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In the context of extreme weather events, i.e., floods, and increased population in urban areas, traditional drainage systems fall short. The need to develop alternative runoff-control in urban environments and promote the circular economy has prompted us to study various draining materials, some of them recycled that might be used SUDS in construction and technosols. These include recycled shatter brick, gravel for draining concrete, recycled rubber from car tires, and substrates with different proportions of organic matter like compost, coconut fiber, peat, and manure. Mechanical parameters like porosity, density, and uniformity coefficients (among others) were calculated to assess hydraulic conductivity in the laboratory under saturated and laminar flow conditions. Alternative methodologies were applied to adapt the materials and samples to current standards procedures (UNE and ISO). The results, based on Darcy's law, show values equivalent to those of natural coarse soils, ranging from 4.4·10-5 to 1.1·10-1 cm·s-1., We would like to thank the “Fundación Séneca” for the scholarship awarded to José Antonio Jiménez Valera [21271/FPI/19 Fundación Séneca. Región de Murcia, Spain]. We also thank Cementos Molins, Crous Expert, Bruc Jardí, and RNC Murcia for donating the material that has allowed us to carry out the research., Peer Reviewed, Postprint (published version)

The main objective of bottom and side barriers in sa-nitary landfills is to prevent the migration of leachates from the interior to the exterior. These liners should be designed by taking into account different properties. In many cases, to reduce costs, local soils are used as construction materials for this purpose. However, due to the great variability in the hydromechanical properties of soils, the design of lines should consider the local conditions of each location. The properties analyzed are hydraulic conductivity, Unconfined Compressive Strength and swelling potential. This article analyzes the possibility of using compacted residual soils and evaluates the va-riability of compaction parameters to determine the optimal construction conditions to meet international specifications for geological barriers for landfills, Las barreras de fondo y laterales de los rellenos sanitarios tienen como principal objetivo evitar la migración de líquidos provenientes del interior hacia el exterior. Para la utilización de estas barreras es necesario considerar diferentes propieda-des. En muchos casos, con el objetivo de disminuir los costos, se utiliza suelos locales en reemplazo de algunos materiales industrializados. Sin embargo, debido a la gran variabilidad en las propiedades hidromecánicas del suelo, se requiere que el diseño considere las condiciones locales de cada sitio. Las propiedades analizadas son la conductividad hidráulica, resisten-cia a la compresión simple y el potencial de hinchamiento. En este artículo se considera la posibilidad de la utilización de los suelos residuales compactados teniendo en la variabilidad de los parámetros de compactación y se determina los entornos óptimos para cumplimentar especificaciones internacionales para la conductividad hidráulica de barreras geológicas para rellenos sanitarios.

Determining hydraulic parameters of aquifers, their associated uncertainties and spatio-temporal variation is important to characterize groundwater flow and mass transport. Of these hydraulic parameters, hydraulic conductivity, effective porosity, and dispersivity are the most crucial ones. Several ex-situ methods such as grain size analysis, and permeameter tests of drilled core samples, and in-situ methods including pumping tests, slug tests, and flowmeter tests, and tracer studies have traditionally been applied for estimating hydraulic conductivity. Effective porosity has been typically estimated by ex-situ and in-situ methods such as mercury intrusion porosimetry, Helium gas pycnometry, magnetic resonance imaging and tracer tests. Compared to the standard drilled core analysis and geophysical methods, groundwater tracer tests have been used for broader applications including in-situ direct hydraulic parameter estimation, transport velocity determination, spatio-temporal variation of hydraulic parameters, and establishing aquifer connectivities. Inorganic salts and fluorescent dyes are the most commonly used groundwater tracers due to their no or low reactivity with sediments, cost efficiency and non-toxicity. In addition to salt and dye tracers, particulate tracers including microspheres, bacteria and bacteriophages have been widely used for characterizing groundwater flow paths, and pathogen migration. Transport behaviour of these microparticle tracers, depending on physico-chemical properties such as size and surface charge, and process variables including ionic strength and particle concentration, can differ from the conservative tracers in terms of transport velocity, mass distribution, and recovery. This dissertation focuses on the applicability of silica encapsulated DNA tagged microparticles (SiDNA) in determining hydraulic parameters (hydraulic conductivity, effective porosity, longitudinal, and transverse dispersivities) of homogeneous and heterog

Mine tailings have shown viability as the fine–grained layer in a capillary barrier structure for controlling acid mine drainage in a circular economy. Their saturated hydraulic conductivities (ksat) under wetting–drying cycles and freeze–thaw cycles remain unexplored. In this study, modified tailings with a weight ratio of 95:5 (tailings/hydrodesulfurization (HDS) clay from waste–water treatment) and an initial water content of 12% were used. The ksat of specimens was measured after up to 15 wetting–drying cycles, each lasting 24 h, with a drying temperature of 105 °C. The ksat for wetting–drying cycles decreased from 3.9 × 10−6 m/s to 9.5 × 10−7 m/s in the first three cycles and then stabilized in the subsequent wetting–drying cycles (i.e., 5.7 × 10−7 m/s–6.3 × 10−7 m/s). Increased fine particles due to particle breakage are the primary mechanism for the ksat trend. In addition, the migration of fines and their preferential deposition near the pore throat area may also promote this decreasing trend through the shrinking and potentially clogging–up of pore throats. This could be explained by the movement of the meniscus, increased salinity, and, subsequently, the shrinkage of the electrical diffuse layer during the drying cycle. Similar specimens were tested to measure ksat under up to 15 freeze–thaw cycles with temperatures circling between −20 °C and 20 °C at 12 h intervals. Compared to the untreated specimen (i.e., 3.8 × 10−6 m/s), the ksat after three freeze–thaw cycles decreased by 77.6% (i.e., 8.5 × 10−7 m/s) and then remained almost unchanged (i.e., 5.6 × 10−7 m/s–8.9 × 10−7 m/s) in subsequent freeze–thaw cycles. The increased fine grain content (i.e., 3.1%) can be used to explain the decreased ksat trend. Moreover, the migration of fines toward the pore throat area, driven by the advancing and receding of ice lens fronts and subsequent deposition at the pore throat, may also contribute to this trend. © 2024 by the authors.

This thesis focuses on the use of the ASTM D6391-11 (the ASTM) Borehole Infiltration Methodology for Measuring Hydraulic Conductivity in the field. The study's primary objective is to establish a procedure for using the ASTM to test the validity of site-specific hydraulic conductivity measurements and liner discharge estimations in the field relative to the current Shelby tube collection and laboratory testing method. The study is conducted through experiments testing hydraulic conductivity values in the laboratory and field, resulting data is analyzed and compared to previous studies, and a numerical model is developed to describe the liner discharge from the system. The findings of this study suggest that when applied to compacted clay liners that (1) the ASTM methodology produced reliable estimates of hydraulic conductivity, and that (2) borehole infiltration can be an effective and economical alternative to traditional laboratory testing for assessing hydraulic conductivity and estimating liner discharge. The study notes the low number of tests completed and the need for future research to investigate the environmental factors which may impact in-situ and laboratory testing. There is opportunity for further study to correlate in-situ and laboratory testing, examine the effect of borehole diameter, varying testing parameters, and subsurface soil conditions on the analysis. The engineering practice should consider using borehole infiltration as a tool for commissioning earthen manure and wastewater storage facilities and to calibrate liner discharge models to better understand and describe the performance of the liner systems and design innovative solutions to remediate deficient liners.

Accurately determining the hydraulic conductivity of unsaturated bentonite is important for modeling subsurface thermo-hydro-mechanical and chemical processes. This study introduced a new hybrid model that employs a constrained categorial boosting (CatBoost) algorithm, combined with a genetic algorithm for hyperparameter tuning, to estimate the hydraulic conductivity of unsaturated compacted bentonite The performance of the constrained CatBoost model was benchmarked against a diverse set of data-driven baseline regression models, including lasso, elastic net, polynomial, k-nearest neighbors, decision tree, bagging tree, random forest, and CatBoost. The results indicated that the constrained CatBoost model offers a superior balance between model robustness and predictive accuracy in estimating the hydraulic conductivity of compacted bentonite-based materials during the wetting phase. The model effectively captured the U-shape relationship between hydraulic conductivity and suction, a key characteristic of bentonite behavior. Additionally, bootstrapping analyses confirmed the model's reliability under data variability, further validating its applicability in environmental and geotechnical applications.

The recent research aims to investigate the petrophysical and hydrogeological parameters of the Nubian aquifer system (NAS) in Northern Khartoum State, Sudan, using integrated geophysical methods, including surface electrical resistivity and geophysical well-logging. The Nubian aquifer is a transboundary regional aquifer that covers vast areas in Sudan, Egypt, Libya and Chad. The well-logs, including self-potential (SP), natural gamma ray (GR), and long normal resistivity (RS), are integrated with Vertical Electrical Sounding (VES) measurements to delineate the hydrostratigraphical units. As a result, two aquifers are detected. An upper aquifer comprises coarse sand with an average thickness of 50 m and a lower aquifer of sandstone with more than 200 m thickness. For a thorough evaluation of the aquifers, in the first stage, the petrophysical and hydrogeological parameters, including formation factor, total and effective porosity, shale volume, hydraulic conductivity, and transmissivity, are measured solely from geophysical well-logs. In the second step, the results of geophysical well logs are combined with VES and pumping test data to detect the spatial variation of the measured parameters over the study area. As a result, the hydraulic conductivity of the Nubian aquifers ranged from 1.9 to 7.8 m/day, while the transmissivity varied between 120 and 733 m2/day. These results indicated that the potentiality of the Nubian formation is high; however, in some regions, due to the sediment heterogeneity, the aquifers have intermediate to high potential. According to the obtained results, it can be concluded that the Nubian Aquifer in Khartoum state is ideal for groundwater development. This research discovered that geophysical approaches can be used to characterize moderately heterogeneous groundwater systems by comparing the Nubian aquifer with similar aquifer systems that have similar hydrogeological settings. This study emphasized the application of universal principl, Water Resources

The spatiotemporal distributions of microbes in soil by different methods could affect the efficacy of the microbes to reduce the soil hydraulic conductivity. In this study, the specimens of bio-mediated sands were prepared using three different methods, i.e. injecting, mixing, and pouring a given microbial solution onto compacted sand specimens. The hydraulic conductivity was measured by constant-head tests, while any soil microstructural changes due to addition of the microbes were observed by scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) tests. The amount of dextran concentration produced by microbes in each type of specimen was quantified by a refractometer. Results show that dextran production increased exponentially after 5–7 d of microbial settling with the supply of culture medium. The injection and mixing methods resulted in a similar amount and uniform distribution of dextran in the specimens. The pouring method, however, produced a nonuniform distribution, with a higher concentration near the specimen surface. As the supply of culture medium discontinued, the dextran content near the surface produced by the pouring method decreased dramatically due to high competition for nutrients with foreign colonies. Average dextran concentration was negatively and correlated with hydraulic conductivity of bio-mediated soils exponentially, due to the clogging of large soil pores by dextran. The hydraulic conductivity of the injection and mixing cases did not change significantly when the supply of culture medium was absent. © 2023 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences

The study of alkali-activated slag (AAS) is motivated by the need for more sustainable alternatives to Portland cement (PC) within the construction industry. Specifically, AAS offers good mechanical and chemical properties. However, the influence of the activator on its pore structure and hydraulic conductivity remains unclear. Both pore structure and hydraulic conductivity are key parameters in understanding the drying process and could potentially explain the high drying shrinkage observed so far. The present study aims to investigate the pore size distribution and hydraulic conductivity of six distinct AAS/sodium hydroxide mortar compositions, with a particular emphasis on the effect of varying the activator’s molarity and the solution-to-binder ratio (s/b). This research uses the mass variation in different relative humidity (RH) conditions from experimental tests to model the pore surface area, the pore size distribution, and the hydraulic conductivity. From the results, it emerges that increasing the molarity from 0.5 to 8 M reduces the open porosity and refines the pore structure, while increasing the s/b from 0.5 to 0.8 increases the open porosity while refining the pore structure. In addition, high molarity compositions are not suitable for testing in high RH and natural carbonation conditions due to the occurrence of deliquescence. Moreover, the main drying mechanism in AAS is water vapour transport even at high relative humidity, contrary to what was observed in the literature for PC. Finally, the hydraulic conductivity of alkali-activated slag presents a minimum of around 85% RH against the 60–70% RH for PC, causing AAS to dry faster when the relative humidity decreases from 85 to 50%., SCOPUS: ar.j, info:eu-repo/semantics/published

Natural laterite fixed-bed columns intercalated with two types of layers (inert materials, such as fine sand and gravel, and adsorbent materials, such as activated carbon prepared from Balanites aegyptiaca (BA-AC)) were used for As(III) removal from an aqueous solution. Investigations were carried out to solve the problem of column clogging, which appears during the percolation of water through a natural laterite fixed-bed column. Experimental tests were conducted to evaluate the hydraulic conductivities of several fixed-bed column configurations and the effects of various parameters, such as the grain size, bed height, and initial As(III) concentration. The permeability data show that, among the different types of fixed-bed columns investigated, the one filled with repeating layers of laterite and activated carbon is more suitable for As(III) adsorption, in terms of performance and cost, than the others (i.e. non-intercalated laterite; non-intercalated activated carbon, repeating layers of laterite and fine sand; and repeating layers of laterite and gravel). A study was carried out to determine the most efficient column using breakthrough curves. The breakthrough increased from 15 to 85 h with an increase in the bed height from 20 to 40 cm and decreased from 247 to 32 h with an increase in the initial As(III) concentration from 0.5 to 2 mg/L. The Bohart–Adams model results show that increasing the bed height induced a decrease in the kAB and N0 values. The critical bed depths determined using the bed depth service time (BDST) model for As(III) removal were 15.23 and 7.98 cm for 1 and 20% breakthroughs, respectively. The results show that the new low-cost adsorptive porous system based on laterite layers with alternating BA-AC layers can be used for the treatment of arsenic-contaminated water., SCOPUS: ar.j, info:eu-repo/semantics/published

1. Trait variation across individuals and species influences the resistance and resilience of ecosystems to disturbance, and the ability of individuals to capitalize on postdisturbance conditions. In trees, the anatomical structure of xylem directly affects plant function and, consequently, it is a valuable lens through which to understand resistance and resilience to disturbance. 2. To determine how hurricanes affect wood anatomy of tropical trees, we characterized a set of anatomical traits in wood produced before and after a major hurricane for 65 individuals of 10 Puerto Rican tree species. We quantified variation at different scales (among and within species, and within individuals) and determined trait shifts between the pre- and posthurricane periods. We also assessed correlations between traits and growth rates. 3. While the majority of anatomical trait variation occurred among species, we also observed substantial variation within species and individuals. Within individuals, we found significant shifts for some traits that generally reflected increased hydraulic conductivity in the posthurricane period. We found weak evidence for an association between individual xylem anatomical traits and diameter growth rates. 4. Ultimately, within-individual variation of xylem anatomical traits observed in our study could be related to posthurricane recovery and overall growth (e.g. canopy filling). Other factors, however, likely decouple a relationship between xylem anatomy and diameter growth. While adjustments of wood anatomy may enable individual trees to capitalize on favourable postdisturbance conditions, these may also influence their future responses or vulnerability to subsequent disturbances.

1. Trait variation across individuals and species influences the resistance and resilience of ecosystems to disturbance, and the ability of individuals to capitalize on postdisturbance conditions. In trees, the anatomical structure of xylem directly affects plant function and, consequently, it is a valuable lens through which to understand resistance and resilience to disturbance. 2. To determine how hurricanes affect wood anatomy of tropical trees, we characterized a set of anatomical traits in wood produced before and after a major hurricane for 65 individuals of 10 Puerto Rican tree species. We quantified variation at different scales (among and within species, and within individuals) and determined trait shifts between the pre- and posthurricane periods. We also assessed correlations between traits and growth rates. 3. While the majority of anatomical trait variation occurred among species, we also observed substantial variation within species and individuals. Within individuals, we found significant shifts for some traits that generally reflected increased hydraulic conductivity in the posthurricane period. We found weak evidence for an association between individual xylem anatomical traits and diameter growth rates. 4. Ultimately, within-individual variation of xylem anatomical traits observed in our study could be related to posthurricane recovery and overall growth (e.g. canopy filling). Other factors, however, likely decouple a relationship between xylem anatomy and diameter growth. While adjustments of wood anatomy may enable individual trees to capitalize on favourable postdisturbance conditions, these may also influence their future responses or vulnerability to subsequent disturbances.

1. Trait variation across individuals and species influences the resistance and resilience of ecosystems to disturbance, and the ability of individuals to capitalize on postdisturbance conditions. In trees, the anatomical structure of xylem directly affects plant function and, consequently, it is a valuable lens through which to understand resistance and resilience to disturbance. 2. To determine how hurricanes affect wood anatomy of tropical trees, we characterized a set of anatomical traits in wood produced before and after a major hurricane for 65 individuals of 10 Puerto Rican tree species. We quantified variation at different scales (among and within species, and within individuals) and determined trait shifts between the pre- and posthurricane periods. We also assessed correlations between traits and growth rates. 3. While the majority of anatomical trait variation occurred among species, we also observed substantial variation within species and individuals. Within individuals, we found significant shifts for some traits that generally reflected increased hydraulic conductivity in the posthurricane period. We found weak evidence for an association between individual xylem anatomical traits and diameter growth rates. 4. Ultimately, within-individual variation of xylem anatomical traits observed in our study could be related to posthurricane recovery and overall growth (e.g. canopy filling). Other factors, however, likely decouple a relationship between xylem anatomy and diameter growth. While adjustments of wood anatomy may enable individual trees to capitalize on favourable postdisturbance conditions, these may also influence their future responses or vulnerability to subsequent disturbances.

1. Trait variation across individuals and species influences the resistance and resilience of ecosystems to disturbance, and the ability of individuals to capitalize on postdisturbance conditions. In trees, the anatomical structure of xylem directly affects plant function and, consequently, it is a valuable lens through which to understand resistance and resilience to disturbance. 2. To determine how hurricanes affect wood anatomy of tropical trees, we characterized a set of anatomical traits in wood produced before and after a major hurricane for 65 individuals of 10 Puerto Rican tree species. We quantified variation at different scales (among and within species, and within individuals) and determined trait shifts between the pre- and posthurricane periods. We also assessed correlations between traits and growth rates. 3. While the majority of anatomical trait variation occurred among species, we also observed substantial variation within species and individuals. Within individuals, we found significant shifts for some traits that generally reflected increased hydraulic conductivity in the posthurricane period. We found weak evidence for an association between individual xylem anatomical traits and diameter growth rates. 4. Ultimately, within-individual variation of xylem anatomical traits observed in our study could be related to posthurricane recovery and overall growth (e.g. canopy filling). Other factors, however, likely decouple a relationship between xylem anatomy and diameter growth. While adjustments of wood anatomy may enable individual trees to capitalize on favourable postdisturbance conditions, these may also influence their future responses or vulnerability to subsequent disturbances.

Aquitards are common hydrogeological features and their hydraulic conductivity is an important property for various groundwater management issues. Predicting their hydraulic conductivity proves challenging, given its dependence on numerous variables. In this study, the dominant factors for predicting aquitard hydraulic conductivity are identified. To this end, a random forest model is trained on a dataset consisting of more than 1000 hydraulic conductivity measurements of core-scale sediment samples from a wide range of stratigraphic units and depths in the Netherlands. The dataset contains textural properties, such as the grain size distribution and porosity, as well as structural data, such as location, sampling depth, stratigraphical unit, lithofacies, organic carbon content, carbonate content and groundwater chloride concentration. Results show that clay fraction, stratigraphic unit, depth, lithofacies and x-coordinate are the most important features for predicting the hydraulic conductivity. Here, x-coordinate is presumably a proxy for distance from marine influence. Using a more detailed grain size distribution or using derived parameters such as the grain size percentiles does not improve the model any further. Our findings indicate that structural properties play a significant role in predicting aquitard conductivity, as they serve as indicators of processes such as compaction and soft-sediment deformation. The model is furthermore an effective method to estimate hydraulic conductivity for sediment samples without conducting costly and time-consuming hydraulic conductivity measurements.

The scope of this work is to discuss the proper choice of macrodispersion coefficients in modeling contaminant transport through the advection dispersion equation (ADE). It is common to model solute concentrations in transport by groundwater with the aid of the ADE. Spreading is quantified by macrodispersivity coefficients, which are much larger than the laboratory observed pore-scale dispersivities. In the frame of stochastic theory, longitudinal macrodispersivity is related to the hydraulic conductivity spatial variability via its statistical moments (mean, variance, integral scales), which are generally determined by geostatistical analysis of field measurements. In many cases, especially for preliminary assessment of contaminant spreading, these data are not available and ad hoc values are adopted by practitioners. The present study aims at recommending dispersivity values based on a thorough analysis of tens of field experiments. Aquifers are classified as of weak, medium, and high heterogeneity and for each class a range of macrodispersivity values is recommended. Much less data are available for the transverse macrodispersivities, which are significantly smaller than the longitudinal one. Nevertheless, a few realistic values based on field data, are recommended for applications. Transport models using macrodispersivities can predict mean concentrations, different from the local ones. They can be used for estimation of robust measures, like plumes spatial moments, longitudinal mass distribution and breakthrough curves at control planes.

The hydraulic conductivity of mine waste soil is considered moderately high attributed to the high percentage of pore spaces. One of the risks associated with this poor property is possible intrusion of contaminated acid drainage into the groundwater or river. Biocementation using enzyme-induced calcite precipitation is relatively new, more inventive, and environmentally sustainable method compared to the other techniques in improving soil properties. However, limited available data on how this method can be applied in improving heavy-metal contaminated mining wastes. This paper summarizes the effect of this treatment include different cementation concentrations, degree of compactions, curing temperatures and curing durations in reducing the hydraulic conductivity of mining waste. Results obtained indicate greater effect of 1.0M compared to 0.5M concentration, degree of compaction of 80% compared to 70%, curing temperature of 25 °C compared to 15 °C and 5 °C, and immediate reaction effect after 1-day then slowed down after 3 and 7-day curing. When compared to control sample, the reduction in hydraulic conductivity is ranging 75.66 to 97.14%. The positive result is attained due to the production of calcite, CaCO3 that biocemented the soil particles together and reduced the pore spaces, indicated by their content obtained ranging 2.0-5.15 % in the treated soil. Visual images through SEM and spectra of x-ray diffraction confirmed the presence of CaCO3 in soil particles. This work contributes significantly to the study of the properties of copper mine tailings in Ranau, Sabah, including the first study on biocementation of copper mine tailings. The method could be used to reduce the hydraulic conductivity of mining waste soils contaminated with heavy metals. Various scenarios such as curing temperature, duration, cementation concentration and degree of compaction have been proposed to optimize the effectiveness of the treatment

Effective groundwater resource management requires appropriate conceptualization of aquifer heterogeneity, which is challenging for pro-deltaic systems. This study focuses on heterogeneity within the Valin River paleodelta (Canada), a complex granular aquifer constituting a system that is a regional water supply source. This study integrates laboratory and field-based experimental measurements of various hydrogeological properties and classifies the sediments using diverse statistical techniques. It demonstrates the advantage of diversified characterization for a better understanding of aquifer heterogeneity. The hydrogeological properties—i.e., hydraulic conductivity (K) and porosity (n)—of 27 lithofacies identified in nine sandpits were estimated and assigned a range of values. The identified lithofacies were grouped into four operative-lithofacies before being assigned to three primary hydrofacies that were used to define the aquifer heterogeneity. The importance of integrated sediment and hydraulic properties assessment is that the techniques allow an understanding of the heterogeneity within a complex prodeltaic aquifer type. Two scales of heterogeneity are defined: (1) lithofacial scale wherein small differences in sediment texture (grain size properties), in sedimentary structures, and in other sediment features of lithofacies (mean grain diameter, sorting, skewness, and kurtosis) cause significant changes in K and n, (2) hydrofacial scale wherein specific lithology units define larger-scale aquifer flow and potential solute movement. The multi-methodology approach used for characterizing the aquifer heterogeneity is a prerequisite to complete necessary information for developing more accurate and complex hydrogeological models. Une gestion efficace de la ressource en eau souterraine requiert une formalisation appropriée de l’hétérogénéité de l’aquifère, ce qui est difficile pour les systèmes pro-deltaïques. La présente étude porte sur l’hétérogénéité au sein

The oxidation of sulfide minerals in mine wastes is a possible threat to the environment as it might have potential to generate acid rock drainage (ARD). A common method to reduce ARD is to apply a dry cover on the mine waste deposit. Considering the massive amounts of mine waste produced in Sweden (104-million-ton in year 2018) there is a great need for suitable dry cover materials. Using non-hazardous industrial residues in the dry cover would be beneficial for both the mining industry and the providing industry as stricter waste management legislation incentivizes them to develop their waste management strategies. The objective of this study was to investigate if an addition of Green Liquor Dregs (GLD), a residue from pulp production, can decrease the hydraulic conductivity and increase the water retention capacity (WRC) of three different tills, with the purpose of improving the performance of a dry cover material on a mine waste deposit. Another objective was to investigate how the hydraulic conductivity and WRC are affected by the contents of fines and clays in the tills. The study concludes that the water retention capacity of the tills improves with GLD addition, however, the hydraulic conductivity did not decrease enough to reach the in Sweden required < 10−8 m/s. Even though, GLD could still successfully be used in the reclamation of mine sites as the high WRC can be seen as the most important factor in deterring acid rock drainage by keeping the sealing layer close to saturation. This study further indicates that there are other factors than the particle size distribution of the materials that controls the hydraulic conductivity of the mixtures, such as initial water content, dry density, and compaction effort., Validerad;2023;Nivå 2;2023-07-20 (sofila);Funder: Boliden Mineral ABLicens fulltext: CC BY License

Environmental contamination with microplastics (MP, 0.1 µm – 5 mm diameter) potentially threatens various soil functions and agricultural production. In this study we evaluated the effects of MP on physical soil parameters (saturated hydraulic conductivity, water retention and water repellency) at MP concentrations (0.5 to 2 % w/w) that have been reported for farmland soils. Polyethylene terephthalate (PET) and polystyrene (PS) of three sizes ranging between 0.5 and 3 mm diameter, were mixed with loess topsoil material from an agriculturally used Luvisol. Results show that increasing MP concentration decreased the saturated hydraulic conductivity (ksat) compared to the control soil (without MP), irrespective of MP type. The highest reduction of ksat was found for the highest concentration (2 %) and the largest size MP (approx. 3 mm diameter). Compared to the control, MP addition significantly decreased soil water retention with increasing concentration. In contrast, air capacity was increased with MP addition where strongest effect was found for largest PET particles at the highest concentration. Soil water repellency (measured as Wilhelmy Plate contact angles) was increased at a concentration of 2 % and for MP sizes > 1 mm, while no effect was observed for lower concentrations and smaller MP. In conclusion, MP type, size, and concentration did affect key soil physical parameters, likely to negatively influence plant growth in contaminated soils.

The scope of this work is to discuss the proper choice of macrodispersion coefficients in modeling contaminant transport through the advection dispersion equation (ADE). It is common to model solute concentrations in transport by groundwater with the aid of the ADE. Spreading is quantified by macrodispersivity coefficients, which are much larger than the laboratory observed pore-scale dispersivities. In the frame of stochastic theory, longitudinal macrodispersivity is related to the hydraulic conductivity spatial variability via its statistical moments (mean, variance, integral scales), which are generally determined by geostatistical analysis of field measurements. In many cases, especially for preliminary assessment of contaminant spreading, these data are not available and ad hoc values are adopted by practitioners. The present study aims at recommending dispersivity values based on a thorough analysis of tens of field experiments. Aquifers are classified as of weak, medium, and high heterogeneity and for each class a range of macrodispersivity values is recommended. Much less data are available for the transverse macrodispersivities, which are significantly smaller than the longitudinal one. Nevertheless, a few realistic values based on field data, are recommended for applications. Transport models using macrodispersivities can predict mean concentrations, different from the local ones. They can be used for estimation of robust measures, like plumes spatial moments, longitudinal mass distribution and breakthrough curves at control planes., QC 20230613

Due to large spatial and temporal variations of soil properties that govern swale infiltration capacities, traditional methods for estimating saturated hydraulic conductivity (ksat) values could potentially lead to erroneous estimation of the total system infiltration capacity. To increase the knowledge of grassed swale infiltration performance and the relationship between hydraulic properties related to the spatial variation within the swale, two methods were applied to estimate ksat values: 1) point measurements using the Modified Philip Dunne (MPD) Infiltrometer, and 2) a full-scale infiltration test (FSIT). A large variation in calculated ksat values was found, ranging from 22 to 1382 mm/hr, with lower/higher values at the swale bottom, and right swale slope respectively. Infiltration point measurements, with a geometric mean of 81 mm/hr, showed higher infiltration rates than those obtained from FSIT, which yielded 34 and 22 mm/hr (for test 1 and 2 respectively). Moreover, FSIT results showed an agreement with ksat values obtained from MPD infiltrometer at the swale bottom. In addition, infiltration rates are significantly reduced as the groundwater mound gets closer to the bottom of the grassed swale., En raison des grandes variations spatiales et temporelles des propriétés du sol qui régissent les capacités d'infiltration des noues, les méthodes traditionnelles d'estimation des valeurs de conductivité hydraulique saturée (ksat) pourraient potentiellement conduire à une estimation erronée de la capacité d'infiltration totale du système. Afin d'accroître la connaissance des capacités d'infiltration des noues enherbées et de la relation entre les propriétés hydrauliques liées aux classes de texture du sol, deux méthodes ont été appliquées pour estimer les valeurs de ksat : 1) des mesures ponctuelles à l'aide de l'infiltromètre Philip Dunne modifié (MPD), et 2) un test d’infiltration à pleine échelle (FSIT). Une grande variation dans les valeurs calculées de ksat a été trouvée, allant de 22 à 1382 mm/h, avec des valeurs inférieures/élevées au fond de la noue et à droite de la pente de la noue respectivement. Les mesures des points d'infiltration, avec une moyenne géométrique de 81 mm/h, ont montré des taux d'infiltration plus élevés que ceux obtenus à partir du FSIT, avec 34 et 22 mm/h (pour les tests 1 et 2 respectivement). De plus, les résultats du FSIT ont montré un accord avec les valeurs de ksat obtenues au fond de la noue. De plus, les taux d'infiltration diminuent considérablement à mesure que le niveau de la nappe phréatique se rapproche du fond de la noue enherbée.

The oxidation of sulfide minerals in mine wastes is a possible threat to the environment as it might have potential to generate acid rock drainage (ARD). A common method to reduce ARD is to apply a dry cover on the mine waste deposit. Considering the massive amounts of mine waste produced in Sweden (104-million-ton in year 2018) there is a great need for suitable dry cover materials. Using non-hazardous industrial residues in the dry cover would be beneficial for both the mining industry and the providing industry as stricter waste management legislation incentivizes them to develop their waste management strategies. The objective of this study was to investigate if an addition of Green Liquor Dregs (GLD), a residue from pulp production, can decrease the hydraulic conductivity and increase the water retention capacity (WRC) of three different tills, with the purpose of improving the performance of a dry cover material on a mine waste deposit. Another objective was to investigate how the hydraulic conductivity and WRC are affected by the contents of fines and clays in the tills. The study concludes that the water retention capacity of the tills improves with GLD addition, however, the hydraulic conductivity did not decrease enough to reach the in Sweden required < 10−8 m/s. Even though, GLD could still successfully be used in the reclamation of mine sites as the high WRC can be seen as the most important factor in deterring acid rock drainage by keeping the sealing layer close to saturation. This study further indicates that there are other factors than the particle size distribution of the materials that controls the hydraulic conductivity of the mixtures, such as initial water content, dry density, and compaction effort., Validerad;2023;Nivå 2;2023-07-20 (sofila);Funder: Boliden Mineral ABLicens fulltext: CC BY License

Variably saturated subsurface flow models require knowledge of the soil hydraulic parameters. However, the determination of these parameters in heterogeneous soils is not easily feasible and subject to large uncertainties. As the modeled soil moisture is very sensitive to these parameters, especially the saturated hydraulic conductivity, porosity, and the parameters describing the retention and relative permeability functions, it is likewise highly uncertain. Data assimilation can be used to handle and reduce both the state and parameter uncertainty. In this work, we apply the ensemble Kalman filter (EnKF) to a three-dimensional heterogeneous hillslope model and investigate the influence of updating the different soil hydraulic parameters on the accuracy of the estimated soil moisture. We further examine the usage of a simplified layered soil structure instead of the fully resolved heterogeneous soil structure in the ensemble. It is shown that the best estimates are obtained when performing a joint update of porosity and the van Genuchten parameters and (optionally) the saturated hydraulic conductivity. The usage of a simplified soil structure gave decent estimates of spatially averaged soil moisture in combination with parameter updates but led to a failure of the EnKF and very poor soil moisture estimates at non-observed locations.

Aquitards are common hydrogeological features and their hydraulic conductivity is an important property for various groundwater management issues. Predicting their hydraulic conductivity proves challenging, given its dependence on numerous variables. In this study, the dominant factors for predicting aquitard hydraulic conductivity are identified. To this end, a random forest model is trained on a dataset consisting of more than 1000 hydraulic conductivity measurements of core-scale sediment samples from a wide range of stratigraphic units and depths in the Netherlands. The dataset contains textural properties, such as the grain size distribution and porosity, as well as structural data, such as location, sampling depth, stratigraphical unit, lithofacies, organic carbon content, carbonate content and groundwater chloride concentration. Results show that clay fraction, stratigraphic unit, depth, lithofacies and x-coordinate are the most important features for predicting the hydraulic conductivity. Here, x-coordinate is presumably a proxy for distance from marine influence. Using a more detailed grain size distribution or using derived parameters such as the grain size percentiles does not improve the model any further. Our findings indicate that structural properties play a significant role in predicting aquitard conductivity, as they serve as indicators of processes such as compaction and soft-sediment deformation. The model is furthermore an effective method to estimate hydraulic conductivity for sediment samples without conducting costly and time-consuming hydraulic conductivity measurements., Water Resources

The necessity to house the worldwide growing population is making the production of Portland cement (PC) grow alongside with its CO2 emissions in the atmosphere. In order to reduce said emissions, the scientific community is looking for viable and greener alternatives with comparable mechanical properties and good durability. Alkali-activated materials seem to represent a possible replacement to PC, even though their long-term durability is still not fully understood.One of the main issues for the durability of construction materials is the volume stability in drying conditions, that is how the volume of the material decreases when exposed to environmental conditions. The main consequence of the volume contraction is the development of microcracks which reduce the mechanical strength, allow for water vapour and CO2 to penetrate further inside the material, and may also lead to failure of the structure. In order to assess the long-term durability of a material is therefore crucial to understand how it shrinks according to the different external conditions.The present study focuses on the activation of Blast Furnace Slag (BFS) using different sodium hydroxide solutions and takes into account three main aspects of durability: the tendency to cracking in restrained conditions, the pore structure and hydraulic conductivity of the material, and the drying shrinkage in free conditions. The first experimental campaign on restrained shrinkage has been conducted using the ring test coupled with the assessment of the mechanical properties both in sealed and drying conditions; the goal is to understand when the formation of microcracks takes place and what is the maximum deformation the material can endure before failure. The second experimental campaign modelled the total porosity, the pore size distribution, and the hydraulic conductivity of the material based on the mass variation of the material exposed to different relative humidity levels. Finally, the third experimental, Doctorat en Sciences de l'ingénieur et technologie, info:eu-repo/semantics/nonPublished

1. Trait variation across individuals and species influences the resistance and resilience of ecosystems to disturbance, and the ability of individuals to capitalize on postdisturbance conditions. In trees, the anatomical structure of xylem directly affects plant function and, consequently, it is a valuable lens through which to understand resistance and resilience to disturbance. 2. To determine how hurricanes affect wood anatomy of tropical trees, we characterized a set of anatomical traits in wood produced before and after a major hurricane for 65 individuals of 10 Puerto Rican tree species. We quantified variation at different scales (among and within species, and within individuals) and determined trait shifts between the pre- and posthurricane periods. We also assessed correlations between traits and growth rates. 3. While the majority of anatomical trait variation occurred among species, we also observed substantial variation within species and individuals. Within individuals, we found significant shifts for some traits that generally reflected increased hydraulic conductivity in the posthurricane period. We found weak evidence for an association between individual xylem anatomical traits and diameter growth rates. 4. Ultimately, within-individual variation of xylem anatomical traits observed in our study could be related to posthurricane recovery and overall growth (e.g. canopy filling). Other factors, however, likely decouple a relationship between xylem anatomy and diameter growth. While adjustments of wood anatomy may enable individual trees to capitalize on favourable postdisturbance conditions, these may also influence their future responses or vulnerability to subsequent disturbances.

Two conventional experimental procedures for determination of the water permeability of saturated porous medium are the constant and the falling head permeability tests. The first one is more applicable on more permeable materials where the outflow from the sample is measured at variety of constant water heads, while the second one is more convenient for low permeable materials, utilizing the continuous measurements of the water head falling due to filtration through the saturated sample. However, neither of the two is useful for materials of high permeability and large cross-sectional area. The constant head permeability test faces technical issues since a significant and continuous water discharge is required, while the falling head permeability test has limitations due to neglection of the Forchheimer's high-velocity flow through the sample, but also the influence of inertia on the fluid mass. Here we proposed an approach for determination of the water permeability of saturated porous medium based on the agreement between the measured water level change in two connected reservoirs containing a porous sample and the new semi-analytical expression describing that change by accounting for the mentioned theoretical deficiencies. This efficient approach has been tested on four pervious paver samples, and results showed satisfactory agreement with the constant head permeability data. It has been also confirmed the proposed semi-analytical solution is more accurate than the falling head permeability approach in case of highly pervious materials, while for low permeable materials it reduces to the conventional approach.

Soil temperature of vegetated landfill earthen covers varies with time during their service, due to heat released by the degradation of municipal solid waste. In this study, an experimental campaign to capture soil water-retention curve (SWRC) and hydraulic conductivity function (HCF) of unsaturated rooted soils was conducted at different temperatures (25, 45, and 60 degrees C). Simplified evaporation tests were conducted by subjecting soil specimens to a prolonged drying period at maintained temperature. Based on the responses of matric suction and water content, SWRC and HCF were determined by the instantaneous profile method. It was found that increasing temperature reduced water-retention capacity, due to root shrinkage, thermal expansion of liquid phase, and reduction in forces of capillarity and adsorption. Soil hydraulic conductivity was enhanced by the increase in soil temperature due to reduction of water viscosity and potential preferential flow at root channels induced by root shrinkage. Temperature effects on SWRC and HCF of rooted soils are suction-dependent. A new nonisothermal SWRC model was developed to capture the dual effects of roots and temperature. By using the same set of calibrated parameters, the model demonstrates its ability to predict SWRCs reasonably well within the range of temperature investigated.

This book focuses on the engineering properties of unsaturated widely graded soils and their influence on slope stability. This book characterizes the natural widely graded colluvial soils from macroscale, mesoscale, and microscale viewpoints, introduces the techniques for measuring hydro-mechanical properties for unsaturated widely graded colluvial soils, and clarifies the hydro-mechanical behavior and the failure mechanism of widely graded colluvial soils subjected to environmental loads. This book improves the understanding of rainfall-induced landslides on natural slopes. Researchers and engineers in the field of civil engineering can benefit from the book. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.

The root tuber of Pinellia ternata has been used as a traditional therapeutic herbal medicine. It is reported to impart beneficial attributes in recovering COVID-19 patients. To meet an increasing demand of P. ternata, this study is intended to investigate the effects of biochar on the soil hydrological and agronomic properties of two decomposed soils (i.e., completely decomposed granite (CDG) and lateritic soil) for the growth of P. ternata. The plant was grown in instrumented pots with different biochar application rate (0%, 3% and 5%) for a period of three months. Peanut shell biochar inclusion in both soils resulted in reduction of soil hydraulic conductivity and increase in soil water retention capacity. These alterations in hydrological properties were attributed to measured change in total porosity, biochar intra pore and hydrophilic functional groups. The macro-nutrient (i.e., N, P, K, Ca, and Mg) concentration of both soils increased substantially, while the pH and cation exchange capacity levels in the amended soils were altered to facilitate optimum growth of P. ternata. The tuber biomass in biochar amended CDG at all amendment rate increases by up to 70%. In case of lateritic soil, the tuber biomass increased by 23% at only 5% biochar application rate. All treatments satisfied the minimum succinic acid concentration required as per pharmacopoeia standard index. The lower tuber biomass exhibits a higher succinic acid concentration regardless of the soil type used to grow P. ternata. The biochar improved the yield and quality of P. ternata in both soils.

Due to large spatial and temporal variations of soil properties that govern swale infiltration capacities, traditional methods for estimating saturated hydraulic conductivity (ksat) values could potentially lead to erroneous estimation of the total system infiltration capacity. To increase the knowledge of grassed swale infiltration performance and the relationship between hydraulic properties related to the spatial variation within the swale, two methods were applied to estimate ksat values: 1) point measurements using the Modified Philip Dunne (MPD) Infiltrometer, and 2) a full-scale infiltration test (FSIT). A large variation in calculated ksat values was found, ranging from 22 to 1382 mm/hr, with lower/higher values at the swale bottom, and right swale slope respectively. Infiltration point measurements, with a geometric mean of 81 mm/hr, showed higher infiltration rates than those obtained from FSIT, which yielded 34 and 22 mm/hr (for test 1 and 2 respectively). Moreover, FSIT results showed an agreement with ksat values obtained from MPD infiltrometer at the swale bottom. In addition, infiltration rates are significantly reduced as the groundwater mound gets closer to the bottom of the grassed swale., En raison des grandes variations spatiales et temporelles des propriétés du sol qui régissent les capacités d'infiltration des noues, les méthodes traditionnelles d'estimation des valeurs de conductivité hydraulique saturée (ksat) pourraient potentiellement conduire à une estimation erronée de la capacité d'infiltration totale du système. Afin d'accroître la connaissance des capacités d'infiltration des noues enherbées et de la relation entre les propriétés hydrauliques liées aux classes de texture du sol, deux méthodes ont été appliquées pour estimer les valeurs de ksat : 1) des mesures ponctuelles à l'aide de l'infiltromètre Philip Dunne modifié (MPD), et 2) un test d’infiltration à pleine échelle (FSIT). Une grande variation dans les valeurs calculées de ksat a été trouvée, allant de 22 à 1382 mm/h, avec des valeurs inférieures/élevées au fond de la noue et à droite de la pente de la noue respectivement. Les mesures des points d'infiltration, avec une moyenne géométrique de 81 mm/h, ont montré des taux d'infiltration plus élevés que ceux obtenus à partir du FSIT, avec 34 et 22 mm/h (pour les tests 1 et 2 respectivement). De plus, les résultats du FSIT ont montré un accord avec les valeurs de ksat obtenues au fond de la noue. De plus, les taux d'infiltration diminuent considérablement à mesure que le niveau de la nappe phréatique se rapproche du fond de la noue enherbée.

Hydrochar is a biomass-derived carbon-rich material produced by the hydrothermal carbonization process which requires less energy than the pyrolysis production of biochar. The effectiveness of using hydrochar to amend soil properties, especially hydraulic conductivity, and the underlying mechanism that hydrochar follow remain unknown. This study measured the effects of grass feedstock and grass-derived hydrochar produced at two temperatures (180°C and 240°C) on the pore size distributions (PSDs) and saturated hydraulic conductivity (ks) of compacted silty-clay sand. Hydrochar affected the ks through predominantly the change of macropores of amended soil. Specifically, the addition of 180°C hydrochar [with a 60% specific gravity (GHs) of the soil] at the mass proportion (fH) of 2.5% evolved the PSD from unimodal to trimodal, creating a more open soil structure and increasing the ks by more than half an order of magnitude. When fH exceeded the threshold of 2.5%, the improvement of ks decreased in effectiveness following the compression of macropores. The 240°C hydrochar that has a larger GHs (than the 180°C case) has a high threshold of 5% and introduced a great increase in ks. Test results highlight the importance of avoiding adding excessive hydrochar to prevent the reduction of the effectiveness of drainage improvement.

Swelling geomaterials in northwestern and northeastern China are exposed to both seasonal wetting-drying (DW) and freezing-thawing (FT) processes. The influence of full-process wetting-drying-freezing-thawing (WDFT) cycles on their hydro-mechanical behaviour has not been well investigated. In this study, a series of swelling and compression tests was conducted on Yanji weathered mudstone subjected to different WD, FT and WDFT processes and the effects of seasonal processes and cyclic number on the swelling strain, compression index, rebound index and hydraulic conductivity were experimentally determined. With the increasing WD, FT and WDFT cycles, the starting time of primary swelling decreased first due to the increasing water infiltration with the appearance of large pores, and then increased because of the decreasing swelling potential of compact aggregates after two cycles. Moreover, as the cyclic number increased, the final swelling strain declined. Upon loading, the specimens after cyclic processes exhibited a smaller compression index at low stresses due to their smaller inter-particle distance after swelling, but a larger one owing to the collapse of large pores and cracks at high vertical stresses. After unloading, the rebound index decreased with the increase of cyclic number due to the irreversible collapse of large pores and cracks. The hydraulic conductivity increased with the increasing cyclic number at low vertical stresses (large void ratios). With the further increase of vertical stress, the increase of hydraulic conductivity induced by cyclic processes became indiscernible. Moreover, a comparison among three processes suggested that the WDFT process exerted a more pronounced influence on the hydro-mechanical behaviour of Yanji mudstone than the separate WD or FT process.

Sorptivity is one of the most important parameters for the quantification of water infiltration into soils. proposed a specific formulation to derive sorptivity as a function of the soil water retention and hydraulic conductivity functions, as well as initial and final soil water contents. However, this formulation requires the integration of a function involving hydraulic diffusivity, which may be undefined or present numerical difficulties that cause numerical misestimations. In this study, we propose a mixed formulation that scales sorptivity and splits the integrals into two parts: the first term involves the scaled degree of saturation, while the second involves the scaled water pressure head. The new mixed formulation is shown to be robust and well-suited to any type of hydraulic function - even with infinite hydraulic diffusivity or positive air-entry water pressure heads - and any boundary condition, including infinite initial water pressure head, h -> -infinity. Lastly, we show the benefits of using the proposed formulation for modeling water into soil with analytical models that use sorptivity.

Forests are threatened globally by increased recurrence and intensity of hot droughts. Functionally close coexisting species may exhibit differences in drought vulnerability large enough to cause niche differentiation and affect forest dynamics. The effect of rising atmospheric [CO2], which could partly alleviate the negative effects of drought, may also differ between species. We analysed functional plasticity in seedlings of two taxonomically close pine species (Pinus pinaster Ait., Pinus pinea L.) under different [CO2] and water stress levels. The multidimensional functional trait variability was more influenced by water stress (preferentially xylem traits) and [CO2] (mostly leaf traits) than by differences between species. However, we observed differences between species in the strategies followed to coordinate their hydraulic and structural traits under stress. Leaf 13C discrimination decreased with water stress and increased under elevated [CO2]. Under water stress both species increased their sapwood area to leaf area ratios, tracheid density and xylem cavitation, whereas they reduced tracheid lumen area and xylem conductivity. Pinus pinea was more anisohydric than P. pinaster. Pinus pinaster produced larger conduits under well-watered conditions than P. pinea. Pinus pinea was more tolerant to water stress and more resistant to xylem cavitation under low water potentials. The higher xylem plasticity in P. pinea, particularly in tracheid lumen area, expressed a higher capacity of acclimation to water stress than P. pinaster. In contrast, P. pinaster coped with water stress comparatively more by increasing plasticity of leaf hydraulic traits. Despite the small differences observed in the functional response to water stress and drought tolerance between species, these interspecific differences agreed with ongoing substitution of P. pinaster by P. pinea in forests where both species co-occur. Increased [CO2] had little effect on the species-specific relative perf

Managed aquifer recharge (MAR) techniques are in demand to cope with water scarcity challenges posed by climate change and groundwater overexploitation. One of the long-lasting technical issues associated with MAR systems is physical clogging. The intrusion and deposition of external fines during water recharge reduce the infiltration capacity of the site over time. Operation and maintenance (O&M) costs are experienced directly at the site to restore the original efficiency of infiltration rates. Thus, investors need reliable estimations of the risk of clogging during the planning of the site. As a rule, in MAR design, the main parameter of concern for physical clogging is the total suspended solids (TSS), and most clogging models rely on experiment calibrations in 1D sand columns. However, secondary processes can control the development and spatial distribution of physical clogging in field conditions. The proposed work aims to detect key clogging factors directly in the field and to model these processes for reproducibility at other sites. The fieldwork is conducted at the two-stage infiltration basin in Suvereto (Tuscany, Italy). Spatial factors are included in the analysis (i.e. basin topography) to explain clogging patterns in the field altered by erosion processes. The observed clogging profiles at two sampled locations exhibiting clogging are replicated by a mathematical model. Based on the computation of annual erosion rates in the pond and fines’ redistribution, the exceeding fines’ contents over depth are validated with an RMSE of 2.53% and 12.53%. The infiltration capacity of the site is estimated to reach a stable value of 90% of the initial infiltration capacity over 20 years, given the Suvereto basin features. The model's parameterisation from field measurements represents a great advantage over existing clogging models due to its transferability to other MAR sites. The assessment of the risk of clogging supported by field characterization and

The hydraulic conductivity of mine waste soil is considered moderately high attributed to the high percentage of pore spaces. One of the risks associated with this poor property is possible intrusion of contaminated acid drainage into the groundwater or river. Biocementation using enzyme-induced calcite precipitation is relatively new, more inventive, and environmentally sustainable method compared to the other techniques in improving soil properties. However, limited available data on how this method can be applied in improving heavy-metal contaminated mining wastes. This paper summarizes the effect of this treatment include different cementation concentrations, degree of compactions, curing temperatures and curing durations in reducing the hydraulic conductivity of mining waste. Results obtained indicate greater effect of 1.0M compared to 0.5M concentration, degree of compaction of 80% compared to 70%, curing temperature of 25 °C compared to 15 °C and 5 °C, and immediate reaction effect after 1-day then slowed down after 3 and 7-day curing. When compared to control sample, the reduction in hydraulic conductivity is ranging 75.66 to 97.14%. The positive result is attained due to the production of calcite, CaCO3 that biocemented the soil particles together and reduced the pore spaces, indicated by their content obtained ranging 2.0-5.15 % in the treated soil. Visual images through SEM and spectra of x-ray diffraction confirmed the presence of CaCO3 in soil particles. This work contributes significantly to the study of the properties of copper mine tailings in Ranau, Sabah, including the first study on biocementation of copper mine tailings. The method could be used to reduce the hydraulic conductivity of mining waste soils contaminated with heavy metals. Various scenarios such as curing temperature, duration, cementation concentration and degree of compaction have been proposed to optimize the effectiveness of the treatment

Managed Aquifer Recharge (MAR) sites suffer from the long-lasting problem of clogging. The causes of clogging are physical, biological, chemical and mechanical processes and their complex interaction, with physical clogging being recognised as the predominant process. The intrusion and deposition of particles during water recharge affect the hydraulic properties of the infiltration surface, resulting in a decline in the infiltration capacity of the site over the operating years. Cleaning operations are necessary to restore the original infiltration rates. For this purpose, assessing the risk of clogging can determine the site’s vulnerability and improve the scheme’s design. Numerical models are essential to replicate physical clogging processes and predict the decline in infiltration rates. So far, predictive tools for physical clogging assessment have been missing in MAR literature. Hence, the purpose of this study is to analyse and reorganise physical clogging models from applied engineering fields dealing with water infiltration in natural heterogeneous systems. The modelling approaches are illustrated, starting from the main assumptions and conceptualisation of the soil volume and intruding particles. The individual processes are untangled from the multiple studies and reorganised in a systematic comparison of mathematical equations relevant to MAR applications. The numerical models’ predictive power is evaluated for transferability, following limitations and recommendations for a process-based model applicable to surface spreading schemes. Finally, perspectives are given for clogging risk assessment at MAR sites from modelling and site characterisation. The predictive tool could assist decision-makers in planning the MAR site by implementing cost-effective strategies to lower the risk of physical clogging.

Cement-bentonite cut-off walls are commonly employed in geoenvironmental applications to limit ground water flow and pollutant transport. The wide diffusion of this artificial material in the current practice is not only due to its low permeability, but also to its simplicity of use. In this paper, experimental evidences about the role of curing on the hydro-mechanical behaviour of cement-bentonite mixtures are presented. Different curing times and curing conditions (representative for either water saturated or hydrocarbon polluted soils) have been considered, and their effects on both hydraulic conductivity and mechanical response in oedometer and triaxial conditions have been assessed. A unified hydro-mechanical framework, accounting for the changes of material fabric occurring with curing time and environment, is formulated. The hydraulic conductivity is very well predicted by a Kozeny-Carman like equation, whereas the mechanical behaviour is finely reproduced via an enhanced elastic–plastic constitutive model., Geo-engineering

The hydrophysical properties of the soil play an important role in agricultural production and ecosystem services, and relate to both parental material and bioclimatic conditions and land use. Given the importance of the topic, an investigation was carried out whose objective was to know the relationship between hydrophysical properties and parental material. To fulfill this purpose, 72 coffee farms were selected in Colombia with soils belonging to five parental materials (volcanic ash, intrusive and extrusive igneous rocks, schists and sedimentary) and 22 cartographic units, established by the National Federation of Coffee Growers of Colombia. Soil samples between 10 and 30 cm depth of the profile were taken and particle size distribution, bulk and particle densities (BD and PD), organic matter content (OM), gravimetric moisture retention at 0.33 and 15 bar were determined (MR 0.33 and MR 15), saturated hydraulic conductivity (HC), total porosity (TP) and water storage capacity. Soils from volcanic ash presented lower PD, BD and clay, and higher OM, while derivatives of intrusive igneous exhibited higher PD, BD and sand, and lower OM, silt, MR at 0.33 and 15 bar and HC. The OM influenced PD and BD, and correlated with TP and MR. For most hydrophysical properties, significant differences were found between parental materials. The analysis of canonical discriminating functions, applied to all parental materials, managed to identify them in 65% of cases. When soils from schists and sedimentary rocks were excluded from this analysis, 91% of hits were achieved; the variables with the highest weight were OM, BD, MR, sand and clay., Las propiedades hidrofísicas del suelo desempeñan un papel relevante en la producción agrícola y los servicios ecosistémicos, y se relacionan tanto con el material parental como con las condiciones bioclimáticas y el uso del suelo. Dada la importancia del tema, se llevó a cabo una investigación cuyo objetivo fue conocer la relación entre las propiedades hidrofísicas y el material parental. Para cumplir con este propósito se seleccionaron 72 fincas cafeteras en Colombia con suelos pertenecientes a cinco materiales parentales (ceniza volcánica, rocas ígneas intrusivas y extrusivas, esquistos y sedimentarias) y 22 unidades cartográficas, establecidas por la Federación Nacional de Cafeteros de Colombia. En las fincas se tomaron muestras de suelo entre 10 y 30 cm de profundidad del perfil y se determinaron la distribución de tamaño de partículas, densidades aparente y real (Da y Dr), contenido de materia orgánica (MO), retenciones gravimétricas de humedad a 0.33 y 15 bar (RH 0.33 y RH 15), conductividad hidráulica saturada, porosidad total (Pt) y capacidad de almacenamiento de agua. Los suelos provenientes de ceniza volcánica presentaron menor Dr, Da y arcilla, y mayor MO, mientras que los derivados de ígneas intrusivas exhibieron mayor Dr, Da y arena, y menor MO, limo, RH a 0.33 y 15 bar y Ch. La MO tuvo influencia sobre Dr y Da, y se correlacionó con Pt y las RH. Para la mayoría de las propiedades hidrofísicas, se encontraron diferencias significativas entre los materiales parentales. El análisis de funciones discriminantes canónicas, aplicado a todos los materiales parentales, consiguió identificarlos en 65% de los casos. Cuando se excluyeron de este análisis los suelos provenientes de esquistos y rocas sedimentarias, se logró un 91% de aciertos; al respecto las variables con mayor peso fueron MO, Da, RH, A, Ar.

The hydrophysical properties of the soil play an important role in agricultural production and ecosystem services, and relate to both parental material and bioclimatic conditions and land use. Given the importance of the topic, an investigation was carried out whose objective was to know the relationship between hydrophysical properties and parental material. To fulfill this purpose, 72 coffee farms were selected in Colombia with soils belonging to five parental materials (volcanic ash, intrusive and extrusive igneous rocks, schists and sedimentary) and 22 cartographic units, established by the National Federation of Coffee Growers of Colombia. Soil samples between 10 and 30 cm depth of the profile were taken and particle size distribution, bulk and particle densities (BD and PD), organic matter content (OM), gravimetric moisture retention at 0.33 and 15 bar were determined (MR 0.33 and MR 15), saturated hydraulic conductivity (HC), total porosity (TP) and water storage capacity. Soils from volcanic ash presented lower PD, BD and clay, and higher OM, while derivatives of intrusive igneous exhibited higher PD, BD and sand, and lower OM, silt, MR at 0.33 and 15 bar and HC. The OM influenced PD and BD, and correlated with TP and MR. For most hydrophysical properties, significant differences were found between parental materials. The analysis of canonical discriminating functions, applied to all parental materials, managed to identify them in 65% of cases. When soils from schists and sedimentary rocks were excluded from this analysis, 91% of hits were achieved; the variables with the highest weight were OM, BD, MR, sand and clay., Las propiedades hidrofísicas del suelo desempeñan un papel relevante en la producción agrícola y los servicios ecosistémicos, y se relacionan tanto con el material parental como con las condiciones bioclimáticas y el uso del suelo. Dada la importancia del tema, se llevó a cabo una investigación cuyo objetivo fue conocer la relación entre las propiedades hidrofísicas y el material parental. Para cumplir con este propósito se seleccionaron 72 fincas cafeteras en Colombia con suelos pertenecientes a cinco materiales parentales (ceniza volcánica, rocas ígneas intrusivas y extrusivas, esquistos y sedimentarias) y 22 unidades cartográficas, establecidas por la Federación Nacional de Cafeteros de Colombia. En las fincas se tomaron muestras de suelo entre 10 y 30 cm de profundidad del perfil y se determinaron la distribución de tamaño de partículas, densidades aparente y real (Da y Dr), contenido de materia orgánica (MO), retenciones gravimétricas de humedad a 0.33 y 15 bar (RH 0.33 y RH 15), conductividad hidráulica saturada, porosidad total (Pt) y capacidad de almacenamiento de agua. Los suelos provenientes de ceniza volcánica presentaron menor Dr, Da y arcilla, y mayor MO, mientras que los derivados de ígneas intrusivas exhibieron mayor Dr, Da y arena, y menor MO, limo, RH a 0.33 y 15 bar y Ch. La MO tuvo influencia sobre Dr y Da, y se correlacionó con Pt y las RH. Para la mayoría de las propiedades hidrofísicas, se encontraron diferencias significativas entre los materiales parentales. El análisis de funciones discriminantes canónicas, aplicado a todos los materiales parentales, consiguió identificarlos en 65% de los casos. Cuando se excluyeron de este análisis los suelos provenientes de esquistos y rocas sedimentarias, se logró un 91% de aciertos; al respecto las variables con mayor peso fueron MO, Da, RH, A, Ar.

Background and Aims Stomatal regulation allows plants to promptly respond to water stress. However, our understanding of the impact of above and belowground hydraulic traits on stomatal regulation remains incomplete. The objective of this study was to investigate how key plant hydraulic traits impact transpiration of maize during soil drying. We hypothesize that the stomatal response to soil drying is related to a loss in soil hydraulic conductivity at the root-soil interface, which in turn depends on plant hydraulic traits. Methods We investigate the response of 48 contrasting maize (Zea mays) genotypes to soil drying, utilizing a novel phenotyping facility. In this context, we measure the relationship between leaf water potential, soil water potential, soil water content and transpiration, as well as root, rhizosphere and aboveground plant traits. Key Results Genotypes differed in their responsiveness to soil drying. The critical soil water potential at which plants started decreasing transpiration was related to a combination of above and belowground traits: genotypes with a higher maximum transpiration and plant hydraulic conductance as well as a smaller root and rhizosphere system closed stomata at less negative soil water potentials. Conclusions Our results demonstrate the importance of belowground hydraulics for stomatal regulation and hence drought responsiveness during soil drying. Furthermore, this finding supports the hypothesis that stomata start to close when soil hydraulic conductivity drops at the root-soil interface.

Arbuscular mycorrhizal fungi (AMF) alter plant water relations and contribute to soil structure. Although soil hydraulic properties depend on soil structure and may limit plant water uptake, little is known about how AMF influence soil water retention (the relation between the soil water content and soil water potential) and hydraulic conductivity in different soils. Instead, these soil hydraulic properties often are considered to be independent of AMF presence in experiments. We asked if this assumption holds true for both sand and loam. We grew maize plants either inoculated with Rhizophagus irregularis or with autoclaved inoculum in pots filled with quartz sand or loam soil until extraradical spread of the fungus throughout the pots was achieved. Each pot contained a hyphal compartment made of a soil sampling core (250 cm3) covered with a 20-µm nylon mesh to encourage fungus ingrowth but to exclude root ingrowth. We measured soil water retention and unsaturated hydraulic conductivity in these undisturbed root-free soil volumes. We observed that in loam harboring the mycorrhizal fungus, the soil water retention decreased, while in sand, it increased without detectable changes in the soil bulk density. The effects of the fungus on the soil water potential were strongest at low soil water contents in both soils. As a consequence of the altered water potentials in soils with the mycorrhizal fungus, soil hydraulic conductivity increased in loam but decreased in sand after fungus ingrowth. We conclude that in our study, the mycorrhizal fungus acted as a soil conditioner even distant from roots, which encouraged drainage in loams prone to sogginess but enhanced water storage in sands prone to quick desiccation. We recommend considering soil hydraulic properties as being dynamic in future studies on water relations of mycorrhizal plants., Peer Reviewed

Groundwater protection and contaminated site remediation efforts continue to be hampered by the difficulty in characterizing physical properties in the subsurface at a resolution that is sufficiently high for practical investigations. For example, conventional well-based field methods, such as pumping tests, have proven to be of limited effectiveness for obtaining information, such as the transmissive and storage characteristics of a formation and the rate at which groundwater flows, across different layers in a heterogeneous aquifer system. In this chapter, we describe a series of developments that are intended to improve our discipline’s capability for high-resolution characterization of subsurface conditions in shallow, unconsolidated settings. These developments include high-resolution methods for hydraulic conductivity (K) characterization based on direct push (DP) technology (e.g., DP electrical conductivity probe, DP permeameter, DP injection logger, Hydraulic Profiling Tool (HPT), and High-Resolution K tool), K and porosity characterization by nuclear magnetic resonance (NMR), and groundwater flux characterization by monitoring the movement of thermal or chemical tracers through distributed temperature sensing (DTS) equipment or the point velocity probe (PVP). Each of these approaches is illustrated using field or laboratory examples, and a brief discussion is provided on their advantages, limitations, as well as suggestions for future developments.

In the French deep geological disposal for radioactive wastes, compacted bentonite/claystone mixtures have been considered as possible sealing materials. After emplacement in place, such mixtures are hydrated by the site solution as well as the cement solution produced by the degradation of concrete. In this study, the effects of synthetic site solution and cement solution on the hydro-mechanical behaviour of compacted mixtures of claystone and two types of bentonites (MX80 Na-bentonite and Sardinia Ca-bentonite) were investigated by carrying out a series of swelling pressure, hydraulic conductivity and mercury intrusion porosimetry (MIP) tests. It was found that for the MX80 bentonite/claystone mixture hydrated with synthetic site solution, the swelling capacity was reduced compared to the case with deionised water owing to the transformation of Na-montmorillonite to multi-cation dominant montmorillonite by cation exchanges. For the Sardinia bentonite/claystone mixture, the similar increasing rate of swelling pressure was observed during the crystalline swelling process for different solutions, suggesting insignificant cation exchanges. Additionally, the cations in the synthetic site solution could reduce the thickness of diffuse double layer and the osmotic swelling for both MX80 bentonite/claystone and Sardinia bentonite/claystone mixtures. The large-pore volume increased consequently and enhanced water flow. In the cement solution, the hydroxide could also dissolve the montmorillonite, reducing the swelling pressure, and increase the large-pore volume, facilitating the water flow. Furthermore, the decrease of swelling pressure and the increase of hydraulic conductivity were more significant in the case of low dry density because of more intensive interaction between montmorillonite and hydroxide due to the high permeability.

Within the framework of the Dutch sustainable landfill project iDS, four compartments of the Dutch landfill Braambergen have been treated by in-situ aeration since 2017. The aeration infrastructure comprises 230 wells with a spacing of 15 to 20 m, distrib-uted over an area of around 10 ha, intercepting a waste body of 1.2 × 106 t of contam-inated soils, soil treatment residues, bottom ashes and construction and demolition waste. The wells, used in an alternating fashion for air injection and gas extraction, can also be used to monitor water tables within the waste body. In order to describe the spatial variability of waste hydraulics, design a larger scale leachate pumping test and, eventually, support model predictions of the site’s water balance and emission potential, analyses of leachate composition and pumping tests on individual wells have been conducted. The spatial variability of leachate quality and water tables is very high with no geospatial relationship between the sampling points. Each sampling point is representative of itself only. Large differences prevail not only between and across the compartments, but also between directly neighbouring wells. Both the small scale differences in leachate tables as well as in leachate quality indicate a spatial pattern of zones with low horizontal connectivity within the waste body. Recovery rates of drawdown in the wells yielded preliminary estimates of horizontal waste hydraulic conductivity in the order of 1×10-7 to 6×10-4 m/s., Geo-engineering