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21 pages, 4010 KB  
Article
Headwater Systems as Green Infrastructure: Prioritising Restoration Hotspots for Sustainable Rural Landscapes
by Selma B. Pena
Land 2025, 14(9), 1704; https://doi.org/10.3390/land14091704 - 23 Aug 2025
Viewed by 468
Abstract
This study aims to assess the role of headwater systems (HS) in enhancing ecological connectivity and supporting Green Infrastructure in the Centre Region of Portugal. Specifically, it identifies restoration opportunity areas within HS by analysing land-use changes over the past 70 years, modelling [...] Read more.
This study aims to assess the role of headwater systems (HS) in enhancing ecological connectivity and supporting Green Infrastructure in the Centre Region of Portugal. Specifically, it identifies restoration opportunity areas within HS by analysing land-use changes over the past 70 years, modelling land-use scenarios to promote ecological resilience, and evaluating connectivity between HS and Natura 2000 sites. The methodology integrates spatial analysis of historical land-use data with connectivity modelling using least-cost path approaches. Results show substantial transformation in HS areas, notably the expansion of eucalyptus plantations and a decline in agricultural land. Approximately 58% of the HS are identified as requiring restoration, including areas within the Natura 2000 network. The connectivity assessment reveals that HS can function as effective ecological corridors, contributing to improved water regulation, soil conservation, gene flow, and wildfire mitigation. A total of 61 potential ecological linkages between Natura 2000 sites were identified. These findings highlight the strategic importance of integrating HS into regional and national Green Infrastructure planning and supporting the implementation of the EU Biodiversity Strategy for 2030. The study recommends prioritising headwater restoration through multi-scale planning approaches and active involvement of local stakeholders to ensure sustainable land-use management. Full article
(This article belongs to the Special Issue Efficient Land Use and Sustainable Development in European Countries)
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15 pages, 2172 KB  
Article
Quantifying Macropore Variability in Terraced Paddy Fields Using X-Ray Computed Tomography
by Rong Ma, Linlin Chu, Lidong Bi, Dan Chen and Zhaohui Luo
Agronomy 2025, 15(8), 1873; https://doi.org/10.3390/agronomy15081873 - 1 Aug 2025
Viewed by 439
Abstract
Large soil pores critically influence water and solute transport in soils. The presence of preferential flow paths created by soil macropores can profoundly impact water quality, underscoring the necessity of accurately assessing the characteristics of these macropores. However, it remains unclear whether variations [...] Read more.
Large soil pores critically influence water and solute transport in soils. The presence of preferential flow paths created by soil macropores can profoundly impact water quality, underscoring the necessity of accurately assessing the characteristics of these macropores. However, it remains unclear whether variations in macropore structure exist between different altitudes and positions of terraced paddy fields. The primary objective of this research was to utilize X-ray computed tomography (CT) and image analysis techniques to characterize the soil pore structure at both the inner field and ridge positions across different altitude levels (high, medium, and low altitude) within terraced paddy fields. The results indicate that there are significant differences in the distribution of large soil pores at different altitudes, with large pores concentrated in the surface layer (0–10 cm) in low-altitude areas, while in high-altitude areas, the distribution of large pores is more uniform. Additionally, as altitude increases, the porosity of large pores shows an increasing trend. The three-dimensional equivalent diameter and large pore volume are primarily characterized by large pores ranging from 1 to 2 mm and 0 to 5 mm3, respectively, with their morphology predominantly appearing spherical or ellipsoidal. The connectivity of large pores in the surface layer of paddy soil is stronger than that in the bunds. However, this connectivity gradually weakens with increasing soil depth. The findings from this study provide valuable quantitative insights into the unique characteristics of soil macropores that vary according to the altitude and position in terraced paddy fields. Moreover, this study emphasizes the necessity for future research that encompasses a broader range of soil types, altitudes, and terraced paddy locations to validate and further explore the identified relationships between altitude and macropore characteristics. Full article
(This article belongs to the Section Precision and Digital Agriculture)
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29 pages, 5505 KB  
Article
Triaxial Response and Elastoplastic Constitutive Model for Artificially Cemented Granular Materials
by Xiaochun Yu, Yuchen Ye, Anyu Yang and Jie Yang
Buildings 2025, 15(15), 2721; https://doi.org/10.3390/buildings15152721 - 1 Aug 2025
Viewed by 444
Abstract
Because artificially cemented granular (ACG) materials employ diverse combinations of aggregates and binders—including cemented soil, low-cement-content cemented sand and gravel (LCSG), and concrete—their stress–strain responses vary widely. In LCSG, the binder dosage is typically limited to 40–80 kg/m3 and the sand–gravel skeleton [...] Read more.
Because artificially cemented granular (ACG) materials employ diverse combinations of aggregates and binders—including cemented soil, low-cement-content cemented sand and gravel (LCSG), and concrete—their stress–strain responses vary widely. In LCSG, the binder dosage is typically limited to 40–80 kg/m3 and the sand–gravel skeleton is often obtained directly from on-site or nearby excavation spoil, endowing the material with a markedly lower embodied carbon footprint and strong alignment with current low-carbon, green-construction objectives. Yet, such heterogeneity makes a single material-specific constitutive model inadequate for predicting the mechanical behavior of other ACG variants, thereby constraining broader applications in dam construction and foundation reinforcement. This study systematically summarizes and analyzes the stress–strain and volumetric strain–axial strain characteristics of ACG materials under conventional triaxial conditions. Generalized hyperbolic and parabolic equations are employed to describe these two families of curves, and closed-form expressions are proposed for key mechanical indices—peak strength, elastic modulus, and shear dilation behavior. Building on generalized plasticity theory, we derive the plastic flow direction vector, loading direction vector, and plastic modulus, and develop a concise, transferable elastoplastic model suitable for the full spectrum of ACG materials. Validation against triaxial data for rock-fill materials, LCSG, and cemented coal–gangue backfill shows that the model reproduces the stress and deformation paths of each material class with high accuracy. Quantitative evaluation of the peak values indicates that the proposed constitutive model predicts peak deviatoric stress with an error of 1.36% and peak volumetric strain with an error of 3.78%. The corresponding coefficients of determination R2 between the predicted and measured values are 0.997 for peak stress and 0.987 for peak volumetric strain, demonstrating the excellent engineering accuracy of the proposed model. The results provide a unified theoretical basis for deploying ACG—particularly its low-cement, locally sourced variants—in low-carbon dam construction, foundation rehabilitation, and other sustainable civil engineering projects. Full article
(This article belongs to the Special Issue Low Carbon and Green Materials in Construction—3rd Edition)
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14 pages, 2915 KB  
Article
An Integrated DEM–FEM Simulation Framework for Preferential Flow Path Evaluation in Waste Landfill Composed of Non-Spherical Particles
by Hiroyuki Ishimori, Kazuto Endo and Masato Yamada
Appl. Sci. 2025, 15(11), 5798; https://doi.org/10.3390/app15115798 - 22 May 2025
Viewed by 475
Abstract
A numerical experimental method combining the discrete element method (DEM) and the finite element method (FEM) is proposed to analyze water channel flow in heterogeneous porous media such as landfill layers. In this study, non-spherical particles —thin plates and rods—are introduced into DEM-FEM [...] Read more.
A numerical experimental method combining the discrete element method (DEM) and the finite element method (FEM) is proposed to analyze water channel flow in heterogeneous porous media such as landfill layers. In this study, non-spherical particles —thin plates and rods—are introduced into DEM-FEM coupling for the first time, which allows for the virtual reconstruction of complex pore structures beyond the capability of traditional experimental approaches, such as soil tanks or X-ray CT. Fluid flow simulations performed on three types of virtual porous media showed that only the case with non-spherical particles generated water channels. Tortuosity analysis was used to quantify the complexity of the flow paths and showed median values of 1.258 and 1.218 for homogeneous and particle size-distributed cases, respectively. In contrast, the case simulating waste media had a significantly lower median tortuosity of 1.051, with a skewed distribution toward shorter paths, indicating dominant water channels. This shift in tortuosity, coupled with higher variance, serves as quantitative evidence of water channel formation. The results demonstrate that tortuosity analysis complements streamline visualization and provides a reliable means to detect and compare water channel flow behavior. The proposed DEM-FEM framework enables both qualitative and quantitative understanding of flow dynamics in large-scale, highly heterogeneous porous systems and is expected to support further research and practical design in landfill and drainage engineering. Full article
(This article belongs to the Special Issue Advanced Technologies in Landfills)
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14 pages, 4634 KB  
Article
Characteristics of Medium Resistivity Response During the Water–Oil Displacement Process
by Guizhang Zhao, Jie An, Huan Zhu and Hongli Zhang
Water 2025, 17(7), 1090; https://doi.org/10.3390/w17071090 - 5 Apr 2025
Viewed by 664
Abstract
Oil leakage during the processes of extraction, storage, and transportation poses a significant challenge due to the complex nature of pollution caused by frequent fluctuations in groundwater levels and variations in the water–oil interface. To effectively identify and monitor the position of the [...] Read more.
Oil leakage during the processes of extraction, storage, and transportation poses a significant challenge due to the complex nature of pollution caused by frequent fluctuations in groundwater levels and variations in the water–oil interface. To effectively identify and monitor the position of the water–oil interface and displacement processes, geophysical methods have proven to be an efficient approach. This study utilizes electrical resistivity measurements to analyze changes in medium resistivity during water–oil displacement, enabling simulation of the spatial relationship between groundwater levels and petroleum contaminants based on resistivity characteristics and natural potential responses. After analysis, the following conclusions can be drawn: (1) During the water displacement process, when water forms a connected flow channel between sand and gravel, the resistivity decreases abruptly. Conversely, during oil displacement by water, when oil fills soil pores and creates a high-resistance conductive path, the resistivity increases abruptly. (2) Changes in resistivity are determined by the position of the water–oil interface. By observing characteristic changes in resistivity, it is possible to verify whether soil is undergoing water–oil displacement. (3) The direction of displacement significantly affects changes in resistivity for all three media involved due to gravity effects during water displacement by the oil process. (4) Resistance values during the water–oil displacement process are directly influenced by the size of sand particles used in experiments. Full article
(This article belongs to the Section Hydraulics and Hydrodynamics)
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20 pages, 6389 KB  
Article
Evaluation of Data Acquisition Areas in Geotechnical Seismic Tests: Insights from Field Applications
by Gunwoong Kim
Sensors 2025, 25(6), 1757; https://doi.org/10.3390/s25061757 - 12 Mar 2025
Viewed by 1110
Abstract
Geotechnical field testing evaluates soil, rock, and groundwater conditions in their natural states, offering critical information about subsurface properties such as the density, strength, permeability, and groundwater flow. These tests are essential in ensuring the safety, reliability, and performance of civil engineering projects [...] Read more.
Geotechnical field testing evaluates soil, rock, and groundwater conditions in their natural states, offering critical information about subsurface properties such as the density, strength, permeability, and groundwater flow. These tests are essential in ensuring the safety, reliability, and performance of civil engineering projects and are increasingly used for 3D geographical visualization and subsurface modeling. While point-based tests like the cone penetration test (CPT) and standard penetration test (SPT) are widely used, area-based methods such as the spectral analysis of surface waves (SASW) and electrical resistivity testing significantly enhance the accuracy of such models by providing broader coverage. Furthermore, these non-destructive techniques are particularly effective in identifying subsurface defects. This study focuses on analyzing the data acquisition areas of various field seismic tests, including SASW, downhole, crosshole, and suspension logging (PS logging). While other tests clearly define data acquisition areas based on their array paths, the SASW test posed challenges due to the complexity of data reconstruction. To address this, 69 datasets from four different sites were analyzed to predict the data acquisition areas for SASW as a function of depth. Moreover, a case study demonstrates the practical application of the SASW method in detecting cavities near a dam spillway. The findings of this research improve the understanding and interpretation of geotechnical seismic test data, enabling more precise geotechnical investigations and advancing the detection of subsurface defects using non-destructive methods. Full article
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22 pages, 5986 KB  
Article
Geodiversity as a Driver of Soil Microbial Community Diversity and Adaptation in a Mediterranean Landscape
by Samuel Pelacani, Maria Teresa Ceccherini, Francesco Barbadori, Sandro Moretti and Simone Tommasini
Land 2025, 14(3), 583; https://doi.org/10.3390/land14030583 - 10 Mar 2025
Viewed by 978
Abstract
Extreme meteorological events and anthropogenic influences determine important variations in microbial community composition. To know the extent of these variations, it is necessary to delve deeper into the geogenic factors to be considered as a baseline. The purpose of this study was to [...] Read more.
Extreme meteorological events and anthropogenic influences determine important variations in microbial community composition. To know the extent of these variations, it is necessary to delve deeper into the geogenic factors to be considered as a baseline. The purpose of this study was to assess the effect of topographic characteristics and soil geochemistry on the spatial distribution of three Actinobacteria genera considered as molecular biomarkers of landforms belonging to Mediterranean environments. Given the important role that Actinobacteria play in the ecosystem, we performed a spatial distribution model of the genera Rubrobacter, Gaiella, and Microlunatus and investigated the fungi/bacteria ratio in a machine learning (ML)-based framework. Variable importance provided insight into the controlling factor of geomicrobial spatial distribution. The spatial distribution of the predicted Actinobacteria genera generally follows topographic constraints, mostly altitude. Rubrobacter was related to the slope aspect and lithium; Microlunatus was related to the topographic wetness index (TWI) and normalized difference water index (NDWI), as well as the fungi/bacteria ratio; and Gaiella was related to flow path and metals. Our results provide new information on the adaptation of Actinobacteria in Mediterranean areas and show the potential of using ML frameworks for the spatial prediction of OTUs distribution. Full article
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21 pages, 16263 KB  
Article
Assessment of Environmental (Dust, Soil, and Groundwater) Impact and Remediation of Lead Smelters for Sustainable Development: A Modeling Approach
by Mohamed ElKashouty and Mohd Yawar Ali Khan
Water 2025, 17(5), 622; https://doi.org/10.3390/w17050622 - 20 Feb 2025
Viewed by 850
Abstract
Lead (Pb) poses a significant risk to human health and the environment. Global Pb production and consumption have markedly risen due to unregulated development and urbanization, Pb smelting, and Pb-acid battery processing. This study addresses the issue of elevated heavy metal concentrations in [...] Read more.
Lead (Pb) poses a significant risk to human health and the environment. Global Pb production and consumption have markedly risen due to unregulated development and urbanization, Pb smelting, and Pb-acid battery processing. This study addresses the issue of elevated heavy metal concentrations in dust, soil, and groundwater in Shubra Al Khaymah due to the Awadallah Pb smelter. Pb concentration in soil and groundwater escalates in proximity to the Awadallah smelter and diminishes with distance from it—the surface soil functions as a repository for heavy metals. The concentrations of Pb (50–1500 µg/L), manganese (Mn) (1–750 µg/L), iron (Fe) (200–1250 µg/L), and boron (B) (250–1750 µg/L) in the groundwater stratum exceeded drinking and irrigation standards. A solution to the groundwater system issue is proposed by employing pumping wells adjacent to the riverbed to recover the contaminated water from the hydrogeological environment. Processing Modflow Path (PMPATH) program may delineate groundwater protection zones according to the travel time of 150 days (Zones 1 and 2) and the whole watershed source (Zone 3). An injection well was constructed to replenish excellent water quality in the groundwater aquifer in the upstream region. A 3D model of dissolved matter transport was created to examine the concentration distribution across remediation time in the contaminated region. This model demonstrates that, after 365 days of injection, the C/Co concentration ratio exceeded 70% in the downstream area, rendering it appropriate for drinking and irrigation. The alternate strategy is to encapsulate the severely contaminated zone. All measures aim to decrease the piezometric pressure in the vicinity, directing groundwater flow towards the contaminated zone, as accomplished by Processing Modflow Windows (PMWIN). Full article
(This article belongs to the Special Issue Groundwater Flow and Transport Modeling in Aquifer Systems)
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19 pages, 11507 KB  
Article
Control Effect of a Novel Polyurethane (W-OH) on Colluvial Deposit Slope Erosion in the Benggang Area of Southern China
by Zhenggang Zhang, Yuyang Chen, Zhehao Zhu, Ying Meng, Wei Wu, Yiyang Zhou, Yue Zhang, Jinshi Lin, Yanhe Huang and Fangshi Jiang
Water 2025, 17(4), 548; https://doi.org/10.3390/w17040548 - 14 Feb 2025
Viewed by 702
Abstract
A novel polyurethane (W-OH), namely an eco-friendly hydrophilic polymer, has been widely applied in the field of soil erosion. However, recent research has not revealed the process and mechanisms through which W-OH application influences the soil detachment by concentrated overland flow (hereinafter referred [...] Read more.
A novel polyurethane (W-OH), namely an eco-friendly hydrophilic polymer, has been widely applied in the field of soil erosion. However, recent research has not revealed the process and mechanisms through which W-OH application influences the soil detachment by concentrated overland flow (hereinafter referred to as soil detachment). In this study, the effects of the W-OH concentration on the physical and mechanical properties and the detachment capacity of colluvial deposit slope soil were investigated, and the impact of the relationship between the flow discharge and the W-OH concentration on the soil detachment capacity was examined under the experimental conditions. The results indicated that W-OH application significantly increased the large-particle content in the soil samples, enhanced the strength properties of the soil samples, reduced their separation capacity, and increased their stability. The structural equation modelling results revealed that W-OH application influences the soil detachment capacity primarily by affecting the shear strength, which exerts a significant negative effect on the detachment capacity (path coefficient = −0.57, p < 0.001). The soil detachment capacity prediction equation, which is based on the flow discharge and W-OH concentration, exhibited satisfactory accuracy (Nash–Sutcliffe efficiency (NSE) = 0.964) and can be used to predict the soil detachment capacity with high precision under similar experimental conditions. In addition, at a W-OH concentration above 1.53%, the impact on the soil detachment capacity is greater than that of the flow discharge. This study focused on investigating the process and mechanisms through which W-OH application reduces soil erosion on colluvial deposit slopes, thereby providing reference data for the management of Benggang erosion. Full article
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24 pages, 4803 KB  
Article
Research on Cold-Energy Loss of Long-Distance Sleeve-Type Insulated Pipe for High-Temperature Deep Mines
by Lijuan Zhang, Wenlong Wang, Fengtian Yue, Jingsheng Wei, Tao Gao, Yangjie Wang and Yang Zhou
Energies 2025, 18(2), 397; https://doi.org/10.3390/en18020397 - 17 Jan 2025
Viewed by 803
Abstract
As mining operations extend to greater depths, they encounter critical challenges, including increased distances and substantial energy losses. To address the challenges of cold-energy loss in deep mine cooling systems and improve the working environment for miners, a long-distance sleeve-type insulated pipe system [...] Read more.
As mining operations extend to greater depths, they encounter critical challenges, including increased distances and substantial energy losses. To address the challenges of cold-energy loss in deep mine cooling systems and improve the working environment for miners, a long-distance sleeve-type insulated pipe system was developed. This system aims to mitigate thermal energy loss caused by heat transfer between the pipe and surrounding soil throughout the water transport path from the source to the deep mine in boreholes. A heat transfer analysis model was developed to assess the impact of variables such as transport time, water flow rate, inlet temperature, and insulation materials on the temperature of cold water. The study reveals that the temperature of cold water increases rapidly during transportation before reaching a stable state. Implementing modifications such as increasing the inlet temperature, enhancing the water flow rate, or utilizing materials with lower thermal conductivity can effectively mitigate temperature rises. Additionally, the novel sleeve-type design enhanced the pipe’s pressure-bearing capacity, reduced the required pipe length by 4752 m and minimized energy loss compared to traditional systems. In practical applications, after 45 h, the supply and return water temperatures increased by 0.45 °C and 0.38 °C, respectively, while maintaining cooling energy loss below 12%. This innovative solution improves mine cooling efficiency and provides guidance to reduce cold-energy loss. Full article
(This article belongs to the Section H: Geo-Energy)
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23 pages, 5685 KB  
Article
Analysis and Experimental Study on the Influence of Louver Separation Device on the Sand Collection Efficiency of Wind Erosion Instrument
by Zhentong Liu, Fengwu Zhu, Dongyan Huang, Man Ao, Yunhai Ma and Xianzhang Meng
Sustainability 2024, 16(22), 10071; https://doi.org/10.3390/su162210071 - 19 Nov 2024
Viewed by 929
Abstract
A wind erosion instrument is a core instrument for collecting sand particles in wind and sand flows and studying the laws of wind and sand movement. To study the influence of the internal structure of the wind erosion instrument on its sand collection [...] Read more.
A wind erosion instrument is a core instrument for collecting sand particles in wind and sand flows and studying the laws of wind and sand movement. To study the influence of the internal structure of the wind erosion instrument on its sand collection efficiency, a built-in louver separation device was designed. Based on CFD and Fluent 2022 software, numerical analysis was conducted using an RNG k-ε model, and the discrete phase model (DPM) method was used to calculate the sand collection efficiency. The flow field analysis of the new wind–sand separator was carried out. The influence of blade inclination angle, blade thickness, and blade number on sand collection efficiency was studied using single-factor and response surface analysis methods. The optimal parameter combination was obtained as blade inclination angle of 30°, blade thickness of 1.25 mm, and blade number of 10. A simulation model was established based on the optimal combination parameters, and the performance of the wind erosion instrument before and after the addition of the louver separation device was compared. The simulation results show that adding a louver separation device can increase static pressure, alleviate short-circuit flow and back-mixing phenomena, and stabilize the flow field; increasing tangential velocity leads to an increase in particle centrifugal force; reduce axial velocity, prolong particle stagnation time, and minimize particle escape. The particle trajectory pattern is mostly a continuous spiral path, which is conducive to capturing particles and improving sand collection efficiency. Compared with the original structure, for particles with diameters ranging from 0.001–0.05 mm, 0.005–0.01 mm, 0.01–0.05 mm, 0.05–0.1 mm, and 0.1–0.5 mm, the addition of a louver separation device increased the sand collection efficiency by 32.74%, 22.55%, 33.17%, 11.45%, and 0.13%, respectively. When the wind speed is 13.8 m/s and the diameter range is 0.001–0.5 mm, the average sand collection efficiency obtained from simulation tests and wind tunnel tests is 86.18% and 84.32%, respectively, with an error of 2.2%. The simulation results are reliable. The research results show that adding a louver separation device can improve the sand collection efficiency of the wind erosion instrument, and has better overall performance compared to the original wind–sand separator. This study provides a basis for further research on the structure of wind erosion gauges and the environmental protection of farmland. Strengthening land management can effectively protect soil resources, reduce wind erosion, ensure the stability of the ecosystem, and lay the foundation for promoting the sustainable use of land. Full article
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17 pages, 10449 KB  
Article
The Effect Characterization of Lens on LNAPL Migration Based on High-Density Resistivity Imaging Technique
by Guizhang Zhao, Jiale Cheng, Menghan Jia, Hongli Zhang, Hongliang Li and Hepeng Zhang
Appl. Sci. 2024, 14(22), 10389; https://doi.org/10.3390/app142210389 - 12 Nov 2024
Cited by 1 | Viewed by 1239
Abstract
Light non-aqueous phase liquids (LNAPLs), which include various petroleum products, are a significant source of groundwater contamination globally. Once introduced into the subsurface, these contaminants tend to accumulate in the vadose zone, causing chronic soil and water pollution. The vadose zone often contains [...] Read more.
Light non-aqueous phase liquids (LNAPLs), which include various petroleum products, are a significant source of groundwater contamination globally. Once introduced into the subsurface, these contaminants tend to accumulate in the vadose zone, causing chronic soil and water pollution. The vadose zone often contains lens-shaped bodies with diverse properties that can significantly influence the migration and distribution of LNAPLs. Understanding the interaction between LNAPLs and these lens-shaped bodies is crucial for developing effective environmental management and remediation strategies. Prior research has primarily focused on LNAPL behavior in homogeneous media, with less emphasis on the impact of heterogeneous conditions introduced by lens-shaped bodies. To investigate the impact of lens-shaped structures on the migration of LNAPLs and to assess the specific effects of different types of lens-shaped structures on the distribution characteristics of LNAPL migration, this study simulates the LNAPL leakage process using an indoor two-dimensional sandbox. Three distinct test groups were conducted: one with no lens-shaped aquifer, one with a low-permeability lens, and one with a high-permeability lens. This study employs a combination of oil front curve mapping and high-density resistivity imaging techniques to systematically evaluate how the presence of lens-shaped structures affects the migration behavior, distribution patterns, and corresponding resistivity anomalies of LNAPLs. The results indicate that the migration rate and distribution characteristics of LNAPLs are influenced by the presence of a lens in the gas band of the envelope. The maximum vertical migration distances of the LNAPL are as follows: high-permeability lens (45 cm), no lens-shaped aquifer (40 cm), and low-permeability lens (35 cm). Horizontally, the maximum migration distances of the LNAPL to the upper part of the lens body decreases in the order of low-permeability lens, high-permeability lens, and no lens-shaped aquifer. The low-permeability lens impedes the vertical migration of the LNAPL, significantly affecting its migration path. It creates a flow around effect, hindering the downward migration of the LNAPL. In contrast, the high-permeability lens has a weaker retention effect and creates preferential flow paths, promoting the downward migration of the LNAPL. Under conditions with no lens-shaped aquifer and a high-permeability lens, the region of positive resistivity change rate is symmetrical around the axis where the injection point is located. Future research should explore the impact of various LNAPL types, lens geometries, and water table fluctuations on migration patterns. Incorporating numerical simulations could provide deeper insights into the mechanisms controlling LNAPL migration in heterogeneous subsurface environments. Full article
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21 pages, 77346 KB  
Article
Soil Erosion Characteristics of the Agricultural Terrace Induced by Heavy Rainfalls on Chinese Loess Plateau: A Case Study
by Hongliang Kang, Wenlong Wang, Liangna Li, Lei Han and Sihan Wei
Agronomy 2024, 14(8), 1840; https://doi.org/10.3390/agronomy14081840 - 20 Aug 2024
Cited by 2 | Viewed by 2229
Abstract
Terrace erosion has become increasingly pronounced due to the rising incidence of heavy rainfalls resulting from global climate change; however, the processes and mechanisms governing erosion of loess terraces during such events remain poorly understood. A field investigation was performed following a heavy [...] Read more.
Terrace erosion has become increasingly pronounced due to the rising incidence of heavy rainfalls resulting from global climate change; however, the processes and mechanisms governing erosion of loess terraces during such events remain poorly understood. A field investigation was performed following a heavy rainfall event in the Tangjiahe Basin to examine the soil erosion characteristics of loess terraces subjected to heavy rainfall events. The results show that various types of erosion occurred on the terraced fields, including rill, gully, and scour hole in water erosion, and sink hole, collapse, and shallow landslide in gravity erosion. Rill erosion and shallow landslide erosion exhibited the highest frequency of occurrence on the new and old terraces, respectively. The erosion moduli of the gully, scour hole, and sink hole on the new terraces were 171.0%, 119.5%, and 308.7% greater than those on the old terraces, respectively. In contrast, lower moduli of collapse and landslide were observed on the new terraces in comparison to the old terraces, reflecting reductions of 34.2% and 23.4%, respectively. Furthermore, the modulus of water erosion (32,102 t/km2) was 4.5 times that of gravity erosion on the new terraces. Conversely, on the old terrace, the modulus of gravity erosion (8804.1 t/km2) exceeded that of water erosion by 14.5%. Gully erosion and collapse dominated the erosion processes, contributing 67.8% and 9.4% to soil erosion on the new terraces and 38.7% and 34.0%, respectively, on the old terraces. In the study area, the new terraces experienced significantly greater erosion (39,252 t/km2) compared to the old terraces (16,491 t/km2). Plastic film mulching, loose and bare ridges and walls, inclined terrace platforms, and high terrace walls, as well as the developing flow paths, might be the key factors promoting the severe erosion of the terraces during heavy rainfall. Improvements in terrace design, construction technologies, temporary protective measures, agricultural techniques, and management strategies could enhance the prevention of soil erosion on terraces during heavy rainfall events. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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15 pages, 4642 KB  
Article
Flow through and Volume Change Behavior of a Compacted Expansive Soil Amended with Natural Biopolymers
by Ahmed Bukhary and Shahid Azam
Geotechnics 2024, 4(1), 322-336; https://doi.org/10.3390/geotechnics4010017 - 20 Mar 2024
Viewed by 1957
Abstract
Natural biopolymers offer a sustainable alternative for improving soil behavior due to their inert nature, small dosage requirement, and applicability under ambient temperatures. This research evaluates the efficacy of natural biopolymers for ameliorating an expansive soil by using a 0.5% dosage of cationic [...] Read more.
Natural biopolymers offer a sustainable alternative for improving soil behavior due to their inert nature, small dosage requirement, and applicability under ambient temperatures. This research evaluates the efficacy of natural biopolymers for ameliorating an expansive soil by using a 0.5% dosage of cationic chitosan, charge-neutral guar gum, and anionic xanthan gum during compaction. The results of laboratory investigations indicate that the flow through and volume change properties of the expansive soil were affected variably. The dual porosity, characterized by low air entry due to inter-aggregate pores (AEV1 of 4 kPa) and high air entry due to the clay matrix (AEV2 of 200 kPa) of the soil, was healed using chitosan and guar gum (AEV of 200 kPa) but was enhanced by the xanthan gum (AEV1 of 100 kPa and AEV2 of 200 kPa). The s-shaped swell–shrink path of the soil comprised structural (e from 1.23 to 1.11), normal (e from 1.11 to 0.6), and residual stages (e ranged from 0.6–0.43). This shape was converted into a j-shaped path through amendment using chitosan and guar gum, showing no structural volume change, with e from about 1.25 to 0.5, but was reverted to a more pronounced form by xanthan gum, with e from 1.5 to 1.32, 1.32 to 0.49, and 0.49 to 0.34 in the three stages, respectively. The consolidation behavior of the soil was largely unaffected by the addition of biopolymers such that the saturated hydraulic conductivity decreased from 10−9 m/s to 10−12 m/s over a void ratio decrease from 1.1 to 0.6. At a seating stress of 5 kPa, the swelling potential (7.8%) of the soil slightly decreased to 6.9% due to the addition of chitosan but increased to 9.4% and 12.2% with guar gum and xanthan gum, respectively. The use of chitosan and guar gum will allow the compaction of the investigated expansive soil on the dry side of optimum. Full article
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23 pages, 7619 KB  
Article
Impact of Structural and Non-Structural Measures on the Risk of Flash Floods in Arid and Semi-Arid Regions: A Case Study of the Gash River, Kassala, Eastern Sudan
by Kamal Abdelrahim Mohamed Shuka, Ke Wang, Ghali Abdullahi Abubakar and Tianyue Xu
Sustainability 2024, 16(5), 1752; https://doi.org/10.3390/su16051752 - 21 Feb 2024
Cited by 7 | Viewed by 3188
Abstract
Sediment precipitation in riverbeds influences the effectiveness of structural and non-structural measures for flash flood mitigation and increases the potential for flooding. This study aimed to disclose the effectiveness of the implemented measures for flood risk mitigation in Kassala town, eastern Sudan. We [...] Read more.
Sediment precipitation in riverbeds influences the effectiveness of structural and non-structural measures for flash flood mitigation and increases the potential for flooding. This study aimed to disclose the effectiveness of the implemented measures for flood risk mitigation in Kassala town, eastern Sudan. We employed remote sensing (RS) and GIS techniques to determine the change in the Gash River riverbed, the morphology, and the leveling of both the eastern and western sides of the river. Flood model simulation and a 3D path profile were generated using the digital elevation model (DEM) with a data resolution of 12.5 m from the ALOS BILSAR satellite. The main purpose of this study is to extract the layer of elevation of the riverbed on both the western and eastern banks and to determine the variations and their relationship to flood occurrence and mitigation. The construction of dikes and spurs near Kassala town has led to sediment precipitation, causing the riverbed to rise. The results show that it is now 1.5 m above the eastern Kassala town level, with a steep slope of 2 m/km, and the cross-section area at Kassala bridge has shrunk, which indicates that the bridge body will partially impede the river’s high discharge and increase the potential for flood risk in the study area. The eastern part of Kassala town has a higher likelihood of flooding than the western side. This study suggests redesigning structural measures like widening the Gash River, extending Kassala bridge for normal water flow, strengthening early warning systems, and implementing soil conservation activities for normal water flow. Full article
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