Дисертації з теми "Drainer"
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1
Ghumrawi, Marwa Jamal. "Potential for Nitrogen Losses from On-Site Wastewater Treatment Systems on Poorly Drained Soils to Curtain Drains." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471876488.
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2
Toledo, De Leon Rogelio. "Predicting Hydrological Performance of Engineered (Curtain) Drains for On-Site Wastewater Treatment Systems Installed in Poorly Drained Soil." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417713887.
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3
Castonguay, Normand G. "Premanufactured band shaped drains an analysis and evaluation of effective drain diameters of band shaped drains : results of full scale laboratory testing programme." Thesis, University of Ottawa (Canada), 1985. http://hdl.handle.net/10393/4752.
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4
Elghaib, Majid Kaissar. "Prediction and interpretation of piezocone data during undrained, drained and partially drained penetration." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14357.
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5
Lennoz-Gratin, Christiane. "Hydraulique à l'interface sol/drain : application à la prévision du risque de colmatage minéral des drains agricoles." Montpellier 2, 1989. http://www.theses.fr/1989MON20240.
Повний текст джерелаАнотація:
Les reseaux de drainage peuvent etre victimes d'accidents de fonctionnement compromettant leur perennite. Un des accidents les plus graves concerne le colmatage mineral des drains, c'est un phenomene irreversible. Il existe des criteres granulometriques pour la prevision du risque de colmatage mineral des drains agricoles, mais leurs limites ont ete souvent mises en evidence par la pratique du drainage. Prevoir le risque de colmatage mineral des drains implique le connaitre et de comprendre le comportement du sol pres du drain. Trois grands types de phenomenes ont ete mis en evidence a l'interface sol/drain: l'organisation des ecoulements dans le sol a l'approche du drain, l'action de l'eau en mouvement sur le sol traverse, le cycle sedimentation/erosion/transport des particules de sol a l'interieur du drain. Seuls les deux premiers phenomenes sont abordes dans la presente etude; ils permettent de comprendre la premiere partie du colmatage mineral interne des drains, c'est-a-dire la penetration de particules de sol par les perforations. Une serie d'experiences en cuve de sable couplee avec un modele numerique aux elements finis permet de visualiser l'organisation de l'ecoulement a l'interface sol/drain et de connaitre les valeurs maximales atteintes par le gradient hydraulique, donc d'evaluer les forces hydrodynamiques qui s'exercent sur les partiucles de sol. Parallelement, un test a ete mis au point qui permet d'evaluer la resistance des sols a l'action de l'eau s'ecoulant vers les perforations du drain. Les resultats des tests associes a des donnees de terrain permettent de proposer une typologie des comportements des sols
6
Lennoz-Gratin, Christiane Zaïdi Kader. "Hydraulique au voisinage du drain : méthodologie et premiers résultats : application au diagnostic du colmatage minéral des drains /." Antony : CEMAGREF-Direction de la communication et de la valorisation, 1987. http://catalogue.bnf.fr/ark:/12148/cb35494853c.
Повний текст джерелаАнотація:
Texte remanié de: Th.--Génie civ.--Paris VI, 1986. Titre de soutenance : Hydraulique au voisinage du drain enrobé ou placé dans une tranchée de drainage. N°: 6583.Bibliogr. p. 133-139. Résumé en français et en anglais.
7
Lennoz-Gratin, Christiane. "Hydraulique à l'interface sol-drain : application à la prévision du risque de colmatage minéral des drains agricoles /." Antony : Montpellier : CEMAGREF-DICOVA ; Université des sciences et techniques du Languedoc, 1991. http://catalogue.bnf.fr/ark:/12148/cb36208121q.
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8
Heathwaite, A. L. "Chemical transformations in drained Fen peat." Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377351.
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9
SOTOMAYOR, JUAN MANUEL GIRAO. "EVALUATION OF DRAINED AND NON-DRAINED MECHANICAL BEHAVIOR OF IRON AND GOLD MINE TAILINGS REINFORCED WITH POLYPROPYLENE FIBERS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36102@1.
Повний текст джерелаАнотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
O presente trabalho estudou o comportamento de rejeitos de minério de ferro e de ouro, reforçados com fibras de polipropileno, com o objetivo da aplicabilidade destes compósitos em aterros (pilhas) de rejeitos de mineração. As fibras foram distribuídas de forma aleatória nos rejeitos (matriz) em um teor de 0.5 por cento em relação ao peso seco da matriz. Os rejeitos de minério de ferro e de ouro são classificados como uma areia siltosa e uma argila siltosa, respectivamente. O programa experimental consistiu em ensaios triaxiais convencionais drenados e não drenados (tensões efetivas de confinamento de 50, 100, 200 e 400 kPa) em amostras não reforçados e reforçados com fibras. Ensaios de cisalhamento direto com superfície polida (tensões normais de 25, 50, 100, 200 e 400 kPa) foram realizados para determinar a influência do reforço na fase residual dos compósitos. Ensaios de Microscopia Eletrônica de Varredura (MEV) foram realizados para visualizar a interação fibra-matriz. A análise global dos resultados permitiu mostrar que fibras de polipropileno não modificam o comportamento elastoplástico do rejeito de minério de ferro, porém no rejeito de minério de ouro o comportamento muda para elastoplástico de enrijecimento. A resistência ao cisalhamento incrementou em ambos os rejeitos reforçados, com um ganho mínimo equivalente ao dobro da tensão cisalhante dos rejeitos sem reforço. Com relação à variação volumétrica, o rejeito de minério de ferro apresenta um comportamento dilatante e a adição de fibras incrementa esse comportamento. No rejeito de minério de ouro observa-se que a tendência volumétrica inicial é de contração e depois apresenta uma leve dilatância, porém, com a adição de fibras, o comportamento dilatante é eliminado. Em conclusão, a aplicabilidade das fibras de polipropileno se mostra como alternativa de reforço e melhoria do comportamento geotécnico dos rejeitos de mineração estudados.
The objective of this work is to study the behavior of iron and gold mine tailings reinforced with polypropylene fibers with the objective of the applicability of these composites in landfills (piles) of mine tailings. The fibers were randomly distributed in the mine tailings (matrix), where was used a content of 0.5 percent in relation to the dry weight of the matrix. The iron and gold mine tailings are classified as a silty sand and a silty clay, respectively. The experimental program consisted of conventional drained and undrained triaxial tests (effective confinement stresses of 50, 100, 200 and 400 kPa) in non-reinforced and reinforced samples. Direct shear tests with a polished surface (normal stresses of 25, 50, 100, 200 and 400 kPa) were performed to determine the influence of reinforcement on the residual phase of the composites. Scanning Electron Microscopy (SEM) tests were performed to visualize the fiber-matrix interaction. The global analysis of the results allowed to show that polypropylene fibers do not modify the elastoplastic behavior of the iron mine tailings, but in the gold mine tailings the behavior changes to the strain hardening elastoplastic. Shear strength increased in both reinforced tailings, with a minimum gain equivalent to twice the shear stress of non-reinforced tailings. The strength parameters in the drained, undrained and residual condition of both mine tailings were increased with the addition of fiber. Regarding the volumetric variation, the iron mine tailings exhibits a dilative behavior and the fiber addition increases this behavior. In the gold mine tailings, it is observed that the initial volumetric tendency is contractive and then presents a slight dilatancy, however, with the fiber addition, the dilative behavior is eliminated. In conclusion, the applicability of the polypropylene fibers is showed as an alternative of reinforcement and improvement of the geotechnical behavior of the studied tailings.
10
Lacoul, Sriranjan. "Consolidated-drained shear-strength of unsaturated soil." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66044.
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11
Tobar, Moreno Franco, and G. Juan Carlos Andueza. "Draiper, dispositivo de rastreo e información personal." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/164103.
Повний текст джерелаАнотація:
TESIS PARA OPTAR AL GRADO DE MAGÍSTER EN ADMINISTRACIÓNTobar Moreno, Franco, [Parte I], Andueza G., Juan Carlos, [Parte II]
En los últimos años hemos visto como el desarrollo tecnológico ha acaparado las miradas de todos los usuarios de tecnologías. Todo el mundo recuerda como hace 10 años estábamos usando teléfonos análogos y hoy no cabe la idea de vivir sin un smartphone. La idea de utilizar esta dependencia tecnológica como medio para cuidar y proteger a nuestros seres queridos son la base de la oportunidad de negocio. La utilización de estos dispositivos para "atacar" la sensación de inseguridad reinante es el problema que se busca combatir. Chile es el país con mayor uso de internet de la región, llegando al 71,7% de la población y por tal razón parece muy atractivo desarrollar distintas tecnologías de información como en este caso, la Seguridad. Draiper es un novedoso sistema de monitoreo y comunicación que permite a los padres o tutores monitorear en línea el trayecto de sus seres queridos y comunicarse con ellos ante cualquier eventualidad a través del mismo dispositivo que posee, entre otras características, sistemas de Geolocalización, alertas de movimiento y velocidad, alertas de golpes, mensajes de texto y llamadas con o sin la intención de efectuarlas. un factor importante a destacar es el sistema que vincula diversos dispositivos como el corazón de producto porque vinculado al mismo, se pueden enlazar muchos dispositivos disponibles en el mercado. Se ha desarrollado un modelo de negocio similar al de las compañías de telefonía móvil en donde proponemos generar ingresos tanto por la venta de dispositivos como por el plan de conectividad mensual que se cobrará para tener el sistema de monitoreo activo. Este último elemento (plan mensual) generará el mayor porcentaje de los ingresos (90% aproximadamente) y por esta razón, es fundamental mantener una cartera de clientes con pocas fugas o de lo contrario el negocio se cae. La venta y distribución viene dada por canales indirectos donde por un lado está el retail que vende equipo prepago y por otro están los dealers, que venden enfocados en colegios y hogares de ancianos que el producto plan básico y full según sea la estrategia definida. Con un capital de MM$ 303, que considera la inversión inicial, puesta en marcha y capital de trabajo para sustentar la operación durante los primeros 22 meses, lograremos comenzar el mercadeo del producto generando flujos de cajas para auto sustentar la operación desde el segundo año en adelante y recuperar la inversión en solo 36 meses. En efecto, los ingresos netos de los 5 años de evaluación alcanzan los MM$ 12.361. Los beneficios económicos estimados superan los MM$ 303 en 5 años considerando un interés del 18% y logrando capturar progresivamente un 30% del mercado objetivo al cabo de este plazo considerando que el tamaño del mercado segmentado es de 110.405 usuarios los cuales físicamente se encuentran en las ciudades de Antofagasta, La Serena, Santiago, Rancagua, Viña de Mar, Valparaíso, Talca, Temuco, Concepción y Puerto Montt. El equipo que desarrolla el proyecto es especialista y multidisciplinario en las funciones claves de éxito del proyecto ya que dentro de la sociedad se cuenta con un ingeniero en informática quien ha desarrollado el sistema Draiper y es quien maneja la operación informática. Por otra parte, forma parte de la sociedad un Ingeniero Civil Industrial experto en administración y finanzas que se encarga del manejo y control de los recursos. Por último, el tercer socio capitalista es un Ingeniero comercial dedicado durante 15 años al desarrollo comercial de empresas ligadas al mundo de las telecomunicaciones y la tecnología. El convencimiento del éxito de este emprendimiento es total por la propuesta de valor diseñada y por la funcionalidad del dispositivo, del sistema y de la aplicación móvil la cual hemos probado durante más de 1 año teniendo certeza de su perfecto funcionamiento tanto en Chile como en el extranjero. Por tal motivo es que en el proyecto se contempla una estrategia de escalamiento que parte en las principales ciudades del Norte‐Centro de Chile, siguiendo con las ciudades del sur al segundo año con posibilidades de lanzarlo al extranjero posteriormente. Draiper es más que un sistema de seguridad, es un sistema innovador de geolocalización y comunicación con innumerables usos que permiten escalabilidad de negocios a otros ámbitos no evaluados en este proyecto.
12
Mangal, Jan Krishna. "Partially-drained loading of shallow foundations on sand." Thesis, University of Oxford, 1999. http://ora.ox.ac.uk/objects/uuid:205bf0bc-b801-4648-a556-8dba0d113cba.
Повний текст джерелаАнотація:
Wave loading on offshore structures founded on sand can result in partially drained response of the foundation soil. The characteristics of the rate of loading, the permeability of the soil, and the size of the foundation affect the degree of partial drainage. Partial drainage refers to situations where pore pressures develop in the soil, and the response of the soil is neither fully drained nor undrained. This thesis is concerned with the effects of loading rate, and consequent drainage, on the behaviour of a flat footing that is founded on the surface of a saturated sand base. The results of physical tests performed in the laboratory on a model-sized footing are reported. The footing was founded on oil-saturated fine sand and was subjected to combined loading. The effect of the vertical, horizontal, and rotational displacements are reported. The response of the footing is analysed in the context of existing drained foundation models that are based on work hardening plasticity theory. The rate dependency of the vertical load:deformation behaviour and the combined yield surfaces are described.
13
Kaushik, Adithya. "Development of Cleaning Robot for Trench Drains." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1573569385569481.
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14
Eskelinen, R. (Riku). "Runoff generation and load estimation in drained peatland areas." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526214924.
Повний текст джерелаАнотація:
Abstract This thesis examined hydrological processes such as snowmelt and groundwater discharge in drained peatland areas in the boreal zone. The studied processes were measured in situ using environmental tracers. Further, performance of a treatment wetland was studied during snowmelt and high flow. A GIS model was developed to estimate groundwater seepage areas in peatland systems surrounding eskers. It was found that soil frost had a clear impact on water quality during snowmelt. This was evident as lower suspended sediments, water colour and dissolved organic carbon concentrations, among other changes. The treatment wetland was found to reduce the suspended solids load during the snowmelt period and late autumn, while reductions in phosphorus and nitrogen loads occurred during summer. A sampling algorithm was built to test how different sampling frequencies affected the estimation of suspended solid loads from the constructed wetland. The results showed increasing uncertainty for sparser sampling (from weekly to monthly sampling), but the uncertainty remained high even at weekly sampling. The GIS model was tested on two eskers and shown to give a fair estimate of groundwater discharge locations. It can thus be used for improving aquifer protection in boreal eskers related to the drainage networks surrounding them. However, to be applied more widely, further efforts are required. The findings in this thesis could be used to develop better water management policies for peat extraction areas, or other industries operating in similar soils and climate. For example, meltwater could be allowed to temporarily bypass treatment facilities in areas with deep soil frost penetration. The wetland study showed that peatland-based wetlands are a suitable approach for improving water treatment performance even under variable hydraulic loads. The uncertainty in the estimated load from a small peat extraction catchment was high, which might limit the use of such data for some purposes. Load estimation methods using the concentration data collected during previous years might be able to reduce the uncertainty, but if the uncertainty needs to be lowered substantially use of sensor technology might be the only viable approachTiivistelmä Tämä väitöskirja käsittelee lumensulannasta syntyvää valuntaa erilaisilla turvemailla ja pintavalutuskentän puhdistustehoa lumensulannan aikaan turvetuontantoalueella. Lisäksi työssä pohditaan miten erilainen näytteenottoohjelma vaikuttaa turvetuotantoalueilta arvioituun kiintoaine kuormitukseen ja kehitetään yleiseen paikkatietoaineistoon perustuva malli jolla on mahdollista ennustaa pohjaveden purkatumispaikkoja harjualueilla. Routaisella turvetuotantoalueelta kiintoaineen, värin ja liuenneen orgaanisen hiilen pitoisuudet olivat pieniä lumensulannan aikaan. Työssä seurattu pintavalutuskenttä vähensi kiintoainekuormitusta alapuoliseen vesistöön myös lumensulannan ja syksyn aikana. Ravinteiden osalta pintavalutuskentän toiminta oli parasta kesäaikaan, lumensulannan ja syksyn aikana havaittiin typen ja fosforin huuhtoutumista. Eri näytteenotto-ohjelmilla havaittiin olevan suuri vaikutus arvioituun kuormitukseen. Yleisesti voidaan sanoa epävarmuuden kasvavan kohti harvempaa näytteenotto väliä (viikoittainen-kuukausittainen), mutta, myös viikoittaisella näytteenotolla epävarmuus on huomattava. Kehitettyä paikka- tietomallia kokeiltiin kahdella harjulla jossa se pystyi antamaan suuntaa antavaa arvioita pohjaveden purkautumispaikoista. Työn tuloksia voidaan hyödyntää turvetuotannon tai muiden turvemailla tai niiden lähellä sijaitsevien teollisuuden vesistövaikutuksia arvioitaessa. Esimerkiksi routaisella turvemaalla voitaisiin harkita lumensulannasta aiheituvan valunnan ohijuoksutusta vesiensuojelurakenteista. Työssä todettiin myös pintavalutuskenttien toimivan vaihtelevan kuormituksen alaisena, sekä lumensulannan että syksyn aikaan. Arvioiduissa kuormituksissa erinäytteenottoväleillä havaitut suuret epävarmuudet saattavat rajoittaa laskelmien käyttöä joissakin tarkoituksissa. Epävarmuutta voidaan vähentää käyttämällä hyväksi edellisinä vuosina tehtyjä vedenlaatumittauksia. Luotettavin tapa epävarmuuden vähentämiseksi on jatkuvatoimisten vedenlaatumittareiden käyttäminen
15
Rose, Michael. "Phosphorous dynamics in periodically flooded and drained riparian soils." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367719.
Повний текст джерелаАнотація:
The aim of the research was to evaluate the processes that determine P stability in riparian floodplain soils, with emphasis on chemical transformations in flood-drained calcareous soil. Flooding of soil columns showed an increase in P solubility (from 0.01 to 1.2 μg ml-1) largely due to the reductive dissolution of Fe minerals (solution Fe increased from < 0.05 to > 50 μg ml-1) and increased solubility of Ca-P minerals (solution Ca increased from < 100 to > 1000 μg ml-1). The periodic drainage of the flooded soil exported the equivalent of approximately O.l5 kg ha-1 (over six flood-drain cycles). Exported P correlated with soil solution P immediately before drainage (r2 = 0.99; P < 0.001). After drainage, there was a reversal of the reactions described above, with solution Fe, Ca and P returning to preflooding levels. Over the course of the 6 flood-drain cycles inorganic P became more stable, with Ca-P and Fe-P pools increasing (from 9 and 11 % respectively both to 14 % of TP) at the expense of labile pools. Similar patterns of P release and retention were observed during batch incubation studies of aerobic - anaerobic cycles using moist soil samples. Solution P and Fe were strongly correlated in both non-calcareous (r2 = 0.96) and calcareous (r2 = 0.73) soils. The role of Ca-P mineral solubility was disguised by the dissolution of calcium carbonate. Drying of the soil can lead to P release on re-wetting (up to eight-fold). This is most likely due to a release of P from ruptured microbial cells and transformations of Fe mineral surfaces. Monitoring suggested that all of these processes were active in the field, as the water table advanced and receded, though more slowly than in the laboratory. Over a four month flood-drain cycle losses of dissolved P from the floodplain were estimated at 0.034 kg ha-1. It is unlikely that this is significant relative to upstream inputs of P to the river from point sources and other types of agricultural land in the River Thames catchment.
16
Napitupulu, Jonner. "The behaviour of silt under undrained and drained loading." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254613.
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17
Ali, Syed Mahtab. "Climate change and water management impacts on land and water resources." Thesis, Curtin University, 2007. http://hdl.handle.net/20.500.11937/202.
Повний текст джерелаАнотація:
This study evaluated the impacts of shallow and deep open drains on groundwater levels and drain performance under varying climate scenarios and irrigation application rates. The MIKE SHE model used for this study is an advanced and fully spatially distributed hydrological model. Three drain depths, climates and irrigation application rates were considered. The drains depths included 0, 1 and 2 m deep drains. The annual rainfall and meteorological data were collected from study area from 1976 to 2004 and analysed to identify the typical wet, average and dry years within the record. Similarly three irrigation application rates included 0, 10 and 16 ML/ha-annum. All together twenty seven scenarios (3 drains depths, 3 climates and 3 irrigation application rates) were simulated. The observed soil physical and hydrological data were used to calibrate and validate the model. Mean square error (R[superscript]2) of the simulated and observed water table data varied from 0.7 to 0.87. Once validated the MIKE SHE model was used to evaluate the effectiveness of 1 and 2 metre deep drains. The simulated water table depth, unsaturated zone deficit, exchange between unsaturated and saturated zones, drain outflow and overland flow were used to analyse their performance. The modeling results showed that the waterlogging was extensive and prolonged during winter months under the no drainage and no irrigation scenario. In the wet climate scenario, the duration of water logging was longer than in the average climate scenario during the winter months. In the dry climate scenario no waterlogging occurred during the high rainfall period. The water table reached soil surface during the winter season in the case of wet and average climate. For the dry climate, the water table was about 0.9 metres below soil surface during winter.One and 2 metre deep drains lowered the water table up to 0.9 and 1.8 metres in winter for the wet climate when there was no irrigation application. One metre deep drains proved effective in controlling water table during wet and average climate without application of irrigation water. One metre deep drains were more effective in controlling waterlogging a in wet, average and dry years when the irrigation application rate was 10 ML/ha-annum. With 16 ML/ha-annum irrigation application, 1 metre deep drains did not perform as efficiently as 2 metre deep drains in controlling the water table and waterlogging. In the dry climate scenario, without irrigation application, 1 metre deep drains were not required as there was not enough flux from rainfall and irrigation to raise the water table and create waterlogging risks. Two metre deep drains lowered the water table to greater depths in the wet, average and dry climate scenarios respectively when no irrigation was applied. They managed water table better in wet and average climate with 10 and 16 ML/ha-annum irrigation application rate. Again in the dry climate, without irrigation application 2 metre deep drains were not required as there was a minimal risk of waterlogging. The recharge to the groundwater table in the no drainage case was far greater than for the 1 and 2 metre deep drainage scenarios. The recharge was higher in case of 1 metre deep drains than 2 metre deep drains in wet and average climate during winter season.There was no recharge to ground water with 1 and 2 metre deep drains under the dry climate scenarios and summer season without irrigation application as there was not enough water to move from the ground surface to the unsaturated and saturated zones. When 10 ML/ha-annum irrigation rate was applied during wet, average and dry climate respectively, 1 metre deep drains proved enough drainage to manage the recharge into the groundwater table with a dry climate. For the wet and average climate scenarios, given a 10 ML/ha-annum irrigation application rate, 2 metre deep drains managed recharge better than 1 metre deep drains. Two metres deep drains with a 10 ML/ha-annum irrigation application rate led to excessive drainage of water from the saturated zone in the dry climate scenario. Two metres deep drains managed recharge better with a 16 ML/ha-annum irrigation application rate in the wet and average climate scenarios than the 1 metre deep drains. Two metres deep drains again led to excessive drainage of water from the saturated zone in dry climate. In brief, 1 metre deep drains performed efficiently in the wet and average climate scenarios with and without a 10 ML/ha-annum irrigation application rate. One metre deep drains are not required for the dry climate scenario. Two metre deep drains performed efficiently in the wet and average climate scenarios with 16 ML/ha-annum irrigation application rate. Two metre deep drains are not required for the dry climate scenario.
18
Lannergård, Emma. "Drained land and nutrient transport in the river Svärtaå catchment." Thesis, Linköpings universitet, Institutionen för tema, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69685.
Повний текст джерелаАнотація:
Land use changes such as lowering of lakes, draining of wetlands and channelizing of streams have affected the hydrological environment in many catchment areas. Numerous studies report that these changes affect the nutrient retention. The river Svärtaå catchment, near Nyköping is identified as one of the areas in Sweden that transport most phosphorus and nitrogen to the Baltic Sea per unit area. The aim of this study was therefore to analyse to which extent land use changes such as lowering of lakes, draining of wetlands and channelizing of streams have affected the nutrient transport to the Baltic Sea. Land use changes were to a large extent performed between the years 1880 and 1930 inSweden, historical maps from the late 19th century have therefore been studied. An application based on the concept of a Geographical Information System (GIS) has been used in order to compare the district map from late 19th century and the terrain map from today. To address the nutrient transport retention coefficients have been found in the literature and implemented on the changes in water area. Changes in the hydrological environment reached totally1068 ha,964 hawere decreasing water areas and104 haincreasing water areas. Wet areas totally decreased with 28 % when the historical setting was compared with the contemporary environment. The loss in wet area represents860 ha. Watercourses with riparian zones have decreased with 54 %, bogs with 53 %, wetlands with 43 % and lakes with 13 %. The loss in retained mass regarding phosphorus was, based on calculations involving retention coefficients, 7,18 – 146 tonnes, and regarding nitrogen 37,9 – 941 tonnes. The changes in the catchment are probably connected to measures like lowering of lakes, draining of wetlands and channelizing of streams. The assumed lost retained masses shows to be high compared to the measured output from the catchment. This leads to questioning of the retention coefficients and the vast range between them, as well as questioning of other assumptions in the method. The consequences of the hydrological changes are therefore difficult to evaluate.
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Natho-Jina, Sultana. "Measurements and analyses of runoff characteristics on subsurface drained farmlands." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65357.
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Kay, Paul. "Fate of veterinary antibiotics on macroporous tile drained clay soils." Thesis, Cranfield University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414673.
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21
Gong, Guobin. "DEM [Discrete Element Method] simulations of drained and undrained behaviour." Thesis, University of Birmingham, 2008. http://etheses.bham.ac.uk//id/eprint/143/.
Повний текст джерелаАнотація:
This thesis reports the results of DEM (Discrete Element Method) simulations of the behaviour of granular material for axisymmetric compression and plane strain deformation under both drained and undrained conditions. The aim is to study the behaviour of saturated granular material using DEM and the objectives of this thesis are: • to explore the drained behaviour of granular material using DEM • to explore the undrained behaviour of loose samples of granular material with and without preshearing history, using DEM • to compare axisymmetric compression and plane strain behaviour of a granular material under both drained and undrained conditions, using DEM A servo-control mode with constant mean stress is used to model drained simulations, and a strain-control model with constant volume is used to model undrained simulations. A periodic cell is used for all the simulations. For the drained simulations, the results of both dense and loose systems are presented, and all the systems reach a unique critical state at large strains. For the undrained simulations, mainly the results of loose systems are presented. The influence of preshearing history is also examined for a loose system under undrained axisymmetric compression conditions. The concept of liquefaction is shown to strongly correlate with mechanical coordination number, and liquefaction is shown to be related to structural mechanism. An attempt has been made to compare the axisymmetric compression and plane strain deformation for the drained and undrained conditions respectively. Shear strength criteria are examined and the Lade criterion is shown to be the most appropriate failure criterion.
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Luscombe, David John. "Understanding the ecohydrology of shallow, drained and marginal blanket peatlands." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/15967.
Повний текст джерелаАнотація:
Peatlands are unique and important landscape systems, providing valuable ecosystem services such as water and carbon storage, water supply and flood attenuation. They are known to account for more than 10% of the world’s terrestrial carbon store and represent 50 – 70% of the global wetland resource. The UK government’s decision to support the IUCN, UK Peatland Program Commission of Inquiry on Peatlands, recognises the importance and urgency with which action is needed to understand and restore damaged peatland landscapes, and their associated ecosystem services. To meet this need, it is recognised that peatlands in the South West of the UK are important as bio-climatically and functionally marginal peatlands that are undergoing extensive restoration to reinstate key ecological and hydrological function. This thesis aims to improve understanding of the temporal and spatial variability of the ecohydrological structure and function of peatland ecosystems in the South West UK, and will provide the first baseline for the spatially distributed extrapolation of change across larger landscape extents. The research seeks to characterise the structure and function of peatland ecohydrology across multiple spatial and temporal scales. This is accomplished by bringing together remote sensing analyses of ecohydrological structure and function coupled with an integrated and high resolution hydrological monitoring system to characterise the spatial and temporal variability of runoff production and water storage across two headwater catchments. Key outcomes of this research are: 1. The development of novel methods to assess the spatial distribution of near surface hydrology in upland ecosystems using airborne thermal imaging data, 2. Improved understanding of how laser altimetry data can be used to measure the ecohydrology of landscapes more appropriately. 3. An empirical understanding of both the spatial and temporal variability of hydrology across representative sites within the moorlands of the South West UK. The high-resolution monitoring data are the first to describe the hydrological processes operating in these peatlands systems effectively, and provide an insight into how these processes are controlled by the anthropogenic drainage networks that are present throughout this shallow marginal peatland system.
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Fall, Claudia. "Microbial Contamination Assessment with SWAT in a Tile-Drained Rural Watershed." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20057.
Повний текст джерелаАнотація:
Microbial contamination of drinking water poses an important health risk which causes severe illnesses and epidemics. In order to improve surface and drinking water quality, the understanding of fecal pathogen contamination processes including their prevention and control needs to be enhanced. The watershed model soil water assessment tool (SWAT) is commonly used to simulate the complex hydrological, meteorological, erosion, land management and pollution processes within river basins. In recent years, it has been increasingly applied to simulate microbial contamination transport at the watershed scale. SWAT is used in this study to simulate Escherichia coli (E.coli) and fecal coliform densities for the agriculturally dominated Payne River Basin in Ontario, Canada. Unprecedented extensive monitoring data that consist of 30 years of daily hydrological data and 5 years of bi-weekly nutrient data have been used to calibrate and validate the presented model here. The calibration and validation of the streamflow and nutrients indicate that the model represent these processes well. The model performs well for periods of lower E. coli and fecal coliform loadings. On the other hand, frequency and magnitude of higher microbial loads are not always accurately represented by the model.
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Marttila, H. (Hannu). "Managing erosion, sediment transport and water quality in drained peatland catchments." Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514293306.
Повний текст джерелаАнотація:
Abstract
Peatland drainage changes catchment conditions and increases the transport of suspended solids (SS) and nutrients. New knowledge and management methods are needed to reduce SS loading from these areas. This thesis examines sediment delivery and erosion processes in a number of peatland drainage areas and catchments in order to determine the effects of drainage on sediment and erosion dynamics and mechanics. Results from studies performed in peat mining, peatland forestry and disturbed headwater catchments in Finland are presented and potential sediment load management methods are discussed for drainage areas and headwater brooks. Particular attention is devoted to erosion of organic peat, sediment transport and methods to reduce the impacts of peatland drainage in boreal headwaters.
This thesis consists of six articles. The first and second papers focus on the erosion and sediment transport processes at peat harvesting and peatland forestry drainage networks. The results indicate that in-channel processes are important in drained peatland, since the drainage network often constitutes temporary inter-storm storage for eroding and transporting material. Sediment properties determine the bed sediment erosion sensitivity, as fluffy organic peat sediment consolidates over time. As flashiness and peak runoff control sediment entrainment and transport from drained peatland areas, water quality management should include peak runoff management.
The third, fourth and fifth papers studies use and application of peak runoff control (PRC) method to the peat harvesting and peatland forestry conditions for water protection. Results indicate that effective water quality management in drained peatland areas can be achieved using this method. Installation of the PRC structures is a useful and cost-effective way of storing storm runoff waters temporarily in the ditch system and providing a retention time for eroded sediment to settle to the ditch bed and drainage network. The main effect of the PRC is on SS and SS-bound nutrients.
The sixth paper is concentrated to test new restoration structure to be used in degraded headwater brooks. The results show that addition of woody restoration structures to the channel is effective and simple sediment management methods in headwater areas.
New information provided in this thesis on sediment erosion and transport processes in drained peatland areas can help to improve water quality control in these areas. In-channel processes are important for both peatland uses, since the drainage network often constitutes temporary inter-storm storage for eroding and transporting material. Therefore, controlling these processes is a key to effective water quality management, which can be achieved using the PRC method in drainage areas or by utilisation of natural fluvial processes in natural channels downstream.
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Wehrle, Kathryn Marie. "Drained shear strength characteriestics of an argillaceous residuum from weathered mudstone." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19905.
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Morris, Samantha Anne. "Molecular ecology of methane-oxidising bacteria in drained and flooded peat." Thesis, University of Warwick, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269192.
Повний текст джерелаАнотація:
Evidence has shown that changes in land-use can affect the potential of the soil to act as a methane sink. The Lakenheath site consists of drained fenland peat, which is being re-converted to wetland. At the time of this study the site consisted of four land-use types, an intensively cultivated plot, unmanaged grassland, woodland, and wetland. Peat cores were taken from the four plots and compared for their ability to act as a methane sink. CH4 uptake was measured throughout the depth profiles using gas chromatography. Clear differences in methane oxidation rates were recorded with depth and land-use. The woodland soil showed the highest capacity for atmospheric methane oxidation, and the wetland soil was only profile that had a distinct peak of methane oxidation activity (just above the water table). Despite the change in land-use, all four soils had the capacity to oxidise both high and low concentrations of methane and so acted as a methane sink. The only exception to this was the wetland soil after persistent rainfall. The uppermost layers were water saturated and all soil sections failed to oxidise methane. Methanotroph diversity in the four soils was compared using molecular biological and enrichment techniques. Total DNA was extracted from depth profiles of the four soils and PCR amplified with 16S rRNA methanotroph group-specific primers and primers specific to subunits of the pMMO and AMO (pmoA and amoA), sMMO (mmoX) and MDH (methanol dehydrogenase, mxaF). In addition, DNA was extracted from the top 5 cm of the cultivated (drained) and flooded soil and PCR amplified with primers specific to subunits of the pMMO and AMO. These PCR products were cloned and gene libraries constructed for each soil. No significant differences were observed in retrieved methanotroph sequences from these two soils, suggesting that the methanotroph population had not altered after flooding. The sequences obtained in the molecular study were predominantly amoA sequences from nitrifiers and pmoA sequences from type II methanotrophs. No type I pmoA sequences were retrieved. Type I methanotrophs, however, were isolated directly from the peat soil in the enrichment study.
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Schepper, Guillaume de. "Simulating surface water and groundwater flow dynamics in tile-drained catchments." Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26532.
Повний текст джерелаАнотація:
Pratique agricole répandue dans les champs sujets à l’accumulation d’eau en surface, le drainage souterrain améliore la productivité des cultures et réduit les risques de stagnation d’eau. La contribution significative du drainage sur les bilans d’eau à l’échelle de bassins versants, et sur les problèmes de contamination dus à l’épandage d’engrais et de fertilisant, a régulièrement été soulignée. Les écoulements d’eau souterraine associés au drainage étant souvent inconnus, leur représentation par modélisation numérique reste un défi majeur. Avant de considérer le transport d’espèces chimiques ou de sédiments, il est essentiel de simuler correctement les écoulements d’eau souterraine en milieu drainé. Dans cette perspective, le modèle HydroGeoSphere a été appliqué à deux bassins versants agricoles drainés du Danemark. Un modèle de référence a été développé à l’échelle d’une parcelle dans le bassin versant de Lillebæk pour tester une série de concepts de drainage dans une zone drainée de 3.5 ha. Le but était de définir une méthode de modélisation adaptée aux réseaux de drainage complexes à grande échelle. Les simulations ont indiqué qu’une simplification du réseau de drainage ou que l’utilisation d’un milieu équivalent sont donc des options appropriées pour éviter les maillages hautement discrétisés. Le calage des modèles reste cependant nécessaire. Afin de simuler les variations saisonnières des écoulements de drainage, un modèle a ensuite été créé à l’échelle du bassin versant de Fensholt, couvrant 6 km2 et comprenant deux réseaux de drainage complexes. Ces derniers ont été simplifiés en gardant les drains collecteurs principaux, comme suggéré par l’étude de Lillebæk. Un calage du modèle par rapport aux débits de drainage a été réalisé : les dynamiques d’écoulement ont été correctement simulées, avec une faible erreur de volumes cumulatifs drainés par rapport aux observations. Le cas de Fensholt a permis de valider les conclusions des tests de Lillebæk, ces résultats ouvrant des perspectives de modélisation du drainage lié à des questions de transport.Tile drainage is a common agricultural management practice in plots prone to ponding issues. Drainage enhances crop productivity and reduces waterlogging risks. Studies over the last few decades have highlighted the significant contribution of subsurface drainage to catchments water balance and contamination issues related to manure or fertilizer application at the soil surface. Groundwater flow patterns associated with drainage are often unknown and their representation in numerical models, although powerful analysis tools, is still a major challenge. Before considering chemical species or sediment transport, an accurate water flow simulation is essential. The integrated fully-coupled hydrological HydroGeoSphere code was applied to two highly tile-drained agricultural catchments of Denmark (Lillebæk and Fensholt) in the present work. A first model was developed at the field scale from the Lillebæk catchment. A reference model was set and various drainage concepts and boundary conditions were tested in a 3.5 ha tile-drained area to find a suitable option in terms of model performance and computing time for larger scale modeling of complex drainage networks. Simulations suggested that a simplification of the geometry of the drainage network or using an equivalent-medium layer are suitable options for avoiding highly discretized meshes, but further model calibration is required. A catchment scale model was subsequently built in Fensholt, covering 6 km2 and including two complex drainage networks. The aim was to perform a year-round simulation accounting for variations in seasonal drainage flow. Both networks were simplified with the main collecting drains kept in the model, as suggested by the Lillebæk study. Calibration against hourly measured drainage discharge data was performed resulting in a good model performance. Drainage flow and flow dynamics were accurately simulated, with low cumulative error in drainage volume. The Fensholt case validated the Lillebæk test conclusions, allowing for further drainage modeling linked with transport issues.
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Kim, Hyung Joon. "Drain Diverter." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/212.
Повний текст джерелаАнотація:
The DI water is commonly used to rinse production wafers to remove mechanical and chemical residue without any problematic chemical reaction in rinse process. The semiconductor industry wants to save their manufacture cost and reduce the industrial residue by recycling the deionized water during CPM process. The conductivity in recycled DI water is integrated over the time period.
The Drain Diverter, deionized wafer filtering system, is the automated system that detects the level of ions and controls the drain system by using conductive probes. The system contains hysteresis loop, valve feedback, relay circuit, and facility interlock. The recycled water valve is immediately closed when the contaminated water is detected by the conductive probes.
The Drain diverter is the project designed for the semiconductor equipments company, and is currently integrated and operating in semiconductor manufacture facility of a chip maker, filtering contaminated DI water from the chamber. And the time delay of the recycled water valve responses is 140mSec for 60PSI of flow pressure.
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Ali, Syed Mahtab. "Climate change and water management impacts on land and water resources." Curtin University of Technology, Faculty of Engineering and Computing, Dept. of Civil Engineering, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=18688.
Повний текст джерелаАнотація:
This study evaluated the impacts of shallow and deep open drains on groundwater levels and drain performance under varying climate scenarios and irrigation application rates. The MIKE SHE model used for this study is an advanced and fully spatially distributed hydrological model. Three drain depths, climates and irrigation application rates were considered. The drains depths included 0, 1 and 2 m deep drains. The annual rainfall and meteorological data were collected from study area from 1976 to 2004 and analysed to identify the typical wet, average and dry years within the record. Similarly three irrigation application rates included 0, 10 and 16 ML/ha-annum. All together twenty seven scenarios (3 drains depths, 3 climates and 3 irrigation application rates) were simulated. The observed soil physical and hydrological data were used to calibrate and validate the model. Mean square error (R[superscript]2) of the simulated and observed water table data varied from 0.7 to 0.87. Once validated the MIKE SHE model was used to evaluate the effectiveness of 1 and 2 metre deep drains. The simulated water table depth, unsaturated zone deficit, exchange between unsaturated and saturated zones, drain outflow and overland flow were used to analyse their performance. The modeling results showed that the waterlogging was extensive and prolonged during winter months under the no drainage and no irrigation scenario. In the wet climate scenario, the duration of water logging was longer than in the average climate scenario during the winter months. In the dry climate scenario no waterlogging occurred during the high rainfall period. The water table reached soil surface during the winter season in the case of wet and average climate. For the dry climate, the water table was about 0.9 metres below soil surface during winter.One and 2 metre deep drains lowered the water table up to 0.9 and 1.8 metres in winter for the wet climate when there was no irrigation application. One metre deep drains proved effective in controlling water table during wet and average climate without application of irrigation water. One metre deep drains were more effective in controlling waterlogging a in wet, average and dry years when the irrigation application rate was 10 ML/ha-annum. With 16 ML/ha-annum irrigation application, 1 metre deep drains did not perform as efficiently as 2 metre deep drains in controlling the water table and waterlogging. In the dry climate scenario, without irrigation application, 1 metre deep drains were not required as there was not enough flux from rainfall and irrigation to raise the water table and create waterlogging risks. Two metre deep drains lowered the water table to greater depths in the wet, average and dry climate scenarios respectively when no irrigation was applied. They managed water table better in wet and average climate with 10 and 16 ML/ha-annum irrigation application rate. Again in the dry climate, without irrigation application 2 metre deep drains were not required as there was a minimal risk of waterlogging. The recharge to the groundwater table in the no drainage case was far greater than for the 1 and 2 metre deep drainage scenarios. The recharge was higher in case of 1 metre deep drains than 2 metre deep drains in wet and average climate during winter season.
There was no recharge to ground water with 1 and 2 metre deep drains under the dry climate scenarios and summer season without irrigation application as there was not enough water to move from the ground surface to the unsaturated and saturated zones. When 10 ML/ha-annum irrigation rate was applied during wet, average and dry climate respectively, 1 metre deep drains proved enough drainage to manage the recharge into the groundwater table with a dry climate. For the wet and average climate scenarios, given a 10 ML/ha-annum irrigation application rate, 2 metre deep drains managed recharge better than 1 metre deep drains. Two metres deep drains with a 10 ML/ha-annum irrigation application rate led to excessive drainage of water from the saturated zone in the dry climate scenario. Two metres deep drains managed recharge better with a 16 ML/ha-annum irrigation application rate in the wet and average climate scenarios than the 1 metre deep drains. Two metres deep drains again led to excessive drainage of water from the saturated zone in dry climate. In brief, 1 metre deep drains performed efficiently in the wet and average climate scenarios with and without a 10 ML/ha-annum irrigation application rate. One metre deep drains are not required for the dry climate scenario. Two metre deep drains performed efficiently in the wet and average climate scenarios with 16 ML/ha-annum irrigation application rate. Two metre deep drains are not required for the dry climate scenario.
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Stylianides, Theodoros. "Highway filter drains maintenance management." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/27533.
Повний текст джерелаАнотація:
Across a large part of the UK highways network the carriageway and pavement foundations are drained by Highway Filter Drains (HFDs). A HFD is a linear trench constructed either at the pavement edge or central reserve, fitted with a porous carrier pipe at the base and backfilled with an initially highly porous aggregate material. This arrangement enables the swift removal of surface runoff and subsurface water from the pavement system minimising road user hazards and eliminating risk of structural damage to the pavement sub-base. The highly porous backfill filters throughout its operational life fines washed from the pavement wearing course or adjacent land. HFDs have been found to be prone to collecting near the basal sections (pipe) or surface layers contaminants or detritus that causes the filter media to gradually block. The process has been defined as HFD clogging and it has been found to lead to reduced drainage capacity and potentially severe drop of serviceability. O&M contractual agreements for DBFO projects usually propose in-service and handback requirements for all assets included in the concession portfolio. Different performance thresholds are thus prescribed for pavements, structures, ancillary assets or street lighting. Similar definitions can be retrieved for drainage assets in such agreements, and these include HFDs. Performance metrics are defined though in a generic language and residual life (a key indicator for major assets that usually drives long-term maintenance planning) is prescribed without indicative means to evaluate such a parameter. Most of pavement maintenance is carried out nowadays using proactive management thinking and engineered assessment of benefits and costs of alternative strategies (what-if scenarios). Such a proactive regime is founded upon data driven processes and asset specific ageing / renewal understanding. Within the spectrum of road management, maintenance Life Cycle Costs are usually generated and updated on an annual basis using inventory and condition data linked to a Decision Support Tool (DST). This enables the assessment and optimisation of investment requirements and projection of deterioration and of treatment impacts aligned to continuous monitoring of asset performance. Following this paradigm shift in infrastructure management, a similar structured methodology to optimise HFD maintenance planning is desired and is introduced in this thesis. The work presented enables the identification of proactive maintenance drivers and potential routes in applying a systemised HFD appraisal and monitoring system. An evaluation of Asset Management prerequisites is thus discussed linked to an overview of strategic requirements to establish such a proactive approach. The thesis identifies condition assessment protocols and focuses on developing the means to evaluate deteriorated characteristics of in service drains using destructive and non-destructive techniques. A probabilistic HFD ageing / renewal model is also proposed using Markov chains. This builds upon existing deterioration understanding and links back to current treatment options and impacts. A filter drain decision support toolkit is lastly developed to support maintenance planning and strategy generation.
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He, Hongxing. "Modeling study of Nitrous Oxide emission from one drained organic forest ecosystem." Thesis, KTH, Mark- och vattenteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99341.
Повний текст джерелаАнотація:
High nitrous oxide (N2O) emission potential has been identified in hemiboreal forest on drained Histosols. However, the environmental factors regulating the emissions were unclear. To investigate the importance of different factors on the N2O emission, a modeling approach was accomplished, using CoupModel with Monti-Carlo based multi-criteria calibration method. The model was made to represent a forest on drained peat soil in south-west Sweden where data of fluxes combined with soil properties and plant conditions were used. The model outcome was consistent with measurements of abiotic (soil temperature, net radiation, groundwater level and soil moisture) and biotic responses (net ecosystem exchange and soil respiration). Both dynamics and magnitude of N2O emissions were well simulated compared to measurements (8.7 ± 2.1 kg N/ha/year). The performance indicators for an ensemble of accepted simulations of N2O emission dynamics and magnitudes were correlated to calibrated parameters related to soil anaerobic fraction and atmospheric nitrogen deposition (correlation coefficient, r ≥ 0.4). A weak correlation with N2O emission dynamics was also found for biotic responses (r ≥ 0.3). However, the ME of simulated and measured N2O emissions was better correlated to the ME of soil moisture (r = -0.6), and also to the ME of both the soil temperature (r = 0.53) and groundwater level (r = -0.7). Groundwater level (range from -0.8 m to -0.13 m) was identified as the most important environmental factor regulating the N2O emissions for present forest soil. Profile analysis indicated that N2O was mainly produced in the deeper layers (≥ 0.35 m) of the soil profile. The optimum soil moisture for N2O production was around 70%.
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Eliadorani, Aliakbar. "The response of sands under partially drained states with emphasis on liquefaction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/NQ48632.pdf.
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Deeks, Lynda Karen. "Investigations of preferential and matrix flow in a mole drained soil block." Thesis, University of Plymouth, 1995. http://hdl.handle.net/10026.1/1925.
Повний текст джерелаАнотація:
An innovative research study was established at IGER, North Wyke, Devon, to investigate preferential flow through a poorly structured relatively impermeable soil. Macropore channels were added by a mole plough in order to investigate soil water pathways and chemical transport in a soil in which preferential flow was guaranteed. The investigation focused on water and solute movement through specific flowpaths, namely macropores and mesopores, and the interaction between mobile and immobile zones within the soil. Two large soil blocks (1 m2 by 0.85 m) of the Hallsworth series were removed from the field and placed on sand tables so that a suction could be induced at the base of the soil block. The edge was sealed using paraffin wax. Eight tensiometers and suction cup lysimeters were installed in each block together with fifteen pairs of time-domain reflectometry wave guides. A regular spacing pattern was employed so that spatial variations could be easily identified. Samples were collected from suction cup lysimeters every 4 hours. Soil water status was observed from the TDR probes daily and from tensiometers every 10 minutes. Five tracer experiments were conducted; three involved the miscible displacement of chloride at concentrations of 100 and 250 mg I"' and two used nitrate (500 mg l ') and chloride (2500 mg 1') applied as a pulse. Tracer and irrigation water was applied through a misting system at an irrigation rate of 2.76 mm h-1. Three techniques were used to examine soil structure in the macropore and mesopore pore size range to investigate potential flowpaths in more detail. The profile tracing method (PTM). binary transect method (BTM) and resinated core section method (RCSM) provided useful quantitative structural information. Soil water status averaged over a large sampling volume (TDR, 1540000 mm3) was considered to be stable through time. Detailed observations of soil water suction using tensiometers showed that soil water conditions remained unsaturated, at approximately 10 to 20 cm H2O, and varied by 3 cm H2O throughout the experiment. Suction varied depending on the location of each tensiometer with respect to position within or between aggregates. Results based on Poiseuille's law and suction data showed that the flowpaths were predominantly mesopores. This result was supported by breakthrough curve analysis for the bulk of the soil although macropore flow was observed towards the mole drain. Flow rates observed from tracer movement varied throughout the soil regardless of depth. Chloride moved quickly towards the mole drain and the arrival of tracer was recorded within 4 hours. Time to breakthrough monitored at the suction cups varied from 4 to 76 hours. When the concentration gradient between applied solute and antecedent solute was large, reduced time to attain peak concentration was noted. As the concentration gradient reduced, speed of rise to peak concentration increased. An advection-dispersion model (CLEARY) fitted change in observed solute concentration through time at the suction cup lysimeters well. The study concluded that although water moved rapidly through the soil, the tortuous nature and increased contact with soil particles encountered as water moved through the mesopores resulted in water with matrix flow solute characteristics.
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Leiva, Daniella Escribano. "Evolution of stiffness and deformation of hostun sand under drained cyclic loading." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659108.
Повний текст джерелаАнотація:
The study of long term cyclic loading has had increased interest in the last few years as many current and future projects for offshore wind turbines are taking place in the UK. Attention has been given to the changes in the foundation's stiffness as this may alter the natural frequency of the structure. As well, during the lifetime of the structure millions of cycles accumulate defoln1ations which may affect its serviceability. The condition of long term cyclic loading of soils can be idealized as a drained boundary problem, as wind and wave loads are applied at low frequencies. This quasi-static loading allows no development of excess pore water pressure in the soil. The main objective of this research was to simulate an element of soil subjected to quasi-static long term loading by means of drained cyclic triaxial tests and applying a simplified version of the stress paths imposed at in situ conditions. The testing program consisted of a set of drained and undrained monotonic triaxial tests, drained cyclic triaxial tests, and a small set of undrained cyclic triaxial tests. The experimental campaign studied,the elastic stiffness at isotropic and anisotropic stress states t6 quantify the inherent and stress induced anisotropy of Hostun sand. In addition, the evolving elastic properties of sand during progressive cyclic loading was investigated. Accumulated deformations during drained cyclic loading were obtained as well as the parameters that influenced their magnitude, intensity, and direction. Specifically, the influence of initial density, stress ratio, cyclic stress amplitude, state parameter, and confining pressure were explored. The relationship between creep deformations and cyclic deformations was analysed. Special attention was given to the limitations of triaxial testing and the effect of constrained boundaries applied to the specimen. Also, the effect of changing the sample preparation method on the results of accumulated volumetric strain. The results obtained from the testing program show the degree of inherent anisotropy of Hostun sand samples prepared by moist tamping method which is lower when compared with samples prepared by pluviation (Sadek, 2006; Sunyer, 2007). The stress-induced anisotropy of Hostun sand was studied by , means of constant mean' stress and constant radial stress paths. The results indicate the influence of vertical and horizontal effective stresses and the importance of quantifying these variables in the empirical expression for the elastic stiffness Go. The drained cyclic triaxial test results discuss about the influence of the stress ratio on the accumulated strains and that the direction of the deviatoric and volumetric strains depends' almost entirely in this parameter. The normalization of the data by stress ratio, cyclic stress amplitude, and the state parameter revealed that similar volumetric deformations are encountered for tests at different confining pressures. Comparison of the test results with simulations using the Severn Trent sand model (Gajo & Muir Wood, 1999) exposed the good agreement between the model and the tests under drained and undrained monotonic stress conditions. The limitations of the model for simulating drained cyclic loading conditions were revealed .
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Wallage, Zoe Elizabeth. "Dissolved organic carbon and colour dynamics in drained and restored blanket peat." Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/377/.
Повний текст джерелаАнотація:
Peatlands are important terrestrial stores of carbon and a principal source of dissolved organic carbon (DOC) to the fluvial environment. Whilst often regarded as a net carbon sink, enhanced DOC concentrations and an associated rise in the level of water discolouration observed in many artificially drained peatland catchments across Europe and North America suggests that continued degradation may shift the balance of the carbon budget, such that they become a net carbon source. Peatland restoration, in the form of drain blocking, is currently being undertaken in a number of these locations. However, a great deal of this work has been carried out on a pragmatic or even an ad-hoc basis, with a distinct lack of process-baseda ssessmentT. hus, very little is known about how such changes in land management affect DOC and colour dynamics. In order to bridge this knowledge gap, this thesis examines a range of processes known to influence DOC/colour production and release. A variety of field monitoring and laboratory measurements were undertaken to assess the upland blanket peat within the Oughtershaw Beck catchment in the Yorkshire Dales National Park, UK. The installation of drainage ditches was found to reduce both the carbon storage potential of the peat and the quality of upland catchment waters. Drainage lowered the depth of the water table across the peat by an average of 10 cm, enhanced the rate of microbial activity by 33 % and increased DOC and colour production in soil water solutions by 35 %, relative to an adjacent intact site that had not been drained. The greater level of aeration in the upper peat layers associated with a lowered water table also appeared to reduce the degree of surface saturation and the occurrence of overland flow (OLF), resulting in a greater volume of water being drawn down into the peat body. The reduced saturation levels caused the subsidence and compaction of the upper soil layers, which increased the bulk density and ultimately reduced the degree of macroporosity within the soil. In turn, this is thought to have increased the residence time and surface area over which percolating waters flow, which is likely to have enhanced the degree of interaction with decompositional products, and thus the mobility of DOC/colour. Drain blocking proved to be a highly effective technique for improving the carbon storage potential of blanket peat and ameliorating upland water quality. Blocking, using regularly spaced peat dams, successfully raised the height of the water table across the peat by an average of 4 cm, relative to the drained site. This increased the level of surface saturation and occurrence of OLF, whilst reducing rates of microbial activity and DOC production by 50 %. However, the volumetric changes associated with drainage appear to have resulted in permanent modifications to the structural and infiltration properties of the peat. Both the water table and the proportion of macropore flow at the drain-blocked site were reduced relative to the intact site, as were microbial activity rates, DOC concentration and colour levels. In addition, DOC composition was markedly different to that produced in the soil waters of both the intact and drained sites. The evidence suggests that a greater volume of percolating water travels through the peat matrix, relative to the intact site, which results in a pore water flushing mechanism and the preferential removal of labile un-coloured DOC components. Furthermore, the lower rate of microbial activity relative to the drained site provides evidence against the commonly quoted hypothesis that an enzyme-latch reaction may be sustained in a peat that has been re-wetted following water table drawdown. Although there was a strong association between DOC and colour, the relationshipvaried significantly between peat layers, land managements, and through time. This challenges the use of spectrophotometric analysis as an indirect method of DOC determination in peat soil waters as the use of a single regression equation resulted in the miscalculation of DOC concentrations by more than 50 %, as it failed to account of the fact that the fraction of coloured DOC components could vary significantly due to modifications made to microbial decomposition and mineralisation pathways and hydrological routing mechanisms.
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Then, Stephanie Rose. "A hydrologic assessment of surface ponding in a drained prairie pothole wetland." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/2154.
Повний текст джерелаАнотація:
This thesis evaluates the surface water hydrology in an artificially drained and farmed prairie pothole wetland located in north-central Iowa as part of the Iowa DNR Wetland Program Development (WPD) project. The purpose of the WPD project was to begin documentation of basic hydrology, wildlife value, and water quality to improve understanding of ecosystem services provided by drained prairie pothole wetlands. The surface water hydrology was evaluated using a daily water balance (PPWB) model. The model development, validation, and applications are described in detail in this thesis.
The PPWB model estimates the water depth and duration in the drained wetland. Several sensitivity analyses were performed to evaluate how site-specific factors affect the frequency, depth, and duration of surface ponding in the drained wetland. In the absence of surface inlets, infiltration was found to have a significant impact on ponding, second only to the amount of precipitation in importance. The topography also plays an important role in surface water ponding, with higher ponding durations occurring for larger catchment-to-pothole area ratios. However, the presence of a surface inlet in a drained prairie pothole wetland significantly alters the hydrology and all other ponding factors become negligible. In addition, long-term ponding was evaluated for historic and future hydrologic trends. The long-term simulation showed increasing trends for precipitation and ponding duration.
The possible implications of continued farming of drained wetlands were explored using PPWB model sensitivity analysis and long-term simulation results. Agricultural implications include mitigation strategies to balance ecosystem needs with crop production and impacts of the projected future outlook with regards to climate. Environmental implications include insight on impacts of wetland restoration.
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Borta, Oxana. "Brain Drain Controversy." Thesis, Linköping University, Department of Management and Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8370.
Повний текст джерелаАнотація:
This thesis focuses on the widely acknowledged so-called brain drain controversy. More concretely on developments in the traditional brain drain literature towards a new shift, claiming the brain gain effect, as an alternative to the brain drain effect, that emigration may bring to a source country. The research investigates not only the obvious direct loss effects – the so called brain drain – but also the possibility of more subtle indirect beneficial effects.
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Vice, President Research Office of the. "Down the Drain." Office of the Vice President Research, The University of British Columbia, 2007. http://hdl.handle.net/2429/2679.
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Foros, Asimakis. "An investigation into the thermal behaviour of external insulation systems with drained cavities." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435460.
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Bousaïd-Finge, Zeina Doanh Thiep. "Contribution à l'étude du comportement non drainé des sables lâches surconsolidés et anisotropes." Villeurbanne : Doc'INSA, 2005. http://docinsa.insa-lyon.fr/these/pont.php?id=finge_bousaid.
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Leeds, Jennifer A. "Phosphorus sorption and flux in northern Everglades soil under drained and flooded conditions." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013561.
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Rasouli, Sogol. "Soluble and particulate nitrogen losses from tile drained fields in Southern Quebec, Canada." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119637.
Повний текст джерелаАнотація:
Eutrophication and cyanobacteria blooms are a growing problem in Missisquoi Bay of Lake Champlain in southern Quebec, and these are largely attributed to non-point source phosphorus and nitrogen (N) pollution from agricultural land in the surrounding watersheds. Residual soil N left after crop harvest contains soluble and particulate forms of N that are at risk of being transported from tile drained agricultural fields to waterways. This study aimed to find the sources of soluble N (mainly nitrate; NO3-N) and particulate organic N (PON) that are susceptible to loss, and the transport pathways by which they move to surface water through tile drained agricultural fields. Water samples were collected at the tile drainage outlet of fields with a clayey and a sandy soil during fall 2010, spring and fall 2011 and spring 2012. There was 1.3 times greater NO3-N concentration and 1.1 fold higher PON concentration in tile drainage water from sandy soil than clayey soil and electrical conductivity measurements indicated that preferential flow was the main pathway for PON loss from clayey soil. Using a dual stable isotopes of δ15N and δ18O of NO3 -N coupled with a mixing model, inorganic NH4 fertilizer was found to be the most important contributor to the NO3-N pool in tile drainage water within two weeks of fertilizer application; however, microbially-processed NO3-N was the main source (40 to 49% of NO3-N in tile drainage water) when crops were not growing in the field. Sources of PON in tile drainage water were manure N (47%) and plant residue N (20%) from topsoil layer of the clayey soil, while soil organic N (SON) contributed 94% of PON lost from the topsoil of the sandy soil. More specifically, the PON pool contained N-rich soil organo-mineral complexes from the top soil layer that reached the tile drains by preferential flow pathways. Decreasing NH4 inputs from fertilizer and allocating sufficient N credits to manure and legume residue inputs could reduce the buildup of NO3-N and organic N, thereby reducing NO3-N and PON losses from these sources. I conclude that source fingerprinting techniques using stable isotope tracers are an effective way of assembling information on the susceptibility of N inputs to loss and transport pathways, which need to be considered when choosing best management practices to reduce non-point source N pollution from the agricultural sector.L'eutrophisation et les proliférations de cyanobactérie sont un problème croissant dans la Baie Missisquoi du Lac Champlain dans le sud du Québec. Celles-ci peuvent être largement imputées a une pollution en phosphore et azote (N) d'origine diffuse, provenant de terres agricoles dans les basins versants s'y déversant. L'azote résiduel du sol, qui demeure après la récolte, comprend des formes soluble et particulaires qui risquent d'être transportées des champs équipés d'une système de drainage souterrain vers les cours d'eau. Cette étude tenta d'identifier les sources d'azote soluble (principalement les nitrates; NO3-N) et d'azote organique particulaire (AOP) qui sont vulnérables aux pertes, et les voies de transport par lesquelles elles se rendent des champs agricoles équipés de systèmes de drainage souterrains aux eaux de surface. Des échantillons d'eau furent prélevés à l'exutoire du système de drainage souterrain de champs aux sols argileux ou sablonneux, à l'automne 2010, au printemps et à l'automne 2011, et au printemps 2012. Les concentrations en NO3-N et en AOP furent 1.3 et 1.1 plus élevées, respectivement, dans l'eau de drainage provenant du sol sablonneux que du sol argileux, Un suivi de l'électroconductivité du sol indiqua que l'écoulement préférentiel fut la principale voie des pertes en AOP dans le sol argileux. Le suivi d'isotopes stables (δ15N et δ18O) du NO3-N du sol et des eaux de drainage, en combinaison avec un modèle de combinaison, démontra que, dans les deux semaines après son épandage, l'engrais inorganique à base de NH4 contribua le plus au stock de NO3-N des eaux de drainage souterraines. Cependant, le NO3-N transformé par les microbes fut la principale source (40 à 49%) du NO3-N dans les eaux de drainage, lorsque les cultures étaient absentes. Or, 47% et 20% de l'AOP dans les eaux de drainage provint, respectivement, d'azote de fumier et d'azote des résidus de cultures ayant leur origine dans la couche arable du sol argileux, tandis que l'azote organique de la couche arable du sol sablonneux contribua 94% de l'AOP perdu. Plus particulièrement, le stock d'AOP de la couche arable contenait des complexes organominéraux riches en azote, qui se sont rendus au drains par des voies préférentielles d'écoulement. Une diminution des apports en NH4 provenant d'engrais, et une prise en compte des crédits d'azote associés au fumier et aux résidus de plantes légumineuses, pourrait réduire l'accumulation de NO3-N et d'azote organique, réduisant ainsi les pertes en NO3-N et AOP provenant de ces sources. Les techniques d'empreinte isotopique on donc permis de faire un suivi efficace des intrants azotées tout en générant de nouvelles connaissances sur la vulnérabilité des intrants azotées aux voies de perte et de transport. Celles-ci devront être considérées lors du choix et de la mise en œuvre de pratiques de gestion optimales dans le secteur agricole visant à réduire la pollution azotée diffuse.
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Laperrière, Lucie. "L'essai d'un nettoyeur de drains hydraulique." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61856.
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Burgess, Magdalena S. E. "Nitrate leaching from a subsurface-drained corn field under different tillage and residue levels." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55481.
Повний текст джерелаАнотація:
Nitrate leaching was studied on a 2.4-ha subsurface-drained corn (Zea mays L.) field in southwestern Quebec. The soil was a sandy loam to loamy sand (mean depth 46 cm) overlying clay. Treatments, begun in fall 1991, consisted of no-till, reduced tillage, and conventional tillage with crop residues either removed or retained at harvest. Drain flow volume and NO$ sb3 sp-$-N concentrations in flow were monitored year-round, and soil NO$ sb3 sp-$-N levels measured in spring and fall. A total of 34 kg NO$ sb3 sp-$-N ha$ sp{-1}$ was recorded in drain flow in 1992 from the site as a whole, equivalent to 20% of applied fertilizer N. In the first 14 months of monitoring, over 70% of water samples had NO$ sb3 sp-$-N levels exceeding Canadian drinking water guidelines (10 mg NO$ sb3 sp-$-N L$ sp{-1}),$ and about 25% had over 40 mg NO$ sb3 sp-$-N L$ sp{-1}.$ Flow-weighted mean concentration for the site as a whole in 1992 was 19 mg NO$ sb3 sp-$-N L$ sp{-1}.$ Unanticipated variations in drain depth significantly affected flow volume and total NO$ sb3 sp-$-N losses, hampering assessment of treatment effects on drain water parameters. In 1992, post-harvest soil NO$ sb3 sp-$-N levels at 0-25 cm were significantly lower in plots with crop residues retained, regardless of tillage system, than in plots with residues removed. In May 1993 (pre-tillage), soil NO$ sb3 sp-$-N levels were similar for all treatments, having dropped in no-residue plots and risen slightly in plots with residues, suggesting immobilization of NO$ sb3 sp-$-N by crop residues in summer-fall and mineralization in spring. The NO$ sb3 sp-$-N measured in drain flow represents a substantial loss of N from the farm system, and has negative implications for water quality. Within the time-frame of the study, crop residues appeared to have a greater effect on soil NO$ sb3 sp-$-N levels, and thus leaching potential, than did tillage system.
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Eastman, Mark 1982. "Field-scale nutrient transport monitoring and modeling of subsurface and naturally drained agricultural lands." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112620.
Повний текст джерелаАнотація:
Eutrophication impacts the quality of many surface waters worldwide. Algal blooms threaten lake water quality and in order to control their growth, understanding of nutrient transport at the field-scale is essential. In order to accomplish this, a combination of field monitoring and computer modeling with the SWAT model was undertaken.Four sites located in the Pike River watershed of southern Quebec were instrumented to monitor nutrient losses from both clay loam and sandy loam soils under both subsurface and naturally drained conditions. Results illustrate how the presence of subsurface drainage influences phosphorus loss depending on soil texture and structure. Total phosphorus loss from the clay loam subsurface drained site was 4.0 kg ha-1, 55% greater than the naturally drained clay loam site. Total phosphorus loss from the sandy loam subsurface drained site was 1.2 kg ha-1, 14% less than the naturally drained sandy loam site. Total phosphorus losses from the subsurface drainage systems in the clay loam field and the sandy loam field were 2.3 and 0.4 kg ha-1, respectively. Particulate phosphorus was the dominant (78%) form of phosphorus loss from the subsurface drainage system at the clay loam site. This indicates that bypass flow through the soil profile in the clay loam field led to excessive total phosphorus loss.
SWAT, a watershed-scale model was calibrated with over 6 site years of data, in an attempt to simulate hydrology and pollutant transport at the field-scale. After calibration, the monthly Nash-Sutcliffe Efficiency varied from 0.09 to 0.74 for total drainage; 0.04 to 0.71 for sediment loading; 0.29 to 0.48 for nitrate loads and 0.28 to 0.64 for total phosphorus loads. Overall, SWAT has shown that it has the ability to simulate long-term sediment and nutrient transport at the field-scale. This makes SWAT a valuable tool for the development and evaluation of various beneficial management practices which control sediment and nutrient loss from agricultural fields.
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Wells, E. Doyle. "The establishment and early growth of trees planted on drained peatlands in Newfoundland, Canada." Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295584.
Повний текст джерелаАнотація:
One part of the afforestation programme consisted of the establishment of an afforestation trial on a bog and fen site in central Newfoundland to determine growth and nutrient response of newly-planted black spruce (Picea mariana (Mill.) B.S.P.) and eastern larch (Larix laricina ((Du Roi) K.Koch). The experimental design was a split-split-plot consisting of surface treatments (untilled, tilled) as main-plot treatments, fertilization (unfertilized, PK) as split-plot treatments and four ditch spacings ( 3 m, 5 m, 7 m, and 15 m) as split-split-plot treatments. A total of 3,960 25-week old container seedlings of each species were planted on each site at spacings of 0.50 m in rows of nine trees, each row being situated at a distance of 1.0 m apart. Surfaces were tilled at 0-200 mm depth using a farm rotovater attached to the back of a tractor. Ditches were made at depths of 0.50-0.75 m with a Dondi ditcher attached to the back of a tractor, and fertilizers were broadcast at the rate of 60 kg/ha P and 50 kg/ha K. The second part of the afforestation programme was a refertilization trial of 1) Japanese larch (Larix leptolepis Seib and Zucc.) and black spruce trees planted on Stephenville bog in western Newfoundland in 1968; and 2) black spruce, white spruce (Picea glauca (Moench) Voss) and lodgepole pine (Pinus contorta Dougl.) planted on Millertown fen in central Newfoundland in 1973. Both sites had been ploughed with a Parkgate-Tyne plough at 1.8 m spacings 1-2 years prior to planting. Following planting of the Stephenville site in 1968, the black spruce and Japanese larch were spot-fertilized (around each tree) with a top-dressing of 57 g of ground mineral rock phosphate. This procedure was repeated in 1970 with 128 g of a mixture of phosphate and potassium (20% P2O2, 20% K2O). On the Millertown site, all trees were spot-fertilized in 1973 with a mixture of 71 g urea, 99 g rock phosphate and 41 g potassium sulfate.
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Xiao, Daping. "Consolidation of soft clay using vertical drains /." Online version, 2001. http://bibpurl.oclc.org/web/26678.
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何旅碧 and Lui-pik Pinky Ho. "Effectiveness of horizontal drains in slope stability." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40722375.
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Ho, Lui-pik Pinky. "Effectiveness of horizontal drains in slope stability." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40722375.
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應慧麗 and Wai-lai Winnie Ying. "The uncertainties of vertical drain design." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31222079.
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