Dissertations / Theses: 'Drainage models'

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Madramootoo, Chandra Alastair 1954. "An agricultural land drainage simulation model /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72017.

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A deterministic computer model was developed to continuously simulate the runoff from surface and subsurface-drained fields in the St. Lawrence lowlands. The model simulates all of the major hydrologic and hydraulic processes occurring both above and below the ground. Input data requirements include hourly rainfall, daily potential evapotranspiration, soil physical properties, field dimensions, open channel geometry and drainage system specifications.
Events for the years 1978 to 1982 were simulated, to compare the runoff characteristics between 20 ha, clay loam, surface-drained and subsurface-drained fields. Further simulations were conducted to examine the hydrologic effects of wide-spaced, deep, parallel field ditches.
Hydrographs for the one-in-200-year storm were also simulated. All of the simulations confirmed that the peak flow rate on the subsurface-drained field was less than that of the surface-drained field. Longer times to peak and lag times occurred on the subsurface-drained field.

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Wu, Guangxi. "Sensitivity and uncertainty analysis of subsurface drainage design." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28529.

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Literature on subsurface drainage theories, determination of drainage parameters, and analysis approaches of uncertainty was reviewed. Sensitivity analysis was carried out on drain spacing equations for steady state and nonsteady state, in homogeneous soils and in layered soils. It was found that drain spacing is very sensitive to the hydraulic conductivity, the drainage coefficient, and the design midspan water table height. Spacing is not sensitive to the depth of the impermeable layer and the drain radius. In transient state, spacing is extremely sensitive to the midspan water table heights if the water table fall is relatively small. In that case steady state theory will yield more reliable results and its use is recommended. Drain spacing is usually more sensitive to the hydraulic conductivity of the soil below the drains than to that of the soil above the drains. Therefore, it is desirable to take samples from deeper soil when measuring hydraulic conductivity. A new spacing formula was developed for two-layered soils and a special case of three-layered soils with drains at the interface of the top two layers. This equation was compared with the Kirkham equation. The new formula yields spacings close to the Kirkham equation if the hydraulic conductivity of the soil above the drains is relatively small; otherwise, it tends to give more accurate results. First and second order analysis methods were employed to analyze parameter uncertainty in subsurface drainage design. It was found that conventional design methods based on a deterministic framework may result in inadequate spacing due to the uncertainty involved. Uncertainty may be incorporated into practical design by using the simple equations and graphs presented in this research; the procedure was illustrated through an example. Conclusions were drawn from the present study and recommendations were made for future research.
Applied Science, Faculty of
Graduate

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Mercurio, Matthew Forrest. "Divider analysis of drainage divides delineated at the field scale." Virtual Press, 2004. http://liblink.bsu.edu/uhtbin/catkey/1306855.

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Previous works have applied the Divider Method to the shapes of drainage divides as measured from maps. This study focuses on the shapes of several drainage divides measured in the field at very fine scale. These divides, chosen for their sharp crests, include portions of the Continental Divide in Colorado and badlands-type divides in Arizona, Wyoming, South Dakota, and Texas. The badlands type divides were delineated using a laser theodolite to collect data at decimeter point spacing, and the Continental Divide segments were delineated using pace and bearing at a constant point spacing of 30 meters. A GIS was used to store and visualize the divide data, and an automated divider analysis was performed for each of the 16 drainage divides.The Richardson plots produced for each of the drainage divide datasets were visually inspected for portions of linearity. Fractal dimensions (D) were calculated using linear regression techniques for each of the linear segments identified in the Richardson plots. Six of the plots exhibited two distinct segments of linearity, nine plots exhibited one segment, and one plot exhibited no segments of linearity. Residual analyses of the trend lines show that about half of the Richardson plot segments used to calculate D exhibit slight curvature. While these segments are not strictly linear, linear models and associated D values may still serve well as approximations to describe degree of divide wandering.Most (20 out of 21) of the dimensions derived from the Richardson plots for the drainage divides fall within the range from 1.01-1.07. The D values calculated for the Continental Divide range from 1.02-1.07. The dimensions calculated for the badlandtype divides were distributed evenly across the range of 1.01-1.06, with a single exceptional D value at 1.12. Only four of the divide D values fall within a range of 1.06–1.12, the range for D established for drainage divides in published map-based studies, despite the apparent dominance of erosion processes on the measured divides.
Department of Geology

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Kalliokoski, J. (Juha). "Models of filtration curve as a part of pulp drainage analyzers." Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514294273.

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Abstract The filtration of pulp suspension is one of the key papermaking processes. It is measured using many kinds of analyzers and modeled using both physical and empirical mathematical expressions. The main target of this thesis was to develop an empirical mathematical model to describe the filtration of a drainage analyzer. In this work the diameter of the screen (10 cm), as well as the amount (1000 cm3), consistency (0.3%) and temperature (20 ˚C) of the sample were (about) the same as those of the Canadian Standard Freeness analyzer. The analyzer was equipped with the measurements of filtrated volume, driving pressure and filtrate consistency. The pressures from the underpressure of 80 kPa to the overpressure of 80 kPa could be used. Pulp types of SGW, PGW, TMP and chemical pulp with freeness levels from 30 to 600 ml were analyzed. A conditioner of the sample volume, temperature and consistency measurements was constructed. The error of freeness value caused by the errors of the conditioner was evaluated to be less than 1%. The equations for the calculation of the possible initial values of the controlled quantities were derived. The optically measured consistencies of the filtrates were different for different pulp types and decreased close to zero before the filtrated volume of 150 cm3. The filtration seemed to change the portion of optically active fines. In the model of this work the filtration time (t) is proportional to an experimental power of the filtrated volume (V): Ve = kt. An auxiliary constant (Ve = kt + V0e) was used during the regression analyses to overcome the disturbances and non-validity of the model in the beginning of the filtration. The correlation coefficients of the fit were higher than 0.999. The exponent 2 suggested by Darcy’s law is a special case while the exponent has also been close to 1 or 3. The curves of specific filtration resistances, based on the model and pressure measurements, were shown to change during the course of drainage and as a function of pressure additionally dependent on the pulp type. The model was successfully used to calculate freeness values and to filter noise from the measurements
Tiivistelmä Paperimassasulpun suotauttaminen on paperinvalmistuksen avainprosesseja. Sitä on mitattu monenlaisilla analysaattoreilla ja kuvattu sekä fysikaalisilla että kokeellisilla matemaattisilla malleilla. Tämän tutkimuksen päätavoite on kehittää suotautuvuusanalysaattorin kokeellista matemaattista mallia. Tutkimuksessa viiran halkaisija (10 cm) sekä näytteen määrä (1000 cm3), sakeus (0.3 %) ja lämpötila (20 ˚C) olivat suunnilleen samat kuin Canadian standard freeness –analysaattorissa. Järjestelmä mittasi suotautettua tilavuutta, suotauttavaa painetta ja suodoksen sakeutta. Suotautuspaineet olivat 80 kPa:n ali- ja ylipaineen väliltä. Testattavana oli hioketta, painehioketta ja termohierrettä sekä kemiallista massaa, joiden freeness oli 30 ml:sta 600 ml:aan. Analysaattoriin rakennettu vakiointijärjestelmä sääti näytteen sakeuden, tilavuuden ja lämpötilan niin tarkasti halutuiksi, että näiden vaihtelu ei olisi muuttanut freeness-arvoa edes prosenttia. Suureiden kehittymiselle johdettiin kaavat. Niiden avulla voidaan laskea ne näytteen arvoalueet, joilta halutut tavoitearvot voidaan saavuttaa. Optisesti mitattu suodoksen sakeus riippui massatyypistä ja hiipui lähes nollaksi ennen kuin 150 ml oli suotautettu. Suotautus muutti optisesti aktiivisen hienoaineen osuutta. Tämän työn suodoskäyrän mallissa aika (t) on verrannollinen suotautetun tilavuuden (V) kokeellisen potenssiin: Ve = kt. Mallinnuksen ajaksi lisätään apuparametri (Ve = kt+V0e), jotta suotautuksen alku ei huononna mallia. Sovituksen korrelaatiokerroin oli yli 0.999. Eksponentin arvo vaihteli vähän yli yhdestä melkein kolmeen, joten Darcyn lain mukainen eksponentin arvo 2 osoittautui erikoistapaukseksi. Mallin ja painemittauksen avulla lasketut ominaisresistanssit muuttuivat suotautuksen kuluessa ja riippuivat myös massatyypistä. Mallin avulla voitiin laskea näytteen freeness sekä suodattaa mittauskohinaa

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Freitas, Henrique Rennó de Azeredo. "Drainage networks and watersheds delineation derived from TIN-based digital elevation models." Instituto Nacional de Pesquisas Espaciais (INPE), 2014. http://urlib.net/sid.inpe.br/plutao/2014/11.16.19.25.

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Digital Elevation Models (DEMs) are objects of great importance in many studies of natural sciences and one relevant area of their application is hydrology, as from a DEM it is possible to generate drainage networks and watersheds, which are essential elements in the understanding of hydrological processes. All the methods developed to generate drainage networks from a DEM depend on its representation and the most common representation is given by regular grids, where elevation values are assigned to cells uniformly distributed over space. However, this representation presents limitations in the flow directions, which are defined in only eight distinct directions. This work considers the terrain model given by a Triangulated Irregular Network (TIN) generated from contour lines and sampled points, where the terrain surface is modeled by several triangles defined from a set of points adequately distributed over space, so that the TIN can efficiently adapt to its irregularities. In addition, flow directions on TINs encompass a11 the possible directions and depend on the slope of the triangles, so this structure is more flexible regarding the calculation of water flows. The triangulation used in this work is the constrained Delaunay triangulation and the method that generates drainage networks considers flow directions given by the gradient of the plane defined from each triangle. Problems that commonly occur in DEMs such as flat areas and pits, which create inconsistencies in the terrain model and discontinuities in flows, also deserve special attention. In the present work, flat areas are removed by the insertion of new points into the triangulation with interpolated elevation values and pits by the definition of paths of points starting from the pit until reaching another point of lower elevation, where all these points have their elevation values re-interpolated. Most importantly, this work describes a methodology for calculating drainage paths from a TIN traced by processing the triangles with an associated priority and then connected defining a drainage graph structure, which is proposed in this work for the calculation of accumulated flows. Afterwards, drainage networks are generated according to given threshold values and watersheds are then delineated from the drainage networks. A11 the results from the TIN are qualitatively compared to regular grid results generated with the TerraHidro computational platform developed at INPE and also to an available drainage network produced by specialists and considered here as a reference of the main courses of water over the terrain. Results are very promising showing that TIN terrain models can be used to generate drainage networks from accumulated flows consistent with real-world hydrological patterns.
Modelos Digitais de Elevação (MDEs) são objetos de grande importância em muitos estudos das ciências naturais e uma área relevante de sua aplicação é a hidrologia, pois a partir de um MDE é possível gerar redes de drenagem e bacias hidrográficas, as quais são elementos essenciais no entendimento de processos hidrológicos. Todos os métodos desenvolvidos para gerar redes de drenagem a partir de um MDE dependem da sua representação e a representação mais comum é dada por grades regulares, onde valores de elevação são atribuídos em células uniformemente distribuídas no espaço. Entretanto, essa representação apresenta limitações nas direções de fluxo, as quais são definidas em apenas oito direções distintas. Este trabalho considera o modelo de terreno dado por uma Rede Triangular Irregular (Triangulated Irregular Network ou TIN) gerada de curvas de nível e pontos amestrados, onde a superfície do terreno é modelada por vários triângulos definidos a partir de um conjunto de pontos adequadamente distribuídos no espaço, de forma que o TIN pode eficientemente se adaptar as suas irregularidades. Além disso, direções de fluxo sobre TINs abrangem todas as direções possíveis e dependem da declividade dos triângulos, de modo que essa estrutura é mais flexível ao se considerar o cálculo dos fluxos de água. A triangulação utilizada neste trabalho é a triangulação de Delaunay restrita e o método que gera redes de drenagem considera direções de fluxo dadas pelo gradiente do plano definido por cada triângulo. Problemas que comumente ocorrem em MDEs tais como áreas planas e fossos, os quais criam inconsistências no modelo de terreno e descontinuidades nos fluxos, também merecem atenção especial. No presente trabalho, áreas planas são removidas pela inserção de novos pontos na triangulação com valores de elevação interpolados e fossos pela definição de caminhos de pontos iniciando do fosso até alcançar um outro ponto de menor elevação, onde todos esses pontos têm seus valores de elevação reinterpolados. Sobretudo, este trabalho descreve uma metodologia para calcular caminhos de drenagem a partir de um TIN traçados ao processar os triângulos com uma prioridade associada e depois conectados definindo uma estrutura de grafo de drenagem, a qual é proposta neste trabalho para o cálculo de fluxos acumulados. Posteriormente, redes de drenagem são geradas de acordo com determinado ti valores ele limiar e bacias hidrográficas são então delimitadas a partir das redes de drenagem. Todos os resultados do TIN são comparados qualitativamente a resultados de grade regular gerados com a plataforma computacional TerraHidro desenvolvida no INPE e também a uma rede de drenagem disponível, produzida por especialistas e considerada aqui como uma referência dos principais cursos d'água no terreno. Os resultados são bastante promissores mostrando que modelos de terreno TIN podem ser utilizados para gerar redes de drenagem a partir de fluxos acumulados consistentes com padrões hidrológicos reais.

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Richard, Paul François. "A computer analysis of the flow of water and nutrients in agricultural soils as affected by subsurface drainage." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29171.

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A computer model was developed in order to determine the effects of drainage practices on nutrient losses from level agricultural soils. The model performs a daily simulation of the vertical flow of water, nitrogen, phosphorus, and heat, and of the growth of crops. A water flow submodel calculates the depth of the water table based on daily predictions of evaporation, transpiration, flow to drains and ditches, and deep percolation. An original saturated-unsaturated flow algorithm is used to determine moisture infiltration, redistribution, and upward flow in the soil matrix, as well as bypassing flow in the soil macropores and horizontal flux between the soil matrix and the macropores, and surface runoff. Nutrient movement occurs by mass flow. Heat flow, nutrient biochemical transformations, and crop growth are determined by using well established relations. Field tests were carried out for a period of two years on an experimental site in the Lower Fraser Valley of British Columbia. The water table depth was measured on a continuous basis. Grab samples of drainwater and observation wells were obtained periodically and analyzed for nitrogen (N0₃-N, NH₄-N, and TKN) and phosphorus (P0₄-P and TP). The field results show a decrease in the concentration of all nutrients over the sampling period, and provide evidence that denitrification and bypassing flow are important mechanisms affecting the nutrient balance of this soil. These results were used to calibrate the model. An excellent fit of the observed water table profile and an adequate fit of the observed drain concentration of nitrate were obtained. The simulation revealed that bypassing flow is a very important transfer mechanism in this soil and must be included in order to obtain a satisfactory fit of the experimental data. A sensitivity analysis of the model showed that the patterns of moisture flow have a predominant influence on the rate of nutrient leaching. In particular, it was found that the nutrient concentration in drain water is a strong function of the hydraulic conductivity of the soil matrix and of the horizontal distance between the soil macropores, which control the ratio of moisture flow in the soil matrix to the macropore flow and the lateral diffusion of nutrients between the soil matrix and the macropores. The effects of four different drainage designs on nutrient losses were simulated over a period of two years for three different soils and two different nutrient distributions in the soil. It was found that there is a large difference between the amount of nutrients leached from drainage systems using different drainage coefficients. There was also a large difference in the response of two drainage designs based on the same drainage coefficient but using different depth and spacing of drains. Transient effects, as determined by the initial vertical distribution of the nutrients, were seen to remain dominant over the two year duration of the simulation. The model was found to be useful in explaining the apparent contradictions found in the literature assessing the effects of subsurface drainage on nutrient losses. The results from the model show these effects to be strongly site and condition specific. Furthermore, the model shows that soils and drainage designs that produce similar volumes of drain flow may exhibit very different leaching responses, and that drainage designs equivalent from a hydraulic standpoint can be very dissimilar in their potential for leaching nutrients. The model provides a tool which can be used to determine the appropriateness of different drainage designs in soils where minimizing nutrient losses is critical.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

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Samsudin, A. B. "An assessment of flow and pressure control in experimental models of glaucoma drainage surgery." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1435420/.

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There are a number of surgical methods for treating glaucoma, including trabeculectomy and the insertion of drainage devices. At the current time, these procedures are still associated with post-operative problems for a significant number of patients, particularly with the control of aqueous humour flow and pressure e.g. hypotony. The main aim of this work was to look at ways of improving the outcomes of the procedures. The usual approach in assessing surgical techniques is to test them on live human or animal eyes. This is inherently complex, with a significant challenge to keep some of the major parameters e.g. aqueous humour inflow and wound healing consistent throughout a series of tests, and with this the problem of reproducibility. The approach used in this work includes a review and analysis of the different surgical methods and devices from an engineering perspective, the use of scaling analysis and a large-scale physical model coupled with image processing to study trabeculectomy scleral flap characteristics and its effect on flow and pressure, and also the use of model drainage devices in ex vivo settings to look at flow and pressure. For each experiment, implications for clinical practice are discussed. Applying engineering principles to glaucoma procedures and devices provided novel insight into their functions. It was found that the trabeculectomy scleral flap acts as a valve to guard from excessive aqueous humour outflow and low pressures, and parameters such as the number and position of sutures and scleral flap geometry can be tailored to alter aqueous humour outflow. Additionally, 50 μm internal diameter tubes show promise for controlled aqueous humour flow into the subconjunctival space with avoidance of low pressures. Engineering methodology can be used in the development of new treatments and devices. However, some results may not translate exactly into the more complex living eye.

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Leandro, Jorge. "Advanced modelling of flooding in urban areas : integrated 1D/1D and 1D/2D models." Thesis, University of Exeter, 2008. http://hdl.handle.net/10036/41949.

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The research presented in this Thesis aims at defining the strengths and weaknesses of an Improved 1D/1D model when compared with a more accurate 1D/2D model. Although both coupled-models (sewer/surface) solve the St.\ Venant equations in both layers, the latter uses a higher approximation (2D two-dimensional) on the surface layer. Consequently, the 1D/1D model is computationally more efficient when compared to the 1D/2D model, however there is some compromise with the overall accuracy. The hypothesis is that "The inundation extent of urban flooding can be reproduced by 1D/1D models in good agreement with the 1D/2D models if the results are kept within certain limits of resolution and under certain conditions". The Thesis starts by investigating ways of improving an existing 1D/1D model to rival the more accurate 1D/2D model. Parts of the 1D/1D model code are changed and new algorithms and routines implemented. An innovative GIS tool translates the 1D output-results into 2D flood-inundation-maps enabling a thorough comparison between the two models. The methodology assures the set-up of two equivalent models, which includes a novel algorithm for calibrating the 1D/1D model vs.\ the 1D/2D model results. Developments are tested in two distinctly different case studies of areas prone to flooding. The conclusion is that the 1D/1D model is able to simulate flooding in good agreement with the 1D/2D model; however, it is found that features such as topography, density of the urbanised areas and rainfall distribution may affect the agreement between both models. The work presented herein is a step forward in understanding the modelling capabilities of the analysed coupled-models, and to some extent may be extrapolated to other models. Research is growing in urban flooding and this work may well prove to be a strong foundation basis for future research.

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Tribe, Andrea S. "Automated recognition of valley heads, valley bottoms and drainage networks from grid digital elevation models." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306257.

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Hiester, Justin. "Investigations into the Regional and Local Timescale Variations of Subglacial Drainage Networks." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1022.

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Subglacial water plays an important role in the regulation of an ice sheet's mass balance. It may be the dominant control on the velocities of ice streams and outlet glaciers on scales of months to millennia. Recent satellite observations of ice surface elevation changes have given researchers new insights into how subglacial water is stored and transported. Localized uplift and settling of the ice surface implies that lakes exist beneath the ice sheet that are being filled and drained on relatively short time scales. %At the base of an ice sheet water can be transported through a variety of drainage networks or stored in subglacial lakes. Here, a numerical investigation of the mechanisms of transport and storage of subglacial water and the associated time scales is presented. Experiments are carried out using a finite element model of coupled ice and water flow. The first experiment seeks to understand the relationship between the depth of a basal depression and the area over which the feature affects basal water flow. It is found that as the perturbation to a topographic depression's depth is increased, water is rerouted in response to the perturbation. Additionally it is found that the relationship between perturbation depth and the extent upstream to which its effects reach is nonlinear. The second experiment examines how the aspect ratio of bed features (prolate, oblate, or equidimensional) influences basal water flow. It is found that the systems that develop and their interactions are mediated by both the topography and the feedbacks taken into account by the coupling of the systems in the model. Features oriented parallel to ice and water flow are associated with distributed fan systems that develop branches which migrate laterally across the domain and interact with one another on monthly and yearly timescales. Laterally oriented features develop laterally extensive ponds. As the ratio of longitudinal to lateral dimension of the topography is increased, a combination of these two water distributions is seen.

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Salazar, Osvaldo. "Modelling water discharge and nitrogen loads from drained agricultural land at field and watershed scale /." Uppsala : Department of Soil and Environment, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200932.pdf.

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Bhadra, Sourav. "Assessing the Impacts of Anthropogenic Drainage Structures on Hydrologic Connectivity Using High-Resolution Digital Elevation Models." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2573.

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Stream flowline delineation from high-resolution digital elevation models (HRDEMs) can be problematic due to the fine representation of terrain features as well as anthropogenic drainage structures (e.g., bridges, culverts) within the grid surface. The anthropogenic drainage structures (ADS) may create digital dams while delineating stream flowlines from HRDEMs. The study assessed the effects of ADS locations, spatial resolution (ranged from 1m to 10m), depression processing methods, and flow direction algorithms (D8, D-Infinity, and MFD-md) on hydrologic connectivity through digital dams using HRDEMs in Nebraska. The assessment was conducted based on the offset distances between modeled stream flowlines and original ADS locations using kernel density estimation (KDE) and calculated frequency of ADS samples within offset distances. Three major depression processing techniques (i.e., depression filling, stream breaching, and stream burning) were considered for this study. Finally, an automated method, constrained burning was proposed for HRDEMs which utilizes ancillary datasets to create underneath stream crossings at possible ADS locations and perform DEM reconditioning. The results suggest that coarser resolution DEMs with depression filling and breaching can produce better hydrologic connectivity through ADS compared with finer resolution DEMs with different flow direction algorithms. It was also found that stream burning with known stream crossings at ADS locations outperformed depression filling and breaching techniques for HRDEMs in terms of hydrologic connectivity. The flow direction algorithms combining with depression filling and breaching techniques do not have significant effects on the hydrologic connectivity of modeled stream flowlines. However, for stream burning methods, D8 was found as the best performing flow direction algorithm in HRDEMs with statistical significance. The stream flowlines delineated using the proposed constrained burning method from the HRDEM was found better than depression filling and breaching techniques. This method has an overall accuracy of 78.82% in detecting possible ADS locations within the study area.

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Galbetti, Marcus Vinícius. "Comparação dos modelos hidrológicos presentes no SSD ABC6 aplicados a uma bacia urbana." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-12082015-155640/.

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No Brasil, o processo de urbanização caracterizou-se pela falta de planejamento e infraestrutura adequada, potencializando os impactos advindos das enchentes e inundações. Para mitigá-los, é necessária a realização de estudos hidrológicos que busquem compreender e representar o comportamento da bacia hidrográfica frente aos eventos chuvosos. Uma das ferramentas mais utilizadas para a execução dessa tarefa são os Sistemas de Suporte à Decisão (SSDs) aplicados na área de recursos hídricos, destacando-se o Sistema de Suporte a Decisões para Análise de Ondas de Cheias em Bacias Complexas (ABC6). O ABC6 caracteriza-se por ser um software brasileiro, gratuito e apresentar diversos modelos de determinação da precipitação efetiva e de geração de hidrogramas sintéticos. Quando os dados hidrológicos da área de estudo, como precipitação e vazão, encontram-se disponíveis, os parâmetros desses modelos podem ser determinados. Caso contrário, faz-se necessário estima-los por meio de formulações empíricas, sendo questionável a aplicação dessas formulações em áreas com características diferentes às de sua determinação. Dessa forma, a proposta do presente trabalho consistiu em avaliar o desempenho dos modelos presentes no ABC6, utilizando suas formulações empíricas para estimar o tempo de concentração e os parâmetros dos modelos de precipitação efetiva e de geração de hidrogramas sintéticos de uma bacia hidrográfica em processo de urbanização. Os resultados obtidos colocaram em xeque a validade dos valores dos parâmetros sugeridos em literatura técnica, do modelo do SCS para a determinação da precipitação efetiva e das rotinas de cálculo do ABC6 para os modelos de Horton e de Green-Ampt. Os resultados demonstraram a necessidade da atualização das rotinas de cálculo presentes no ABC6, de forma a torna-lo mais robusto, e da elaboração de um manual técnico detalhado de suas rotinas computacionais, orientando ao usuário de forma a extrair o máximo de sua potencialidade em estudos hidrológicos. Demonstrou-se, também, a necessidade de estudos regionalizados, de forma a incorporar as características e peculiaridades de cada região aos parâmetros a serem utilizados.
In Brazil, the urbanization process was characterized by the lack of planning and adequate infrastructure, strengthening the arising of floods and flooding. In order to mitigate them, it is necessary to conduct hydrological studies that seek to understand and represent the behavior of the watershed when facing rainfall events. One of the most used tools to perform this task is the Decision Support Systems (DSS) applied in the water resources area, highlighting the Decision Support System for Flood Wave Analysis in Complex Watersheds (ABC6). The ABC6 is characterized by being a free Brazilian software and it presents many models to determine the effective precipitation and to generate synthetic hydrographs. When the hydrological data of the study area are available, such as precipitation and flow, the models parameters can be determined. Otherwise, it is necessary to estimate them through empirical formulations so that the application of these formulations is questionable in areas with different characteristics from those of their determination. Thus, the purpose of this study was to assess the performance of the models presented in ABC6 by using their empirical formulations in order to estimate the time of concentration and the model parameters of effective precipitation and synthetic hydrograph generation for a watershed in the process of urbanization. The results put into question the validity of the parameters values suggested in the technical literature of the SCS model, which is used for the effective precipitation determination and the ABC6 calculation routines for models of Horton and Green-Ampt. The results presented the need of updating the calculation routines presented in the ABC6 in order to make it more robust, and the need of the elaboration of a detailed technical manual of its computational routines, guiding the user in order to make the most of its potential in hydrological studies. In addition, it has been demonstrated a need for regionalized studies in order to incorporate the features and characteristics of each region to the parameters to be used.

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Campos, Elaine Franco de. "Avaliação da distribuição da chuva nas vazões maximas urbanas usando dados de radar e de pluviografo." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257877.

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Orientador: Abel Maia Genovez
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: A precipitação é um componente do ciclo hidrológico que apresenta grande variabilidade espacial. Postos pluviométricos fornecem registros válidos apenas para um pequeno entorno do instrumento. A baixa densidade e as curtas séries de dados dos postos pluviométricos em bacias brasileiras tem sido fatores determinante nas incertezas dos resultados de diversos modelos hidrológicos que têm sido aplicados no país. Nesse contexto, o estudo de estimativas espaciais de precipitação podem ser extremamente úteis na busca de hidrogramas de projeto. Essas estimativas, embora a precariedade dos dados observados, devem fornecer uma boa noção da distribuição espacial das chuvas. Assim, com este trabalho, utilizam-se as estimativas da distribuição espacial da precipitação, obtidas a partir de dados de radar meteorológico, que são comparados aos dados da rede pluviométrica. Os dados da distribuição espacial da precipitação são usados como dados de entrada do modelo hidrológico distribuído Storm Water Management Model (SWMM), o qual foi aplicado a uma pequena bacia urbana da cidade de Campinas - SP, com área de drenagem de 7,59 km2. Os resultados são analisados comparando os hidrogramas simulados com os observados. Foram realizados estudos de caso na Bacia Hidrográfica Ralph Stettinger pertencente à Bacia do Ribeirão das Anhumas, na cidade de Campinas, estado de São Paulo, Brasil, que conta com boa rede pluviométrica para aferir as estimativas da distribuição espacial da chuva e com dados fluviométricos de várias enchentes ocorridas na bacia. Os dados de radar utilizados foram os do radar meteoro lógico localizado na cidade de São Paulo. A precipitação acumulada estimada pelo radar meteorológico para os nove eventos representou satisfatoriamente a chuva, quando comparados com os valores medidos nas estações pluviográficas, na qual, as diferenças obtiveram valor médio de 28%. Os hidrogramas resultantes da aplicação dos dados de radar reproduziram resultados satisfatórios se comparados aos resultados gerados pelo uso de dados de pluviógrafos, pois o coeficiente de eficiência obtido usando dados de radar foi de 0,69, já o coeficiente de eficiência encontrado usando dados de pluviógrafos foi de 0,85.
Abstract: The precipitation is one variable of the hydrological cycle that shows a large spatial variability. Conventional rain gauges only provide valid records from the positions next to the instrument. The low density of rainfall data recording posts in Brazilian watersheds has been the determinant factor of the uncertainties on the results of various hydrological models that have been applied in this country. In this context, the study of spatial estimates of precipitation can be extremely useful to find more accurate hydrographs of projects. These estimates, despite these poor data observed, may provide a good knowledge of the spatial rain distribution at the environment. With this study, the estimates of the spatial distribution of precipitation, using a weather radar, may be compared with the rainfall data from the recording stations. The data of the spatial distribution of precipitation is used as an input at the distributed hydrological model "Storm Water Management Model (SWMM)", which was applied to a urban watershed in the city Campinas - SP, with a drainage area in about 7,59 km2. The results are analyzed by comparing , the simulated hydrographs to observed flow rates. Studies of case were made in the watershed Ralph Stettinger belonging to Ribeirão das Anhumas watershed, which has a good pluviometric record to measure the estimates of the spatial distribution of rainfall and with tluviometric data from several flooding, occurred in this watershed. The radar data used was from the weather radar located in the city of São Paulo. The accumulated precipitation that the weather radar predicted for the nine events, represented the rain as well when compared with the values already measured in the rain gauges, which the average value differences was 28%. The resultant hydrographs of the application of radar data reproduced satisfactofy results if compared to the generated results by the rain gauges, because the obtained efficiency coefficient using radar data was 0,69, otherwise, the efficiency coefficient that was found using rain gauges data was 0,85.
Universidade Estadual de Campi
Recursos Hidricos, Energeticos e Ambientais
Mestre em Engenharia Civil

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Mohammadighavam, S. (Shahram). "Hydrological and hydraulic design of peatland drainage and water treatment systems for optimal control of diffuse pollution." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526214511.

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Abstract Peatland drainage for forestry, agriculture and peat extraction results in runoff rich in organic matter, sediments and nutrients. This has a significant effect on downstream ecosystems. Therefore, water purification using sedimentation basins and wetlands is required in environmental permits for peat extraction in Finland, to reduce downstream impacts. Due to increasingly strict environmental regulations, more advanced water purification methods need to be developed. Using field measurements, laboratory experiments and hydrological/hydraulic modelling, this thesis sought to develop new methods based on: i) more refined hydrological information related to runoff and pollutant load control and ii) hydraulic design of sedimentation basins used in chemical purification. The hydrology of three peatland forestry and two drained peat extraction areas in northern Finland was studied and simulated using the DRAINMOD 6.1 hydrological model. Watertable depth (WTD) and drainage outflow were recorded continuously during several years and the data were used for model calibration and validation. Despite some under- and over-estimation of certain events, WTD fluctuations were simulated quite accurately for all peatland areas. The results demonstrated that DRAINMOD 6.1 can satisfactorily simulate WTD fluctuations in a cold climate such as northern Finland, but the model did not simulate drainage outflow adequately. Chemical treatment facilities were optimised using 3D computational fluid dynamic (CFD) models. COMSOL Multiphysics 5.1 was employed to evaluate the influence of inlet design on treatment efficiency in commonly used treatment basins without any barrier, and for optimization of barrier design through gravity-driven hydraulic ﬂocculators. The results showed that inlet design had a significant effect on treatment efficiency. Several barrier designs were simulated and the best combination was tested for different distances between barriers, to find a geometry ratio and flow depth producing optimal mixing conditions for the treatment process
Tiivistelmä Turvemaiden ojitus metsätaloutta, maataloutta ja turvetuotantoa varten lisää orgaanisen aineen, kiintoaineineen ja ravinteiden huuhtoutumista alapuolisiin vesistöihin. Lisääntyneellä kuormituksella voi olla merkittäviä vaikutuksia vesiekosysteemeihin, minkä vuoksi turvetuotannon ympäristöluvissa vaaditaan valumavesien puhdistamista mm. laskeutusaltaiden ja pintavalutuskenttien avulla. Tiukentuneiden vesiensuojelumääräysten vuoksi tarvitaan uusia vesiensuojelumenetelmiä sekä tulee tehostaa jo käytössä olevien menetelmien toimintaa. Tämän työn tavoitteena on suositella uusia menetelmiä perustuen I) entistä tarkempaan hydrologiseen tietoon valunnasta ja vesistökuormituksesta ja II) kemiallisen vesienpuhdistuksen yhteydessä käytettävien laskeutusaltaiden hydrauliseen suunnitteluun. Tämä väitöstyö rakentuu maastossa ja laboratoriossa tehtyjen tutkimusten sekä hydrologisen/hydraulisen mallinnuksen varaan. Valuma-alueiden hydrologiaa tutkittiin ja mallinnettiin kolmella turvemetsäalueella ja kahdella turvetuotantoalueella Pohjois-Suomessa. Ojituksen hydrologisten vaikutusten arviointiin käytettiin DRAINMOD 6.1 ohjelmaa, jonka kalibrointia ja validointia varten kerättiin jatkuvatoimisilla antureilla aineistoa pohjaveden pinnankorkeuksista ja virtaamasta useiden vuosien ajalta. Mallin avulla voitiin pohjaveden pinnan vaihtelut kuvata yleisesti melko hyvin kaikilla tutkimusalueilla yksittäisistä sadanta-valuntatapahtuminen yli- tai aliarvioinneista huolimatta. Saadut tulokset osoittavat, että DRAINMOD 6.1 ohjelmalla voidaan riittävällä tarkkuudella simuloida pohjaveden pinnan vaihteluita kylmässä ilmastossa, kuten Pohjois-Suomessa, mutta malli ei soveltunut hyvin ojitusalueelta lähtevän valunnan tarkkaan määrittämiseen. Kemiallisen vesienpuhdistusrakenteiden optimointiin käytettiin COMSOL Multiphysics 5.1 ohjelmaa, jolla voidaan toteuttaa ja laskea veden virtauksia kolmessa dimensiossa (computational fluid dynamic, CFD, model). Mallilla arvioitiin kemikalointialtaan tuloaukon rakenteen vaikutuksia tyypillisesti kemikaloinnissa käytetyn allasrakenteen puhdistustehokkuuteen. Lisäksi mallilla mitoitettiin virtausesteitä optimaalisen sekoittumisolosuhteiden saamiseksi ja puhdistustehokkuuden parantamiseksi painovoimaisesti toimivissa flokkausaltaissa (hidas sekoitus). Saadut tulokset osoittavat, että laskeutusaltaiden tuloaukon rakenteella on merkittävä vaikutus kemikaloinnissa saavutettuun puhdistustehokkuuteen. Lisäksi työssä esitettiin optimaalisia virtausesteiden mitoituksia (geometria, esteiden välinen etäisyys, virtaussyvyys yms.) puhdistuksen kannalta parhaiden mahdollisten sekoitusolosuhteiden saavuttamiseksi

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Rahman, Mohammed Mizanur. "Application of SWAT for Impact Analysis of Subsurface Drainage on Streamflows in a Snow Dominated Watershed." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29555.

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The wet weather pattern since the early 1990's has created two problems for the people living in the Red River Valley (RRV): (1) wet field conditions for farmers and (2) more frequent major spring floods in the Red River system. Farmers in the region are increasingly adopting subsurface drainage practice to remove excess water from their fields to mitigate the first problem. However, it is not clear whether subsurface drainage will deteriorate or mitigate the spring flood situation, the second problem. The Soil and Water Assessment Tool (SWAT) model was applied to evaluate the impacts of tile drainage on the Red River's streamflows. The model was calibrated and validated against monthly streamflows at the watershed scale and against daily tile flows at the field scale. The locations and areas of the existing and potential tile drained (PTD) areas were identified using a GIS based decision tree classification method. The existing and maximum PTD areas were found to be about 0.75 and 17.40% of the basin area, respectively. At the field scale, the range of Nash-Sutcliffe efficiency (NSE) for model calibration and validation was 0.34-0.63. At the watershed scale, the model showed satisfactory performance in simulating monthly streamflows with NSE ranging from 0.69 to 0.99, except that the model under-predicted the highest spring flood peak flows in three years. The results of modeling a 100% tiled experimental field showed that about 30-40% of water yield was produced as tile flow. Surface runoff and soil water content decreased about 34% and 19%, respectively, due to tile drainage. However, the impact of subsurface drainage on evapotranspiration (ET) and water yield was mixed. ET slightly decreased in a wet year and slightly increased in a dry year, while the pattern for water yield was opposite to that of ET. The watershed-scaled modeling results showed that a tiling rate of 0.75-5.70% would not have significant effects on the monthly average streamflows in the Red River at Fargo. For the 17.40% tiling rate, the streamflow in the Red River at Fargo might increase up to 1% in April and about 2% in Fall (September to November), while decreasing up to 5% in the remaining months. This SWAT modeling study helped to better understand the impact of subsurface drainage on the water balance and streamflows in the Red River of the North basin. The findings will also help watershed managers in making decisions for the purpose of managing agricultural drainage development in the RRV and other snow dominated watersheds around the world.

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Burgholzer, Robert William. "Using Accumulation Based Network Identification Methods to Identify Hill Slope Scale Drainage Networks in a Raster GIS." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32001.

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The simple accumulation-based network identification method (ANIM) in a raster Geographic Information System (GIS) posed by Oâ Callaghan and Mark (1984) has been criticized for producing a spatially uniform drainage density (Tarboton 2002) at the watershed scale. This criticism casts doubt on the use of ANIMs for deriving properties such as overland flow length for nonpoint source pollution models, without calibrating the accumulation threshold value. However, the basic assumption that underlies ANIMs is that convergent topography will yield a more rapid accumulation of cells, and thus, more extensive flow networks, with divergent, or planar terrain yielding sparser networks. Previous studies have focused on networks that are coarser than the hill-slope scale, and have relied upon visual inspection of drainage networks to suggest that ANIMs lack the ability to produce diverse networks. In this study overland flow lengths were calculated on a sub-watershed basis, with standard deviation, and range calculated for sub-watershed populations as a means of quantifying the diversity of overland flow lengths produced by ANIM at the hill slope scale. Linear regression and Spearman ranking analyses were used to determine if the methods represented trends in overland flow length as suggested by manual delineation of contour lines. Three ANIMs were analyzed: the flow accumulation method (Oâ Callaghan and Mark, 1984), the terrain curvature method (Tarboton, 2000) and the ridge accumulation method (introduced in this study). All three methods were shown to produce non-zero standard deviations and ranges using a single support area threshold, with the terrain curvature method producing the most diverse networks, followed by the ridge accumulation method, and then the flow accumulation method. At an analysis unit size of 20 ha, the terrain curvature method produced a standard deviation that was most similar to those suggested by the contour crenulations, -13.5%, followed by the ridge accumulation method, -21.5%, and the flow accumulation method, -61.6%. The ridge accumulation produced the most similar range, -19.1%, followed by terrain curvature, -24.9%, and flow accumulation, -65.4%. While the flow accumulation networks had a much narrower range of predicted flow lengths, it had the highest Spearman ranking coefficient, Rs=0.722, and linear regression coefficient, R2=0.602. The terrain curvature method was second, Rs=0.641, R2=0.469, and then ridge accumulation, Rs=0.602, R2=0.490. For all methods, as threshold values were varied, areas of dissimilar morphology (as evidenced by the common stream metric stream frequency) experienced changes in overland flow lengths at different rates. This results in an inconsistency in ranking of sub-watersheds at different thresholds. When thresholds were varied to produce average overland flow lengths from 75 m to 150 m, the terrain curvature method showed the lowest incidence of rank change, 16.05%, followed by the ridge accumulation method, 16.73%, then flow accumulation, 25.18%. The results of this investigation suggest that for all three methods, a causal relationship exists between threshold area, underlying morphology, and predicted overland flow length. This causal relationship enables ANIMs to represent contour network trends in overland flow length with a single threshold value, but also results in the introduction of rank change error as threshold values are varied. Calibration of threshold value (varying threshold in order to better match observed overland flow lengths) is an effective means of increasing the accuracy of ANIM predictions, and may be necessary when comparing areas with different stream frequencies. It was shown that the flow accumulation method produces less diverse networks than the terrain curvature and ridge accumulation methods. However, the results of rank and regression analyses suggest that further investigation is required to determine if these more diverse ANIM are in fact more accurate than the flow accumulation method.
Master of Science

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Desmond, Eric D. "Studies including hydrologic modeling and data analysis at the Ohio management systems evaluation." Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1070465699.

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Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xvii, 104 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Andy Ward, Dept.of Food, Agricultural, and Biological Engineering. Includes bibliographical references (p. 100-104).

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CARVALHO, Maíra de. "Calibração de modelos de drenagem urbana utilizando algoritmos evolucionários multiobjetivo." Universidade Federal de Goiás, 2011. http://repositorio.bc.ufg.br/tede/handle/tde/613.

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CARVALHO, M. Calibration models of urban drainage using multiobjective evolutionary algorithms. 2011. Dissertation (Masters of Environmental Engineering) - Civil Engineering College, Post-Graduation Stricto Sensu Program in Environmental Engineering - Federal University of Goiás, Goiânia, Goiás, Brazil, 2011.. This study proposed to develop and implement a calibration routine hydrological models applied to urban drainage using multiobjective optimization techniques. To make this work possible model was adopted Storm Water Management Model (SWMM) and the computational algorithms developed in MATLAB environment using an evolutionary algorithm. The method was applied to two different levels of detail in representing the Arroyo Cancels basin, located in the urban area of Santa Maria-RS, submitted to the hydrological processes involved in the process of rainfall-runoff transformation in the search for optimal values of hydrological parameters the basin. Objective functions were defined and applied simultaneously in the calibration parameters. Worked with the simulation of events of low and high intensity settings for two discretization of the watershed, and other simple and subdivided into 18 sub-basins. The sensitivity analysis performed made it possible to check that the parameters that most influenced the basin were simple: Percentage of impervious area and outlet width. Regarding the results for the various watershed discretization can be seen that in most cases when working with a more detailed watershed they were better, except for some isolated events. Overall the model showed better results when high-intensity simulated events for the best compromise solutions, thus showing the importance of using a multiobjective model.
CARVALHO, M. Calibração de modelos de drenagem urbana utilizando algoritmos evolucionários multiobjetivo. 2011. Dissertação (Mestrado em Engenharia do Meio Ambiente) Escola de Engenharia Civil, Programa de Pós-Graduação Stricto Sensu em Engenharia do Meio Ambiente, Universidade Federal de Goiás, Goiânia, 2011. O presente trabalho propôs desenvolver e aplicar uma rotina de calibração de modelos hidrológicos aplicados a drenagem urbana empregando técnicas de otimização multiobjetivo. Para tornar possível a realização deste trabalho foi adotado o modelo Storm Water Management Model (SWMM) e as rotinas computacionais desenvolvidas em ambiente MATLAB, utilizando um algoritmo evolucionário. O método foi aplicado a dois diferentes níveis de detalhamento na representação da bacia do Arroio Cancela, localizada na zona urbana do município de Santa Maria-RS, na busca de valores ótimos de parâmetros hidrológicos da bacia. Foram definidas funções objetivo e aplicadas simultaneamente na calibração de parâmetros. Trabalhou-se com a simulação de eventos de baixa e alta intensidade para duas configurações de bacia hidrográfica, sendo simples e outra subdividida em 18 sub-bacias. A análise de sensibilidade realizada possibilitou a verificação de que os parâmetros que mais influenciaram na bacia simples foram: Porcentagem de área impermeável e Largura do escoamento. Em relação aos resultados para as diferentes configurações de discretização da bacia hidrográfica pode-se verificar que na maioria dos casos quando se trabalhou com uma bacia mais detalhada estes foram melhores, salvo alguns eventos isolados. No geral o modelo apresentou melhores resultados quando simulou eventos de alta intensidade para as soluções de melhor compromisso, assim mostrando a importância da utilização de um modelo multiobjetivo.

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Amikiya, Emmanuel Adoliwine. "Flow and reactive transport processes in porous media." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85838.

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Thesis (MSc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Flow and reactive transport of chemical species is a very common phenomenon that occurs in natural and artificial systems. However in this study, the topic is related to acid mine drainage in the South African mining environment. Due to the hazards associated with acid mine drainage, prevention or treatment of mine effluent water before discharging to receiving waters and other environments is a necessity. A new time-dependent mathematical model is developed for a passive treatment method, based on multi-scale modelling of the coupled physico-chemical processes such as diffusion, convection, reactions and filtration, that are involved in the treatment process. The time-dependent model is simulated on a two-dimensional domain using finite volume discretization to obtain chemical species distributions.
AFRIKAANSE OPSOMMING: Vloei en reagerende transport van chemiese spesies is ’n baie algemene verskynsel wat in natuurlike en kunsmatige stelsels plaasvind. In hierdie studie is die onderwerp egter verwant aan suurmyndreinering in die Suid-Afrikaanse mynbou-omgewing. As gevolg van die gevare wat verband hou met suurmyndreinering, is die voorkoming of die behandeling van die afval-mynwater voor dit in opvangswaters en ander omgewings beland ’n noodsaaklikheid. ’n Nuwe tydafhanklike wiskundige model vir ’n passiewe behandelingsmetode is ontwikkel. Dit is gebaseer op die multi-skaal modulering van gekoppelde fisies-chemiese prosesse soos diffusie, konveksie, reaksies en filtrasie, wat by die behandelingsproses betrokke is. Die tydafhanklike model word gesimuleer op ’n twee-dimensionele domein met behulp van eindige volume diskretisasie om die verspreiding van chemiese spesies te bepaal.

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Van, Heerden George Adrian. "Evaluation of alternatives for hydraulic analysis of sanitary sewer systems." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86534.

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Thesis (MScEng)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: This research project focuses on sanitary sewer systems. When performing an analysis of a sewer drainage system with known constraints, an appropriate model needs to be chosen depending on the objectives of the analysis. Uncertainties are also present in the analysis of sewer drainage systems. The uncertainties and the errors in hydraulic models need to be understood and considered. The required level of accuracy and the type of hydraulic problem that needs to be solved may alter the complexity of the hydraulic model used to solve a drainage system. The wide variety of available simulation models further complicates model selection. With various models available, selecting the most appropriate model for a particular drainage system simulation is important. The various models for sewer drainage system analysis can be categorised in different ways. For example, it is possible to categorise models according to their purpose, which could be evaluation, design or planning. Evaluation models are mainly used to test whether existing systems or planned systems are adequate and require the highest hydraulic detail. Design models are used to determine the size of conduits within a drainage system and require moderate levels of hydraulic detail. Planning models are primarily used for strategic planning and decision making for urban or regional drainage systems and require the least amount of hydraulic detail. An understanding of the available models is required in order to choose the most suitable simulation model for the desired purpose. Some models are derived from the Saint-Venant equations of flow. The most detailed models are typically referred to as fully dynamic wave models and utilise all the components of the Saint-Venant flow equations. By removing terms from the Saint-Venant equations a kinematic wave model can be created. Some less complex models ignore basic principles of hydraulics in order to make assumptions that simplify the process of simulating flows. In this thesis three different models were compared: a detailed model using fully dynamic flow equations, a simplified model using kinematic wave equations and a basic model using contributor hydrograph routing equations. For the drainage system analysis SWMM-EXTRAN was used as the fully dynamic wave model, SWMM-TRANSPORT was used as the kinematic wave model and SEWSAN was used as the contributor hydrograph model. Two drainage systems situated in South Africa were used as case studies and are referred to as Drainage System A and Drainage System B in this thesis. The actual flow rate was recorded at two points with flow loggers, one in each of the two systems. The flow rate was continually recorded at 1 hour intervals for the period 1 July 2010 to 9 July 2010 in Drainage System A as well as in Drainage System B. The same input parameters were used for each model allowing the modelled flow rates to be compared to the measured flow rates. The models provided peak flow results that were within 2% of the measured peak flow rates and the modelled mean flows were within 8.5% of the measured mean flows in most situations. However, when rapidly varied flows occurred the kinematic wave and contributor hydrograph models returned conservative results as they were unable to account for hydraulic effects such as acceleration. The effect of acceleration became most pronounced up and downstream of drop structures and sections where the slope changed considerably. The kinematic wave and contributor hydrograph models were therefore unable to accurately simulate surcharge conditions. The results suggest that the fully dynamic wave model can be used in all scenarios. The kinematic wave model can be used for a design analysis if no hydraulic structures occur in the system. The contributor hydrograph model should not be used for an evaluation analysis, but can be used for a design analysis if a relatively high level of confidence in the parameter set exists and no areas of rapidly varying flow or hydraulic structures exist within the system.
AFRIKAANSE OPSOMMING: Hierdie navorsing projek is gefokus op riool dreineringsisteme. Wanneer ŉ analise van ŉ riool dreineringsisteem met bekende beperkinge onderneem word, moet ŉ geskikte model gekies word afhangende van die doelwitte van die analise. Onbekendes is ook teenwoordig in die analise van riool dreineringsisteme. Dit word belangrik dat die onsekerhede en die foute in hidroliese modelle moet verstaan en oorweeg word. Die verwagte vlak van akkuraatheid en die tipe hidroliese probleem wat opgelos moet word mag die ingewikkeldheid van die hidroliese probleem, wat gebruik word om ŉ rioolsisteem op te los, verander. Die wye verskeidenheid van beskikbare simulasie modelle bemoeilik verder die keuse van ŉ model. Met etlike modelle beskikbaar vir seleksie, is die mees geskikte model vir ŉ spesifieke dreineringsisteem simulasie belangrik. Die verskeie modelle vir riool dreineringsisteem analise kan op verskillende wyses gekategoriseer word. Byvoorbeeld, dit is moontlik om modelle te kategoriseer volgens hulle doel, wat evaluasie, ontwerp en beplanning kan wees. Evaluasiemodelle word hoofsaaklik gebruik om te toets of huidige of beplande sisteme voldoende is en of hulle die hoogs moontlike hidroliese besonderhede benodig. Ontwerpmodelle word gebruik om die grootte van ŉ leipyp binne ŉ rioolsisteem te bepaal en benodig matige vlakke van hidroliese besonderhede. Beplanningsmodelle word hoofsaaklik gebruik vir strategiese beplanning en besluitneming vir stedelike en landelike rioolsisteme en benodig die laagste vlak van hidroliese data. ŉ Begrip van die beskikbare modelle is nodig om ŉ keuse te maak rakende die mees geskikte simulasie model vir die verlangde doelwit. Sommige modelle is afkomstig van die Saint-Venant vergelykings van vloei. Die mees gedetailleerde modelle word tipies na verwys as die volledige dinamiese golf modelle en benut alle komponente van die Saint-Venant vloei vergelykings. Deur die verwydering van terme van die Saint-Venant vergelykings kan ŉ kinematiese golf model daargestel word. Sommige minder gekompliseerde modelle ignoreer die basiese beginsels van hidrologie om aannames te maak wat die proses van golf simulering vereenvoudig. In hierdie tesis is drie verskillende modelle vergelyk; ŉ gedetailleerde model wat volledige dinamiese vloeivergelykings gebruik; ŉ vereenvoudigde model wat kinematiese golfvergelykings gebruik en ŉ basiese model wat bydraende hidroliese versending vergelykings. Vir die dreineringsisteem analise was SWMM-EXTRAN gebruik as die volledige dinamiese golfmodel, SWMM-TRANSPORT was gebruik as die kinetiese golfmodel en SEWSAN was gebruik as die bydraende hidroliese model. Twee dreineringsisteme in Suid-Afrika was gebruik as gevallestudies en word na verwys as Dreineringsisteem A en Dreineringsisteem B. Die werklike vloeikoers was aangeteken by twee punte met vloeimeters, een in elk van die sisteme. Die vloeikoers was deurlopend opgeteken met 1 uur tussenposes vir die periode 1 Julie 2010 tot 9 Julie 2010 in Dreinering Sisteem A sowel as Dreinering Sisteem B. Dieselfde inset parameters was gebruik vir elke model wat dit moontlik gemaak het dat die gemoduleerde vloeikoerse met die gemete vloeikoerse vergelyk kon word. Die modelle het spits vloeiresultate voorsien wat binne 2% van die gemete spits vloeikoerse was en, in die meeste situasies, dat die gemoduleerde gemiddelde vloei binne 8.5% van die gemete gemiddelde vloei was. Wanneer vinnig varierende vloei voorgekom het, die kinetiese golf and bydraende hidrograaf modelle konserwatiewe resultate gelewer het, aangesien hulle nie in staat was om hidroliese effekte soos versnelling te verklaar nie. Die effek van versnelling was op sy duidelikste stroomopwaarts en stroomafwaarts onder valstrukture en by gedeeltes waar die helling aansienlik verander het. Die kinetiese golf en bydraer hidrograaf modelle was gevolglik nie in staat om oorladingsomstandighede akkuraat te simuleer nie. Die resultate wys dat die volledige dinamiese vloeimiddel gebruik kan word in alle omstandighede. Die kinematiese vloeimiddel kan gebruik word vir ŉ ontwerp analise indien geen hidroliese struktuur in die sisteem voorkom nie. Die bydraer hidrograaf model behoort nie gebruik te word vir ŉ evaluerings analise nie, maar kan gebruik word vir ŉ ontwerp analise indien ŉ relatiewe hoë vlak van vertroue in die parameter stel bestaan en geen area van vinnig veranderende vloei of hidroliese strukture binne die sisteem bestaan nie.

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22

Vercueil, Didier. "Etude de la liquéfaction de matériaux composites sols-géotextiles : application au génie parasismique." Grenoble 1, 1997. http://www.theses.fr/1997GRE10237.

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La liquefaction des sables fins satures est un phenomene rheologique extremement spectaculaire et tres dangereux en zone d'activite sismique, parce qu'il est responsable a travers le monde de nombreux degats d'ampleur difficilement previsible. L'implantation d'un reseau de bandes textiles au sein du sol pourrait contribuer a lutter efficacement contre ce phenomene. La partie a) rappelle le mecanisme et la rheologie du phenomene de liquefaction mis en evidence en laboratoire, et le parti qu'on peut tirer d'un composite sol-geotextile pour attenuer le potentiel de liquefaction sur un site de projet. La partie b) presente tout d'abord les equipements specifiques concus et mis au point pour etudier la resistance cyclique du composite sol-geotextile. Les analyses respectives, de l'etat de contrainte a l'interface sol-inclusion et de la distribution des pressions interstitielles au sein du materiau renforce permettent de comprendre le mecanisme induit par les inclusions de geotextile. La partie c) propose une approche numerique du role de geotextiles drainants sous action sismique. La resolution numerique par la methodes des elements finis montrent que des geotextiles compressibles-drainants, mis en place a la maniere des drains verticaux contribuent a augmenter la securite du site en cas de seisme.

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23

Henrichs, Malte. "Einfluss von Unsicherheiten auf die Kalibrierung urban-hydrologischer Modelle." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-181398.

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Der Einsatz von hydrologischen Modellen zur Unterstützung von Planung und Betrieb von Entwässerungssystemen ist als Stand der Technik anzusehen. Realitätsnahe und sichere Modellergebnisse stellen dabei die Grundlage für eine zielgerichtete Entscheidungsfindung dar. Nur durch eine Kalibrierung können Parameter von konzeptionellen Modellen zur Berechnung des Niederschlag-Abfluss-Prozesses an die Randbedingungen des zu simulierenden technischen oder natürlichen Systems angepasst werden. Auch wenn die Kalibrierung eines Modells entscheidend zur Erhöhung der Realitätsnähe beiträgt, kann diese durch unterschiedliche Faktoren beeinflusst werden. Dies ist darauf zurückzuführen, dass bei hydrologischen Modellen nicht ausschließlich deterministische Gleichungen mit physikalisch basierten Parametern eingesetzt werden. Wesentliche Einflussfaktoren auf die Kalibrierung von urbanhydrologischen Modellen sind die gewählte Modellstruktur, die Eingangsdaten, die Kalibrierdaten, die Auswahl von Kalibrierereignissen sowie die eigentliche Kalibriermethodik. Im Rahmen dieser Arbeit wurden die Einflüsse der Kalibrierdaten, der Auswahl von Ereignissen und der Kalibriermethodik auf die Ergebnisse der automatischen Kalibrierung mittels multikriterieller Optimierungsverfahren untersucht.

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24

Sivertun, Åke. "Geographical Information Systems (GIS) as a tool for analysis and communications of multidimensional data." Doctoral thesis, Umeå universitet, Institutionen för geografi och ekonomisk historia, 1993. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-100703.

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An integrating approach, including knowledge about whole systems of processes, is essential in order to reach both development and environmental protection goals. In this thesis Geographical Information Systems (GIS) are suggested as a tool to realise such integrated models. The main hypothesis in this work is that several natural technical and social systems that share a time-space can be compared and analysed in a GIS. My first objective was to analyze how GIS can support research, planning, and, more specifically, bring a broad scattering of competence together in an interdisciplinary process. In this process GIS was ivestigated as a tool to achieve models that give us a better overview of a problem, a better understanding for the processes involved, aid in foreseeing conflicts between interests, find ecological limits and assist in choosing countermeasures and monitor the result of different programs. The second objective concerns the requirement that models should be comparable and possible to include in other models and that they can be communicated to planners, politicians and the public. For this reason the possibilities to communicate the result and model components of multidimensional and multi-temporal data are investigated. Four examples on the possibilities and problems when using GIS in interdisciplinary studies are presented. In the examples, water plays a central role as a component in questions about development, management and environmental impact. The first articles focus on non-point source pollutants as a problem under growing attention when the big industrial and municipal point sources are brought under control. To manage non-point source pollutants, detailed knowledge about local conditions is required to facilitate precise advices on land use. To estimate the flow of metals and N(itrogen) in an area it is important to identify the soil moisture. Soil moisture changes over time but also significantly in the landscape according to several factors. Here a method is presented that calculate soil moisture over large areas. Man as a hydrologie factor has to be assessed to also understand the relative importance of anthropogen processes. To offer a supplement to direct measurements and add anthropogen factors, a GIS model is presented that takes soil-type, topography, vegetation, land-use, agricultural drainage and relative position in the watershed into account. A method to analyse and visualise development over time and space in the same model is presented in the last empirical study. The development of agricultural drainage can be discussed as a product of several forces here analyzed together and visualized with help of colour coded "Hyper pixels" and maps. Finally a discussion concerning the physiological and psychological possibilities to communicate multidimensional phenomena with the help of pictures and maps is held. The main conclusions in this theses are that GIS offer the possibilities to develop distributed models, e.g., models that calculate effects from a vide range of factors in larger areas and with a much higher spatial resolution than has been possible earlier. GIS also offer a possibility to integrate and communicate information from different disciplines to scientists, decision makers and the public.

Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 6 uppsatser.

digitalisering@umu

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25

Hackwell, Stuart G. "Verification of an agricultural land drainage model." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61699.

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26

Bertram, Douglas George. "Developing an integrated urban drainage model and proxy-model methodologies." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6405/.

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Surface water flooding due to the inadequacy of local drainage is a significant UK concern (DEFRA, 2005; POST, 2007). Urban flood modelling and mapping are typified by characteristic terrain difficulties (Charteris et al., 2001). These difficulties include topographic complexity (road crests and gutters; raised house pads); infrastructure (including houses, fences, garden beds, etc); and, complex underground pipe networks (Charteris et al., 2001; Mark et al., 2004a & b; Hunter et al., 2008; Neelz & Pender, 2007; Syme 2008). Designed to mitigate surface waters, drainage systems play a central role and include key features such as sewer pipes, kerbside gutter channels, gully pots and drains. These systems are often highly complex and spatially varied, simultaneously representing alternate flood pathways, hydraulic sinks and, potentially, additional flood sources (DEFRA, 2005). Accurate flood mapping (DEFRA, 2012) requires data rich modelling and, potentially, dynamic linking of models to form an integrated representation of urban surface and subsurface systems (DEFRA, 2005). Predicted data serves to estimate potential physical impacts, assessing likely damage to buildings and urban infrastructure (Kelman & Spence, 2004); or enhancing mapping further with peak velocities to provide detailed assessment of hazards to people (DEFRA, 2006; 2012). However such Integrated Urban Drainage (IUD; Gill, 2008) approaches are resource expensive (time and data requirements). Research into approaches offering more efficient representations is considered essential and timely. Therefore, the possible inclusion of proxy-model approaches offers an alternate tool for rapid hazard appraisal. Using a UK case-study approach, this Thesis addresses IUD modelling deficiencies through two specific aims: (i) examining IUD model development and impact on hazard prediction and, (ii) investigation of more resource-efficient proxy model approaches to the fully Integrated Urban Drainage model. Using TUFLOW hydrodynamic software (WBM, 2008), an IUD model of a dense UK urban area (2 sq km) is developed and examined. Firstly through small-scale IUD modelling showing improved IUD model performance with kerbside drainage and flow capture systems, particularly when based on depth-inflow criteria and, secondly, through enhanced infrastructure representation. Outputs are examined for both fluvial and pluvial source floods of the statutory 1% AEP event (HMSO, 2009). Data indicates significant IUD impact in terms of extent reductions of 56% (fluvial) and 30% (pluvial), and consequently mean peak depth reductions of 33% (fluvial) and 20% (pluvial) flood events. Velocity impacts are shown to be near negligible, recording less than 1% variation for each flood event. Examination of IUD proxy-model approaches identified inappropriate use for fluvial flood event modelling. Pluvial event surface water modelling identified approaches based on a uniformly applied adjustment of the 5% AEP Design Flood Frequency event (BS, 2008) showed most (95%) agreement to the full pluvial IUD model. This Thesis’ outcomes have supported current flood risk modelling and appraisal practice by Capita Symonds and WBM Pty Ltd (TUFLOW authors). Notable recent projects include Hereford, England (2010), Gold Coast City, Australia (2012) and Christchurch, New Zealand (2014).

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Peyrow, Farzad. "Field testing of an agricultural land drainage computer model." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66172.

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28

Kuhn, Eloise M. R. "Microbiology of fly ash-acid mine drainage co-disposal processes." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&amp.

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The waste products acid mine drainage formed during coal mining and fly ash from coal burning power generation, pose substantial environmental and economic problems for South Africa. Eskom has developed a remediation system employing alkaline fly ash to neutralize and precipitate heavy metals from toxic acidic acid mine drainage streams. The aim of this study was to assess the microbial diversity in and microbial impact on this remediation system.

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29

LAMMALI, NASSIMA. "Recherche automatique du reseau hydrographique a l'aide du modele numerique de terrain." Toulouse 3, 1989. http://www.theses.fr/1989TOU30006.

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L'objectif de notre travail est la cartographie automatique du reseau hydrographique a partir d'un modele numerique de terrain (m. N. T. ). Cette etude se place dans le cadre d'un systeme expert en cartographie. Nous presentons deux methodes de recherche du reseau hydrographique. La premiere construit des composantes annexes a partir d'un ensemble de "points de drainage" obtenu a partir de methodes existantes originales et experimentees. Les m. N. T. Presentant beaucoup d'imperfections au niveau des talwegs nous proposons une seconde methode qui permet de pallier a ce probleme; les grandes structures du relief et plus particulierement les "fonds grandes vallees" sont localisees, le reseau hydrographique en sera deduit

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30

Jang, Wonyong. "Unsteady Multiphase Flow Modeling of In-situ Air Sparging System in a Variably Saturated Subsurface Environment." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7517.

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In order to preserve groundwater resources from contamination by volatile organic compounds and to clean up sites contaminated with the compounds, we should understand fate and transport of contaminants in the subsurface systems and physicochemical processes involving remediation technologies. To enhance our understanding, numerical studies were performed on the following topics: (i) multiphase flow and contaminant transport in subsurface environments; (ii) biological transformations of contaminants; (iii) in-situ air sparging (IAS); and, thermal-enhanced venting (TEV). Among VOCs, trichloroethylene (TCE) is one of the most-frequently-detected chemicals in the contaminated groundwater. TCE and its daughter products (cis-1,2-dichloroethylene (cDCE) and vinyl chloride (VC)) are chosen as target contaminants. Density-driven advection of gas phase is generated by the increase in gas density due to vaporization of high-molecular weight contaminants such as TCE in the unsaturated zone. The effect of the density-driven advection on fate and transport of TCE was investigated under several environmental conditions involving infiltration and permeability. Biological transformations of contaminants can generate byproducts, which may become new toxic contaminants in subsurface systems. Sequential biotransformations of TCE, cDCE, and VC are considered herein. Under different reaction rates for two bioreaction kinetics, temporal and spatial concentration profiles of the contaminants were examined to evaluate the effect of biotransformations on multispecies transport. IAS injects clean air into the subsurface below the groundwater table to remediate contaminated groundwater. The movement of gas and the groundwater as a multiphase flow in the saturated zone and the removal of TCE by IAS application were analyzed. Each fluid flow under IAS was examined in terms of saturation levels and fluid velocity profiles in a three-dimensional domain. Several scenarios for IAS systems were simulated to evaluate remedial performance of the systems. TEV was simulated to investigate its efficiency on the removal of a nonaqueous phase liquid in the unsaturated zone under different operational conditions. For numerical studies herein, the governing equations for multiphase flow, multispecies transport, and heat energy in porous media were developed and solved using Galerkin finite element method. A three-dimensional numerical model, called TechFlowMP model, has been developed.

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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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Havard, Peter. "Linkflow, a linked saturated-unsaturated water flow computer model for drainage and subirrigation." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41608.

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A computer simulation model, LINKFLOW, has been developed to simulate the movement of water during various water table management practices, such as subsurface drainage, controlled drainage and subirrigation. Water movement is simulated to, or from, a buried tile drainage system through a heterogeneous and anisotropic soil to a zone of water extraction by plant roots and the atmosphere. The computer package links a newly-developed one-dimensional unsaturated ground water flow model to a three-dimensional saturated water flow model that was modified for the linkage and for simulating water flow under different water table management systems and varying climatic conditions. The movement of water is determined for a region of the field and the model can show the effectiveness of a water table management scheme to meet moisture conditions for crop growth for a wide range of soil, topographical, drain layout and weather conditions. LINKFLOW was validated and verified with measurements on subsurface drainage, controlled drainage and subirrigation systems in a corn field in southwestern Quebec. The model provides a powerful tool for the design and evaluation of water table management systems, and it can assist in developing control strategies for efficient management of water resources. LINKFLOW is unique among soil water models for the following features: (1) it can be used to simulate with varying topography; (2) it determines 3-D flows from drains in a heterogeneous, anisotropic soil; (3) it presents results in tabular format, contour map format, or 3-D surface format; and (4) it contains software routines for automated control in subirrigation. The formation of the conceptual model, numerical relations, methods of solution, validation, field verification and examples are presented.

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Jin, Qinghua. "GASMAK2 model for longwall gob gas emission." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2706.

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Thesis (M.S.)--West Virginia University, 2002.
Title from document title page. Document formatted into pages; contains x, 93 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 71-72).

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Surender, Damini. "Active neutralisation and amelioration of acid mine drainage with fly ash." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6989_1297416088.

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Fly ash and AMD samples were characterised by standard analytical methods for selection of the test materials. Active treatment by means of mixing fly ash with AMD in beakers and a large tank at pre-determined ratios have shown that fly ash is capable of neutralising AMD and increasing the pH beyond neutral values, which optimises the removal of heavy metals and ions. The trend was: the more fly ash added the quicker was the reaction time and higher the pH values achieved. Iron was reduced by as much 99 % in beaker scale experiments via Fe(OH)3 precipitation at pH values >
4.0. A 99 % decrease in aluminium concentration was observed which was attributed to the precipitation of primarily gibbsite and various other mineral phases at pH values >
5.5. As the pH increases, sulphate is adsorbed via Fe(OH)3 and gypsum precipitation at elevated pH. Sulphate attenuation with fly ash was excellent, achieving 98 % attenuation with beaker scale experiments and 1:1 fly ash:AMD ratio. Sulphate attenuation with fly ash was comparable to membrane and ion exchange systems and exceeded the performance of limestone treatment. Except for the larger volumes of fly ash needed to neutralise the AMD, fly ash proved to be a feasible and cost efficient alternative to limestone treatment. Fly ash produced competing results to limestone concerning acidity removal and sulphate attenuation. The comparison highlighted the advantages of utilising fly ash in comparison to limestone and demonstrated its cost effectiveness. The results of this study have shown that fly ash could be successfully applied for the neutralisation of acid mine drainage (AMD) and effectively attenuate the sulphate load in the treated water. The critical parameters to this technology are the variations of chemical composition and mineralogy of fly ash, which could influence the pH, contact time of the neutralisation reaction, and the same is true if the AMD quality varies.

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35

Lee, Seungsoo. "Study on Development of Integrated Urban Inundation Model Incorporating Drainage Systems." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180480.

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Moccellin, Juliana. "Estudo da dinâmica fluvial em duas sub-bacias e proposição de cenários para a sustentabilidade dos recursos hídricos no baixo Ribeira de Iguape, SP." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-13072010-145601/.

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A qualidade da água do século XXI é um dos principais problemas da humanidade em decorrência de atividades de mineração, lançamentos de esgotos domésticos e industriais sem tratamento, utilização de agrotóxicos e pesticidas, retirada da vegetação ripária e depósito de lixo. A gestão dos recursos hídricos engloba, entre outras ações, caracterização ambiental, avaliação dos impactos das atividades instaladas na área de influência, investigação da capacidade de assimilação do corpo receptor, monitoramento ambiental e retroalimentação do processo de gestão como um todo. A proposta deste trabalho foi estudar a dinâmica dos rios Jacupiranguinha, município de Cajati - SP e Pariquera-Açu, município de Pariquera-Açu - SP (Bacia do Rio Ribeira de Iguape) nas diferentes fases do ciclo hidrológico, e propor cenários com vistas à sustentabilidade dos recursos hídricos do Baixo Ribeira de Iguape. Foram medidas variáveis físicas e químicas da água e do sedimento, além da quantidade de coliformes fecais e as estruturas da comunidade bentônica dos rios, além de variáveis climatológicas e hidrológicas. O modelo QUAL2K foi utilizado como ferramenta para diferentes simulações de cenários para a sub-bacia do rio Jacupiranguinha. Os resultados mostraram que os rios sofrem os impactos decorrentes da urbanização tanto com relação ao escoamento superficial urbano quanto com a entrada de efluentes clandestinos e de estações de tratamento. Este fato foi percebido pela alteração da qualidade das águas em relação à concentração de nutrientes e coliformes totais e fecais. Os sedimentos foram classificados como mineral e a constituição granulométrica pode ter contribuído para a estrutura da comunidade de macroinvertebrados que foi maior no rio Pariquera-Açu, pois este possui sedimento mais heterogêneo. A classe Insecta foi representada por maior quantidade de taxa e a família Chironomidae foi a que apresentou maior densidade absoluta de organismos. Estes resultados podem indicar comprometimento da saúde das sub-bacias. Pôde-se constatar através das simulações que a sub-bacia do rio Jacupiranguinha necessita de algumas intervenções em saneamento para a melhoria da qualidade de suas águas e que, para algumas variáveis, o estágio de poluição supera os limites de autodepuração do rio. Neste caso, medidas de conservação já não seriam suficientes, necessitando da implantação de um processo de recuperação da qualidade destas águas.
The twenty-first century water quality is one of the main problems of mankind as a result of mining activities, release of untreated industrial and domestic sewage, use of agrochemicals and pesticides, removal of riparian vegetation and garbage dump. Water resources management includes environmental characterization, impact assessment of activities located in influence area, to investigate the receiving body assimilative capacity, environmental monitoring and feedback management process as a whole. The purpose of this work was to study the dynamics of rivers Jacupiranguinha, Cajati city and Pariquera-Açu, Pariquera-Açu city - Brazil (Ribeira de Iguape River Basin) in different phases of the hydrological cycle, and propose scenarios to water resources sustainability of the Ribeira de Iguape basin. Water and sediment physical and chemical variables, fecal coliforms and benthic community structure of rivers were measured, besides the weather and hydrological conditions. QUAL2K model was used as a tool for simulations of different scenarios for the sub-basin of Jacupiranguinha river. The results showed that the rivers are suffering the impacts of urbanization both in relation to urban runoff as the discharge of illegal domestic effluents and those from treatment stations. This fact was noticed by water quality changes on nutrient concentrations and total and fecal coliforms. The sediments were classified as mineral formation and particle size may have contributed to the benthic community structure which was higher in Pariquera-Açu river, because of its sediment heterogeneity. Insecta was dominant and Chironomidae showed the largest absolute density of organisms. These results may indicate impairment of health of sub-basins. It could be observed through simulations that Jacupiranguinha river needs some assistance in sanitation to improve the quality of its waters and the stage of pollution exceeds the limits of river self-purification. In this case, conservation measures would no longer be sufficient, necessitating the deployment of a recovery process of the quality of these waters.

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37

Damons, Rinaldi Eduardo. "Development of an Aspen model for the treatment of acid mine drainage." Thesis, Cape Technikon, 2001. http://hdl.handle.net/20.500.11838/872.

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Thesis (MTech(Chemical Engineering))--Cape Technikon, Cape Town, 2001
Although numerous methods exist to treat mine water that is rich in CaS04 they all have inherent disadvantages. A means of treating acid mine drainage is by forming a precipitate known as ettringite. Ettringite is a low solubility calcium hydrosulphoaluminate that is stable between pH values of 11.4 and 124. Ettringite is made up of calcium, sulphate, aluminium and a large amount of water. The formation of this precipitate is a result of calcium sulphate which is brought into contact with an aluminium containing agent. Decomposition of ettringite takes place by reducing the pH to a near neutral value. A 5 stage process is proposed to treat acid mine drainage of which the formation of ettringite forms the cornerstone of this process. The process incorporates the formation of more than one precipitate, namely; metal hydroxides, gypsum, CaS04 and CaCOJ. To facilitate the formation of ettringite, gibbsite is recycled as a result of ettringite being decomposed. The results obtained in this paper are as a result of modeling this process on an Aspen Plus simulator. The simulation package is useful for investigating how this process behaves under non-ideal conditions and under various sensitivities. The process and its behavioral patterns are also analyzed in order to ascertain its economic viability.

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38

Harris, Deborah C. "Fremont Site Distribution in the Upper Escalante River Drainage." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2831.pdf.

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39

Saracusa, Emily L. "A Mathematical Model for Acid Mine Drainage Removal and Iron Hydroxide Crust Formation." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1302448347.

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40

Mambo, Mutsa Prudence. "Towards a sustainable bioprocess for the remediation of acid mine drainage." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1006167.

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Acid mine drainage is of growing concern for both developing and developed economies. Thus there is increasing pressure to develop alternative remediation strategies. Biological sulphidogenic mechanisms have long since been studied but, very few have been implemented on a large scale. Limitations are due to the inability to acquire a suitable, low cost, environmentally friendly, renewable carbon source. The present study investigated the use of an algae biomass generated by the HRAOP of an IAPS as a carbon source for the EBRU 00AB/06 SRB consortium. The algae biomass and consortium were utilized together to remediate simulated AMD. Remediation involved decreasing the sulphate and metal concentrations in solution and decreasing the acidity of a simulated AMD. Experiments were carried out to investigate the capability of the EBRU 00AB/06 SRB consortium for sulphate reduction and sulphide generation. The consortium produced colonies when grown under anaerobic conditions in Petri dishes containing modified lactate SRB medium. The SRB consortium reduced the sulphate concentration of modified Postgates medium B and generated sulphide. Further analysis of the EBRU 00AB/06 SRB consortium revealed that the consortium was minimally impacted at pH 5 and by sulphate and iron at 3 g.L-1 and 0.5 g.L-1 respectively. The EBRU 00AB/06 SRB consortium was exposed to Actinomycin D and Ethidium Bromide to determine whether transcription and translation of proteins was required for sulphate reduction. Results indicated that sulphide generation and sulphate reduction were inducible. Analysis of the algae biomass used in this study revealed the empirical formula C1.0H1.91N0.084S0.003O0.36 indicating a carbon source rich in the nutrients required to sustain microbial development. Light microscopy revealed that algae cell walls and in particular those of Pediastrum were susceptible to acid hydrolysis. Dinitrosalicylic acid, Nile red, Bradford and Ninhydrin assays were used to determine the reducing sugar, lipid, protein and amino acid content respectively, of the mixed algae biomass. Results showed that upon exposure of the biomass to simulated AMD at pH 1 and pH 3, the concentration of reducing sugars and amino acids in solution increased. Whereas levels of lipids remained unchanged while the protein concentration decreased, indicating that, upon exposure of algae biomass to AMD, simulated or otherwise, cells ruptured, proteins were hydrolyzed and polysaccharides were broken down to sugars which are immediately available for SRB utilization. Exposure of biomass to simulated AMD revealed further that the presence of algae biomass increased the pH of simulated AMD (pH 3) to pH 7.67 after 4 d. Likewise, the pH of simulated AMD at 1 increased to 1.77 after 2 d while pH of the neutral control increased to 8.1 after 4 d. A direct comparison between lactate and algae biomass revealed 94 % sulphate removal after 23 d in the presence of algae biomass while 82 % sulphate removal was measured in the presence of lactate. Thus the EBRU 00AB/06 SRB consortium successfully utilized algae biomass for sulphate reduction and sulphide generation. In another experiment to establish if the consortium could remediate simulated AMD (pH 5) containing 0.5 g.L-1 iron and 3 g.L-1 sulphate while utilizing an algae biomass as the carbon source no residual iron was detected after 14 d and by day 23, an 89.07 % reduction in sulphate was measured. The results of this investigation are discussed in terms of utilizing a readily available and renewable biomass in the form of microalgae produced in HRAOPs as an effective carbon source in the SRB catalysed remediation of AMD.

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41

Puech, Christian. "Détermination des états de surface par télédétection pour caractériser les écoulements des petits bassins versants : application à des bassins en zone méditerranéenne et en zone tropicale sèche." Grenoble 1, 1993. http://www.theses.fr/1993GRE10175.

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La liaison entre la teledetection des etats de surface et l'hydrologie est etudiee sur deux sites, revelant l'importance des problemes d'echelle et la necessite d'informations hydrologiques de type versant. Sur les bassins du real collobrier (var, france) apres des corrections imposees par le fort relief, le traitement de l'imagerie satellitaire conduit a une cartographie des essences forestieres. La part d'ecoulement relative a chaque zone homogene est calculee a des pas de temps annuel, trimestriel, mensuel et sur des episodes. Une liaison coherente entre zones et types d'ecoulement est obtenue mais la signification exacte de zone homogene, et le manque d'observations hydrologiques de versant rendent la validation delicate. Sur des bassins saheliens, un traitement d'image specifique a des zones heterogenes est mis au point, base sur une detection en deux niveaux: paysage, puis etats de surface type du sahel. Le ruissellement elementaire correspondant est agrege sur le bassin versant selon le modele lineaire de l'orstom. Certaines zones non contributives en grand rendent indispensable une approche complementaire a un autre niveau d'echelle

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42

Gustafsson, Jacob. "Mapping drainage of the rootless shield volcano at Dimmuborgir, northern Iceland." Thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-131405.

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Dimmuborgir is thought to be a former rootless shield volcano, which was fed with lava from a nearby crater row, 2170 ± 38 calendar years before present. In this study, the orientation of striations on the sides of lava channels, collapse structures and lava pillars were measured to find out how the enigmatic ~2 km by 2 km volcanic structure at Dimmuborgir was drained. During one week of field work 149 striations were found and measured, with respect to their dip angle, dip direction and elevation. Their locations were recorded with a GPS (Global Positioning System) receiver. The orientations of the striations were visualized on Google Earth satellite images and on images from a Digital Terrain Model (DTM) of Dimmuborgir. Resulting visualizations show that Dimmuborgir was drained radially and in multiple stages. It is concluded that Dimmuborgir was drained towards the west, the northeast and the southeast. The drainage towards the west was channeled. The drainage towards the northeast and the southeast was radially inwards, towards the collapsed parts of Dimmuborgir.

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43

Moreira, Giuliana Chaves. "Previsão de níveis fluviais em tempo atual com modelo de regressão adaptativo: aplicação na bacia do rio Uruguai." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/147081.

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Este trabalho avaliou o potencial da aplicação da técnica recursiva dos mínimos quadrados (MQR) para o ajuste em tempo atual dos parâmetros de modelos autorregressivos com variáveis exógenas (ARX), as quais são constituídas pelos níveis de montante para melhorar o desempenho das previsões de níveis fluviais em tempo atual. Três aspectos foram estudados em conjunto: variação do alcance escolhido para a previsão, variação da proporção da área controlada em bacias a montante e variação da área da bacia da seção de previsão. A pesquisa foi realizada em três dimensões principais: a) metodológica (sem recursividade; com recursividade; com recursividade e fator de esquecimento); b) temporal (6 alcances diferentes: 10, 24, 34, 48, 58 e 72 horas); e c) espacial (variação da área controlada da bacia e da área da bacia definida pela seção de previsão). A área de estudo escolhida para essa pesquisa foi a bacia do rio Uruguai com exutório no posto fluviométrico de Uruguaiana (190.000 km²) e as suas sub-bacias embutidas de Itaqui (131.000 km²), Passo São Borja (125.000km²), Garruchos (116.000 km²), Porto Lucena (95.200 km²), Alto Uruguai (82.300 km²) e Iraí (61.900 km²). Os dados de níveis fluviométricos, com leituras diárias às 07:00 e às 17:00 horas, foram fornecidos pela Companhia de Pesquisa de Recursos Minerais (CPRM), sendo utilizados os dados de 1/1/1991 a 30/6/2015. Para a análise de desempenho dos modelos, foi aplicado como estatística de qualidade o coeficiente de Nash-Sutcliffe (NS) e o quantil 0,95 dos erros absolutos (EA(0,95): erro que não foi ultrapassado com a frequência de 0,95). Observou-se que os erros EA(0,95) dos melhores modelos obtidos para cada bacia sempre aumentam com a redução da área controlada, ou seja, a qualidade das previsões diminui com o deslocamento da seção de controle de jusante para montante. O ganho na qualidade das previsões com a utilização dos recursos adaptativos torna-se mais evidente, especialmente quando observam-se os valores de EA(0,95), pois esta estatística é mais sensível, com diferenças maiores em relação ao coeficiente NS. Além disso, este é mais representativo para os erros maiores, que ocorrem justamente durante os eventos de inundações. De modo geral, foi observado que, à medida que diminui a área da bacia, é possível obter previsões com alcances cada vez menores. Porém a influência do tamanho da área controlada de bacias a montante melhora o desempenho de bacias menores quando se observam principalmente os erros EA(0,95). Por outro lado, se a proporção da bacia controlada de montante já é bastante grande, como é o caso das alternativas 1 e 2 utilizadas para previsão em Itaqui (entre 88,5% e 95,4 %, respectivamente), os recursos adaptativos não fazem muita diferença na obtenção de melhores resultados. Todavia, quando se observam bacias com menores áreas de montante controladas, como é o caso de Porto Lucena para a alternativa 2 (65% de área controlada), o ganho no desempenho dos modelos com a utilização dos recursos adaptativos completos (MQR+f.e: mínimos quadrados recursivos com fator de esquecimento) torna-se relevante.
This study evaluated the potential of the application of the recursive least squares technique (RLS) to adjust in real time the model parameters of the autoregressive models with exogenous variables (ARX), which consists of the upstream levels, to improve the performance of the forecasts of river levels in real time. Three aspects were studied jointly: the variation of the lead time chosen for the forecast, the variation in the proportion of controlled area in upstream basins and variation in the area of forecasting section of the basin. The research was conducted in three main dimensions: a) methodological (without recursion; with recursion; with recursion and forgetting factor); b) temporal (6 different lead times: 10, 24, 34, 48, 58 and 72 hours); and c) spatial (variation in the controlled area of the basin and the area of the basin defined by the forecast section). The study area chosen for this research was the Uruguay River basin with its outflow at the river gage station of Uruguaiana (190,000 km²) and its entrenched sub-basins in Itaqui (131,000 km²), Passo São Borja (125,000 km²), Garruchos (116,000 km²), Porto Lucena (95,200 km²), Alto Uruguai (82,300 km²), and Iraí (61,900 km²). The river levels data, with daily readings at 7am and 5pm, were provided by the Company of Mineral Resources Research (CPRM), with the data used from January 1, 1991 to June 30, 2015. We applied the Nash-Sutcliffe coefficient (NS) and the quantile 0.95 of absolute errors (EA(0,95): error has not been exceeded at the rate of 0.95) for the analysis of models performances. We observed that the errors EA(0.95) of the best models obtained for each basin always increase with the reduction of the controlled area then the quality of the forecasts decreases with displacement of the downstream control section upstream. The gain in quality of the forecasts with the use of adaptive resources becomes more evident especially when the observed values of EA(0.95) as this statistic is more sensitive with greater differences in relation to the Nash-Sutcliffe Coefficient (NS). Moreover, this is most representative for larger errors which occur precisely during flooding events. In general, we observed that, as much as the area of the basin decreases, it is possible to obtain forecasts with smaller lead times, but the influence of the size of the area controlled upstream basins improves the performance of smaller basins when observing, especially the errors EA (0.95). However, if the proportion of the upstream of controlled basin is already quite large - as in the case of the alternatives 1 and 2 used for forecast in Itaqui (between 88.5% and 95.4%, respectively) - the adaptive resources do not differ too much in getting better results. However, when observing basins with smaller areas controlled upstream - as is the case of Porto Lucena to alternative 2 (65% controlled area) - the performance gain of the models with the use of the complete adaptive resources (MQR+f.e.) becomes relevant.

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44

Schober-Eimer, Anita. "Analyse de la variabilité des paramètres caractéristiques de l'hydrologie d'un bassin versant et modélisation des crues en présence de données hydrologiques succintes." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10043.

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Le but de cette etude est d'elaborer une strategie de predetermination ou meme de prevision sur les bassins pour lesquels les donnees hydrometeorologiques sont rares ou inexistantes. Dans une premiere partie deux methodes susceptibles d'apporter rapidement des informations hydrologiques sont explores: une methode experimentale a base de simulations de pluie physique sur diverses petites parcelles d'un bassin versant s'avere difficile a mettre en uvre notamment si le sol est couvert de vegetation. L'autre approche est statistique. En analysant les evenements pluie-debit faibles a moyennement forts sur cinq bassins versants dont quatre dans la region mediterraneenne et un en afrique, nous tentons de decouvrir les evolutions des reactions d'un bassin versant en vue d'une extrapolation en situation extreme. On examine ainsi quelles sont les grandeurs caracteristiques de la pluie et de l'etat initial d'un bassin versant qui jouent un role sur la fonction de production et sur la fonction de transfert. On etudie en particulier la variabilite de la fonction de transfert sur un bassin versant donne. Dans la deuxieme partie on presente des essais de modelisation en profitant des resultats anterieurs. Le modele empirique intitule storhy est ajuste selon nos criteres. On propose deux versions du modele ; une version avec trois variables d'initialisation et un parametre et une autre version parametrique sans variables d'initialisation. Les performances de la derniere categorie sont etudiees et comparees a celles d'un autre modele (gr3h). Le modele avec trois variables d'initialisation est analyse en vue de son utilisation dans un contexte de donnees rares et semble donner des resultats encourageants

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45

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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46

Abdelnour, Alex Gabriel. "Assessing ecosystem response to natural and anthropogenic disturbances using an eco-hydrological model." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42899.

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The impact of natural and anthropogenic disturbances on catchment hydrological and biogeochemical dynamics are difficult or impossible to capture through experimentation or observation alone. Process-based simulation models can address this need by providing a framework for synthesizing data describing catchment responses to climate, harvest, fire, and other disturbances. However, existing models are either too simple to capture important process-level hydrological and biogeochemical controls on ecosystem responses to disturbance, or are too computationally expensive to simulate the local dynamics over large watershed areas, or require a high level of expertise to implement. To this end, a spatially distributed, physically based, eco-hydrological model (VELMA: Visualizing Ecosystems for Land Management Assessments) that is both computationally efficient and relatively easy to implement is developed. VELMA is a state-of-the-art model with real-time visualization tools that shows temporal and spatial patterns of state and flux variables, and is used to address the effects of changes in climate, land-use, and other interacting stressors on multiple ecosystem services such as timber production, carbon sequestration, regulation of water quality and quantity and reduction of greenhouse gases at scales relevant to formulating management decisions. In this study, VELMA was applied to the H.J. Andrews Experimental forest, an intensively studied watershed with observed daily temperature, precipitation, streamflow, and nutrient losses data. VELMA was first used to explore the factors that controls catchment response to forest harvest. Specifically, elucidate how forest harvest factors such as harvest location and amount control watershed hydrological and biogeochemical fluxes. Thereafter, VELMA was used to reconstruct and analyze the impact of two significant disturbance events − a stand replacing fire and a 100% clearcut − on vegetation and soil carbon and nitrogen dynamics. Finally, VELMA was used to explore the potential impact of climate change on catchment hydrological regime, site productivity and carbon and nitrogen dynamics at high spatial resolution relevant to formulating management decision. The main insights from this study include: (1) streamflow, nutrient losses to the stream, and gaseous carbon and nitrogen losses to the atmosphere are strongly sensitive to the location of harvest as a result of the spatial variation in soil water content, plant nitrogen uptake, soil organic carbon decomposition, nitrification, and denitrification within the watershed, (2) forested riparian buffers reduce water and nutrient losses to the stream through plant transpiration, plant nitrogen uptake, soil storage, and soil microbial decomposition, (3) following fire and harvest, losses of N from the terrestrial system to the stream are tightly constrained by the hydrological cycle and driven mainly by wet-season rain events large enough to generate hydrologic connectivity and flushing of nutrients along hillslopes, (4) climate change strongly impacts the hydrological regime in the Pacific Northwest as a result of less snowpack, earlier snowmelt, higher winter streamflow, lower summer streamflow, and soil moisture deficit, and (5) climate change increases plant and soil biomass accumulation as a result of longer growing season and higher soil organic decomposition, reduce water quality by increasing the amount of nutrients that reach the stream, and transforms the ecosystem into a net source of carbon to the atmosphere.

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47

Gitari, Wilson Mugera. "Evaluation of the leachate chemistry and contaminants attenuation in acid mine drainage by fly ash and its derivatives." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6041_1254305614.

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This study aimed at understanding the chemistry of the neutralization of the acid mine drainage with fly ash by considering the acid mine drainage : fly ash ratios that produce neutral and alkaline process waters.

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48

Meyer, Nicolas. "Evaluation de l'impact des cultures intermédiaires multi-services sur le bilan hydrique des sols : approche par expérimentation et simulation. Application au bassin Adour-Garonne." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0017.

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Les cultures intermédiaires multi-services (CIMS) sont un des piliers de l’agroécologie et elles peuvent être introduites dans les systèmes de culture actuels sans les modifier fortement. Cependant, dans un contexte de changement climatique avec une modification des régimes pluviométriques, l’impact des CIMS sur la dynamique et le bilan hydrique pourrait être négatif. Le bassin Adour-Garonne (BAG), connaît des problèmes de gestion de la quantité et de la qualité (nitrates, pesticides) de ses masses d’eau. Quantifier l’impact des CIMS en fonction de leur gestion sur la dynamique et le bilan hydrique des sols agricoles du territoire du BAG représente donc un enjeu social et scientifique crucial. Mon objectif est d’évaluer l’impact des CIMS sur le bilan hydrique et les flux d’eau à l’échelle de la parcelle, en fonction de leur mode de gestion, et à l’échelle du territoire, pour évaluer les conséquences possibles sur la recharge des nappes en cas de réduction de drainage. J’ai mis en place une démarche scientifique couplant 3 types de méthodes : méta-analyse de la littérature scientifique, expérimentations et mesures de terrains et simulations avec le modèle de culture STICS à l’échelle de la parcelle, puis par extrapolation à l’échelle du territoire du BAG. J’ai analysé l’impact des CIMS sur l’évapotranspiration, le drainage, la lixiviation des nitrates et les stocks d’eau et d’azote en fonction de divers facteurs : pédoclimat, espèce de CIMS (et mélange d’espèces), date de semis et de destruction et gestion des résidus (enfouissement par travail du sol ou laissés en mulch). Les résultats indiquent que les CIMS diminuent le drainage par une augmentation de l’évapotranspiration réelle en situation avec couvert végétal, en comparaison à un sol nu. Toutefois, si les CIMS sont bien gérées, avec une adaptation des espèces composant le couvert végétal, des dates de semis et de destruction, elles n’induisent pas de stress hydrique et azoté entrainant des baisses de rendements des cultures principales suivantes. La généralisation des CIMS sur l’ensemble du BAG, sans adaptation locale de leur gestion et avec des destructions tardives (cas de l’agriculture de conservation), pourrait cependant modifier le grand cycle de l’eau en augmentant l’évapotranspiration et diminuant le drainage, qui est le processus déterminant de la recharge des nappes. Ces modifications pourraient accentuer le déficit entre les besoins en eau grandissant et les ressources toujours plus restreintes dans un contexte de changement climatique
Cover crops are one of the pillars of agroecology and can be introduced into current cropping systems without major changes. However, in a context of climate change with changing rainfall patterns, the impact of cover crops on water dynamics and balance could be negative. The Adour- Garonne basin (BAG) has problems managing the quantity and quality (nitrates, pesticides) of its water bodies. Quantifying the impact of cover crops according to their management on the soil water dynamics and balance in the BAG is therefore a crucial social and scientific issue. My objective is to evaluate the impact of cover crops on water balance and water flows at the field scale, depending on their management, and at the territorial scale, to assess the possible consequences on groundwater recharge in the event of reduced drainage. I have implemented a scientific approach combining three types of methods: meta-analysis of the scientific literature, experiments and field measurements and simulations with the STICS crops model at the plot scale, then by extrapolation to the BAG scale. I analysed the impact of cover crops on evapotranspiration, drainage, nitrate leaching, water and nitrogen content according to various factors: soil and climate, cover crops species (mixture), sowing and termination date, and residue management (returned by plough or left in mulch at the soil surface). The results indicate that cover crops reduce drainage by increasing actual evapotranspiration in a vegetative cover situation compared to a bare soil. However, if cover crops are well managed, with adaptation of the species making up the plant cover, planting and destruction dates, they do not induce water and nitrogen stress leading to lower yields of the following main crops. The generalization of cover crops throughout the BAG, without local adaptation of their management and with late termination (case of conservation agriculture), could however modify the major water cycle by increasing evapotranspiration and decreasing drainage, which is the determining process for groundwater recharge. These changes could increase the gap between growing water needs and evertightening resources in the context of climate change

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Giron, Efrain. "Development of a SWMM-GIS Flood Model for New Orleans Drainage Pumping Station No 4 Basin." ScholarWorks@UNO, 2005. http://scholarworks.uno.edu/td/261.

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An urban flood damage model for the drainage area serve by Pump Station No. 4 (Prentiss, New Orleans, Louisiana) has been completed. This study presents the research effort needed to develop a stormwater management model (SWMM) integrated with GIS that includes a Damage Model to estimate the losses produced by storm events on flood prone areas. The latest LIDAR data are used for the topography. The drainage area for this study covers approximately 3218 acres, with elevations ranging from -9 ft to 6 ft above sea level. The runoff produced is pumped into Lake Pontchartrain via London Outfall Canal. The study area includes a pump station with a capacity of 106 m3/s and a complex drainage system including a 10 ft siphon that drains the runoff on the western side. The hydrology and hydraulic routing for the watershed was estimated using the U.S. EPA Storm Water Management Model (SWMM) and the input of the model was created using a geodatabase composed of nodes, conduits and subcatchment areas developed in ArcGIS 8.2. The GIS was designed to take advantage of the importing node and graphic capabilities of the SWMM. Since all features used by SWMM were georeferenced, node flood elevation data were transferred back for display in geographic space. This approach allows for a more accurate volume computation of flooded areas by using Boolean operations on a Triangular Irregular Network (TIN) surface of node elevations and a TIN surface of LIDAR elevation data. Flood volumes were obtained for the study area by simulating a series of rain events. These flood volumes were then incorporated into a Damage model to estimate damage rating curves for the study area. The 1:100 year damage was estimated to be 17.2 million of dollars (2005 US dollars). The average annual flood damage was estimated to be 5.5 million of dollars (2005 US dollars). The developed Annual Flood Maps can be used to set rational flood insurance rates or to plan improvements to the drainage system. This information can be used by FEMA and by the private insurance industry of the State

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Ampofo, Edward Akwasi. "The use of numerical groundwater model to improve effectiveness of subsurface drainage system in irrigated field." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/146869/.

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The research demonstrates that Three-Dimensional Variable-Density Groundwater Flow models such as the SEAWAT model can be effectively used for design of subsurface drainage systems for controlling salt concentration in the root zone on salt affected irrigated land. The SEAWAT model was used to optimize subsurface drainage design to ensure that the salt concentration of the groundwater at the base of the root zone does not exceed pre determined levels instead of the conventional approach of maintaining the groundwater at a predetermined water table level. The study was carried out on a conceptual uniform homogenous block of irrigated flat field of shallow water table depth of 0.5 m and salt concentration of 7200 mg/l with impermeable layer at 20 m deep and impermeable field boundaries. Using the model, spacings were designed to be used as design criteria for subsurface drainage system to maintain salt concentrations of 6000, 5000 and 4000 mg/l at the base of the root zone and water table depth of 0.8 m from the soil surface. The results showed that over a wide range of irrigation water quality and aquifer hydraulic conductivity the optimum drain spacing using SEAWAT was, depending on irrigation water quality and aquifer hydraulic conductivity, wider by between 3 and 50 % and the amount of drain discharge reduced by 1 and 27 % than would be recommended using conventional design equations. It was concluded that Three-Dimensional Variable-Density Groundwater Flow models are better for designing effective drainage systems than Conventional drain spacing design equations such as Hooghoudt.

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Dissertations / Theses on the topic 'Drainage models'

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