detail is lost and less variability is observable. Many of the terrain attributes are useless with this approach. Elevation, slope, relief intensity, potential drainage density and the curvature variables are the most informative digital variables for characterizing the soil-landscape in small scale inventories. The resulting soil databases will have all the advantages of quantitatively derived databases, including consistency, homogeneity, and reduced data generalization and edge-matching problems. Although the results from the above procedures are believed to be accurate enough to serve as a basis for global and regional studies, they should be checked and further revised by local and regional experts to ensure quality. Research should continue on improving the procedures, augmenting the pedon data with new field sampling, and incorporating new image and DEM data sources. One of the most important results of these studies is the demonstration of the usefulness of these data sources for small scale soil mapping and the overall validity and representatitivity of the AVHRR-terrain/soil correlation within the temperate region of the world. Further studies will need to be performed to test the use of AVHRR and terrain data for other climate zones of the World, where potential problems, like continuous cloud cover, may occur.
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Larson, Johannes, William Lidberg, Anneli M. Ågren, and Hjalmar Laudon. "Predicting soil moisture conditions across a heterogeneous boreal catchment using terrain indices." Hydrology and Earth System Sciences 26, no. 19 (October 5, 2022): 4837–51. http://dx.doi.org/10.5194/hess-26-4837-2022.
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Abstract. Soil moisture has important implications for drought and flooding forecasting, forest fire prediction and water supply management. However, mapping soil moisture has remained a scientific challenge due to forest canopy cover and small-scale variations in soil moisture conditions. When accurately scaled, terrain indices constitute a good candidate for modelling the spatial variation of soil moisture conditions in many landscapes. In this study, we evaluated seven different terrain indices at varying digital elevation model (DEM) resolutions and user-defined thresholds as well as two available soil moisture maps, using an extensive field dataset (398 plots) of soil moisture conditions registered in five classes from a survey covering a (68 km2) boreal landscape. We found that the variation in soil moisture conditions could be explained by terrain indices, and the best predictors within the studied landscape were the depth to water index (DTW) and a machine-learning-generated map. Furthermore, this study showed a large difference between terrain indices in the effects of changing DEM resolution and user-defined thresholds, which severely affected the performance of the predictions. For example, the commonly used topographic wetness index (TWI) performed best on a resolution of 16 m, while TWI calculated on DEM resolutions higher than 4 m gave inaccurate results. In contrast, depth to water (DTW) and elevation above stream (EAS) were more stable and performed best on 1–2 m DEM resolution. None of the terrain indices performed best on the highest DEM resolution of 0.5 m. In addition, this study highlights the challenges caused by heterogeneous soil types within the study area and shows the need of local knowledge when interpreting the modelled results. The results from this study clearly demonstrate that when using terrain indices to represent soil moisture conditions, modelled results need to be validated, as selecting an unsuitable DEM resolution or user-defined threshold can give ambiguous and even incorrect results.
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Indraratna, Buddhima, Nghi Minh Phan, Thanh Trung Nguyen, and Jinsong Huang. "Simulating Subgrade Soil Fluidization Using LBM-DEM Coupling." International Journal of Geomechanics 21, no. 5 (May 2021): 04021039. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0001997.
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Jiang, Mingjing, Yongsheng Dai, Liang Cui, and Banglu Xi. "Experimental and DEM analyses on wheel-soil interaction." Journal of Terramechanics 76 (April 2018): 15–28. http://dx.doi.org/10.1016/j.jterra.2017.12.001.
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KOIZUMI, Takayuki, Nobutaka TSUJIUCHI, Yusuke KATO, and Masato ANDO. "1005 Grouser-soil Interaction Simulation by Parallel DEM." Proceedings of The Computational Mechanics Conference 2007.20 (2007): 471–72. http://dx.doi.org/10.1299/jsmecmd.2007.20.471.
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Liu, S. H., and D. A. Sun. "Simulating the collapse of unsaturated soil by DEM." International Journal for Numerical and Analytical Methods in Geomechanics 26, no. 6 (2002): 633–46. http://dx.doi.org/10.1002/nag.215.
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Balamonica, K., and Siang Huat Goh. "Characterisation of contact parameters of sand grains to be used for discrete element modelling." E3S Web of Conferences 92 (2019): 14002. http://dx.doi.org/10.1051/e3sconf/20199214002.
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Discrete element method (DEM) is a numerical technique that models the material as a combination of discrete particles which interact with each other through the contacts springs. While modelling soil in finite element method (FEM), approximations are made which considers soil as a continuous material. Hence certain properties such as void ratio which are intrinsic properties of the soil cannot be directly modelled or monitored. FEM also requires the failure criteria to be defined to predict the post elastic behaviour of the soil. DEM overcomes such drawbacks and the particle contacts are the only parameters that has to be defined. In the present work the contact parameters for sand grains are estimated for the purpose of being modelled in DEM, using direct measurement approach. The parameters required for defining the contact springs between the particles are the young's modulus, coefficient of restitution, friction coefficient, Poisson's ratio and density. The estimated parameters from the experiments were used to model the soil behaviour in an oedometer test. The obtained results from the DEM modelling are compared with the experimental results to benchmark the parameters estimated for the sand grains.
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Ding, Xiaogang, Zhengyong Zhao, Zisheng Xing, Shengting Li, Xiaochuan Li, and Yanmei Liu. "Comparison of Models for Spatial Distribution and Prediction of Cadmium in Subtropical Forest Soils, Guangdong, China." Land 10, no. 9 (August 27, 2021): 906. http://dx.doi.org/10.3390/land10090906.
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Cadmium (Cd) is a toxic metal and found in various soils, including forest soils. The great spatial heterogeneity in soil Cd makes it difficult to determine its distribution. Both traditional soil surveys and spatial modeling have been used to study the natural distribution of Cd. However, traditional methods are highly labor-intensive and expensive, while modeling is often encumbered by the need to select the proper predictors. In this study, based on intensive soil sampling (385 soil pits plus 64 verification soil pits) in subtropical forests in Yunfu, Guangdong, China, we examined the impacting factors and the possibility of combining existing soil information with digital elevation model (DEM)-derived variables to predict the Cd concentration at different soil depths along the landscape. A well-developed artificial neural network model (ANN), multi-variate analysis, and principal component analysis were used and compared using the same dataset. The results show that soil Cd concentration varied with soil depth and was affected by the top 0–20 cm soil properties, such as soil sand or clay content, and some DEM-related variables (e.g., slope and vertical slope position, varying with depth). The vertical variability in Cd content was found to be correlated with metal contents (e.g., Cu, Zn, Pb, Ni) and Cd contents in the layer immediately above. The selection of candidate predictors differed among different prediction models. The ANN models showed acceptable accuracy (around 30% of predictions have a relative error of less than 10%) and could be used to assess the large-scale Cd impact on environmental quality in the context of intensifying industrialization and climate change, particularly for ecosystem management in this region or other regions with similar conditions.
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Huang, Jingyi, Terence Nhan, Vanessa N. L. Wong, Scott G. Johnston, R. Murray Lark, and John Triantafilis. "Digital soil mapping of a coastal acid sulfate soil landscape." Soil Research 52, no. 4 (2014): 327. http://dx.doi.org/10.1071/sr13314.
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Coastal floodplains are commonly underlain by sulfidic sediments and coastal acid sulfate soils (CASS). Oxidation of sulfidic sediments leads to increases in acidity and mobilisation of trace metals, resulting in an increase in the concentrations of conducting ions in sediment and pore water. The distribution of these sediments on floodplains is highly heterogeneous. Accurately identifying the distribution of CASS is essential for developing targeted management strategies. One approach is the use of digital soil mapping (DSM) using ancillary information. Proximal sensing instruments such as an EM38 can provide data on the spatial distribution of soil salinity, which is associated with CASS, and can be complemented by digital elevation models (DEM). We used EM38 measurements of the apparent soil electrical conductivity (ECa) in the horizontal and vertical modes in combination with a high resolution DEM to delineate the spatial distribution of CASS. We used a fuzzy k-means algorithm to cluster the data. The fuzziness exponent, number of classes (k) and distance metric (i.e. Euclidean, Mahalanobis and diagonal) were varied to determine a set of parameters to identify CASS. The mean-squared prediction error variance of the class mean of various soil properties (e.g. EC1:5 and pH) was used to identify which of these metrics was suitable for further analysis (i.e. Mahalanobis) and also determine the optimal number of classes (i.e. k = 4). The final map is consistent with previously defined soil–landscape units generated using traditional soil profile description, classification and mapping. The DSM approach is amenable for evaluation on a larger scale and in order to refine CASS boundaries previously mapped using the traditional approach or to identify CASS areas that remain unmapped.
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Krenz, Juliane, Philip Greenwood, and Nikolaus J. Kuhn. "Soil Degradation Mapping in Drylands Using Unmanned Aerial Vehicle (UAV) Data." Soil Systems 3, no. 2 (May 7, 2019): 33. http://dx.doi.org/10.3390/soilsystems3020033.
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Arid and semi-arid landscapes often show a patchwork of bare and vegetated spaces. Their heterogeneous patterns can be of natural origin, but may also indicate soil degradation. This study investigates the use of unmanned aerial vehicle (UAV) imagery to identify the degradation status of soils, based on the hypothesis that vegetation cover can be used as a proxy for estimating the soils’ health status. To assess the quality of the UAV-derived products, we compare a conventional field-derived map (FM) with two modelled maps based on (i) vegetation cover (RGB map), and (ii) vegetation cover, topographic information, and a flow accumulation analysis (RGB+DEM map). All methods were able to identify areas of soil degradation but differed in the extent of classified soil degradation, with the RGB map classifying the least amount as degraded. The RGB+DEM map classified 12% more as degraded than the FM, due to the wider perspective of the UAV compared to conventional field mapping. Overall, conventional UAVs provide a valuable tool for soil mapping in heterogeneous landscapes where manual field sampling is very time consuming. Additionally, the UAVs’ planform view from a bird’s-eye perspective can overcome the limited view from the surveyors’ (ground-based) vantage point.
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Liu, Chao, Liufeng Pan, Fei Wang, Zixin Zhang, Jie Cui, Hai Liu, Zheng Duan, and Xiangying Ji. "Three-Dimensional Discrete Element Analysis on Tunnel Face Instability in Cobbles Using Ellipsoidal Particles." Materials 12, no. 20 (October 14, 2019): 3347. http://dx.doi.org/10.3390/ma12203347.
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Soil disturbance has always been the major concern in shield tunneling activity. This paper presents the investigation on the micro-scale responses of the soils during shield tunnel excavation in sandy-cobble stratum. The code paraEllip3d is employed in discrete element method (DEM) analysis in which the soils are mimicked as an assembly of ellipsoids. Triaxial tests on the micro-scale responses of cobbles are carried out using the materials sampled from the tunnel face during construction period, and corresponding DEM simulations are performed to calibrate the micro parameters for the ellipsoids. On this basis, the face instability process during the shield tunneling in cobbles is studied using 1 g model test as well as corresponding DEM simulation. The micro-scale responses of cobbles are investigated by triaxial test as well as corresponding DEM simulations. Multiple material responses are discussed in the DEM simulations, including the stress–strain relationship, the contact distribution, and the force chain evolution in the elementary and model test. Finally, the mechanism of tunnel face instability in cobbles are discussed on the basis of aforementioned investigations.
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Wang, Xu, Makoto Fujisawa, and Masahiko Mikawa. "Visual Simulation of Soil-Structure Destruction with Seepage Flows." Proceedings of the ACM on Computer Graphics and Interactive Techniques 4, no. 3 (September 22, 2021): 1–18. http://dx.doi.org/10.1145/3480141.
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This paper introduces a method for simulating soil-structure coupling with water, which involves a series of visual effects, including wet granular materials, seepage flows, capillary action between grains, and dam breaking simulation. We develop a seepage flow based SPH-DEM framework to handle soil and water particles interactions through a momentum exchange term. In this framework, water is seen as a seepage flow through porous media by Darcy's law; the seepage rate and the soil permeability are manipulated according to drag coefficient and soil porosity. A water saturation-based capillary model is used to capture various soil behaviors such as sandy soil and clay soil. Furthermore, the capillary model can dynamically adjust liquid bridge forces induced by surface tension between soil particles. The adhesion model describes the attraction ability between soil surfaces and water particles to achieve various visual effects for soil and water. Lastly, this framework can capture the complicated dam-breaking scenarios caused by overtopping flow or internal seepage erosion that are challenging to simulate.
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Li, Ao, X. C. (John) Zhang, and Baoyuan Liu. "Effects of DEM resolutions on soil erosion prediction using Chinese Soil Loss Equation." Geomorphology 384 (July 2021): 107706. http://dx.doi.org/10.1016/j.geomorph.2021.107706.
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Tamás, Kornél, and István J. Jóri. "The Influence of the Soil Water Content in the Soil-Tool DEM Model." Progress in Agricultural Engineering Sciences 11, no. 1 (December 2015): 43–70. http://dx.doi.org/10.1556/446.11.2015.5.
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The Discrete Element Method (DEM) for describing the action mechanism between soil and sweep tool can be used to perform a detailed analysis of draft force, soil cutting, clod-crushing and loosening by taking into account the tillage speed and the three soil phases. This study describes the simulation of the 3D DEM soil model and a cultivator sweep digitized with a 3D scanner, showing the soil—sweep interaction as a function of implement draft force and implement operating speed. The suitability of the model is validated by comparing the results of laboratory and simulated shear tests (static validation) with the results of soil bin tests (dynamic validation). The mechanical parameters of the sandy soil used for the soil bin tests were measured using the direct shear box test. Cohesion for the soil model used during simulations was set using the parallel bond contact model, where the determining factors were the Young modulus for particle contact (Ec) and bonding (Ēc), the Poisson’s ratio (nu), the normal (σ) and shear (τ) bond strength and the radius of the related volume (cylinder). Once the DEM model parameters were set, the draft force values measured during dynamic testing were harmonized using the value for viscous damping (ci). The dynamic soil—sweep model was validated using the viscous damping applied based on the simulated and measured draft force values. The validation of the Young modulus to 0.55e6 Pa (Kn = 1.73e4 N/m, Ks = 8.64e3 N/m) enabled us to set the draft force values of the model for different speeds (0.8–4.1 m/s) with an accuracy of 1–4%. During the analysis of changes in tillage quality, the developed dynamic soil—sweep model showed a high degree of porosity (48%) due to grubbing in the attenuated speed range (0.5–2.1 m/s), and a decreasing tendency (0.41–0.39%) in the non-damped speed range (2.1–4.1 m/s). After the initial equilibrium state, the ratio of average particle contacts for the given porosity decreased in the attenuated speed range (coord number: 4.8), and a slight decrease was also found above speeds of 2.1 m/s (coord number: 5.2). In the model, clod-crushing was examined based on the ratio of sliding contacts, and we found a continuous increase (sliding fraction: 2–15%) in the speed range used for the simulation (0.8–4.1 m/s).
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Zhou, Wenqi, Chao Song, Xiaobo Sun, Ziming Liu, Xue Ni, Kangjia Shen, Yi Jia Wang, and Liquan Tian. "Design of High-Efficiency Soil-Returning Liquid Fertilizer Deep-Application Furrow Openers for Improving Furrowing Performance in Cold Regions of Northeast China." Agriculture 12, no. 9 (August 23, 2022): 1286. http://dx.doi.org/10.3390/agriculture12091286.
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Liquid-fertilizer deep-application techniques are techniques for applying fertilizers to the root system of crops, which can effectively improve the utilization rate of fertilizers and reduce application amounts. Due to the soil viscosity of soils in the cold region of Northeast China, the soil return rate of furrow openers for liquid-fertilizer deep applications is low, which can easily cause excessive volatilizations of liquid fertilizers. Therefore, aiming at the operational requirements of low soil disturbance for liquid-fertilizer furrowing and deep applications, an efficient soil-returning liquid-fertilizer deep-application furrow opener was innovatively designed based on soil characteristics during the inter-cultivation period in the cold region of Northeast China. The discrete element method (DEM) was used to analyze the operating performance of the high-efficiency soil-returning liquid-fertilizer deep-application furrow openers, which is determined by key operating parameters including width and slip cutting angle. The DEM Virtual Simulation Experiment results show that the optimal combination is the width of 37.52 mm and a slip cutting angle of 43.27°, and the test results show that the optimal performance of the high-efficiency soil-returning liquid-fertilizer deep-application furrow opener is that the soil disturbance rate is 51.81%, and the soil-returning depth is 52.1 mm. This paper clarifies the relationship between the width and the slip cutting angle in furrowing resistance and soil disturbance and the mechanism by which the width and slip cutting angle affect soil disturbance. Above all, this study provides a theoretical and practical reference for the design of liquid-fertilizer deep-application furrow openers.
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Li, Qian, Junping Li, and Lanlan Xie. "Calculation of the Influence Zone for Planetary Sampling Based on DEM Simulation." International Journal of Aerospace Engineering 2021 (May 25, 2021): 1–11. http://dx.doi.org/10.1155/2021/6652273.
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In the design of planetary sampling devices, calculating the reaction force acting on the sampling devices is crucial. According to related research, the influence zone caused by sampling plays an important role in calculating the reaction force. A new method for estimating the range of the influence zone based on 3D DEM simulation is discussed in this paper. Taking lunar soil as an example, first, via validation of physical experiments, the DEM lunar soil simulant was proven to have mechanical properties similar to those of real lunar soil. Second, stress was selected as an indicator to identify the influence zone by computing the match percentage via a comparison between classical soil mechanics and DEM simulation. Using the proposed calculation method, it can be observed that the trend of change of influence zone at different sampling moments showed similar to the change of reaction force. Calculation of the influence zone can be used to analyze the reaction force of different gravity environments, sampling device structures, and motions.
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KWOK, C. Y., and M. D. BOLTON. "DEM simulations of soil creep due to particle crushing." Géotechnique 63, no. 16 (December 2013): 1365–76. http://dx.doi.org/10.1680/geot.11.p.089.
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Liu, Xin, Annan Zhou, Shui-Long Shen, Jie Li, and Arul Arulrajah. "Modelling unsaturated soil-structure interfacial behavior by using DEM." Computers and Geotechnics 137 (September 2021): 104305. http://dx.doi.org/10.1016/j.compgeo.2021.104305.
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Zhao, Xue Liang. "Numerical Modeling of Granular Assembly Using Discrete Element Method." Advanced Materials Research 146-147 (October 2010): 738–42. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.738.
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Discrete element method (DEM) is a powerful tool for the study of granular materials. Some issues in numerical modeling of DEM including parameter selection and mass/density scaling method are discussed. A new method to simulate the resin membrane in the laboratory which is more accurate and simpler is proposed. Using DEM, microscale behavior of soil including particle rotation and mesoscale void ratio distribution are analyzed. Failure modes and stain localization are revealed from the particle scale analysis. Configurations of the shear band are investigated. It shows that microstructure and micromechanics is the underlying mechanics of the macroscale behavior of the granular soil. Being a simpler, faster, and cheaper method compared with traditional experimental method, DEM can capture the discrete characteristics and provide deeper insight of the granular materials.
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Guadagnin Moravia, Marcus, Pascal Villard, and Delma De Mattos Vidal. "Geogrid pull-out modelling using DEM." E3S Web of Conferences 92 (2019): 13015. http://dx.doi.org/10.1051/e3sconf/20199213015.
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With the advancement of the use of synthetic reinforcements in geotechnics, a greater understanding of the mechanisms involved in soil-reinforcement interaction is the focus of major research centres on the subject. The topic of this study is the shearing behaviour at interfaces between granular materials and geogrids. The main objective is to provide a more fundamental understanding of some micromechanisms present in this type of interface, which in turn are important to optimize the design of such reinforcement. The numerical modelling of these reinforced structures must deal with the complexity of the material-reinforcement interaction problem; therefore, it requires specific numerical models whose formulations admit localized behaviours in the contacts as well as the granular nature of the material (e.g., soil, gravel, ballast). A robust and flexible way of modelling this problem is through the Discrete Element Method (DEM). The DEM proposes to model this granular nature by representing the soil as interacting constituent particles, whose behaviour is ruled by physical laws defined at the contact points. The numerical approach is desirable since it allows, in an articulated and relatively fast way, studying closely different regions of the interface, in order to identify factors and variables that are important for the problem. The purpose involves the DEM for a 3D modelling of a geogrid pull-out test to calculate the magnitude of forces in different elements of the geogrid (i.e., nodes, longitudinal and transverse members). Preparation of numerical samples has a particular importance in the final results of simulations. Thus, the numerical techniques used to obtain better geometry for the geogrid and a granular assembly with a representative grain rolling effect are also presented in this paper.
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Carabassa, Vicenç, Pau Montero, Josep Maria Alcañiz, and Joan-Cristian Padró. "Soil Erosion Monitoring in Quarry Restoration Using Drones." Minerals 11, no. 9 (August 30, 2021): 949. http://dx.doi.org/10.3390/min11090949.
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Mining is an essential activity that supports the provision of raw materials. However, the extraction process of mining has deep environmental impacts. For this reason, restoration actions are mandatory, and monitoring is a key step in ensuring the renaturalization of affected areas. Erosion processes are one of the main problems that affect restored areas in extractive activities due to the frequently steep slopes and the difficulty of revegetating the technosols constructed using mining debris. This research aims to develop a method for determining soil losses due to water erosion in mine-restored areas by using Geographic Information Systems (GIS) and Remote Sensing (RS) tools. For the study, images obtained using Unmanned Aerial Systems (UAS) in an open pit mine in the process of restoration are used, from which the Digital Elevation Model (DEM) of the current state of the slopes is obtained (0.10 m spatial resolution). With GIS techniques, ridges of the rills and gullies generated in the slopes are detected, whereby an estimation of a first DEM before the erosive process and a second DEM after the erosive process can be constructed. Each of these DEMs are evaluated individually in order to determine the height differences and estimate the volumetric loss. At the same time, the results are validated with the DEM derived from official mapping agencies’ airborne Lidar data (1.00 m spatial resolution), which yield consistent data in the volumetric quantification of the erosion despite the difference in spatial resolution. In conclusion, the high spatial resolution of drone images facilitated a detailed monitoring of erosive processes, obtaining data from vast and inaccessible slopes that are usually immeasurable with traditional field techniques, and altogether improving the monitoring process of mine restoration.
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Momeni, Ali, Barry Clarke, and Yong Sheng. "An Introduction to the Geometrical Stability Index: A Fabric Quantity." Geotechnics 2, no. 2 (March 25, 2022): 297–316. http://dx.doi.org/10.3390/geotechnics2020013.
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Natural soils are often modelled as a continuum characterized by the composition of the soil, a particulate material. Yet, in situ, the fabric and structure of soil may govern its behavior. Discrete element modelling is used to simulate the composition of soil as a particulate material and develop fabric quantities. These quantities are presented as average quantities for a volume of particles. It is possible to use DEM to study the evolution of fabric at the particle level. This paper describes a state-of-the-art fabric term, referred to as geometrical stability index, ʎ, which can measure the contacts deviation of each particle from the most stable contacts arrangement during loading. The parameters required to define this new fabric term were attained from a designed algorithm. 2D discrete element method (DEM) biaxial test simulations were performed to validate the effectiveness of the geometrical stability index in defining the local instability. As the sample is loaded, a shear band is formed. The geometric stability index in that band increases relative to the surrounding relatively intact soil. Thus, a brittle failure is associated with an increase in the variation of inter-particle contacts from a stable configuration. The geometric stability index is able to model the development of discontinuities in a particulate material at the particle level. The DEM modelling results demonstrate the correlations between the new fabric term and the progressive of localized failure in densified particulate systems such as over consolidated clay, where the failure is a function of progressive development of local fissure spacing.
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Galindo-Torres, Sergio Andres, Alexander Scheuermann, David Williams, and Hans Mühlhaus. "Micro-Mechanics of Contact Erosion." Applied Mechanics and Materials 553 (May 2014): 513–18. http://dx.doi.org/10.4028/www.scientific.net/amm.553.513.
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In the present paper a simulation framework is presented coupling the mechanics of fluids and solids to study the contact erosion phenomenon. The fluid is represented by the Lattice Boltzmann Method (LBM) and the soil particles are modeled using the Discrete Element Method (DEM). The coupling law considers accurately the momentum transfer between both phases. A soil composed of particles of two distinct sizes is simulated by the DEM and then hydraulically loaded with an LBM fluid. It is observed how the hydraulic gradient compromises the stability of the soil by pushing the smaller particles into the voids between the largest ones. The hydraulic gradient is more pronounced in the areas occupied by the smallest particles due to a reduced constriction size, which at the same time increases the buoyancy acting on them. At the mixing zone, where both particles sizes coexist, the fluid transfers its momentum to the small particles, increasing the erosion rate in the process. The results offer new insights into the erosion and suffusion processes, which could be used to better predict and design structures on hydraulically loaded soils.
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Winzeler, Hans Edwin, Phillip R. Owens, Quentin D. Read, Zamir Libohova, Amanda Ashworth, and Tom Sauer. "Topographic Wetness Index as a Proxy for Soil Moisture in a Hillslope Catena: Flow Algorithms and Map Generalization." Land 11, no. 11 (November 11, 2022): 2018. http://dx.doi.org/10.3390/land11112018.
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Topographic wetness index (TWI) is used as a proxy for soil moisture, but how well it performs across varying timescales and methods of calculation is not well understood. To assess the effectiveness of TWI, we examined spatial correlations between in situ soil volumetric water content (VWC) and TWI values over 5 years in soils at 42 locations in an agroforestry catena in Fayetteville, Arkansas, USA. We calculated TWI 546 ways using different flow algorithms and digital elevation model (DEM) preparations. We found that most TWI algorithms performed poorly on DEMs that were not first filtered or resampled, but DEM filtration and resampling (collectively called generalization) greatly improved the TWI performance. Seasonal variation of soil moisture influenced TWI performance which was best when conditions were not saturated and not dry. Pearson correlation coefficients between TWI and grand mean VWC for the 5-year measurement period ranged from 0.18 to 0.64 on generalized DEMs and 0.15 to 0.59 for on DEMs that were not generalized. These results aid management of crop fields with variable moisture characteristics.
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Khosravi, A., A. Martinez, and J. T. DeJong. "Discrete element model (DEM) simulations of cone penetration test (CPT) measurements and soil classification." Canadian Geotechnical Journal 57, no. 9 (September 2020): 1369–87. http://dx.doi.org/10.1139/cgj-2019-0512.
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This paper presents a study on the simulation of cone penetration tests (CPTs) using the discrete element model (DEM) method. This study’s main objective is to investigate the effect of different modeling parameters and simulation configurations on the ability of three-dimensional DEM simulations to replicate realistic CPT tip resistance (qc) and friction sleeve shear stress (fs) measurements. The CPT tests were simulated in virtual calibration chambers (VCCs) containing particles calibrated to model the behavior of sand. The parameters investigated included the granular assembly properties, interparticle contact parameters, particle–probe interface characteristics, and simulation configuration. Results indicate that the interparticle contact parameters, boundary conditions, and void ratio have an important role in the tip resistance and friction sleeve measurements obtained from the simulations. Particle-level interactions such as particle displacements and rotations and interparticle contact forces were analyzed throughout to provide insight into the differences in measured CPT response. Interpretation of the qc and fs measurements using soil behavior type (SBT) charts for soil classification indicates that the simulated CPT response is representative of the response of coarse-grained soils measured during field soundings. Analysis of results within the SBT framework can provide insight into the influence of soil particle properties on CPT-based soil classification.
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Svіtlуchnyi, Oleksandr, and Alla Piatkova. "Problems of spatially distributed quantitative evaluation of soil erosion losses." Visnyk of V.N. Karazin Kharkiv National University, series Geology. Geography. Ecology, no. 56 (June 1, 2022): 184–97. http://dx.doi.org/10.26565/2410-7360-2022-56-13.
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Formulation of the problem. Water erosion of soils is the most widespread and dangerous soil degradation process in Ukraine. The development of an effective system of soil protection measures requires the use of spatially distributed mathematical models of soil erosion losses. This, in turn, highlights the problem of spatially distributed source data, which adequately reflect the spatial differentiation of factors of the erosion process, among which the main one is the relief. The purpose of the article. Assessing the adequacy of available spatially distributed source data, including cartographic and freely distributed global digital elevation models (DEMs), for spatially distributed quantitative assessment of soil erosion losses at the local level of territorial coverage is the aim of the article. Assessing from this point of view the scale of the original cartographic data, different global DEMs and their spatial resolution, as well as the degree of spatial generalization of the original data. Materials and methods. The solution of the set tasks was performed by the method of simulation modeling with the use of physical-statistical GIS-realized mathematical model of soil erosion-accumulation, developed at Odessa I. I. Mechnikov National University. Source data arrays were tested with DEMs SRTM90 and SRTM30 with a spatial resolution of 3 and 1 angular seconds, respectively, and AW3D30 with a spatial resolution of 1 angular second, as well as with cartographic DEMs based on topographic maps of scale 1:10000 and 1:25000. For testing the initial data, three test plots with an area of 2.67, 0.59 and 0.21 km2 were selected. The plots are located in the Balta district of Odessa region on the southern spurs of the Podolska upland. Results. It is established that freely distributed global digital elevation models SRTM and AW3D30 in the conditions of flat terrain do not always allow to adequately display the structure of slope runoff and, accordingly, to correctly perform calculations of soil erosion losses. The maximum deviation of the average soil erosion losses calculated for the test plots using global DEMs from the soil losses calculated using the reference DEM for SRTM30 and AW3D30 was 27%, for SRTM90 – almost 70%. The distribution of soil losses over the area of test plots obtained using different global DEMs differs even more. When using DEM based on topographic maps, reducing the scale of the original maps from 1: 10000 to 1: 25000 leads to a decrease in the average value of soil erosion losses by about 20% due mainly to reducing the magnitude and area of distribution of maximum soil losses, and on slopes of complex shape also due to changes in the area of accumulation zones. The degree of spatial generalization of the initial data significantly affects the results of the assessment of soil erosion losses both in relation to the average values and their distribution over the area. For small areas, the use of raster cells larger than 50 m is impractical. Scientific novelty and practical significance. It has been shown for the first time that in the conditions of flat terrain at the local level of spatial coverage, the freely distributed global DEM SRTM and AW3D30 are not always hydrologically correct. The reasons and conditions of violation of this correctness are specified. It has been established that the global DEM AW3D30 has local instrumental errors that may make it impossible to use it. The most realistic values of soil erosion losses are provided by DEM SRTM with a spatial resolution of 1 angular second.
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Liu, Jiangui, Elizabeth Pattey, Michel C. Nolin, John R. Miller, and Oumar Ka. "Mapping within-field soil drainage using remote sensing, DEM and apparent soil electrical conductivity." Geoderma 143, no. 3-4 (February 2008): 261–72. http://dx.doi.org/10.1016/j.geoderma.2007.11.011.
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Wang, Jian Feng, and Run Qiu Huang. "DEM Study on Energy Allocation Behavior in Crushable Soils." Advanced Materials Research 871 (December 2013): 119–23. http://dx.doi.org/10.4028/www.scientific.net/amr.871.119.
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Detailed knowledge of particle-scale energy allocation behavior under the influence of particle breakage is of fundamental importance to the development of micromechanics-based constitutive models of sands. This paper reports original results of the energy input/dissipation of an idealized crushable soil using 3D DEM simulations. Particle breakage is modeled as the disintegration of synthetic agglomerate particles which are made up of parallel-bonded elementary spheres. Simulation results show that the initial specimen density and crushability strongly affect the energy allocation of the soil both at small and large strains. The major role of particle breakage, which itself only dissipates a negligible amount of input energy, is found to advance the soil fabric change and promote the interparticle friction dissipation. Particularly, at small strains, particle breakage disrupts the strain energy buildup and thus reduces the mobilized shear strength and dilatancy of a granular soil. At large strains where particle breakage is greatly reduced, a steady energy dissipation by interparticle friction and mechanical damping is observed. Furthermore, it is found that shear bands develop in most dense crushable specimens at large strains, but they are only weakly correlated to the anisotropy of the accumulated friction dissipation.
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Zhao, Zhengyong, David A. MacLean, Charles P. A. Bourque, D. Edwin Swift, and Fan-Rui Meng. "Generation of soil drainage equations from an artificial neural network-analysis approach." Canadian Journal of Soil Science 93, no. 3 (August 2013): 329–42. http://dx.doi.org/10.4141/cjss2012-079.
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Zhao, Z., MacLean, D. A., Bourque, C. P.-A., Swift, D. E. and Meng, F.-R. 2013. Generation of soil drainage equations from an artificial neural network-analysis approach. Can. J. Soil Sci. 93: 329–342. Soil properties, especially soil drainage, are known to be related to topo-hydrologic variables derived from digital elevation models (DEM), such as vertical slope position, slope steepness, sediment delivery ratio, and topographic wetness index. Such relationships typically are strongly non-linear and thus difficult to define with conventional statistical methods. In this study, we used artificial neural network (ANN) models to establish relationships between soil drainage classes and DEM-generated topo-hydrologic variables and subsequently formulated the relationships to generate soil drainage equations for soil mapping. A high-resolution field soil map of the Black Brook Watershed in northwest New Brunswick, Canada, was used to calibrate/validate the ANN models, and the obtained equations. Independent data from an experimental farm, about 180 km away, were also used for validation. Results indicated that vertical slope position was the best predictor of soil drainage classes (r=0.55), followed by slope steepness (r=0.44), sediment delivery ratio (r=0.39), and topographic wetness index (r=0.38). The obtained soil drainage equations fitted well to the ANN model predictions (r 2=0.78–0.99; root mean squared error=0.39–4.55). Analyses indicated that soil drainage equations clearly reflected the actual relationships between soil drainage classes and DEM-generated topo-hydrologic variables, and have the potential to minimize bias originated from over-training the ANN models when applied outside the area of calibration, especially when the ranges of input variables were outside of the range of calibration data.
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Zhao, Xueliang, Jian Xu, Youhu Zhang, and Zhong Xiao. "Coupled DEM and FDM Algorithm for Geotechnical Analysis." International Journal of Geomechanics 18, no. 6 (June 2018): 04018040. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0001128.
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McDowell, Glenn, and John de Bono. "Relating Hydraulic Conductivity to Particle Size Using DEM." International Journal of Geomechanics 21, no. 1 (January 2021): 06020034. http://dx.doi.org/10.1061/(asce)gm.1943-5622.0001670.
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