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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Metropolitan Manila: A Vulnerability Issue

Bul-lalayao, Carmela 07 September 2016 (has links)
This practicum is an exploration of the meaning of resiliency within the discourse of the Landscape Architecture discipline. Its significance to ecological thinking and its conjunction to engineering solutions are examined for developing of an integrated approach towards flood mitigation strategies. Although not the only hazard experienced in the Philippines, floods are the most pervasive. The severity of this natural event and the corresponding disaster is augmented by factors produced within the socio-economic realm. To measure the increasing frequency of disasters from floods, the inherent vulnerability of the study area, Metropolitan Manila and historical reports of said events are considered. To further comprehend the role of Landscape Architecture within an integrated framework the three types of resiliency organized by Dovers and Handmer are examined and applied at various scale (regional, local, and micro) pertaining to the study area. This part of the practicum explores methods of resiliency in conventional response as well as ecological resiliency to flood events. / October 2016
102

The long now: Re-framing prairie rivers

Workman, Trent W. 06 May 2016 (has links)
Spring flooding regularly occurs in the plain along the Assiniboine River’s low-lying terminus in eastern Manitoba as the river attempts to accommodate snowmelt drained from the central plains territory of North America. The annual insensitive response to the changing state of the river is a physical expression of competing understandings of time made manifest in the landscape. Can the consideration of time shift our understanding of flooding in the prairie context? How can a deep sense of time be expressed in our reaction to the design of the land? Shifting to thinking of a time-sensitive response to flooding, I aim to construct a hybrid cartography that addresses the relationship between observer and understanding fundamental to relevant critical projects in the landscape. This approach aims to understand the geographic and temporal context to reveal deep synchronicities ignored by rational approaches to both fluvial engineering and design. / May 2016
103

Testing the Waters: The Social Contexts of Homeowner Flood Mitigation

Olivier, Maggie L. 16 May 2008 (has links)
South Louisiana regularly experiences effects from flooding. This study looks at what homeowners are doing to reduce their losses from floods through the practices of flood mitigation. I developed four hypotheses to predict homeowners' mitigation behavior. (1) Homeowners with a history of flooding are likely to mitigate more than those without previous flooding. (2) High-disposable-income homeowners are more likely to mitigate than lowdisposable- income homeowners. (3) The stronger the place attachment among homeowners, the higher the likelihood they will mitigate. (4) Homeowners who have experienced effective mitigation measures in the past are more likely to mitigate than those who have not. To test these hypotheses, a survey was administered in five different neighborhoods throughout Orleans and Jefferson parishes having high concentrations of repeatedly flooded homes. The findings suggest severity of past flooding, disposable savings, strong relationships with neighbors, and discussion of flooding with neighbors are the strongest predictors of flood mitigation.
104

Pore network modelling of wettability effects on waterflood oil recovery from Agbada sandstone formation in the Niger Delta, Nigeria

Wopara, Onuoha Fidelis January 2016 (has links)
A thesis Submitted to the School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy Johannesburg, 2016 / Wettability of a porous reservoir rock is an important factor that affects oil recovery during waterflooding. It is recognized as being important for multiphase properties. Understanding the variation of these properties in the field, due to wettability trends and different pore structures, is very critical for designing efficient and reliable processes and projects for enhanced hydrocarbon recovery. After primary drainage the reservoir wettability changes: if it was oil-wet initially, it gradually changes to water-wet during waterflooding. This change in reservoir wettability towards water-wet will reduce the residual oil saturation and improve the oil displacement efficiency. However, knowledge of the constitutive relationship between the pore scale descriptors of transport in the porous system is required to adequately describe wettability trend and its impact on oil recovery, particularly during waterflooding. In this work, the petrophysical properties that define fluid flow in the Agbada, Nigeria sandstone reservoir were determined using conventional experimental and x-ray CT scanning methods. Experimentally measured average porosity is 0.28, average permeability is 1699 mD, while the initial and irreducible water saturation is 0.22. Permeability in the x, y and z directions, ranging from 50 to 200 mD, were calculated from the pore network extracted from the Agbada sandstone rock. Results obtained from the Amott-Harvey wettability measurement method indicate that the reservoir is strongly water-wet, with Amott-Harvey index of about 0.9. The cross-over between the water and oil relative permeabilities occurred at saturations of the samples above 0.5, giving an indication of strong water-wetness. The work summarizes the mechanism of wettability alteration and characterizes the performance of the reservoir during waterflooding from injecting water, and relates the residual oil saturation, relative permeability and volumes of water injected to wettability and its effects on oil recovery. Waterflood oil recovery is computed using the Buckley-Leverett method based on the reservoir rock and fluid properties. Computed waterflood oil recovery using this method was about 60% of the oil initially in place. Plots of spontaneous imbibition rate show that the injection rate for optimal oil recovery is 40 bbls of injected water per day. At this rate, both the mobility and shock front mobility ratios are less than 1, leading to a stable flood front and absence of viscous fingering. Waterflooding is by far the most widely applied method of improved oil recovery over the years with good results in conventional and unconventional (tight oil) reservoirs It is relatively simple and cost effective: abundance and availability of water. Waterflood oil recovery factor is affected by internal and external factors. The placement of the injection and production wells, for example, impacts on the effectiveness of the waterflooding process. I considered the placement of the wells in a five-spot pattern as elements of an unbounded double periodic array of wells and assumed the reservoir to be homogeneous, infinite and isotropic, with constant porosity and permeability. Both fluids are treated as having slight but constant compressibility and their flow governed by Darcy’s law. The average pressure in the reservoir satisfies quasi-static flow or diffusion equation. I then assumed piston-like displacement of oil by injected water that takes account of viscosity diffence between both fluids and proposed a model based on the theory of elliptic functions, in particular Weierstrass p-functions functions. Oil-water contact movement, dimensionless time for water breakthrough at the production well, areal sweep and average reservoir pressures were modeled. The model was tested using Wolfram Mathematica 10 software and the results are promising. The thesis has therefore established that the Agbada sandstone reservoir is strongly water-wet and that waterflooding is a viable option for enhanced oil recovery from the reservoir. / MT2016
105

Avaliação do potencial de aplicação de técnicas compensatórias em áreas urbanas consolidadas / Assessment of application potential of compensatory techniques in consolidated urban areas

Martins, Leandro Guimarães Bais 10 February 2017 (has links)
O desenvolvimento urbano altera significativamente o ciclo natural das bacias hidrográficas. Com o surgimento da drenagem urbana sustentável, o rápido escoamento das águas pluviais deu lugar à restituição das características naturais da bacia hidrográfica através do planejamento do desenvolvimento urbano aliado ao uso de técnicas compensatórias que promovem a infiltração e detenção de águas pluviais. Entretanto, em bacias urbanizadas, o uso das técnicas compensatórias tem alcance limitado, principalmente pelo alto grau de impermeabilização das bacias, pela falta de preocupação com a drenagem durante a expansão urbana, pela baixa disponibilidade de espaço e pelos altos custos de aplicação de medidas estruturais de drenagem urbana. Assim, os princípios de drenagem urbana sustentável são muitas vezes considerados inadequados a ambientes de urbanização consolidada. Desta forma, este trabalho teve por objetivo avaliar o desempenho do uso em conjunto de diversas técnicas compensatórias definidas através do desenvolvimento de mapas de adequabilidade de uma bacia hidrográfica urbana à aplicação das técnicas compensatórias e de simulação hidrológica. Foram avaliadas bacias de detenção, pavimentos permeáveis, jardins de chuva, telhados verdes, trincheiras de infiltração e microreservatórios individuais. O desempenho das técnicas compensatórias foi avaliado individualmente e trabalhando em conjunto. Mapas de adequabilidade foram criados para locação e quantificação das técnicas compensatórias na bacia hidrográfica. Os resultados mostraram que a aplicação extensiva de técnicas compensatórias em ambiente urbano pode provocar melhoras significativas na redução de vazão de pico e controle do volume de hidrogramas de cheia, com melhores desempenhos individuais de até 35,5% de redução de pico e 32,48% de redução de volume de hidrogramas (TR 2 anos) com o uso de trincheiras de infiltração e 12,77% de redução de vazão de pico e 9,57% de redução de volume (TR 100 anos) com o uso de telhados verdes. Simulando as técnicas compensatórias mais eficientes funcionando em conjunto, foram obtidas reduções de 59,00% de vazão de pico e 46,37% de redução de volume para precipitações de tempo de retorno de 2 anos e 25,66% de vazão de pico e 26,45% de redução de volume em precipitações de 100 anos de tempo de retorno. Assim, concluiu-se que a adaptação de regiões urbanizadas aos princípios da drenagem urbana sustentável é possível e eficiente, e bons resultados podem ser obtidos mesmo nos ambientes mais densamente ocupados. Entretanto, a falta de planejamento durante o desenvolvimento urbano e a pouca disponibilidade de espaço impede a otimização do arranjo espacial dos dispositivos e limita a eficiência de algumas técnicas compensatórias, principalmente aquelas de grande porte. / Urban development significantly alters the natural cycle of river basins. With the emergence of sustainable urban drainage, rapid stormwater runoff gave way to recovering the natural characteristics of the river basin through the urban development planning coupled with the use of compensatory techniques that promote the infiltration and detention of stormwater. However, in already urbanized basins, the use of compensatory techniques have limited reach, especially by the high impermeabilization of the basins, the lack of concern with drainage during urban sprawl, low space availability and high implementation costs of structural measures of urban drainage. Thus, the principles of sustainable urban drainage are often considered inadequate to consolidated urban environments. Therefore, this study aimed to evaluate the performance of the conjunction use of several compensatory techniques defined after developing suitability maps for the urban basin and hydrologic simulation. We evaluated detention basins, permeable pavements, rain gardens, green roofs, infiltration trenches and individuals cisterns. We assessed the performance of compensatory techniques working individually and working together. Suitability maps were created for positioning and quantification of compensatory techniques in the watershed. The results showed that extensive application of compensatory techniques in an urban environment could lead to significant improvements in peak flow reduction and control of hydrograms volume, with best individual performance up to 35.5% peak reduction and 32.48% hydrograms volume reduction (TR 2 years) using infiltration trenches and 12.77% peak flow reduction and 9 57% volume reduction (TR 100 years) using green roofs. Simulating the most efficient compensatory techniques working together, the results shown 59.00% of peak flow reductions and 46.37% of volume reduction to 2-years rainfalls and 25.66% peak flow reduction and 26.45% of volume reduction in 100-years rainfalls. Thus, we concluded that the adaptation of urbanized areas to sustainable urban drainage principles is possible and efficient, and good results can be obtained even in the more densely occupied environments. However, the lack of planning for urban development and the limited space availability prevents the optimization of devices spatial arrangement and limits the effectiveness of certain compensatory techniques, especially those large as detention basins.
106

Arquitetura em tempo: estudo das áreas inundáveis urbanizadas em Eldorado - SP / Architecture in time: study of urbanized floodable areas in Eldorado - SP

Wagner Isaguirre do Amaral 03 November 2014 (has links)
O problema das inundações em Eldorado foi abordado integrando disciplinas e assuntos das áreas de Geociências, de Urbanismo, e de Arquitetura e de Defesa Civil, incluindo também a interação com diversas instituições e grupos acadêmicos, com o propósito de verificar os presentes esforços institucionais e comunitários na abordagem da crescente questão dos desastres. O estudo, aproveitando metodologias de cartografia e SIG, procurou contribuir com o desenvolvimento de meios para concretizar medidas de prevenção, mitigação, resposta e recuperação nas áreas mais sujeitas aos desastres relacionados aos processos hidrológicos ou geológicos na bacia hidrográfica em estudo. A urbanização no Vale do Ribeira de Iguape ocorreu historicamente em estreita relação com as condições que a hidrografia permitiu inicialmente ao transporte fluvial de pessoas e materiais. Este fato condicionou em grande medida a localização dos principais assentamentos e é possível vinculá-lo a períodos pré-cabralinos, quando outros grupos culturais já teriam iniciado a ocupação que hoje vemos sob o espectro de um processo de industrialização, implicando em uma intensificação da ocupação e do uso dos recursos do meio ambiente. No caso de Eldorado-SP, se a proximidade dos corpos d\'água trazia benefícios ao desenvolvimento e manutenção dos núcleos assentados, a expansão e adensamento da ocupação, sem a devida integração urbanística às condições do meio ambiente, tem incrementado as vulnerabilidades da cidade. Nas cheias do Rio Ribeira de Iguape e seus afluentes, muitas famílias estão sujeitas a riscos à vida, às condições de saúde e de perdas de recursos materiais e econômicos. / Floods in Eldorado (SP) was approached integrating disciplines and subjects of the Geosciences, Urban Planning, Architecture and Civil Defence, also including the interaction with various institutions and academic groups, in order to verify the present institutional and community efforts in facing growing issue of disasters. The study, taking advantage of cartography and GIS methodologies, sought to contribute to the development of means to implement prevention, mitigation, response and recovery in susceptible areas to disaster related to geological or hydrological. Urbanization in the Ribeira do Iguape Valley occurred historically in close relationship with the hydrographic conditions that initially allowed the fluvial transport of people and materials. This fact, conditioned the location of the major settlements and we can relate it to pré-cabralinosperiods when other cultural groups have already begun the occupation that we see today under of an industrialization process, resulting in increased occupancy, whitout urban integration to environmental conditions, has increased the vulnerability of the city. In the floods of Ribeira and its tributaries, many families are subject to risks to life, health conditions, material losses and economic resources losses.
107

Community Resilience in Thailand: a Case Study of Flood Response in Nakhonsawan City Municipality

Khunwishit, Somporn 05 1900 (has links)
Natural disasters such as flooding often affect vast areas and create infinite demands that need to be addressed in the same time. The wide scopes and severe impacts of such catastrophes often exceed, if not overwhelm, capacity of the national government to handle. In such a situation, communities such as cities and neighborhoods need to rely on their own capacity (resources, strategies, and expertise) to respond to disaster impacts at least until external assistance can be reached. Thus, studying how communities can be resilient to the impacts of natural disasters is important because this would enhance their ability to respond to the next disaster better. Within the context of great flooding in Thailand in 2011, this dissertation investigated the factors that generated or enhanced resilience of flood stricken-communities in Thailand. Nakhonswan City Municipality was selected as the research site. Qualitative research methods were employed in this study. Data were collected using in-depth interview and focus group. Thirty-six participants (28 for in-depth interview and 8 for focus group interview) from various organizations were recruited using snowball and purposive sampling strategies. Interview data from the field research were transcribed, translated from Thai language to English, and then analyzed using open coding and focused coding strategies. Analyses of in-depth interview data revealed eight conceptual themes representing factors that constituted resilience of Nakhonsawan City Municipality, as the leading organization responded to the flood. These factors are: availability of resources for resilience; managerial adaptability; crisis leadership; quality workforce; knowledge sharing and learning; organizational preparedness; organizational integration; and sectoral integration. In addition, findings from the focus group interview with members of three strong neighborhoods found eight factors that helped these neighborhoods respond effectively to the flood crisis. They included: self-reliance; cooperation; local wisdom; preparedness; internal support; external support; crisis adaptability; and pre-disaster social cohesion. This dissertation ended with the discussion of implications, limitations and suggestions for future research.
108

Continuous watershed-scale hydrologic modeling of conservation practices for peak flow reduction

Krasowski, Michael 01 May 2019 (has links)
Iowa first started seeing largescale changes to its landscape with the arrival of Europeans and ensuing conversion of forest and prairie to row crops and pasture and would see its landscape altered again in the early 1900s through the conversion of wetlands to row crops. Watersheds in Iowa, and the Midwest at large, have been drastically altered hydrologically—through land use change, tile drainage, digging of drainage ditches, and channelizing of meandering streams. Though drainage practices maximize arable land, they also induce higher flood peaks. Along with these practices, climate change also has the potential to increase flood peaks. Conservation practices —typically employed to reduce erosion and agricultural pollution—have been proposed to be used to reduce flood peaks, but little analysis has been done on their ability to do so at the watershed-scale. To quantify the impact implementing conservation practices at the watershed-scale has on flood peaks, a novel hydrologic model is run to simulate five conservation scenarios under both historic and increased precipitation continuously for seventeen years. The Generic Hydrologic Overland-Subsurface Toolkit (GHOST) is used to model the Boone River, an agriculturally dominated watershed in Iowa. The Boone River model is calibrated against the United States Geological Survey gaging station near the outlet of the watershed and achieves notable success. For the seventeen year study period from 2002 to 2018, calibration achieved a Nash Sutcliffe efficiency of 0.79, percent bias of -6.0 percent, and R2 of 0.80. To simulate the change from the baseline to a conservation practice, changes were made to the parameters of the baseline, calibrated model to reflect the effects of conservation practices. Scenarios run were the return of row crop acres to native vegetation, improved soil health via cover crops and no-till farming, distributed wetlands, conversion of river-adjacent row crop elements to native vegetation, and conversion of stream order one river-adjacent row crop elements to native vegetation. Results for the seventeen year study period show the average peak flow reductions simulated for the conservation scenarios are 82, 39, 9, 13, and 9 percent respectively for annual maximums and 75, 29, 10, 11, and 7.5 percent respectively for the peaks over the 2-year flood threshold. Of the five scenarios modeled, only native vegetation and cover crops were able to offset the increased precipitation anticipated from climate change.
109

Application of storm transposition to the Middle Cedar Watershed : a reanalysis of the 2008 Cedar Rapids Flood

Brenner, Iris 01 May 2019 (has links)
On June 13, 2008, after many days of rain, the Cedar River flooded the city of Cedar Rapids. With a peak discharge of 139,987 cfs and at 19.12 feet above flood stage, the 2008 flood of Cedar Rapids was the largest flood in the city’s historic record. As rivers rose, the city had received forecasts of an incoming flood as early as June 8. Then, on June 12, it began to rain in Cedar Rapids. Finally, on June 13, 2008, the Middle Cedar crested at 31.12 feet. This thesis project modeled a variety of rainfall patterns on June 12, 2008, to determine the effect of varying rainfall intensity and location on the magnitude of the 2008 flood of Cedar Rapids. Using a method known as Stochastic Storm Transposition (SST), I overwrote precipitation data in a hydrologic model of the Middle Cedar Watershed with rainfall data extracted from specific storm events that occurred in the Upper Midwest. We used a physically-based, semi-distributed hydrologic model known as GHOST (Generic Hydrologic Overland-Subsurface Toolkit) developed by Marcela Politano at the University of Iowa. Traditionally, hydrologic modeling for watersheds has used design storms to create rainfall inputs in flood modeling. These design storms have uniform rainfall timing and accumulation patterns across a watershed and are determined by designated equations for a geographic region. In large watersheds such as the Middle Cedar (2,400 square miles), design storms are not physically realistic because of their uniformity. Additionally, design storms fail to capture unique storm patterns such as high intensity periods or the movement of a storm across a watershed. By implementing SST into GHOST, we used physically realistic storm events that have unique rainfall patterns and intensities within a designated return period. SST extracts rainfall data from real storm events and transposes the storm patterns onto watersheds to provide physically realistic rainfall data for hydrologic modeling. A tool called RainyDay, developed by Professor Daniel Wright at the University of Wisconsin, provided the storm transpositions used in this research. We assigned the storm transpositions return periods created by RainyDay, corresponding to their average transposed rainfall across the Middle Cedar Watershed. Replacing the June 12 rainfall with RainyDay’s two-year transposed storm events (average rain accumulation 1.8 inches) resulted in modeled flood peaks larger than the unaltered June 12 flood peak. Storm transpositions of 5-, 10-, and 2,000-year return periods showed even larger peaks, illustrating the potential for floods much larger than the 2008 flood. In addition to the analysis of flood magnitude in 2008, we modeled a set of storm transposition scenarios for a variety of soil-moisture conditions. The increased discharge levels in scenarios with high soil moisture emphasize the importance of initial conditions in flooding scenarios. Finally, we modeled the effect that two-year RainyDay storms would have had on the 2016 flood of Cedar Rapids had they occurred on the day before the peak. The two-year transpositions showed that with an impending flood crest smaller than the 2008 crest, several two-year RainyDay scenarios would have resulted in floods nearly equal in magnitude to the 2008 flood event. Our manipulation of the rainfall in the Middle Cedar Watershed on June 12, 2008, using the GHOST model provided the opportunity to re-examine the influence that a specific day of rainfall had on the 2008 flood of Cedar Rapids. The potential for higher flooding under conditions of repeated rainfall and high soil moisture illustrates the susceptibility of the Middle Cedar Watershed to future flood events under similar conditions. Applying SST in hydrologic modeling also provided an opportunity to model a variety of rainfall scenarios and to better understand watershed responses to nuanced and physically realistic rainfall patterns.
110

Oil recovery by spontaneous imbibition and viscous displacement from mixed-wet carbonates

Tie, Hongguang. January 2006 (has links)
Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on Dec. 21, 2007). Includes bibliographical references (p. 199-216).

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