Dissertations / Theses on the topic 'Soil and Water Engineering'
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1
Ekanayake, Jagath C. "Soil water movement through swelling soils." Lincoln University, 1990. http://hdl.handle.net/10182/1761.
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The present work is a contribution to description and understanding of the distribution and movement of water in swelling soils. In order to investigate the moisture distribution in swelling soils a detailed knowledge of volume change properties, flow characteristics and total potential of water in the soil is essential. Therefore, a possible volume change mechanism is first described by dividing the swelling soils into four categories and volume change of a swelling soil is measured under different overburden pressures. The measured and calculated (from volume change data) overburden potential components are used to check the validity of the derivation of a load factor, ∝. Moisture diffusivity in swelling soil under different overburden pressures is measured using Gardner's (1956) outflow method. Behaviour of equilibrium moisture profiles in swelling soils is theoretically explained, solving the differential equation by considering the physical variation of individual soil properties with moisture content and overburden pressure. Using the measured volume change data and moisture potentials under various overburden pressures, the behaviour of possible moisture profiles are described at equilibrium and under steady vertical flows in swelling soils. It is shown that high overburden pressures lead to soil water behaviour quite different from any previously reported.
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Dalton, James A. "Contribution of upward soil water flux to crop water requirements." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/344938/.
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Guo, Yuan. "Multiscale and Multiphysics Modeling of Soil Water Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1527760301074766.
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Ashraf, Muhammad. "Dynamics of soil water under non-isothermal conditions." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336299.
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Simas, Maria Joao Correia de 1966. "Soil water determination by natural gamma radiation attenuation." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/278348.
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The purpose of the study was to determine the soil moisture content by measuring the naturally occurring gamma radiation in the soil. A calibration procedure was developed both in laboratory and in the field. In the laboratory, two different sample sizes were used: three-inch diameter, and 18-inch diameter columns, both 15 cm long. Small size soil samples (three-inch diameter) cannot be used to predict the calibration curve in the field, whereas the larger soil samples (18-inch diameter) calibration may be used to predict the field calibration curve. The prediction limits for the calibration curve done in the field are of ±5%, which is an unacceptable level of precision. It was also observed that the distance between the detector and the soil should always be kept constant, and that the top 15 cm of the soil contribute to approximately 95% of the radiation measured at the soil surface.
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Ketteringham, Wayne Stuart. "Transient flow of water in saturated-unsaturated soil profiles." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/8296.
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Includes bibliography.In this thesis tile transient flow of water, during tile drainage process in saturated-unsaturated soil profiles, was studied. Drainage experiments were performed on two different soil profiles. The first experiment undertaken was tile drainage of a vertical column of sand. This experiment was performed on two sands of differing grain size and grading. The second experiment undertaken was the drainage towards a well from a wedge of sand (cake slice) using yet a different coarse sand.
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Pan, Luan. "Means to optimize soil water management through monitoring spatial and temporal variability of geophysical soil attributes." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117181.
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To optimize irrigation water use, temporal and spatial sensor-based data related to soil water content were integrated. Nine locations in a 37-ha agricultural field were selected using field elevation and soil ECa maps for monitoring the soil matric potential and temperature at four depths (18, 48, 79 and 109 cm) with a wireless sensor network. Using a linear regression approach, a series of time-specific equations were developed to quantify both the temporal and spatial soil water stress status through a Water Stress Index (WSI). The WSI was estimated using soil matric potential measurements along with supplemental soil characteristics, such as site-specific soil matric potential corresponding to 25% soil water depletion that was derived based on soil physical properties. Further analysis was performed to quantify the percentage of the field that undergoes a potential shortage in water supply. These results could be used to optimize irrigation scheduling and to assess the potential for variable-rate irrigation. The second study investigated the way in which the WSI prediction quality is affected by the number and placement of temporal soil water content monitoring sites. The concept, potentially, could be used to investigate a variety of site-specific crop management strategies. It was developed to assess WSI predictability in context that the modeled relationship between WSI and spatial field data (ECa and elevation) is not perfect at any given point of time. The established regression model between ECa, field topography maps and WSI from the first study was applied to construct WSI maps representing a specific point in time in six experimental fields with different crop growing conditions located in Nebraska, USA. Artificial regression error models with different degrees of spatial structure were superimposed onto these maps to simulate actual WSI distribution across the fields. Both random and optimized monitoring site placement strategies were evaluated in terms of the ability to predict the simulated WSI maps. The results showed that it was necessary to optimize the selection when the number of monitoring sites was low. However, a random placement method was equally efficient when the number of monitoring sites was high. Careful selection of representative field areas representing significant field areas with extreme conditions should allow only 2 or 3 monitoring sites to produce results with relatively low WSI prediction error.Through the process of water management optimization, it was noted that the ability to detect site-specific water storage capacity is an important task. Since it is related to the change of soil physical properties with depth, a third study was conducted to develop a dynamic scanning of soil profile tools using a galvanic contact resistivity approach. Transmitting and receiving electrodes were configured in an equatorial dipole array. An automated scanner system has been developed and tested in the agricultural field environment with different soil profiles. While operating in the field, the distance between the current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The resulting scans were evaluated against 1-m deep soil profiles and that of an electromagnetic induction instrument at various depths, up to 3 m.Pour atteindre l'utilisation optimale de l'eau d'irrigation, des données spatio-temporelles provenant de sondes et reliées au contenu en eau du sol ont été intégrées. Ainsi, dans un champ agricole de 37 hectares, neuf sites ont été sélectionnés en utilisant les cartes d'élévation et de CEa du sol afin d'assurer le suivi du potentiel matriciel et de la température du sol à quatre profondeurs (18, 48, 79 et 109 cm) avec un réseau de capteurs sans fil. Utilisant une approche de régression linéaire, une série d'équations spécifiques au temps a été développée pour quantifier l'état de stress hydrique du sol dans le temps et l'espace à l'aide d'un Indice de Stress Hydrique (ISH). L'ISH a été estimé en utilisant des mesures de potentiel matriciel du sol combiné à ses caractéristiques supplémentaires, telles que celles calculées à partir de ses propriétés physiques et du potentiel matriciel spécifique au site correspondant à un appauvrissement de 25% des eaux du sol. Une analyse additionnelle a permis de quantifier la fraction du site ayant un potentiel d'approvisionnement en eau déficitaire. Ces résultats pourraient être utilisés afin d'optimiser la planification de l'irrigation et d'évaluer le potentiel d'irrigation à débits variables.La seconde étude a permis un examen plus approfondi de la qualité de prédiction de l'ISH influencé par le nombre et l'emplacement de sites chronologiques de surveillance du contenu hydrique du sol. Le concept pouvant potentiellement être utilisé pour étudier une diversité de stratégies de gestion de cultures a été développé afin d'évaluer la prévisibilité de l'ISH en tenant compte de la relation imparfaite entre cet indice et les données spatiales à tout temps donné. Le modèle de régression établi entre la CEa, les cartes topographiques du champ et l'ISH de la première étude a été appliqué afin de construire des cartes d'ISH représentant un moment spécifique pour six champs expérimentaux sous différentes conditions de croissance au Nebraska, USA. Des modèles artificiels d'erreur de régression avec différents degrés de structure spatiale ont été superposés sur ces cartes pour simuler la distribution réelle de l'ISH à travers ces champs. Autant de stratégies aléatoires et optimisées de placement de sites de surveillance ont été évaluées en termes de leur habilité à prédire les cartes d'ISH simulées. Les résultats démontrent qu'il était nécessaire d'optimiser la sélection de sites de surveillance lorsque leur nombre était bas. Cependant, la méthode de placement aléatoire était tout aussi efficace lorsque le nombre de sites était élevé. Une sélection rigoureuse des régions du champ permettant de représenter ses aires significatives avec des conditions extrêmes devrait permettre la production de résultats ayant une erreur de prédiction de l'ISH très basse à partir de seulement deux ou trois sites de surveillance.À travers le processus d'optimisation de la gestion de l'eau, il a été noté que l'aptitude à détecter la capacité d'emmagasinement d'eau spécifique au site est une tâche importante. Puisqu'elle est liée au changement de propriétés physiques du sol avec la profondeur, la troisième étude a été menée afin de développer un outil de balayage (scan) dynamique des profils du sol en utilisant une approche de résistance du contact galvanique. Les électrodes émettrices et réceptrices ont été configurées suivant un dispositif dipôle équatorial. Un système de scanner automatisé a été développé et testé dans un environnement de terre agricole avec différents profils de sol. Lors de l'utilisation sur le terrain, la distance entre les pairs d'électrodes roulantes d'injection et de mesure variait continuellement de 40 à 190 cm. Les balayages résultants ont été évalués avec des profils de sols de 1m de profondeur, alors que ceux fait à partir d'un appareil d'induction électromagnétique ont été évalués à des profondeurs variées allant jusqu'à 3m.
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Arief, Ismail Shoieb Akaram. "Evaluation of biochar soil amendments in reducing soil and water pollution from pathogens in poultry manure." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117216.
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This project addresses concerns from the Canadian public about the quality of water in regions where many agricultural operations are located. Fecal coliforms are endemic in poultry and are difficult to eradicate from production facilities. Poultry manure is a reservoir of Campylobacter jejuni, Escherichia coli (including O157:H7) and Salmonella spp. Biochar, the charcoal produced from pyrolysis of biomass, is gaining global recognition due to its unique properties when applied as a soil amendment. Biochar could play an important role in controlling the mobility of pathogens in soil and water environment. Its half-life is estimated to be hundreds of years so it is expected that its role in reducing agricultural pollution could be very long-lasting, and hence very cost-effective.In this study we investigated the effectiveness of biochar in preventing the leaching of fecal coliforms into surface water. The target organisms in this study were Escherichia coli (E .coli) and total coliform. E. coli is widely recognized as the indicator organism for presence of fecal coliform and total coliforms to determine disinfection rate. The study was divided into two components, namely laboratory study and field study.In laboratory study, the effectiveness of three different types of biochar (variation based on production temperature, time and raw material) in adsorption and desorption of E. coli was studied. In adsorption test, a comparative analysis was carried out to understand the differences between biochar, soil amended biochar (soil to biochar ratio of 99:1) and un-amended soil in the removal of E. coli. The statistical analysis showed the adsorption of E. coli was significantly higher in the soil amended biochar treatment. The soil amended biochar and the un-amended soil treatments were further subjected to desorption to test their retention capacity. The statistical analysis showed that two types of soil amended biochars (slow pyrolysis biochar and fast pyrolysis biochar) retained E. coli significantly better. The adsorption capacity of biochar was directly proportional to its porosity and inversely proportional to its ash content. The two types of soil amended biochar were shortlisted based on sorption and retention capacity and were used as treatments in the field study.A sixty-day study was conducted using field lysimeters to evaluate the effectiveness of soil amended biochar in removing or reducing the leaching of fecal coliforms (E. coli) from poultry manure. Lysimeter with only soil was used as control and the shortlisted biochars (slow pyrolysis biochar and fast pyrolysis biochar) were used as treatments. In the biochar-amended treatments, the top 0.05 m of soil was amended with biochar in a proportion of 1:99 biochar:soil. Poultry manure was spread over the soil in all lysimeters. The lysimeters were protected from natural rainfall, and the simulated rainfall was applied as 4 events over a sixty day period. Both soil (3 sampling depths) and leachate samples were collected and analyzed at predetermined time intervals. In the experiment, E. coli and total coliform were found to leach down through the soil profiles, and their concentrations decreased with soil depth and time. The statistical analysis of soil samples and leachate showed that the concentration of E. coli in the treatments at the three sampling depths and in the leachate were significantly different from control (P ≤ 0.05), which is attributed to the effectiveness of the treatments in reducing the leaching of fecal coliforms. However, the concentration of total coliforms was significant (P ≤ 0.05) on certain intervals and insignificant in the others; this can be attributed to already present total coliforms in the soil system and effectiveness of the treatments to hinder coliform transport. Soil biochar amendment was thus seen to be effective in reducing the leaching of fecal coliforms through soil profiles and providing fecal coliforms free leachate.Ce projet répond aux préoccupations du public canadien au sujet de la qualité de l'eau dans les régions où de nombreuses exploitations agricoles sont présentes. Les coliformes fécaux sont endémiques chez les volailles et sont difficiles à éradiquer des sites de production. Le biochar, un charbon produit par pyrolyse de la biomasse, gagne de plus en plus de reconnaissance à l'échelle mondiale en raison de ses propriétés uniques lorsqu'il est utilisé comme amendement de sol. Sa demi-vie est estimée à des centaines d'années. Par conséquent, son rôle dans la réduction de la pollution agricole pourrait s'étendre sur une longue période.Dans cette étude, nous examinons l'efficacité du biochar dans la prévention de la lixiviation des coliformes fécaux dans l'eau de surface. Les organismes ciblés dans cette étude sont Escherichia coli (E coli.) et les coliformes totaux. E. coli est reconnu comme étant l'organisme indicateur de la présence de coliformes fécaux et les coliformes totaux comme étant révélateur du taux de désinfection. L'étude est composée de deux parties, l'une effectuée en laboratoire et l'autre sur le terrain.Dans l'étude en laboratoire, l'efficacité d'absorption et de désorption d'E. coli de trois différents types de biochar a été étudiée. Par le moyen de tests d'adsorption, une analyse comparative a été effectuée afin de déterminer la différence entre du biochar pur, un sol amendé par du biochar et un sol non-amendé dans leur efficacité d'élimination d'E. coli. Les analyses statistiques ont montré que le biochar comme amendement du sol joue un rôle important dans l'adsorption d'E. coli.Le sol amendé par du biochar et le sol non-amendé ont ensuite été soumis à un test de désorption afin de tester leur capacité de rétention. Les analyses statistiques ont démontré que deux types de sol amendés de biochar (l'un issu de la pyrolyse lente et l'autre de la pyrolyse rapide) retenaient E. coli. La capacité d'adsorption du biochar s'est révélée être directement proportionnelle à sa porosité et inversement proportionnelle à sa teneur en cendres. Les deux types de biochars ont été sélectionnés et utilisés comme traitements dans l'étude de terrain. L'étude de terrain a été réalisée sur des lysimètres pendant soixante jours afin d'évaluer l'efficacité du biochar dans l'élimination et la réduction du lessivage des coliformes fécaux (E. coli) venant du fumier de volaille. Le témoin contenait seulement du sol et le biochar sélectionné (l'un issu de la pyrolyse lente et l'autre de la pyrolyse rapide) a été utilisé comme traitement. Le biochar a été mélangé avec 5 cm de sol en partant de la surface (rapport de sol a biochar de 99:1). Le fumier de volaille a été répandu sur le sol dans tous les lysimètres. Les lysimètres ont été protégés de la pluie afin de simuler l'irrigation. L'irrigation a été simulée en 4 événements au cours des soixante jours. Le sol (3 profondeurs d'échantillonnage) et les échantillons de lixiviat ont été prélevés et analysés à des intervalles temporels prédéterminés. Dans cette étude, E. coli et les coliformes totaux se sont infiltrés à travers les profils de sol, et leurs concentrations ont diminués avec le temps et la profondeur du sol. Les analyses statistiques (P ≤ 0.05) des échantillons de sol et des lixiviats ont montré que la concentration d'E. coli dans les traitements aux trois profondeurs et dans le lixiviat étaient différente du contrôle, ce qui est attribué à l'efficacité des traitements de réduction du lessivage des coliformes fécaux. Cependant, la concentration de coliformes totaux était significatif (P ≤ 0.05) sur certains intervalles et insignifiant sur d'autres, ce qui peut être lié a une présence antérieure de coliformes totaux dans le sol et a l'efficacité des traitements qui suggèrent un taux de désinfection efficace. Le sol amendé de biochar a donc été considéré comme étant efficace dans la réduction du lessivage des coliformes fécaux a travers les profils de sol.
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Konings, Alexandra Georges. "Microwave remote sensing of water in the soil - plant system." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101833.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 171-191).
Remotely sensed measurements made by radars or radiometers in the low microwave frequency range are sensitive to soil moisture, soil roughness, and vegetation water content. Measurements made at multiple polarizations can be used to determine additional ancillary parameters alongside the primary variable of interest. However, if an attempt is made to retrieve too many parameters from too few measurements, the resulting retrievals will contain high levels of noise. In this thesis, I introduce a framework to determine an upper bound on the number of geophysical parameters that can be retrieved from remotely sensed measurements such as those made by microwave instruments. The principles behind this framework, as well as the framework itself, are then applied to derive two new ecohydrological variables: a) soil moisture profiles across much of the root-zone and b) vegetation optical depth, which is proportional to vegetation water content. For P-band observations, it is shown that soil moisture variations with depth must be accounted for to prevent large forward modeling - and thus retrieval - errors. A Tikhonov regularization approach is then introduced to allow retrieval of soil moisture in several profile layers by using statistics on the expected co-variation between soil moisture at different depths. The algorithm is tested using observations from the NASA Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) Mission over the Harvard Forest in Western Massachusetts. Additionally, at L-band, a multi-temporal algorithm is introduced to determine vegetation optical depth (VOD) alongside soil moisture. The multi-temporal approach used reduces the chance of compensating errors between the two retrieved parameters (soil moisture and vegetation optical depth), caused by small amounts of measurement noise. In several dry tropical ecosystems, the resulting VOD dataset is shown to have opposite temporal behavior to coincident cross-polarized backscattering coefficients, an active microwave indicator of vegetation water content and scattering. This possibly shows dry season bud-break or enduring litter presence in these regions. Lastly, cross-polarized backscattering coefficients are used to test the hypothesis that vegetation water refilling slows down under drought even at the ecosystem scale. Evidence for this hypothesis is only found in the driest location tested.
by Alexandra Georges Konings.
Ph. D.
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Alsanabani, Mohamed Moslih. "Soil water determination by time domain reflectometry: Sampling domain and geometry." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185550.
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This work investigates several aspects of time domain reflectometry (TDR) theory and application. One of these aspects is the study of the influence of TDR probe geometries on the travel time. No change in the travel time resulted from increasing either the diameter of wire or spacing. However, we found a linear relationship between the travel time and the length of the probe for measurements in water. Also we found the reflected voltage was inversely proportionally to the incident voltage in water. Another aspect is the volume of sensitivity for the TDR which depends on the electrical properties of the medium and the geometry of the probe. The sensitivity of TDR in soil is different than in water. The observations in soils indicate that soil with a high water content (θᵥ) has a smaller sample volume than the one with low θᵥ. A probe with a large wire diameter has a larger sample volume than a probe with a small wire diameter. Also, a simple model and a mixing model were investigated and compared to Topp's model, for relating θᵥ to the effective dielectric constant. The distance to wetting front over time was observed and calculated using an expression which relates the travel time in soil before and after water application. This was tested with probes of different geometries. The wetting front from a point source were monitored for two and three dimensions in a plexiglas tank using TDR. Contour maps for the calculated radius of wetting front vs. the depth over time were produced.
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Thadei, Simon Yuda. "Evaluation of effective rainfall by a physically-based soil-water balance model." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316263.
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Di, Bonito Marcello. "Trace elements in soil pore water : a comparison of sampling methods." Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/10123/.
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This thesis examined a range of methods for sampling soil pore water to investigate the chemistry of trace elements. In particular, the study assessed whether Rhizon samplers, centrifugation, high pressure squeezing and soil suspensions in simulated pore water can be viable approaches for obtaining representative samples of equilibrated soil pore water. Results for metal solubility and speciation were interpreted in terms of both soil morphological effects on trace metal dynamics and artefacts introduced at various stages during sample preparation and handling. The main soil used in the study was an organic-rich sandy silt from a site which has served as a sewage re-processing facility for almost a century. This soil was chosen because of its importance as a long-term repository for metal-enriched sludge applied to arable land, providing a suitable medium on which to study trace metal behaviour. Pore waters were extracted and analysed for major and trace cations and anions, pH, Dissolved Inorganic Carbon (DIC) and Dissolved Organic Carbon (DOC) at two different temperatures (5 degrees Celsius and 15 degrees Celsius), in order to evaluate the extent of bacterial activity, organic decomposition and their consequences on solute composition, during pore water extractions. Speciation was estimated from analysis of pore water chemistry using two software packages (PHREEQCi and WHAM-VI). Pore waters showed different ranges of concentration between the various methods. Different mechanisms and/or chemical reactions were involved during the different extractions; a range of processes was identified, mainly dominated by metal complexation by humus acids and redox reactions. Results revealed that the soil studied was able to partially buffer the free ion activities of the metal ions in pore water with increasing dilutions, but demonstrated virtually no ability to buffer DOC. Identification of the source (i.e. location of pore space) of water extracted was also investigated using water with different isotopic composition (18O/16O). Evidence showed that centrifugation was not able to differentiate between more and less mobile water at FC conditions, rather enhancing the mixing between the two pools of water (native and labelled) by and apparent process of 'infusion'. By contrast, Rhizon samplers appeared to sample water preferentially from the more accessible pool (extra-aggregate), which proved to have a composition showing incomplete mixing with the native water. The results also suggested that mixing of the two pools was rather fast and that was almost completely attained prior to pore water extraction. The study established that the most important factors affecting pore water chemistry during extraction are the conditions to which the samples are exposed during the extraction process. For these reasons Rhizon samplers should be used as a disposable device, and are only applicable for use in high soil moisture soil contents. In contrast, they present no 'side-effects' (providing enough equilibration time) if M2+ (free ion activity) were needed as opposed to Msol (total metal concentration in pore water), as often required in environmental studies. Centrifugation is optimal for bulk solution studies, or when homogenisation represents a key experimental point; targeted studies are also possible. Soil squeezing is subject to severe limitations in the case of prolonged extractions of biologically active soils, due to the effects of anaerobism. Squeezing should only be used for 'fast' extractions of soils. Finally, batch extractions are well suited to studies on M2+ equilibria, but more studies are needed to clarify the effect of soil: solution ratio on metal and DOC solubility.
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Pandya, P. A. and Rank H. D. "Summer sesame response to irrigation methods and mulching. Research on Crops." Dissertation/Thesis, Junagadh Agricultural University,JUNAGADH, 2011. http://krishi.icar.gov.in/jspui/handle/123456789/31686.
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ThesisA field experiment was conducted at instructional farm of Soil and Water Engineering Department, College of Agricultural Engineering and Technology, Junagadh Agricultural University, Junagadh during summer season (Feb-May) - 2011 to study the "summer sesame response to irrigation methods and mulching". Surface wetting front movement was studied under four drip irrigation treatments viz. 41phX0.5mX0.9m, 81phX0.8mX1.2m, 141phX0.8mX2.1m and 201phX1.0mX2.4m respectively. Based on wetting front movement, time required to irrigate 3, 4, 7 and 8 rows of sesame crop having 30 cm row spacing was found as 2.08 hr, 2.31 hr, 3.55 hr and 3.41 hr and 3 hours for Porous pipe irrigation system. The depth of each irrigation for these respective water application times were found as 21, 20, 26, 29 and 38 mm respectively. The summer sesame response to irrigation methods and mulching was studied by experiment adopting split plot design with twelve treatment combinations comprised of irrigation methods as a main factor with six levels viz;, surface irrigation system (border) (lo), drip irrigation system-4 Iph x 0.5m x 0.9 m(i2), drip irrigation system-14 Iph x 0.8m X 2.1m(i3), drip irrigation system-20 Iph x Im x 2.4 m(i4) and subsurface porous pipe irrigation system-22mm x 0.9m x 101ph/m(i5), and mulching as a sub factor with two levels viz; 5 tone/ha (Mi) and no mulch (Mo). These treatment combinations were embedded with three replications. The response of sesame was evaluated in terms of plant height, weed intensity, grain yield, straw yield and water use efficiency. The irrigation interval during growing period was decided based on the irrigation depth and cumulative evapotranspiration of the crops for the 1.0 IW/ETc. The total number of 15, 18, 19, 14,14 and 11 irrigations were given in treatment- lo, Ii, h, I3,14 and I5 respectively. Grain yield of sesame was significantly influenced by different methods of irrigation. Treatments I5 and Ii gave significantly higher grain yield of 1623.23kg/ha and 1554.57 kg/ha respectively than rest of the treatments. The significantly lowest grain yield of 1204.06 kg/ha was found under lo (control). Grain yield under the treatments I5 and h were 35% and 29% higher than lo (control). Water use efficiency for different irrigation methods was according to their respective yields. Significantly highest weed intensity (14.8 No. /m^) was recorded with treatment lo. It was 64 % more under the treatment lo as compared to treatment- I5. Grain yield was significantly higher (11.2 %) under treatment-Mi (1499.87 kg/ha) as compare to no mulch (1348.07kg/ha). The weed intensity under no mulch-Mo (13.16 No. /m^) was found 39 % higher than Mi (9.44 No. /m2). The costs of cultivation excluding the cost of irrigation with mulch and without mulch were found as Rs 17550 per ha and Rs 13200 per ha respectively. The fix cost of irrigation with pumping was found as 4979, 10833, 8313, 6062, 6151, 17062 Rs/ha/season for surface irrigation system treatment-Io, drip irrigation treatments-Ii, I2, I3, and U and porous pipe irrigation system treatment-Is. The highest and lowest benefit cost ratio under irrigation with mulch was found as 3.67 and 2.87 respectively under irrigation treatment T13 and Tis respectively. While highest and lowest benefit cost ratio under irrigation without mulch was found as 4.03 and 3.15 respectively under irrigation treatment T03 and Tos respectively. The highest and lowest ICBR of irrigation methods with mulch was found as 13.43 and 2.25 respectively under the treatment I13 and I15 respectively. While the highest and lowest ICBR for irrigation without mulch was found as 18.19 and 3.11 respectively under the treatment I03 and lo5 respectively. It was revealed that drip irrigation in combination with much was the most suitable practice for the cultivation of summer sesame in the semi arid zone of Saurashtra region having sacristy of water in summer season.
Not Available
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Dryden, Garri A. "Optimum gravel size for use as a soil surface cover for the prevention of soil erosion by water." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280469.
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Eleven series of replicated tests were conducted using 38.1 mm, 15.9 mm, and 9.5 mm gravel to determine the most effective soil surface cover to prevent soil erosion from rainfall. A sediment tray one meter square in size with an integrated rainfall simulator was used to generate data after initial trial runs had established test procedures. Various size gravels and a control with no cover were tested in a laboratory using simulated rainfall to evaluate their effectiveness in preventing erosion. Through thirty-three experiments, signature traits of specific rock sizes were identified. Experiments on 38.1 mm gravel indicated the usefulness of rock mulches in soil erosion prevention. Evaluations with 9.5 mm material indicated that erosion prevention varies inversely with particle size. Experiments with 15.9 mm gravel suggested that this material could increase erosion. This study reflects the ambivalence in the literature and points to the complexity of micro-interactions and erosion potential as influenced by gravel size. Six mechanisms governing rock mulch erosion were proposed.
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Harlow, Robert C. "Remote and in situ measurements of soil and vegetation water content." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280356.
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Accurate estimates of soil moisture are necessary to predict evapotranspiration, runoff, infiltration, and groundwater recharge and, through these variables, weather, climate, and fire and flood frequencies. This dissertation is motivated by the need to estimate soil water content from remotely sensed passive microwave emission. Two different approaches are taken: (1) improved modeling of the microwave emission from the land surface; and (2) measurements of the average dielectric properties of the soil media and vegetation canopies. Consequently, the first part of the dissertation describes how a stratified dielectric model of the microwave emission from the soil was extended to take into account the effects of vegetation. The model parameters were calibrated using observed data and a robust optimization routine. However, the availability of measurements of some of these parameters, particularly the profile of dielectric permittivity of the canopy, would facilitate a more complete evaluation of the accuracy of the extended microwave emission model. The second part of this dissertation describes progress towards the development of a technique to measure the dielectric of vegetation canopies. This technique is based on gated time domain transmission measurements through the substance of interest. Preliminary studies carried out using soils with varying salinity and water content and vegetation show (1) an unexpected response of the signal to saline soils, and (2) a possible dielectric signature of the onset of stress in plant stems.
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Ma, Ning. "Mathematical Modelling of Water Soil Erosion and Sediment Yield in Large Catchments." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/575.
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Sakhaee, Farhad. "Silver Creek Watershed Hydrological Modeling with SWAT for Discharge Calibration (Soil & Water Assessment Tool)." Thesis, Southern Illinois University at Edwardsville, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10808742.
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Local, national and regional water supplies needed for energy production, meet the irrigation demands, industrial and domestic usage have come under sever degradation hence decreased the piezo metric water table level in the groundwater resources which finally results in negative environmental impacts. Silver Creek basin (area 154.8 mile2 equals to approximately 400.930 km 2) locates in southern part of Illinois State, is connected to highland lake (which has a huge impact in the area and specifically Highland City) with east fork tributary. In this research watershed modeled in a hydrological model called SWAT (Soil and Water Assessment Tool) which is an extension of ArcGIS software, then watershed area is divided into 75 sub watersheds. Different parameters and variables are considered for sensitivity analysis in order to figuring out the most sensitive parameters and their ranges for flow rate calibration within different hydrological response units (HRUs). The flow rate quantified at sub basin level with daily time intervals. The model inputs are precipitations and meteorological data such as Solar Radiation, Wind speed and direction, Temperature and Relative Humidity, then model was calibrated with two sets of real data for Troy and Freeburg Stations in the middle and pouring point of watershed respectively. The main object was to test the performance of SWAT and the feasibility of using this model as a simulator of flow rate at a watershed scale. Model calibration and uncertainty analysis performed with SUFI-2 (sequential Uncertainty Fitting) which is interfaced with SWAT applying iSWAT generic program.
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Mohn, Douglas M. "Impact of Gypsum Bearing Water On Soil Subgrades Stabilized With Lime or Portland Cement." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430836216.
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Pandey, Lopa Mudra. "Electrical resistivity of sandy soil with water, leachates and seawater." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1724.
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Liners are used in the engineered containment systems such as landfills for controlling the migration of contaminants. Although there are several techniques for detecting the leakages through the liners, use of the electrical resistivity method can assist in timely detection of contaminant migration in cost-effective manner. This method is based on the well-established fact that the electrical resistivity of soils and other geomaterials is much higher than the electrical resistivity of water, leachates or any liquid effluents which may permeate the landfill foundation material. Additionally, the geotechnical properties of a soil exhibit a close relationship with its electrical resistivity values for different conditions.
This thesis presents the results of investigation into the interaction between the various electrical factors pertaining to resistivity tests in Perth sandy soil (specifically AC-input voltage and frequency) and those controlling the soil characteristics, specifically water/fluid content and relative density of the soil, and the types of permeant employed in the tests, namely distilled water, tap water, three leachates and seawater. For a landfill system situated near a salt water body, the effects of seawater and seawater-leachate intrusion have also been scrutinized. For the measurement of electrical resistivity for different soil density and contamination conditions, the experimental apparatus was developed as per Australian standard AS 1289.4.4.1-1997 as a significant part of the thesis work.
The test results indicate that the resistivity of the sandy soil is almost independent of both AC-input voltage and frequency within the ranges used, while the choice of electrode material has an insignificant effect on the outcome of tests using this method. It is observed that the resistivity of sandy soil decreases rapidly with an increase in water/fluid content, but the rate of decrease reduces considerably for water contents over 12% in the case of distilled water and 10% for tap water, irrespective of the relative density. The resistivity is found to decrease almost linearly with an increase in relative density. However, the effect of relative density on the electrical resistivity of the soil is found to be negligible at higher water contents.
In the landfills and similar containment systems, there is a possibility of leakage of leachate across the liners and/or seawater intrusion, depending on the location of the landfills. Hence, the study was conducted to evaluate the effects of contamination on the electrical resistivity of the Perth soil by changing the fluid content with various combinations of tap water, three different leachates and seawater. The study shows that for any mix of leachate and tap water, the resistivity decreases rapidly with increasing fluid content; however, the rate of decrease reduces significantly for fluid contents over 9%, irrespective of the type of leachate. Almost the same trend is observed for the case of seawater.
Correlations between electrical resistivity, water content, relative density, amount and the composition of permeating fluid, which are applicable to the soil and permeating fluids used in the study, have also been developed and presented.
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Teeluckdharry, Sahil. "An experimental investigation of leakage flow paths in soil surrounding leaks in water distribution systems." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/24917.
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Over the last few decades, water stress has been imminent in most municipalities around the world. The problem of water losses from pipelines is a major concern due to the increasing demands. Leakage is normally responsible for a large percentage of water losses in distribution systems and results in enormous wastage of valuable resources and energy. Leaks may be developed in many forms and locations in the system and active leak detections are required to find and repair damaged pipes. Few studies have been done on the soil-leak interaction in real pipeline systems. Recent research have shown that the high velocity water jets entering the surrounding soil causes a fluidisation zone outside leaks. The fluidised zone of soil and water is responsible for dissipating most of the energy of the water jet from the pipe leak and thus, limiting the leak's ability to reach soil surface. In municipalities where active leak detections are not implemented, it is easier for municipalities to detect leaks if they appear on the surface and thus, it is crucial to understand the routes of water leaks and the factors causing them to appear above the ground. This study investigated the soil-leak interaction focusing mainly on factors affecting leakage flow paths in water distribution systems. An experimental set up was designed and built to study the different factors in a controlled environment. A series of experiments were performed where water jets from manufactured circular leaks were released in different trench set ups. Three main variables were investigated namely flow rate, leak orientation and in-situ soil to start understanding the movement of the leak flow as a preliminary study. The volumetric moisture content were measured using EC-5 moisture sensors at different locations in the tank to analyse the movement of leakage water and iPERLS smart water meters were used to measure the flow of water through the walls of the trench. The results of the experiments showed how much leakage water is actually lost through the side and bottom walls. The volumetric moisture content readings indicated the movement of the leak in the tank. The results of the study indicated that leak orientation has the greatest influence on the paths of the leaks. Also, the flow rate had to be increased to a very high value so that the leak appears above the sand surface. The permeability of the in-situ soil was found to have the least effect on the leakage flow paths.
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Chulakadabba, Apisada. "Water and carbon flux responses to soil moisture pulses in the Western United States." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122233.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 37-38).
In this study, the relationships among plant water and carbon flux responses to soil moisture resource pulses in semi-arid lands of the Western United States were diagnosed. Measurements from twelve AmeriFlux tower (in situ) and SMAP (satellite) sites across the region were used to estimate relationships between carbon flux and resource availability. The differences between respiration and photosynthesis dominant regimes and the transition from water to energy limited regimes could be observed. Water use efficiency of plants in the regions was estimated to be around 5.0 grams of carbon dioxide per 1 kilograms of water when water was excess. Response patterns were shared among the similar ecosystems. The role of water and carbon flux response to intermittency resource availability could lead to improved estimation of land carbon budgets.
by Apisada Chulakadabba.
S.B.
S.B. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
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Malizia, John Paul. "Effect of Water Content and Density on the Strength and Deformation Behavior of Clay Soils." Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1460407680.
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Baigys, Giedrius. "Soil water regime and nitrate leaching dynamics applying no-tillage." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20090217_111111-32108.
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The impact of different agricultural systems used in agriculture on the leaching of nutrients and nitrates first of all depends on many factors that are not noticed and sometimes even underestimated by farmers trying to reach larger yields and better economic results. This article analysis the issue of changes in water regime and nitrate nitrogen leaching under the change of agricultural systems; such issue has not been investigated in Lithuania before. This research is especially relevant under the conditions of the Middle Lithuanian Lowland, where annual crops (cereals and sugar beet) area mainly cultivated, the ground is aerated in-tensely thus increasing the mineralization of organic substances and a lot of fertilizers are used. The change of conventional tillage for reduced tillage resulted in the decrease of the resources of surface soil water by 4,91-5,85 % and after changing it into no-tillage water resources decreased by 23,4 %. Reduced tillage and late ploughing are appropriate environmental means reducing nitrate nitrogen leaching from soil.Įvairių žemdirbystės sistemų naudojamų žemės ūkyje poveikis maisto medžiagų ir labiausiai nitratų išsiplovimui priklauso nuo daugelio veiksnių, kurių žemdirbiai siekdami didesnių derlių ir geresnių ekonominių rezultatų nepastebi, o kartais ir reikiamai neįvertina. Šiame darbe, nagrinėjamas šalyje netirtas vandens režimo ir nitratų azoto išplovimo pasikeitimų, keičiantis žemdirbystės sistemoms, klausimas. Šie tyrimai ypač aktualūs Lietuvos Vidurio lygumos sąlygomis, kur daugiausia auginama vienmečių augalų (javų ir cukrinių runkelių), kasmet žemė intensyviai aeruojama, taip didinant organinių medžiagų mineralizaciją, naudojama daug trąšų. Pakeitus tradicinį žemės dirbimą į sumažintą žemės dirbimą paviršinio dirvožemio sluoksnio vandens atsargos sumažėjo 4,91-5,85 %, o pakeitus į neariminį žemės dirbimą vandens atsargos sumažėjo 23,4 %. Sumažintas žemės dirbimas bei vėlyvas arimas yra tinkamos aplinkosauginės priemonės, mažinančios nitratų azoto išplovimą iš dirvožemio.
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Peng, Sheng. "Characterizing air-water interfacial area in variably saturated sandy porous media." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280732.
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Air-water interface plays an important role in the transport of many contaminants in the vadose zone. It is also a limiting factor for many processes involve mass or energy transfer between air and water phases in vadose zone. In this research, the gas-phase partitioning tracer method was used to measure air-water interfacial area for eight porous media. The experimental results were used to investigate the influencing factors of the magnitude of air-water interfacial area and the relationship between the air-water interfacial area and water saturation, and capillary pressure. The porous media comprised a series of sands with narrow particle-size ranges, a sand with a wider particle-size distribution, a sandy soil, and a loamy sandy soil. The measurement range was extended to very low water contents in an attempt to determine upper limits for air-water interfacial areas. The measured values were compared to the normalized surface areas of the porous media. The results of the experiments showed that the magnitude of the air-water interfacial areas increased with decreasing water saturation, and approached that of the normalized surface areas. Generally, air-water interfacial areas were larger for media with larger specific surface areas. The change in air-water interfacial area with changing water saturation was less near saturated water contents and greater at smaller values. In addition, the change was greater for the poorly-sorted media than the well-sorted media. An empirical model was developed to describe the observed relationship between air-water interfacial area and water saturation. The coefficients of the model were found to correlate to the porous-medium uniformity coefficient. With this model and associated correlations, only bulk density, specific surface area, and uniformity coefficient are needed to estimate air-water interfacial area for a given water saturation. The model was shown to provide a reasonable description of a literature data set. Potential relationships between air-water interfacial area and capillary pressure under higher water-content conditions are investigated for unsaturated sandy porous media. A conceptual relationship between air-water interfacial area and capillary pressure is hypothesized, and is tested using air-water interfacial area data obtained from gas-phase tracer tests and saturation-pressure data obtained from water-drainage experiments. The results show that the magnitude of the air-water interfacial area increases with increasing capillary pressure, which corresponds to decreasing water content. (Abstract shortened by UMI.)
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Griffin, Joshua E. "Wastewater Irrigation in Freezing Conditions and the Impacts to Runoff Water Quality and Soil Freezing." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420584627.
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Uribe-Chavez, Armando. "A numerical model and semi-analytic equations for determining water table elevations and discharges in non-homogeneous subsurface drainage systems." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289956.
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A free water surface finite element model was developed. The method was implemented with the Galerkin approach to solve the Laplace equation in the saturated region. It was developed in the object oriented Visual C ++ computer language to permit easy update and drawing of the adaptive mesh. For each time step, the new water table position was calculated based on flux across the water table, a Brooks-Corey equation mass balance for the unsaturated region, and an equation that calculates water table position for the saturated region. An equation was developed to calculate a drainage transfer coefficient, alpha, based on percentage of perforated area in the drain tube wall. The drainage transfer coefficient was incorporated into the finite element model as a Fourier boundary condition. To validate the finite element model, its results were compared with the Kirkham equation results for steady state recharge of three subsurface drainage systems. The finite element model was used to calibrate a semi-analytical frozen stream tube model for subsurface drainage of heterogeneous soils. The first step in the calibration procedure is to run the finite element model for steady state recharge and calculate the water table height divided by recharge rate (the stream tube resistance to flow) as a function of distance between drains. Least squares regression is used to fit a polynomial logarithmic equation, called the resistance function, to the stream tube resistance to flow vs. distance from the drain curve. A differential equation based on the principle of conservation of mass and application of Darcy's law to the frozen stream tube was solved to obtain an equation that calculates stream tube flow rate and final water table elevation as a function of the resistance function and initial water table elevation. An example was developed for a non-homogeneous subsurface drainage system to illustrate the use of the semi-analytical model to predict water table fall and discharge.
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Dlamini, Musa V. "Short-Term Water Use Dynamics in Drainage Lysimeters." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/5877.
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Turfgrass water use (seasonal turfET) and crop coefficients were determined and a mathematical soil-water balance model for non-weighing drainage lysimeters, which simulates the occurrence (timing and amount) of drainage, was developed. Pairs of non-weighing drainage lysimeters were used to determine crop coefficients for turfgrass in four locations in the state of Utah: Logan Golf and Country Club, Murray Golf Course, Brigham Young University (Spanish Fork) Experiment Farm, and Sunbrook Golf Course (St. George).
Daily weather data including air temperature, relative humidity, average wind travel, total solar radiation, precipitation, and average soil temperature were collected with an electronic weather station at each site. Daily precipitation was measured in three sites throughout the season: Murray, Spanish Fork, and Sunbrook. At Logan Golf and Country Club, precipitation was measured to November 10,2002.
Water use (averages of two lysimeters) during the growing season varied from 684 to 732 mm for three years (2000- 2002) for the mid-April through late-October observation period at Logan Golf Course; 699 mm for May through October at Murray; 469 mm at Spanish Fork; and 896 mm for late-February through early November at Sunbrook, for 2002 growing season. Calculated seasonal Etr using the 82 Kimberly Penman equation with a 1 00-miles-per-day wind travel limit varied from 1166 to 1229 mm at Logan Golf and Country Club, 1067 mm at Murray, 839 mm at Spanish Fork, and 1574 mm at Sunbrook. Seasonal Etr calculated using the PM ASCE std Etr equation was greater than the 82 Kimberly Peru11an . Seasonal Eto calculated using the FAO#56 Eto equation was less than both the 82 Kimberly Penman and the PM ASCE std Etr equations.
Calculated crop coefficients (as a ratio of measured crop water use and calculated potential evapotranspiration) based on alfalfa reference evapotranspiration with the 1982 Kimberly-Penman equation averaged 0.58 for the three years at Logan. Seasonal averages varied from 0.57 to 0.60. Seasonal crop coefficients (2002) were 0.57 for Logan, Spanish Fork, and Sunbrook, and 0.65 for Murray. Short-period crop coefficients also varied within a given season. Short-term crop coefficients derived from a time of wetting and drainage experiment averaged 0.55 at Logan, 0.56 at Murray, 0.60 at Spanish Fork, and 0.56 at Sunbrook.
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Zwierschke, Kerry Hughes. "IMPACT OF TURFGRASS SYSTEMS ON THE NUTRIENT STATUS OF SURFACE WATER, AND GROUND WATER." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1235150457.
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Gustafsson, David. "Boreal land surface water and heat balance : Modelling soil-snow-vegetation-atmosphere behaviour." Doctoral thesis, KTH, Mark- och vattenteknik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3406.
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The water and heat exchange in thesoil-snow-vegetation-atmosphere system was studied in order toimprove the quantitative knowledge of land surface processes.In this study, numerical simulation models and availabledatasets representing arable land, sub-alpine snowpack, andboreal forest were evaluated at both diurnal and seasonaltimescales. Surface heat fluxes, snow depth, soil temperatures andmeteorological conditions were measured at an agriculturalfield in central Sweden during three winters and two summersfrom 1997 to 2000 within the WINTEX project. A one-dimensionalsimulation model (COUP) was used to simulate the water and heatbalance of the field. Comparison of simulated and measured heatfluxes in winter showed that parameter values governing theupper boundary condition were more important for explainingmeasured fluxes than the formulation of the internal mass andheat balance of the snow cover. The assumption of steady stateheat exchange between the surface and the reference height wasinadequate during stable atmospheric conditions. Independentestimates of the soil heat and water balance together with thecomparison of simulated and measured surface heat fluxes showedthat the eddy-correlation estimates of latent heat fluxes fromthe arable field were on average 40 % too low. The ability of a multi-layered snowpack model (SNTHERM) tosimulate the layered nature of a sub-alpine snowpack wasevaluated based on a dataset from Switzerland. The modelsimulated the seasonal development of snow depth and densitywith high accuracy. However, the models ability to reproducethe strong observed snowpack layering was limited by theneglection of the effect of snow microstructure on snowsettling, and a poor representation of water redistributionwithin the snowpack. The representation of boreal forest in the land surfacescheme used within a weather forecast (ECMWF) model was testedwith a three-year dataset from the NOPEX forest site in centralSweden. The new formulation with separate energy balances forvegetation and the soil/snow beneath the tree cover improvedthe simulation of seasonal and diurnal variations in latent andsensible heat flux. Further improvements of simulated latentheat fluxes were obtained when seasonal variation in vegetationproperties was introduced. Application of the COUP model withthe same dataset showed that simulation of evaporation fromintercepted snow contributed to a better agreement with themeasured sensible heat flux above forests, but also indicatedthat the measurements might have underestimated latent heatflux. The winter sensible heat flux above the forest wasfurther improved if an upper limit of the aerodynamicresistance of 500 s m-1 was applied for stable conditions. A comparison of the water and heat balance of arable landand forest confirmed the general knowledge of the differencesbetween these two surface types. The forest contributed withconsiderably more sensible heat flux to the atmosphere than thearable land in spring and summer due to the lower albedo andrelatively less latent heat flux. Latent heat flux from theforest was higher in winter due to the evaporation ofintercepted snow and rain. The net radiation absorbed by theforest was 60 % higher than that absorbed by the arable land,due to the lower surface albedo in winter. Key words:soil; snow; land surface heat exchange;forest; arable land; eddy-correlation.QC 20100614
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Qiao, Shuang Ye. "Modeling water flow and phosphorus fate and transport in a tile-drained clay loam soil using HYDRUS (2D/3D)." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123033.
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Phosphorus (P) is an important agricultural non-point source pollutant that could contribute to eutrophication of surface waters. In this study, the HYDRUS (2D/3D) model was evaluated for simulation of water flow and P transport in a clay loam soil in southern Ontario. The model was calibrated and validated using field data from two 0.1 ha test plots between 2008-2011. These plots have controlled tile drainage and a corn-soybean crop rotation. The surface and sub-surface water flows in test plots were monitored and samples collected continuously year round using an auto-sampling system. The model simulated water flow and P relatively well, with weekly modeling efficiency of 0.513 to 0.738 for validation of water flow, and weekly modeling efficiency of 0.587 to 0.768 for validation of dissolved P loss in tile drainage. Most of the deviation of simulated water flow occurred between November to February, which suggests the model would greatly benefit from optimization of snow dynamics and frozen soil conditions. Some of the simulation errors may also be attributed to soil cracking in the summer which consequently enhanced macropore flow. The model predicted daily water flow poorly, suggesting presence of time lag between simulation and measurements. Limitations of the model include lack of simulation of particulate P loss and surface runoff P loss. This model should be tested further for other soils in southern Ontario as well as other parts of Canada before its validity can be established.Le phosphore (P) est un important polluant de sources diffuses qui pourrait contribuer à l'eutrophication des eaux de surface. Dans cette étude, la capacité à simuler le débit de l'eau et le transport de P dans les sols argileux ou limon argileux du Sud de l'Ontario du modèle HYDRUS (2D/3D) a été évalué. Le modèle a été calibré et validé utilisant des données de terrain de deux parcelles d'essai de 0.1 ha entre 2008 et 2011. Ces parcelles ont contrôlées le drainage et la rotation des cultures de maïs et de soya. Les écoulements des eaux de surface et dans le sol inclus dans les parcelles d'essai ont été contrôlés et les échantillons collectés continuellement toute l'année à l'aide d'un système d'échantillonnage automatisé. Le modèle a relativement bien simulé le débit de l'eau et le P, avec des efficacités de modélisation sur une base hebdomadaire de 0.513 à 0.738 pour la validation du débit de l'eau, et une efficacité de modélisation sur une base hebdomadaire de 0.587 à 0.768 pour la validation de la perte du P dissous dans le réseau de drainage. Une déviation du débit de l'eau simulé est survenue davantage entre les mois de novembre et février, ce qui suggère que le modèle aurait avantage à s'attarder à l'optimisation de la dynamique de la glace et de la neige sur les conditions du sol. Certaines des erreurs de simulation peuvent être attribuées aux fissures dans le sol qui surviennent en été, qui conséquemment, favorisent la circulation des micropores. Le modèle prédit mal le débit de l'eau journalier, démontré par la présence de décalage temporel entre la simulation et les prises de mesure. Les limites du modèle incluent un manque de simulation de la perte de la matière particulaire P et de la perte P en écoulement de surface. Ce modèle devra être testé davantage sur d'autres sols dans le Sud de l'Ontario ainsi que sur d'autres régions du Canada avant sa validité puisse être reconnue.
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Lundmark, Annika. "Modelling the impacts of deicing salt on soil water in a roadside environment." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280.
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Pandey, Ganesh. "Feasibility Study of Water Based / Polymer Modified EICP for Soil Improvement Involving Recycled Glass Aggregate." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron153115070027817.
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Leiker, Curtis Joseph. "Determining pen surface water in a cattle feedlot with thermal infrared remote sensing." Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/6684.
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Master of ScienceDepartment of Biological & Agricultural Engineering
Ronaldo G. Maghirang
Particulate matter (PM) emissions from open beef cattle feedlots depend heavily on the level of water on the pen surface. Wet pen surfaces are able to keep PM emissions low, while dry surfaces have much higher rates of emission. Current research shows that 20-25% surface water content is a critical threshold for minimizing PM emissions from open cattle feedlots. The amount of water on the pen surface will also dictate the level of gaseous emissions, such as ammonia, nitrous oxide, and hydrogen sulfide. Traditional methods of measuring pen surface water are not sufficient within a dense cattle feedlot and cannot provide a continuous method of measurement unattended. The process of using infrared thermometry and meteorological variables to remotely sense surface water provides an inexpensive, ground level approach. Testing in laboratory, outdoor, and feedlot conditions was conducted to analyze the potential of using the thermal inertia remote sensing approach. This approach involved continuous measurement of weighted soil water content, surface temperature of the soil, air temperature, solar radiation, wind speed, and relative humidity. Controlled laboratory testing performed the best at predicting soil water content from the difference in soil surface and air temperature, with the coefficient of determination (R2) at 0.91 for a Smolan silt loam and 0.83 for dry feedlot soil. Outdoor testing achieved mixed results with R2 values only as high as 0.38 for 10-cm soil layer and 0.67 for 5-cm soil layer. Testing in a cattle feedlot with dry, loose manure layer proved to be imprecise, but was able to differentiate surface water levels varying from 4.1% to 9.1% wet basis.
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Maurer, Kyle D. "Effects of Climate, Forest Structure, Soil Water, & Scale on Biosphere-Atmosphere Gas Exchange in a Great Lakes Mixed-Deciduous Forest." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366036482.
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Montesino, Malmberg Martina, and Rebecka Olofsson. "An Inventory of the Waste Disposal Site Jhumjhumpur in Jessore, Bangladesh, via Soil and Water Sampling." Thesis, KTH, Skolan för kemivetenskap (CHE), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207104.
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The aim of this study was to make an inventory of the open dumping site Jhumjhumpur in Jessore, Bangladesh, in order to investigate whether spreading of heavy metals had occurred to surrounding soil and groundwater. The study is based on a thorough literature study as well as a field study, including soil and groundwater sampling, at the dumping site Jhumjhumpur. The literature study covers the current waste management system in three cities of Bangladesh: Dhaka, Jessore and Khulna. The results from the field study indicate that metals from the dumping site have been transported and spread to the groundwater in connection to the site and the agricultural land south of the site. A more complete investigation is needed to be able to determine how big a risk the open dumping site is for the surrounding environment. Measurements for avoiding further contamination of the groundwater and the agricultural land should be implemented.
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Rogers, Maile Anne. "Water Vapor Movement in Freezing Aggregate Base Materials." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4013.
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The objectives of this research were to 1) measure the extent to which water vapor movement results in water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement in freezing base materials; 3) determine if the corresponding changes in water content are sufficient to cause frost heave during winter; 4) determine if the corresponding changes in water content are sufficient to cause reductions in stiffness during spring; 5) evaluate relationships between selected material properties, freezing conditions, and the occurrence and impact of water vapor movement; and 6) numerically simulate heat and water movement in selected pavement design scenarios. The research involved extensive laboratory and field testing, statistical analyses, and numerical modeling. The results of the laboratory testing, which included gradations, Atterberg limits, soil classifications, specific gravity and absorption values, electrical conductivity values, moisture-density relationships, soil-water characteristic curves, moisture-stiffness curves, hydraulic conductivity values, and frost susceptibility assessments, were used to characterize each material and enable subsequent statistical analyses. Testing of both treated and untreated materials enabled investigation of a wide variety of material properties. The results of the field testing, which included temperature, moisture content, water potential, elevation, and stiffness data over time, provided the basis for comparing pavement sections with and without capillary barriers and established the framework for numerical modeling. In a pavement section with a capillary barrier underlying the base layer, water vapor movement from the subgrade through the capillary barrier may be expected to increase the water content of the base layer by 1 to 3 percent during a typical winter season in northern Utah for base materials similar to those studied in this research. During winter, cold temperatures create an ideal environment for water vapor to travel upward from the warm subgrade soil below the frost line, through the capillary barrier, and into the base material. Soil stabilization can lead to increased or decreased amounts of water vapor movement in freezing base materials depending on the properties of the stabilized soil, which may be affected by gradation, mineralogy, and stabilizer type and concentration. Accumulation of water from long-term water vapor movement into frost-susceptible base materials underlain by a capillary barrier can lead to frost heave of the base layer as it approaches saturation, as water available in the layer can be redistributed upwards to create ice lenses upon freezing. However, the incremental increase in total water content that may occur exclusively from water vapor movement during a single winter season in northern Utah would not be expected to cause measurable increases in thaw weakening of the base layer during spring. Because water in a base layer overlying a capillary barrier cannot drain until nearly reaching positive pore pressures, the base layer will remain indefinitely saturated or nearly saturated as demonstrated in this research. For materials similar to those studied in this research, potentially important material properties related to the occurrence of water vapor movement during freezing include dry density, percent of material finer than the No. 200 sieve, percent of material finer than 0.02 mm, apparent specific gravity, absorption, initial water content, porosity, degree of saturation, hydraulic conductivity, and electrical conductivity. The rate at which water vapor movement occurs is also dependent on the thermal gradient within the given material, where higher thermal gradients are associated with higher amounts of water vapor movement. The numerical modeling supported the field observations that the capillary barrier effectively trapped moisture in the overlying base material, causing it to remain saturated or nearly saturated throughout the monitoring period. Only non-frost-susceptible aggregate base materials should be specified for use in cold climates in conjunction with capillary barriers, and the base material in this case should be assumed to remain in a saturated or nearly saturated condition during the entire service life of the pavement. Further study is recommended on water vapor movement in freezing aggregate base materials.
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Blomgren, Axel. "Influence of logging residues on MeHg accumulation in soil." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-234263.
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Forestry has been found to increase the accumulation of methyl mercury (MeHg), a highly neurotoxic compound, in forest soils. However, little is known about how forestry influences catchment processes that governs the mercury (Hg) methylation process. Logging residues are used in harvested catchments in stick roads to reduce soil disturbances caused by forestry machinery. Logging residues left on site after harvest have been suggested to act as a source of high-quality organic matter that stimulates the activity of the microorganisms that carry out the methylation of Hg. In addition, logging residues might influence the activity and abundance of methylating bacteria by reducing the temperature fluctuations in soils below residues and by increasing the soil moisture content. To evaluate the impact of logging residues on the accumulation of MeHg, an experimental field study was carried out in three sites, one in Uppland and two in Västerbotten. The concentration of MeHg was compared between soils covered with residues and soils without residues, and between the lower and upper parts residue piles. Logging residues were not found to influence the levels of MeHg in soils. However, an increased accumulation of MeHg was found in the lower part of residue piles. The accumulation of MeHg in the lower parts was accompanied by a reduced temperature amplitude and an increased water content compared to the upper part of the piles. The increased formation of MeHg might have been mediated by an increased water content in the lower part of the residue piles, possibly by increasing the abundance and activity of Hgmethylating microorganisms due to suboxic/anoxic conditions within biofilms around decomposing needles. The dissolved organic matter composition in soil water differed in soils below residues compared to without residues, but the organic matter signature in soil water under residues was not found to be compliant with an elevated mercury methylation rate. As MeHg accumulated in the lower part of residue piles could become mobilized and transferred to surface water, the suitability of using logging residues in stick roads depends on the location within the catchment. The removal of logging residues could prevent the potential mobilization of MeHg from residue piles. Though, as soil disturbances may cause an increased Hg methylation rate and mediate MeHg export to surface waters, other form of protection, e.g. logging mats, should be used if logging residues are not used to protect soils.Mänsklig aktivitet har lett till förhöjda halter av kvicksilver (Hg) i atmosfären. Genom långväga transport och deposition har detta orsakat förhöjda halter i svensk natur. Den huvudsakliga exponeringsvägen av Hg för människan sker genom konsumtion av fisk. Halterna av Hg i svensk insjöfisk överstiger EU:s gränsvärden för god kemisk status samt Världshälsoorganisationens riktlinjer för konsumtion i majoriteten av svenska vatten. Ackumuleringen av Hg i biota sker främst i form av metylkvicksilver (MeHg) som är starkt neurotoxiskt. Avverkning av skog tros bidra till en ökad bildning av MeHg i skogsmark genom att skapa miljöer som gynnar etableringen och aktiviteten av de mikroorganismer som omvandlar icke-organiskt kvicksilver (Hg(II)) till organiskt kvicksilver (MeHg). Dessutom kan skogsbruk bidra till en ökad export av MeHg till följd av ändrade hydrologiska förhållanden samt markskador. En ökad bildning av MeHg är oönskad då mobilisering sedermera kan ske till vattendrag där MeHg kan ackumuleras i akvatisk biota. Dock är kunskapen om hur skogsbruk påverkar specifika processer som är av betydelse för metyleringen av Hg begränsad. Inom skogsbruk används avverkningsrester, bestående av till exempel grenar och toppar, i rishögar för att skydda marken mot körskador. Avverkningsrester som lämnas kvar på området efter avverkning tros bidra till en ökad metylering genom att utgöra en källa av högkvalitativt organiskt material vilket kan stimulera bakteriell aktivitet. Dessutom kan avverkningsrester bidra till en ökad metylering av Hg genom att minska temperaturfluktuationerna i mark täckt med ris samt öka markens vattenhalt, vilket kan bidra till en ökad etablering samt att stimulera aktiviteten av Hg-metylerande mikroorganismer. För att utvärdera effekten av avverkningsrester på ackumuleringen av MeHg genomfördes en experimentell fältstudie där koncentrationen av MeHg jämfördes i mark täckt med ris och mark utan ris. Dessutom undersöktes huruvida en ökad metylering kan ske i den nedre delen av riset, vilket skulle kunna möjliggöras av bakterier i biofilmer kring ris under nedbrytning. Koncentrationen MeHg var högre i den nedre delen av rishögarna jämfört med den övre delen. I den nedre delen av riset var temperaturfluktuationerna lägre och vattenhalten högre än i den övre delen av riset. Ackumuleringen av MeHg kan ha skett via biofilmer i de nedre delarna av riset, där tillgången till hög kvalitativt organiskt material samt mer syrefria förhållanden kan ha gynnat etableringen och aktiviteten av de bakterier som utför metyleringen av Hg. Däremot hade typen av marktäcke, dvs mark täckt med ris och mark utan ris, inte någon påverkan på metyleringen av Hg. Karaktären av organiskt material i markvatten skiljde sig mellan typ av marktäcke, men visar inte på att avverkningsrester utgör en källa av högkvalitativt organiskt material. Vattenhalten i mark under rishögar skiljde sig inte jämfört med mark utan ris, men temperaturen var lägre med mindre variation i mark under rishögar. Därmed visar resultatet på att avverkningsrester kan bidra till en ökad bildning av MeHg. En potentiell mobilisering av MeHg som bildats i rishögarna skulle därför kunna bidra till en ökad export av MeHg från avverkade områden. Användningen av avverkningsrester, för att skydda marken vid körning med skogsmaskiner, anses ändå vara fördelaktig för att minimera utläckage av MeHg. Körskador kan skapa stående vattensamlingar där MeHg kan bildas samt kompaktera mark och skapa snabba ytliga flödesvägar i området. Däremot tyder resultatet på att användningen bör ske med hänsyn till att förhindra eventuell transport av MeHg till vattendrag. Ifall avverkningsrester inte används för att motverka markskador bör ett substitut användas, exempelvis stock-mattor, då körskador kan bidra till en ökad metylering och mobilisering av MeHg. Dock saknas kunskap om eventuell mobilisering av MeHg från rishögar till vattendrag och detta bör utvärderas i framtida studier.
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Vins, Wesley J. "Residential Septic Tank Effluent Treatment by Disturbed Darien Soil." Connect to resource online, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1266610669.
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McDonald, Spencer Dean. "SWAT Online: Development of a Web-Based Decision Support System for the Soil and Water Assessment Tool." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/8810.
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As satellite and climate modelling technology continues to improve and as climatological disasters and issues continue to impact the global community, climate data will increase in size and relevance. With this new influx of information, it is becoming more and more important for scientists to simply and concisely communicate their findings to both decision makers in governments and disaster preparedness organizations and also to the general public. The Soil and Water Assessment Tool (SWAT) is a powerful modelling tool that allows scientists to simulate essentially all of the physical processes involved in the water cycle. The data that SWAT produces can be valuable information as people strive to better plan for and understand various hydrologic events. The work presented in this thesis represents an effort to overcome some of the limitations of the previously developed SWAT visualization software by creating a set of modular web applications that can be duplicated, customized, and run by any organization or individual interested in visualizing and sharing data from SWAT. By eliminating the technical knowledge barriers that are inherent in running and using SWAT models, this work has the potential to increase SWAT’s impact on non-technically trained stakeholders and decision makers in areas where water and climate management is important.
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Hortin, Joshua. "Behavior of Copper Oxide Nanoparticles in Soil Pore Waters as Influenced by Soil Characteristics, Bacteria, and Wheat Roots." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6895.
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The goal of this project was to study the behavior of copper oxide nanoparticles in soil environments. Copper oxide nanoparticles have antimicrobial properties and may also be used in agricultural settings to provide a source of copper for plant health, but accidental or misapplication of these nanoparticles to soil may be damaging to the plant and its associated bacteria.
Dissolved soil organic matter that is present in soil pore waters dissolved nanoparticles, but did not dissolve the expected amounts from a geochemical model because the geochemical model did not take into account surface chemistry or coating of the nanoparticles by dissolved organic matter. Wheat grown in soil pore water increased the solubility of the nanoparticles. The nanoparticles and dissolved copper were harmful to wheat, but dissolved soil organic matter remediated a portion of the damage. These studies were conducted with Utah soils and wheat, a highly valuable Utah crop.
These results suggest that contamination of soils by copper oxide nanoparticles will be partially mitigated by the organic matter content of the soil. Producers of fertilizers and fungicides may use various forms of organic matter to deliver products that are targeted to specific plants or pathogens and avoid damage to non-target organisms.
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Kim, Won-Seok. "Biodegradation of Bisphenol-A and 17B-Estradiol in Soil Mesocosms Under Alternating Aerobic/Anoxic/Anaerobic Conditions." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3183.
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Soil-aquifer treatment (SAT) has been proposed as a method for reusing treated municipal wastewater. SAT is characterized by alternating cycles of aerobic and anaerobic conditions in the subsurface, in response to alternating cycles of flooding and drainage of a surface impoundment. It is not yet known how these alternating redox conditions affect the removal of potentially harmful endocrine-disrupting compounds (EDCs) from treated effluent.
The overall objective of my doctoral research is to determine the fate of EDCs in alternating aerobic/anoxic/anaerobic conditions under simulated SAT conditions. To assess the fate of EDCs in simulated SAT conditions, I first had to develop appropriate analytical methods. Prior researchers have developed sophisticated analytical methods for measuring low concentrations of EDCs in water. However, it is not inherently clear which of these methods is preferable for analysis of any particular set of environmental samples. Therefore, in order to compare the analytical methods, solid-phase extraction (SPE) and solid-phase micro-extraction (SPME) were compared for the analysis of two EDCs, bisphenol-A (BPA) and 17B-estradiol (E2), in water samples of water. Following extraction by SPE or SPME, the target EDCs were derivatized (silylated) and then analyzed by gas chromatography (GC) with mass spectrometry (MS). Also, the performance of two candidate derivatization agents, N,O-bis-(trimethylsiyl) trifluoroacetamide (BSTFA), N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), was compared. SPME is more convenient, is less labor-intensive, and allows for analysis of smaller sample volumes, but it is expensive because fibers need frequent replacement, and the range of linearity was limited. SPE has a lower material cost and allows for the analysis of a broader range of concentrations, but it is more labor-intensive and large sample volumes may be required. Therefore, the selection of which method is "best" depends upon the constraints (time, money, sample volume, acceptable detection limit) associated with any particular set of samples. The two derivatization agents performed equally when used in conjunction with SPE, but MSFTA yielded higher peak areas for headspace (on-fiber) derivatization during SPME.
To investigate how alternating redox conditions of SAT may affect the removal of harmful EDCs, a simulated SAT systems were constructed in 4-L reactors with 500 g of sediment (collected from a wetland) and 3 L of treated effluent from a municipal wastewater treatment plant; then BPA and E2 were spiked into reactors, two common EDCs often found in treated wastewater. Redox conditions in the mesocosms were controlled by switching the air between air (to induce aerobic conditions) and nitrogen (to induce anaerobic conditions); the length of the anoxic/anaerobic cycles was varied to determine how this affects biodegradation of the target EDCs. The mesocosm environment was supplemented with either nitrate or sulfate to serve as potential electron acceptors during the anoxic/anaerobic cycles. In addition to monitoring the concentrations of the target EDCs in the mesocosms over time, I also monitored the concentration of dissolved oxygen in the water; the redox potential; the concentrations of nitrate, nitrite, and sulfate; and the concentration of bacteria in the water (estimated via flow cytometry).
BPA was biodegraded only during aerobic cycles, but E2 was biodegraded during both aerobic and anoxic/anaerobic cycles. Whenever the redox conditions in the system were switched, there was a temporary drop in the bacterial population, followed by a recovery of the population. When redox conditions were switched from anoxic/anaerobic to aerobic, biodegradation of the target EDCs commenced after a lag period during which no biodegradation was observed. The lag time for biodegradation in the aerobic cycle was longer when the anaerobic cycles were longer in duration. More biodegradation of E2 was observed under anoxic conditions than under anaerobic conditions.
SPE and SPME methods that included derivatization agent are useful method for detection and quantification of EDCs in water. I concluded that SAT is a viable technology to produce potable water from treated WWTP effluent, but the optimal length of flooding and drying cycles of SAT required removing the targeted contaminants during infiltration through the vadose zone.
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Yassin, Adel Taha. "The Vertical Distribution of Salts in a Soil Profile During the Drainage Process." DigitalCommons@USU, 1986. https://digitalcommons.usu.edu/etd/4642.
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The purpose of this study was to develop a model to predict water extraction patterns and therefore salt distribution patterns in a one dimensional homogeneous soil profile for a specified root distribution .
Water extraction was simulated as a function of the total potential and the root density at any level of the profile.
Salt redistribution caused by irrigation was simulated by assuming a partial and proportional displacement of the water in each soil layer.
A computer program was written for the model in Fortran language and implemented on the Vax. To evaluate the performance of the model, test studies were carried out in the laboratory using two lysimeters and wheat as a crop.
A neutron probe and the four-probe electrode method were used to follow the change in the soil moisture and the salinity in the profile during the growing season. Comparisons were made between the measured and simulated values of water content and salinity. Application of the model results and recommendations for further research were suggested to improve the performance of the model.
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Lee, Jangguen. "The Behavior of Pore Water Pressure in Cohesive Subgrade Soils." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1364216774.
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Govender, Kuveshan. "A laboratory investigation of the effect of flow rate and bedding characteristics on the interaction of a vertical water jet with an idealised soil medium." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/24884.
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Water conveyed through pipes systems installed beneath the ground surface has become standard practice in which treated fresh water is transported to communities. This kind of water delivery is successful in many regards but also results in considerable amounts of water wastage in the form of undetectable leakage. This is a serious concern since fresh water reserves throughout the world are being depleted faster than it is replenished; yet, there exists a large gap in understanding how leaks outside water distribution pipes behave. Recent studies that have investigated external leakage behaviour have discovered that when water under pressure passes through a leak opening (orifice); a water jet is formed, which interacts with the surrounding soil (bedding material) in a manner that causes the granular medium to fluidise. This fluidisation process was seen to exhibit complex behaviour, which restricted shallow leaks under relatively high pipe pressures from growing and reaching the bed surface. As a result, leaks are able to remain bound beneath the ground surface with reduced chances of being detected and repaired. The goal of this study was to conduct experiments aimed of performing a sensitivity analysis on how leakage conditions in the bed are affected when soil-leak characteristics including jet flow rate, bed height and the size of the granular particles in the bed are varied. In this study a vertical water jet in an idealised granular bed (glass beads) was used. The leakage conditions that were examined for each soil-leak factor comprised of measuring the height of the fluidised region and distributions of pore pressure, fluid velocity and energy within the bed. The sensitivity analysis was based on data collected from experiments, which were conducted using an apparatus that was able to simulate an unbound pipe leak. The apparatus comprised of a glass tank, which housed the bedding material. An orifice installed at the bottom of the tank assisted in creating the water jet required for the pipe leak and, a Pitot tube positioning system above the tank allowed for positioning of straight and L-type Pitot tubes in the granular bed, which were used to measure the leakage conditions within the bed. Results from the experiments revealed that the soil-leak factors, which were investigated had significantly affected leakage conditions, each to varying degrees. Larger jet flow rates led to an exponential increase in fluidisation height and higher maximum pore pressures, velocities and energies were measured in the bed. It was found that by varying the bed height, fluidisation height increased linearly with decreasing bed height and only the pore pressure distribution was considerably affected, where larger maximum pore pressures were measured in beds that were shallower. The effects of varying particle size included lower fluidisation heights and maximum pore pressures in beds that contained larger particles. Interestingly, the velocity and energy distribution remained substantially unaffected.
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Zaman, Bushra. "Remotely Sensed Data Assimilation Technique to Develop Machine Learning Models for Use in Water Management." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/584.
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Increasing population and water conflicts are making water management one of the most important issues of the present world. It has become absolutely necessary to find ways to manage water more efficiently. Technological advancement has introduced various techniques for data acquisition and analysis, and these tools can be used to address some of the critical issues that challenge water resource management. This research used learning machine techniques and information acquired through remote sensing, to solve problems related to soil moisture estimation and crop identification on large spatial scales. In this dissertation, solutions were proposed in three problem areas that can be important in the decision making process related to water management in irrigated systems. A data assimilation technique was used to build a learning machine model that generated soil moisture estimates commensurate with the scale of the data. The research was taken further by developing a multivariate machine learning algorithm to predict root zone soil moisture both in space and time. Further, a model was developed for supervised classification of multi-spectral reflectance data using a multi-class machine learning algorithm. The procedure was designed for classifying crops but the model is data dependent and can be used with other datasets and hence can be applied to other landcover classification problems. The dissertation compared the performance of relevance vector and the support vector machines in estimating soil moisture. A multivariate relevance vector machine algorithm was tested in the spatio-temporal prediction of soil moisture, and the multi-class relevance vector machine model was used for classifying different crop types. It was concluded that the classification scheme may uncover important data patterns contributing greatly to knowledge bases, and to scientific and medical research. The results for the soil moisture models would give a rough idea to farmers/irrigators about the moisture status of their fields and also about the productivity. The models are part of the framework which is devised in an attempt to provide tools to support irrigation system operational decisions. This information could help in the overall improvement of agricultural water management practices for large irrigation systems. Conclusions were reached based on the performance of these machines in estimating soil moisture using remotely sensed data, forecasting spatial and temporal variation of soil moisture and data classification. These solutions provide a new perspective to problem–solving techniques by introducing new methods that have never been previously attempted.
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Bhatt, Rajesh. "Investigating the Variability of Water and Soil Salinity using Watershed Model and Remote Sensing Techniques: A Case Study of Mentor Marsh, Ohio." Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1596549383903397.
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Raveendiraraj, Arunasalam. "Coupling of mechanical behaviour and water retention behaviour in unsaturated soils." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/717/.
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Previous research has shown coupling of mechanical behaviour and water retention behaviour in unsaturated soils at a constitutive level, with degree of saturation (in addition to suction) influencing mechanical behaviour and volumetric strains influencing water retention behaviour. An innovative elasto-plastic modelling framework incorporating coupling of mechanical behaviour and water retention behaviour has been proposed by Wheeler, Sharma and Buisson (2003) for isotropic stress states. These authors presented a single constitutive model for both mechanical behaviour and water retention behaviour. They did not, however, fully validate the model against experimental results. The objectives of the current research included undertaking an experimental programme specifically designed to investigate the coupling between mechanical behaviour and water retention behaviour, and using experimental results to investigate the validity of the Wheeler et al. (2003) model. Developments and refinement of the model were also to be explored An experimental programme of suction-controlled testing was carried out on one-dimensionally compacted samples of speswhite kaolin in a single steel-walled triaxial cell and an isotropic cell. In addition to standard stress paths, such as isotropic loading, unloading, wetting, drying and shearing, many non-standard stress path tests were also performed. These produced a unique data set, providing evidence of aspects of behaviour never previously studied. In terms of constitutive model development, the Wheeler et al. (2003) model was extended to triaxial stress states, to include the role of deviator stress. In addition, bounding surface plasticity concepts were used to develop simple realistic water retention models for rigid or deformable unsaturated soils, and a new bounding surface plasticity version of the Wheeler et al. (2003) model was developed. However, a problem of theoretical inconsistency in the Wheeler et al. (2003) model was identified, which occurs if plastic volumetric strains are predicted while the soil is fully saturated. A simple, but rather unsatisfactory, solution to this inconsistency was identified, and further research is required to identify a more satisfactory solution. Codes were developed for stress point simulations with the original version of the Wheeler et al. (2003) model, the new bounding surface plasticity version of the model and the conventional Barcelona Basic Model. Simulations were performed of all the experimental tests performed in the current research, to explore the performance of the different models. Comparison of model simulations with experimental results showed that the Wheeler et al. (2003) model was able to represent basic concepts of the mechanical behaviour of unsaturated soils, but sometimes not with the same level of accuracy or flexibility as the Barcelona Basic Model. The Wheeler et al. (2003) model was however able to capture features of mechanical and water retention behaviour that could not be represented by the Barcelona Basic Model or by other conventional models for mechanical or water retention behaviour. The bounding surface plasticity version of the Wheeler et al. (2003) model sometimes produced improved predictions. There remained, however, specific aspects of behaviour that were not well matched by either versions of the Wheeler et al. (2003) model. Some of these may be solved in the future by refinement of specific constitutive equations within the Wheeler et al. (2003) model, but others appear more likely to be insoluble without a major change to the proposed modelling framework.
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Hassan-Esfahani, Leila. "High Resolution Multi-Spectral Imagery and Learning Machines in Precision Irrigation Water Management." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4480.
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The current study has been conducted in response to the growing problem of water scarcity and the need for more effective methods of irrigation water management. Remote sensing techniques have been used to match spatially and temporally distributed crop water demand to water application rates. Remote sensing approaches using Landsat imagery have been applied to estimate the components of a soil water balance model for an agricultural field by determining daily values of surface/root-zone soil moisture, evapotranspiration rates, and losses and by developing a forecasting model to generate optimal irrigation application information on a daily basis. Incompatibility of coarse resolution Landsat imagery (30m by 30m) with heterogeneities within the agricultural field and potential underestimation of field variations led the study to its main objective, which was to develop models capable of representing spatial and temporal variations within the agricultural field at a compatible resolution with farming management activities. These models support establishing real-time management of irrigation water scheduling and application. The
AggieAirTM Minion autonomous aircraft is a remote sensing platform developed by the Utah Water Research Laboratory at Utah State University. It is a completely autonomous airborne platform that captures high-resolution multi-spectral images in the visual, near infrared, and thermal infrared bands at 15cm resolution. AggieAir flew over the study area on four dates in 2013 that were coincident with Landsat overflights and provided similar remotely sensed data at much finer resolution. These data, in concert with state-of-the-art supervised learning machine techniques and field measurements, have been used to model surface and root zone soil volumetric water content at 15cm resolution. The information provided by this study has the potential to give farmers greater precision in irrigation water allocation and scheduling.
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Cucarella, Cabañas Victor. "Recycling Filter Substrates used for Phosphorus Removal from Wastewater as Soil Amendments." Doctoral thesis, KTH, Mark- och vattenteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10204.
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This thesis studied the viability of recycling filter substrates as soil amendments after being used in on-site systems for phosphorus (P) removal from wastewater. Focus was put on the materials Filtra P and Polonite, which are commercial products used in compact filters in Sweden. A prerequisite for this choice was to review filter materials and P sorption capacity. The filter substrates (Filtra P, Polonite and wollastonite tailings) were recycled from laboratory infiltration columns as soil amendments to a neutral agricultural soil and to an acid meadow soil to study their impacts on soil properties and yield of barley and ryegrass. The amendments tended to improve the yield and showed a liming effect, significantly increasing soil pH and the availability of P. In another experiment, samples of Filtra P and Polonite were equilibrated in batch experiments with the two soils in order to study the P dynamics in the soil-substrate system. Batch equilibrations confirmed the liming potential of Filtra P and Polonite and showed that improved P availability in soils was strongly dependent on substrate P concentration, phase of sorbed P, and soil type. Finally, samples of Polonite used for household wastewater treatment were recycled as soil amendments to a mountain meadow and to an agricultural field for wheat cropping. The liming effect of Polonite was confirmed under field conditions and the results were similar to those of lime for the mountain meadow soil. However, the results were quite different for the agricultural field, where Polonite did not affect soil pH or any other chemical and physical soil properties investigated and had no impact on wheat yield and quality. The results from field experiments suggested that Polonite can be safely recycled to meadows and cropping fields at rates of 5-10 ton ha-1 but long-term studies are needed to forecast the effects of accumulation.QC 20100708
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Siddiqi, Rubia. "Removal of Nitrates from Stormwater Using Nanoclays." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1776.
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Creeks and rivers are often polluted as a result of stormwater runoff that carries various contaminants in to open water bodies, causing adverse environmental and health effects. Low impact development (LID) techniques are currently employed to treat this runoff prior to discharge. Nitrate, however, is not consistently removed by these LID techniques. This study analyzed the ability of several nanoclays to remove nitrate in runoff and determined the feasibility of using them as a soil supplement for LID implementation. Six different nanoclays and HCl-treated clays were compared (pre-modified trimethyl stearyl ammonium nanoclay, pre-modified dimethyl dialkyl amine nanoclay, unmodified hydrophilic bentonite, unmodified halloysite nanoclay, HCl modified hydrophilic bentonite and HCL modified kaolin) to the control clay, unmodified kaolin, for their ability to adsorb nitrate solution by batch adsorption experiments. The findings determined that the pre-modified trimethyl stearyl ammonium nanoclay was the most effective adsorbent, decreasing the nitrate concentration up to 86% for a nitrate to clay ratio of 6.25 mg: 1 g under normal pH (5-6) and temperature (25⁰C) conditions. The HCl acid modification did not prove to provide significant additional benefits to the clays. Column studies were also conducted on the most successful clay, pre-modified trimethyl stearyl ammonium nanoclay, to assess the breakthrough point when 0.1% w/w and 1% w/w of the nanoclay were added to Nevada Sand. The results showed a projected breakthrough pore volume of 17 when the larger fraction was added to the sand, and a corresponding hydraulic conductivity of 12.6 in/hr, which is 35% slower than the un-amended Nevada Sand. Such a high hydraulic conductivity indicated that future work can test larger fractions of clay to sand mixtures to achieve a higher number of pore volumes before the soil reaches its breakthrough point. Future studies can also further explore both batch and column experiments to assess the feasibility of implementing soil amendments to a filtration system by changing the experimental parameters, such as base soil material, types of nanoclays used, and the nanoclay to nitrate ratios. Additionally, synthetic stormwater from runoff should be used as the influent instead of a nitrate-only solution to reflect more realistic scenarios for a potential real-world application.