Soil Units Research Articles

Comparison of direct and indirect soil organic carbon prediction at farm field scale

To advance sustainable and resilient agricultural management policies, especially during land use changes, it is imperative to monitor, report, and verify soil organic carbon (SOC) content rigorously to inform its stock. However, conventional methods often entail challenging, time-consuming, and costly direct soil measurements. Integrating data from long-term experiments (LTEs) with freely available remote sensing (RS) techniques presents exciting prospects for assessing SOC temporal and spatial change. The objective of this study was to develop a low-cost, field-based statistical model that could be used as a decision-making aid to understand the temporal and spatial variation of SOC content in temperate farmland under different land use and management. A ten-year dataset from the North Wyke Farm Platform, a 20-field, LTE system established in southwestern England in 2010, was used as a case study in conjunction with an RS dataset. Linear, additive and mixed regression models were compared for predicting SOC content based upon combinations of environmental variables that are freely accessible (termed open) and those that require direct measurement or farmer questionnaires (termed closed). These included an RS-derived Ecosystem Services Provision Index (ESPI), topography (slope, aspect), weather (temperature, precipitation), soil (soil units, total nitrogen [TN], pH), and field management practices. Additive models (specifically Generalised Additive Models (GAMs)) were found to be the most effective at predicting space-time SOC variability. When the combined open and closed factors (excluding TN) were considered, significant predictors of SOC were: management related to ploughing being the most important predictor, soil unit (class), aspect, and temperature (GAM fit with a normalised RMSE = 9.1%, equivalent to 0.4% of SOC content). The relative strength of the best-fitting GAM with open data only, which included ESPI, aspect, and slope (normalised RMSE = 13.0%, equivalent to 0.6% of SOC content), suggested that this more practical and cost-effective model enables sufficiently accurate prediction of SOC.

Regional and farm level droughts characteristics for southwestern Uganda during 1981–2017

An increase in drought events associated with rising temperatures indicates that Uganda is facing a growing challenge from climate variability. Despite these challenges, there is a lack of comprehensive information on how climate variability affects soils, particularly drought characteristics. In an effort to address this limitation, this study utilised high-quality, in-situ climate data and soil Available Water Capacity (AWC) specific to south-western Uganda. The study employed the Palmer Drought Severity Index (PDSI) and the Standardised Precipitation-Evapotranspiration Index (SPEI) to assess drought occurrences over the period 1981–2017. Notably, the results from the 3-month SPEI indicated higher frequencies across all drought categories. Meanwhile, the 12-month SPEI exhibited more stabilised negative and positive truncations for drought and wet events, respectively. Analysing the temporal evolution of monthly PDSI values for five major soil mapping units revealed distinct patterns. Moderate droughts were observed over Lixic Ferralsols between 1981 and 1992 and between 1998 and 2008. Extreme drought events occurred during the first 5–7 months of 2017. Luvisols exhibited prolonged negative truncation levels, indicating a water deficit during several periods: 1982–1984, 1990–1994, 1998–2000, 2010, and 2012–2014. Histosols experienced drought conditions from 1982 to 1986, interspersed with wet events in 1988, 1997, 1999–2002, and 2005. The study emphasises the differential response of soil units to drought and wet conditions. As a result, the research recommends implementing water management practices such as irrigation, mulching, conservation tillage, zero tillage, and drainage for all soils to enhance resilience and sustainable agricultural practices in the region.

Soil environmental carrying capacity and its spatial high-precision accounting framework

Human activity intensity should be controlled within the carrying capacity of soil units, which is crucial for environmental sustainability. However, the existing assessment methods for soil environmental carrying capacity (SECC) rarely consider the relationship between human activity intensity and pollutant emissions, making it difficult to provide effective early warning of human activity intensity. Moreover, there is a lack of spatial high-precision accounting methods for SECC. This study first established a spatial soil environmental capacity (SEC) model based on the pollutant thresholds corresponding to the specific protection target. Next, a spatial net-input flux model was proposed based on soil pollutants' input/output fluxes. Then, the quantitative relationship between human activity intensity and pollutant emissions was established and further incorporated into the SECC model. Finally, the spatial high-precision accounting framework of SECC was proposed. The methodology was used to assess the SECC for the copper production capacity in a typical copper smelting area in China. The results showed that (i) the average SECs for Cu, Cd, Pb, Zn, As and Cr are 427.89, 16.84, 306.41, 376.8, 71.63, and 392.7 kg hm−2, respectively; (ii) heavy metal (HM) concentrations and land-use types jointly influence the spatial distribution pattern of SEC; (iii) atmospheric deposition is the dominant HM input pathway and the high net-input fluxes are mainly located in the southeast of the study area; (iv) with the current human activity intensity for 50 years, the average SECs for Cu, Cd, Pb, Zn, As and Cr are 202.31, 1.71, 20.9, 66.15, 36.73, and 3 kg hm−2, respectively; and (v) to maintain the protection target at the acceptable risk level within 50 years, the SECC for the increased copper production capacity is 1.53 × 106 t. This study provided an effective tool for early warning of human activity intensity.

Estimating mechanical properties of natural siliceous offshore sands

Large area civil engineering projects, such as offshore wind farms, require extensive soil investigations for detailed soil characterisations. Site-wide geotechnical soil units are commonly defined for simplification due to budgetary constraints. Consequently, practitioners rely on a limited number of costly laboratory tests and a set of semi-empirical CPT correlations, predominantly established based on research sands, for deriving sand parameters. A recent publication by the authors highlights some valid concerns about currently often applied idealisation when deriving strength parameters of natural sands and presents some possible pathways to address the limitations with a grading curve parameter (d10 +d30 ). In the current paper, the size of the original laboratory test database is increased to improve the robustness of the methods. In addition, the database is used to also explore the potential of the d10 +d30 -parameter to improve estimations of drained stiffness parameters. However, since the current database mainly consists of relatively fine sands with varying fines content, a previously published database of much coarser clean sands is applied to investigate the limitations of the presented methods. Finally, a new independent trial database is collected to demonstrate the performance of the new methods for estimating drained strength and stiffness parameters compared with commonly applied industry-acknowledged methods. Even though limitations of the presented methods are identified for coarser clean sands, significantly improved reliability is demonstrated when deriving drained strength and stiffness parameters of relatively fine and slightly silty to very silty siliceous offshore sands.

A case study on soil slope landslide failure and parameter analysis of influencing factors for safety factor based on strength reduction method and orthogonal experimental design.

In civil engineering, stability analysis of slope is one of the main content of design. By using the finite element limit analysis software OptumG2, a landslide geological model is established to simulate the failure process of the landslide in Huadu District, Guangzhou City, China. The analysis focused on the deformation and failure characteristics, as well as the mechanical mechanism of landslide; the landslide mode of homogeneous soil is circular sliding. Additionally, investigating the influencing factors affecting slope stability is crucial in engineering implementation; in which the five influencing factors are considered as follow: slope height, slope gradient, soil cohesion, soil internal friction angle, and soil unit weight, respectively. A stability calculation model for a soil slope is established under 25 working conditions based on strength reduction method and orthogonal experimental design, in which the relationship between the safety factor and slope height, slope gradient, soil cohesion, soil internal friction angle, and soil unit weight is obtained. As the slope height increases from 5m to 45m, the safety factor of soil slope gradually decreases from 2.21 to 0.94; As the slope gradient increases from 20° to 60°, the safety factor of soil slope decreases approximately linearly from 1.80 to 0.95; As the cohesion of soil increases from 10kpa to 30kpa, the safety factor of soil slope increases approximately linearly from 1.04 to 1.60; As the internal friction angle of soil increases from 10° to 30°, the safety factor of soil slope increases approximately linearly from 1.00 to 1.81; As the unit weight of soil increases from 13kN/m3 to 21kN/m3, the safety factor of soil slope decreases approximately linearly from 1.50 to 1.21. The influencing factors affecting the safety factor of soil slope in descending order are slope height, slope angle, soil internal friction angle, soil cohesion, and soil unit weight. The research has reference significance for studying the stability and failure laws of soil slopes and conducting landslide control on soil slopes.

Slope failure lines analysis to determine landslide potential based on standard penetration test method

Landslide events cause road access to be cut off, such as in the Payung area of Batu City, which connects Malang and Kediri. Analysis and evaluation of landslide disasters need to be carried out in this area to anticipate the next landslides and reduce economic losses. This study aims to determine landslide potential in the Payung Area, Batu City, using the SPT method. The test is carried out at 2 points of the slope on the provincial roads and the slope above the road so that the two measurement points can be correlated. The data needed to analyze slope stability include the internal shear angle, cohesion, and soil unit weight; analysis and modeling of slope stability using Geostudio SLOPE/W software. The results of the slope stability analysis at point 1 show that the average failure line is at a depth of 6.00 m with the smallest Safety Factor (SF) value of 0.710 in scenario 2. While the slope at point 2, the failure line is at a depth of 1.50 m with the smallest FK value of 0.840 in scenario 2. Significant changes in the N-SPT value indicate differences in soil mechanical properties, such as shear angle and cohesion that affect the stability of the slope and cause landslides.

Comparing shallow landslide susceptibility maps in Northeastern Türkiye (Beşikdüzü, Trabzon): a multivariate statistical, machine learning, and physical data-based analysis

This study endeavors to assess and compare the efficacy of various modeling approaches, including statistical, machine learning, and physical-based models, in the creation of shallow landslide susceptibility maps within the Besikduzu district of Trabzon province, situated in the Black Sea Region of Türkiye. The landslide inventory data, spanning from 2000 to 2018, was acquired through meticulous field surveys and analysis of Google Earth satellite imagery. Key topographic and geologic input parameters, such as slope, aspect, topographic wetness index, stream power index, plan and profile curvature, and geologic units, were extracted from a high-resolution 10 m spatial DEM (Digital Elevation Model) and a 1:25,000 scaled digital geology map, respectively. Additionally, soil unit weight and shear strength parameters, critical for the physical-based model, were determined through field samples. To evaluate landslide susceptibility, logistic regression, random forest, and Shalstab were employed as the chosen methods. The accuracy of susceptibility maps generated by each method was assessed using the area under the curve method, yielding impressive values of 0.99 for the random forest model, 0.97 for the logistic regression model, and 0.93 for the Shalstab model. These results underscore the robust performance of all three methods, suggesting their applicability for generating shallow landslide susceptibility maps not only in the Black Sea Region but also in analogous areas with similar geological characteristics.

Geophysical methods reveal the soil architecture and subsurface stratigraphic heterogeneities across land-lake interfaces along Lake Erie

PurposeThe land-lake interface is a unique zone where terrestrial and aquatic ecosystems meet, forming part of the Earth’s most geochemically and biologically active zones. The unique characteristics of this interface are yet to be properly understood due to the inherently high spatiotemporal variability of subsurface properties, which are difficult to capture with the traditional soil sampling methods. Geophysical methods offer non-invasive techniques to capture variabilities in soil properties at a high resolution across various spatiotemporal scales.MethodsWe combined electromagnetic induction (EMI), electrical resistivity tomography (ERT), and ground penetrating radar (GPR) with data from soil cores and in situ sensors to investigate hydrostratigraphic heterogeneities across land-lake interfaces along the western basin of Lake Erie.ResultsEMI revealed high spatial heterogeneities in ECa distribution across the land-lake interfaces, with higher values in the wetland and transition zones compared to the upland zone. Soil ECa maps matched soil maps from a public database with the hydric soil units delineated as high conductivity zones (ECa > 40 mS/m). ERT and GPR showed vertical variation in soil properties with clear stratigraphic boundaries, and correlation of ERT profiles with lithologs from piezometers revealed the stratigraphic units of silt–clay and till sequence down to 3.5 m depth which are consistent with the surficial geology of the study area.ConclusionsThese results validate the use of multiple geophysical methods for extrapolating soil properties and mapping stratigraphic structures at land-lake interfaces, thereby providing the missing information required to improve the earth system model (ESM) of coastal interfaces.

The performance of Karasu Bridge following the February 6, 2023 Kahramanmaras-Turkiye earthquake sequence

The evaluation liquefaction-induced excessive ground displacements of the approach embankments of the Karasu Bridge, as surveyed following the Pazarcik M7.8 and Ekinozu-Elbistan M7.6, Kahramanmaras-Turkiye earthquakes on February 6, 2023, is presented. The Karasu Bridge, located on the Karasu River, connects the metropolitan city of Hatay and the State Hospital. The approach embankments of the bridge are underlain by layers of low to high plasticity stiff clay and liquefaction susceptible clayey and silty medium dense sand units. Specifically, the non-plastic silty sands with fines contents ranging from 21% to 42%, were evaluated as the critical (liquefied) soil units during the Pazarcik earthquake. Liquefaction triggering assessments, following the procedure outlined by Cetin et al. (2018), estimated factor of safety against liquefaction <1.0, confirming the surface manifestations of liquefaction at the site. Empirical approaches suggested by Hamada et al. (1986) and Youd et al. (2002) predicted lateral ground displacements triggered by liquefaction, averaging 137 cm and 383 cm, respectively. These values are comparable with mapped lateral displacements, which exceeded 150 cm. Volumetric settlement assessments, utilizing the method outlined by Cetin et al. (2009), predicted 14 to 26 cm, approximately one third to half of the mapped settlement values ranging from 40 to 55 cm. The discrepancy is attributed to the three-dimensional nature of site behavior and induced deviatoric strains, contributing to additional settlements beyond the volumetric component.

Assessment of salt-affected soil in selected rice irrigation schemes in Tanzania: understanding salt types for optimizing management approaches

Salt-affected soils have serious implications for agricultural land quality and productivity, leading to a reduction in the net cultivable area available for food production. This issue has emerged as one of the foremost global challenges in recent years, impacting both food security and environmental sustainability. This research focuses on soil characterizations conducted in three irrigation schemes to understand the types, distribution, and nature of salt-affected soils. Auger observations served as the basic methodology for soil unit delineation in this study. Twelve representative soil pits with a depth of more than 160 cm were described, and undisturbed and disturbed samples were collected and analyzed for physical and chemical properties. The schemes were characterized by low levels of available phosphorus, organic carbon, and total nitrogen, as well as variations in exchangeable bases. Furthermore, 37.5% of the analyzed horizons highlighted the presence of salt-affected soils. Sodium was the predominant cation, followed by magnesium, potassium, and calcium. Likewise, HCO3− was the dominant anion, followed by Cl− and SO42−. The results of this study reveal the existence of two types of salt-affected soil. Uturo irrigation scheme had sodic soils, while the Ndungu irrigation scheme had saline-sodic soils. Additionally, both sodic and saline-sodic soils have been discovered in the Mawala irrigation scheme. The root cause of this challenge is inherent soil conditions, exacerbated by inadequate drainage infrastructure. Therefore, measures such as the application of gypsum followed by salt leaching, improving soil drainage by incorporating organic matter, improving drainage infrastructure, and using rice-tolerant varieties are recommended to mitigate salt stress and improve soil fertility. It is imperative to establish a robust framework for continuous monitoring and regular assessment of soil health to enable timely interventions and informed decisions for sustainable agricultural management.

Impact of different sterilisation techniques on sorption and NER formation of test chemicals in soil

Standard OECD tests are used to generate data on biodegradation (OECD 307) and sorption (OECD 106) of test chemicals in soil. In such tests, data on abiotic degradation using sterile samples are utilised to investigate any losses due to abiotic processes. The data from sterile samples are also used to interpret results and findings of non-sterile samples, especially in the context of sorption and non-extractable residue (NER) formation. However, to ensure the comparability of the data obtained from sterile and non-sterile experiments, effects of sterilisation on the soil matrix should be minimal. The objective of this study was to investigate the efficiencies of different sterilisation techniques and the impact of the sterilisation on sorption and NER formation in soil. In this study, experiments in accordance with OECD 307 and OECD 106 guidelines were performed with two soils covering wide range of soil characteristics and treated with the three sterilisation techniques autoclaving, gamma(γ)-radiation and adding 1% (w/w) sodium azide. As a test item, 14C-labelled phenanthrene and bromoxynil was used for OECD 307 test, whereas non-labelled phenanthrene and atrazine was used for OECD 106. The sterilisation efficiencies were investigated using traditional viable plate count and molecular approaches (RNA extraction method). The results suggest that none of the tested techniques resulted in completely sterilised soil with autoclaving being the most efficient technique. Adding sodium azide led to most inefficient sterilisation and a significant increase (0.56 units) in soil pH. OECD 307 results showed differences in NER formation of the test chemicals, especially for soil poisoning and γ-radiation, which could be due to inefficient sterilisation and/or change in soil physico-chemical properties. OECD 106 results suggest that none of the sterilisation techniques considerably affected sorption behaviour of the test chemicals. Based on our results, we recommend autoclaving as most suitable sterilisation technique.

Research Progress on Ecological Security Technology of Slope Treatment on Loess Plateau

The Loess Plateau is an important source of Eastern civilization, but also the most serious soil erosion in our country and in the world. Controlling soil erosion and improving the ecological environment are not only the needs of local social and economic development, but also the needs of long-term peace and stability of the country. Since the 1950s, large-scale soil and water conservation work has been carried out on the Loess Plateau. It has played a significant role in improving ecological environment, changing agricultural production conditions and developing rural economy. It is a very effective measure to take small watershed as a unit to conduct comprehensive management. There are 45,000 small watersheds of 6-10 km2 in the Loess Plateau, which are not only the basic units of soil and water loss, but also the units of comprehensive management. Slope is the source of runoff and sediment in small watershed, and slope treatment is an important part of comprehensive management of small watershed. Therefore, it is an urgent task to deepen the study of slope management.

Micro-constructive Damage Model of Dry-Wet Cyclic Red Clay Based on Weibull Distribution

Abstract To address the strength damage of red clay under dry-wet cycles, systematic conventional triaxial tests under specific circumferential pressure and scanning electron microscope observation were carried out to describe the damage evolution of soil units under load conditions of dry-wet cycle red clay microunits based on the Weibull distribution. Damage variable expressions obeying the Weibull distribution were established and the micro-parameter pore area ratio and the macro-parameter dry-wet cycle number were introduced. The cross-scale characterization of macroscopic and microscopic parameters was realized by combining the damage mechanics equation of red clay under loading. The microscopic damage intrinsic model of red clay considering the number of dry-wet cycles was constructed. The model was verified to be reasonable and effective based on triaxial tests, in which the calculation errors of the secant modulus damage threshold, probability density function shape parameter, and dry-wet cycle red clay damage stress were within 10 %, 5 %, and 5 %, respectively.

Spatial variability of shear wave velocity: implications for the liquefaction response of a case study from the 2010 Maule Mw 8.8 Earthquake, Chile

Assessing the potential and extent of earthquake-induced liquefaction is paramount for seismic hazard assessment, for the large ground deformations it causes can result in severe damage to infrastructure and pose a threat to human lives, as evidenced by many contemporary and historical case studies in various tectonic settings. In that regard, numerical modeling of case studies, using state-of-the-art soil constitutive models and numerical frameworks, has proven to be a tailored methodology for liquefaction assessment. Indeed, these simulations allow for the dynamic response of liquefiable soils in terms of effective stresses, large strains, and ground displacements to be captured in a consistent manner with experimental and in-situ observations. Additionally, the impact of soil properties spatial variability in liquefaction response can be assessed, because the system response to waves propagating are naturally incorporated within the model. Considering that, we highlight that the effect of shear-wave velocity Vs spatial variability has not been thoroughly assessed. In a case study in Metropolitan Concepción, Chile, our research addresses the influence of Vs spatial variability on the dynamic response to liquefaction. At the study site, the 2010 Maule Mw 8.8 megathrust Earthquake triggered liquefaction-induced damage in the form of ground cracking, soil ejecta, and building settlements. Using simulated 2D Vs profiles generated from real 1D profiles retrieved with ambient noise methods, along with a PressureDependentMultiYield03 sand constitutive model, we studied the effect of Vs spatial variability on pore pressure generation, vertical settlements, and shear and volumetric strains by performing effective stress site response analyses. Our findings indicate that increased Vs variability reduces the median settlements and strains for soil units that exhibit liquefaction-like responses. On the other hand, no significant changes in the dynamic response are observed in soil units that exhibit non-liquefaction behavior, implying that the triggering of liquefaction is not influenced by spatial variability in Vs. We infer that when liquefaction-like behavior is triggered, an increase of the damping at the shallowest part of the soil domain might be the explanation for the decrease in the amplitude of the strains and settlements as the degree of Vs variability increases.

Structural, acoustical, and thermal evaluation of an experimental house built with reinforced/hollow interlocking compressed stabilized earth brick-masonry

With the increasing demand on affordable construction that addresses the global challenges of the modern world, earthen construction is being reintroduced and investigated as a potential sustainable and affordable building method. Compressed stabilized earth blocks (CSEBs) are a common form of enhanced earthen building materials. Previous studies focused on the structural performance of CSEB walls and prisms consisting of one type of bricks with the same mixture, analyzed their thermal and acoustic properties as units only, or evaluated the thermal performance of solid unreinforced CSEB masonry.The present research is the first complete structural, acoustical, and thermal investigation of an experimental house built with a novel reinforced/hollow interlocking compressed stabilized earth brick-masonry (ICSEB) using varying stabilizer contents, compliant with the Egyptian code for building with stabilized soil—Part One: Building with compressed stabilized soil units (EG-SE2016). Methods depend on experimental testing, codified theoretical calculations, finite element analysis, and live measurements. According to the structural experimental testing program, reinforcement was found to triple the load bearing capacity of ICSEB columns and, although minimal rebars were used in the ICSEB walls, it has improved their load bearing capacity by 23% for single walls (125 mm) and 58% for double walls (250 mm). In addition, doubling the thickness of the unreinforced ICSEB walls increased the load bearing capability by 164%, while raising the thickness of the reinforced wall from 125 mm to 250 mm increased the load bearing capacity by more than threefold (3.38). Based on the codified theoretical calculations and findings of the finite element analysis, it is safe to recommend reinforced double ICSEB walls as a reliable construction for a two-story residential building. Acoustically, double ICSEB walls attained the noise reduction index value of 40 dB, which is required by the Egyptian code for acoustic insulation and noise control in residential buildings, to protect against the average outdoor noise levels of 65–70dBA. Thermally, reinforced double ICSEB walls kept the indoor air temperature and relative humidity values within the thermal comfort zone, 23.9–25.7 °C and 28–36%, respectively, despite the fluctuating outdoor temperatures and relative humidities (16–37 °C and 7–88%, respectively). Indoor air temperatures were 1.5–2 °C lower than those of concrete masonry walls. Additional research is required to evaluate resistance to environmental aspects, such as exposure to water, wind, and corrosion, and to further investigate their thermal and acoustical properties.

Reclamation, land suitability evaluation and management strategy for soils of Tin mined area of Barkin Ladi, Plateau State, Nigeria

The rate of increase in land area used by man is continuously increasing with population growth, with resultant environmental degradation caused by mining and other anthropogenic activities. However, reclamation as well as land suitability evaluation are considered the basis and critical steps for determining the reuse direction of degraded land caused by several years of mining activities. Therefore, the present study was carried out to evaluate the land suitability for different crops production and suggest management practices for their reclamation. Parcel of land covering 224.29 ha on the northern part of Barkin Ladi in Plateau State, Nigeria was surveyed at a detailed scale of 1:6,000. Soil physical condition (petroplinthite), chemical fertility (nutrient retention and availability), low to moderate plant available water, poorly drained condition and erosion hazard were the land qualities that critically limited the suitability of soil mapping units BL II to BL V for the different crops. The evaluation showed that BL I was highly suitable under current suitability for maize, cowpea, green bean, onion and mango (55.55 % of the crops). The crop proportion rated as S1 increased to 88.88 % under potential suitability. The upgrade is expected to occur when the limitations identified are properly managed. Soil unit BL V degraded by previous mining is the least rated with most of the crops as temporarily and permanently not suitable. Land levelling or terrace construction and planting of mango as well as avoidance of bush burning were among management practices suggested to reclaim the deep gully associated with the degraded mined lands. For sustainable crops production and management of the study area; contour ridges, incorporation of organic matter and inorganic fertilizers as well as construction of drainage canals are recommended.

Data-Driven Prediction of Maximum Settlement in Pipe Piles under Seismic Loads

The structural stability of pipe pile foundations under seismic loading stands as a critical concern, demanding an accurate assessment of the maximum settlement. Traditionally, this task has been addressed through complex numerical modeling, accounting for the complicated interaction between soil and pile structures. Although significant progress has been made in machine learning, there remains a critical demand for data-driven models that can predict these parameters without depending on numerical simulations. This study aims to bridge the disparity between conventional analytical approaches and modern data-driven methodologies, with the objective of improving the precision and efficiency of settlement predictions. The results carry substantial implications for the marine engineering field, providing valuable perspectives to optimize the design and performance of pipe pile foundations in marine environments. This approach notably reduces the dependence on numerical simulations, enhancing the efficiency and accuracy of the prediction process. Thus, this study integrates Random Forest (RF) models to estimate the maximum pile settlement under seismic loading conditions, significantly supporting the reliability of the previously proposed methodology. The models presented in this research are established using seven key input variables, including the corrected SPT test blow count (N1)60, pile length (L), soil Young’s modulus (E), soil relative density (Dr), friction angle (ϕ), soil unit weight (γ), and peak ground acceleration (PGA). The findings of this study confirm the high precision and generalizability of the developed data-driven RF approach for seismic settlement prediction compared to traditional simulation methods, establishing it as an efficient and viable alternative.

Using Geospatial Technologies to Separate Soil Units and Predict Some of Their Characteristics in Basra Governorate (Indices)

This study was conducted to classify the soils of eastern Basra Governorate, southern Iraq, within the administrative borders of Abu Al-Khasib District extending south to Al-Faw District, using remote sensing techniques and geographic information systems. The soil units were separated by adopting remote sensing technology through the use of satellite image from Landsat8, the TIRS - OLI sensor (The Operational Land Imager), and spectral indices with field observations. A map of the soil units was prepared using the GIS program. Eight locations of soil pedons were identified, and they were divided The study area is divided into two paths, and each path contains four typical pedons within the boundaries of the study area as follows:&#x0D; 1 - First stripe: represents the river levees unit within pedons 1, 3, 5 and 7.&#x0D; 2 - Second stripe: represents the river basin unit within pedons 2, 4, 6 and 8.&#x0D; The results of Indices showed a variation in their values between all the pedons through which spatial variation in surface soil characteristics can be distinguished. The values of NDVI ranged between &lt; 0 – 0.79, &lt; 0 – 1.64 for BSI, and between &lt; 0 – 0.408 for SAVI. The spectral indices NDVI and SAVI gave results that match the ground facts present on the ground, represented by vegetation, while the bare soil index BSI gave reflectivity values similar to barren lands. The lands of the study area were characterized by a lack of vegetation, especially in the low-lying areas of the river plains, while the areas of natural vegetation and the parts close to the river levees were characterized by a medium to high vegetation cover, and these results are consistent with the values of the NDVI and SAVI spectral indices.

Investigation of site fundamental frequency using H/V method guided by geomorphic features derived from old aerial photos

The fundamental frequency of soil (non-lithified cover on the bedrock) is one of the most important factors in seismic hazard evaluations. On the other hand, this frequency expresses several factors such as the clast size, sorting, and the degree of compaction and cementation of soil, which is in close relationship with both the geomorphic setting and processes responsible for the soil formation. We present a rapid and cost-effective multi-disciplinary approach to study site effect in developing urban areas using the spatial correlation between geomorphic setting of soil units and their fundamental frequencies. As a case study, the city of Zanjan was selected because like many other cities of developing countries has been expanded drastically during the last half-century. We use old aerial photos (produced in 1966) of Zanjan and its surroundings to reconstruct a unified orthophoto-mosaic of the study area. This orthophoto-mosaic exhibits pristine geomorphic landforms and features, which predate the current urban coverage of the city, and provides an excellent possibility for mapping Quaternary geological units with distinct geomorphic settings and soil characteristics. Besides, the site effect is measured through the H/V spectral ratio method at 91 points along the profiles pre-designed based on our geomorphic mapping. Subsequently, the spatial pattern described in the geomorphic map was compared with the site effect values. This comparison shows a general correlation between the geomorphic setting of alluvia and the corresponding fundamental frequencies of the soil such that the closer to the mountain front, the higher the fundamental frequency. The results indicate that the peak frequency is observed in the northern regions of the city where a relatively thin layer of unsorted coarse-grained alluvium overlies the bedrock. In the southern geomorphic depressions close to the Zanjanrood river and behind the East-dipping North Zanjan reverse fault (east of the city), where a pile of fine-grained deposits is found, the fundamental frequency reaches its lowest values, namely less than 1 Hz. A comparison of the soil frequency map with the map of shear-wave velocities provided by geotechnical borehole data also indicates a meaningful correlation. Our approach provides a twofold benefit by (1) reducing both the time consumption and expenses in site effect studies through an optimal design of H/V measurement points and borehole drillings based on a precise mapping of distinct geomorphic units, and (2) proposing a unique possibility to produce a reliable site effect map in the urban areas developed during the last half-century.

The misconception of soil organic carbon sequestration notion: When do we achieve climate benefit?

AbstractSoil organic carbon (SOC) sequestration is a key function of natural and semi‐natural ecosystems. Restoring this property in terrestrial ecosystems has become central to the EU's climate change mitigation and adaptation strategies. However, SOC sequestration is a widely misunderstood concept. The different methodological approaches used to investigate and compare SOC stock under sustainable agricultural practices play a key role in reinforcing misconceptions about this complex process. This commentary paper aimed not only to provide a clear definition of SOC sequestration, but also to interpret the results that can be obtained for SOC stock change estimation using the SOC stock difference and the paired comparison methods, as well as to identify the soil carbon‐related processes that achieve climate mitigation. SOC sequestration can be defined as the progressive increase in a site's SOC stock compared with pre‐intervention via a net depletion and transfer of atmospheric CO2 into the soil, where it is retained as soil organic matter (SOM), by plants, plant residues, or other organic solids such as the material derived from the organic fraction of farming solid waste, which can be used as a fertilizer (e.g., manure, compost, biochar, and digestate), and that is produced or derived from that land unit. To date, the most appropriate way to determine whether a land unit's soil is a sink or rather a source of atmospheric CO2 is to implement the SOC stock difference method, provided the non‐occurrence of carbon exchange between ecosystems.