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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.
121

The Pika and the Watershed

January 2012 (has links)
abstract: As much as 40% of the world's human population relies on rivers which originate on the Qinghai-Tibetan Plateau (QTP) (Xu et al. 2009, Immerzeel et al. 2010). However, the high alpine grasslands where these rivers emanate are at a crossroads. Fed by seasonal monsoon rains and glacial runoff, these rivers' frequent flooding contributes to massive losses of life and property downstream (Varis et al. 2012). Additionally, upstream grasslands, which regulate the flow of these rivers, are considered to be deteriorating (Harris 2010). This thesis examines the regional vulnerability of these rivers and highlights the impacts of several policy responses, finding that both climate change and grassland degradation pose significant challenges to Asia's water security. Additionally, I suggest that many of the responses elicited by policy makers to meet these challenges have failed. One of these policies has been the poisoning of a small, endemic, burrowing mammal and keystone species, the plateau pika (Ochotona curzoniae) (Smith and Foggin 1999). Contrary to their putative classification as a pest (Fan et al. 1999), I show that the plateau pika is instead an ecosystem engineer that actively increases the infiltration rate of water on the QTP with concomitant benefits to both local ecosystems and downstream hydrological processes. / Dissertation/Thesis / M.S. Biology 2012
122

Planejamento de povoamentos de eucalipto com condicionantes hidrológicos : um estudo de caso em Eldorado do Sul/RS

Cavalcante, Rosane Barbosa Lopes January 2011 (has links)
O presente estudo avalia a inclusão de indicadores hidrológicos em modelos tradicionais de gestão de povoamentos comerciais de eucalipto. As restrições adicionadas referem-se a uma redução máxima da vazão em cada ano do período de análise de 300, 200 e 100mm.ano-1. Os valores de vazão foram estimados utilizando um modelo simplificado de balanço hídrico que considera as perdas por interceptação e por evapotranspiração dependentes de fatores ambientais. Funções foram ajustadas a fim de descrever a variação das características da vegetação ao longo de seu crescimento. A área de estudo corresponde a uma microbacia de 0,97km² localizada no município de Eldorado do Sul/RS. Foram consideradas 1296 alternativas de regime de manejo para a área, variando a espécie, densidade de plantio, índice de solo, idades de corte e sistema de condução. O índice de área foliar apresentou-se como um importante descritor do dossel florestal, de grande influência sobre o impacto hidrológico das plantações florestais. Os resultados dos modelos de programação linear utilizados demonstraram que quanto maior a restrição hidrológica imposta, mais se altera o plano de manejo da área e o valor do projeto obtido. A utilização do modelo com restrição de 200mm.ano-1, comparado ao modelo sem restrição hidrológica, ocasionou um aumento médio na vazão anual de 22% e uma redução no valor esperado de terra de 15%. Para a região de estudo, a utilização de regimes de manejo com diferentes idades e a definição do material genético foram as variáveis de manejo mais afetadas pela imposição das restrições hidrológicas. A consideração da microbacia como unidade de manejo e a adição das restrições hidrológicas aos modelos econômicos mostraram-se ferramentas úteis à integração do planejamento florestal e de recursos hídricos. / This study evaluates the inclusion of hydrological goals in the traditional planning models for commercial stands of eucalyptus. The constraints added to the linear programming model relate to maintaining a minimum flow of 300, 200 and 100mm.ano-1 in each year of the analysis. The flow values were estimated using a simplified water balance model that considers the interception loss and evapotranspiration dependent on environmental factors. Functions were fitted to describe the variation of the vegetation parameters along its growth. The study area represents a watershed of 0,97km² located in Eldorado do Sul (RS, Brazil). It were considered 1296 alternative forest regimes for the area, ranging species, planting density, site index, cutting age and the conduction system. The leaf area index was presented as an important descriptor of the forest canopy with great influence on the hydrological impact of forest plantations. The results showed that the greater the restriction imposed hydrology, the more you change the management plan for the area and the project value obtained. Using the model with constraint 200mm.ano-1, compared to the not hydrologically constrained model, causes an increase in average annual flow of 22% and a reduction of 15% in the expected value of the land. For the study area, the definition of the genetic material was the variable that most influenced the results. The consideration of watershed as the management unit and the addition of hydrological constraints in economic models proved to be useful tools in planning the integration of forestry and water resources.
123

Water Efficiency in Agriculture: a Study of the Adoption of Water Conserving and Profitable Irrigation Technology in Arizona.

January 2014 (has links)
abstract: With the projected population growth, the need to produce higher agricultural yield to meet projected demand is hindered by water scarcity. Out of many the approaches that could be implemented to meet the water gap, intensification of agriculture through adoption of advanced agricultural irrigation techniques is the focus for this research. Current high water consumption by agricultural sector in Arizona is due to historical dominance in the state economy and established water rights. Efficiency gained in agricultural water use in Arizona has the most potential to reduce the overall water consumption. This research studies the agricultural sector and water management of several counties in Arizona (Maricopa, Pinal, and Yuma). Several research approaches are employed: modeling of agricultural technology adoption using replicator dynamics, interview with water managers and farmers, and Arizona water management law and history review. Using systems thinking, the components of the local farming environment are documented through socio-ecological system/robustness lenses. The replicator dynamics model is employed to evaluate possible conditions in which water efficient agricultural irrigation systems proliferate. The evaluation of conditions that promote the shift towards advanced irrigation technology is conducted through a combination of literature review, interview data, and model analysis. Systematic shift from the currently dominant flood irrigation toward a more water efficient irrigation technologies could be attributed to the followings: the increase in advanced irrigation technology yield efficiency; the reduction of advanced irrigation technology implementation and maintenance cost; the change in growing higher value crop; and the change in growing/harvesting time where there is less competition from other states. Insights learned will further the knowledge useful for this arid state's agricultural policy decision making that will both adhere to the water management goals and meet the projected food production and demand gap. / Dissertation/Thesis / Masters Thesis Sustainability 2014
124

Ecological, Environmental and Hydrological Integrity in Sustainable Water Resource Management for River Basins

January 2015 (has links)
abstract: This dissertation presents a new methodology for the sustainable and optimal allocation of water for a river basin management area that maximizes sustainable net economic benefit over the long-term planning horizon. The model distinguishes between short and long-term planning horizons and goals using a short-term modeling component (STM) and a long term modeling component (LTM) respectively. An STM optimizes a monthly allocation schedule on an annual basis in terms of maximum net economic benefit. A cost of depletion based upon Hotelling’s exhaustible resource theory is included in the STM net benefit calculation to address the non-use value of groundwater. An LTM consists of an STM for every year of the long-term planning horizon. Net economic benefits for both use and non-use values are generated by the series of STMs. In addition output from the STMs is measured in terms of sustainability which is quantified using a sustainability index (SI) with two groups of performance criteria. The first group measures risk to supply and is based on demand-supply deficits. The second group measures deviations from a target flow regime and uses a modified Hydrologic Alteration (HA) factor in the Range of Variability Approach (RVA). The STM is a linear programming (LP) model formulated in the General Algebraic Modeling System (GAMS) and the LTM is a nonlinear programming problem (NLP) solved using a genetic algorithm. The model is applied to the Prescott Active Management Area in north-central Arizona. Results suggest that the maximum sustainable net benefit is realized with a residential population and consumption rate increase in some areas, and a reduction in others. / Dissertation/Thesis / PHP files / Doctoral Dissertation Civil and Environmental Engineering 2015
125

Analysis of Alfalfa Production in a Water-Stressed Region: A Dynamical Modeling Approach

January 2015 (has links)
abstract: Alfalfa is a major feed crop widely cultivated in the United States. It is the fourth largest crop in acreage in the US after corn, soybean, and all types of wheat. As of 2003, about 48% of alfalfa was produced in the western US states where alfalfa ranks first, second, or third in crop acreage. Considering that the western US is historically water-scarce and alfalfa is a water-intensive crop, it creates a concern about exacerbating the current water crisis in the US west. Furthermore, the recent increased export of alfalfa from the western US states to China and the United Arab Emirates has fueled the debate over the virtual water content embedded in the crop. In this study, I analyzed changes of cropland systems under the three basic scenarios, using a stylized model with a combination of dynamical, hydrological, and economic elements. The three scenarios are 1) international demands for alfalfa continue to grow (or at least to stay high), 2) deficit irrigation is widely imposed in the dry region, and 3) long-term droughts persist or intensify reducing precipitation. The results of this study sheds light on how distribution of crop areas responds to climatic, economic, and institutional conditions. First, international markets, albeit small compared to domestic markets, provide economic opportunities to increase alfalfa acreage in the dry region. Second, potential water savings from mid-summer deficit irrigation can be used to expand alfalfa production in the dry region. Third, as water becomes scarce, farmers more quickly switch to crops that make more economic use of the limited water. / Dissertation/Thesis / Masters Thesis Sustainability 2015
126

Development and Characterization of Chemical Resistant Water Separation Composite Membranes by Using Impermeable Polymer Matrix

January 2016 (has links)
abstract: Water recovery from impaired sources, such as reclaimed wastewater, brackish groundwater, and ocean water, is imperative as freshwater resources are under great pressure. Complete reuse of urine wastewater is also necessary to sustain life on space exploration missions of greater than one year’s duration. Currently, the Water Recovery System (WRS) used on the National Aeronautics and Space Administration (NASA) shuttles recovers only 70% of generated wastewater.1 Current osmotic processes show high capability to increase water recovery from wastewater. However, commercial reverse osmosis (RO) membranes rapidly degrade when exposed to pretreated urine-containing wastewater. Also, non-ionic small molecules substances (i.e., urea) are very poorly rejected by commercial RO membranes. In this study, an innovative composite membrane that integrates water-selective molecular sieve particles into a liquid-barrier chemically resistant polymer film is synthetized. This plan manipulates distinctive aspects of the two materials used to create the membranes: (1) the innate permeation and selectivity of the molecular sieves, and (2) the decay-resistant, versatile, and mechanical strength of the liquid-barrier polymer support matrix. To synthesize the membrane, Linde Type A (LTA) zeolite particles are anchored to the porous substrate, producing a single layer of zeolite particles capable of transporting water through the membrane. Thereafter, coating the chemically resistant latex polymer filled the space between zeolites. Finally, excess polymer was etched from the surface to expose the zeolites to the feed solution. The completed membranes were tested in reverse osmosis mode with deionized water, sodium chloride, and rhodamine solutions to determine the suitability for water recovery. The main distinguishing characteristics of the new membrane design compared with current composite membrane include: (1) the use of an impermeable polymer broadens the range of chemical resistant polymers that can be used as the polymer matrix; (2) the use of zeolite particles with specific pore size insures the high rejection of the neutral molecules since water is transported through the zeolite rather than the polymer; (3) the use of latex dispersions, environmentally friendly water based-solutions, as the polymer matrix shares the qualities of low volatile organic compound, low cost, and non- toxicity. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2016
127

Transport of Bacteria, Viruses and a Visual Tracer in a Saturated 2-Dimensional Porous Media Model

January 2017 (has links)
abstract: This study was designed to provide insight into microbial transport kinetics which might be applied to bioremediation technology development and prevention of groundwater susceptibility to pathogen contamination. Several pilot-scale experiments were conducted in a saturated, 2 dimensional, packed porous media tank to investigate the transport of Escherichia coli bacteria, P22 bacteriophage, and a visual tracer and draw comparisons and/or conclusions. A constructed tank was packed with an approximate 3,700 cubic inches (in3) of a fine grained, homogeneous, chemically inert sand which allowed for a controlled system. Sampling ports were located at 5, 15, 25, and 25 vertical inches from the base of the 39 inch saturated zone and were used to assess the transport of the selected microorganisms. Approximately 105 cells of E. coli or P22 were injected into the tank and allowed to move through the media at approximately 10.02 inches per day. Samples were collected intermittently after injection based off of an estimated sampling schedule established from the visual tracer. The results suggest that bacteriophages pass through soil faster and with greater recovery than bacteria. P22 in the tank reservoir experienced approximately 1 log reduction after 36 hours. After 85 hours, P22 was still detected in the reservoir after experiencing a 2 log reduction from the start of the experiment. E. coli either did not reach the outlet or died before sampling, while P22 was able to be recovered. Bacterial breakthrough curves were produced for the microbial indicators and illustrate the peak concentrations found for each sampling port. For E. coli, concentrations at the 5 inch port peaked at a maximum of 5170 CFU/mL, and eventually at the 25 inch port at a maximum of 90 CFU/mL. It is presumed that E. coli might have experienced significant filtration, straining and attachment, while P22 might have experienced little adsorption and instead was transported rapidly in long distances and was able to survive for the duration of the experiment. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2017
128

Coordination and Power in Water Governance: The Case of Prescott Active Management Area

January 2017 (has links)
abstract: Studies of governance have focused on the interactions among diverse actors while implicitly recognizing the role of power within those relationships. Explicit power analyses of water governance coordination are needed to better understand the conditions for and barriers to sustainability. I therefore utilized a novel conceptual framework to analyze vertical and horizontal governance, along with power, to address how governance interactions affect water sustainability in terms of (1) interactions among governance actors across local to state levels; (2) coordination among actors at the local level; and (3) the exercise of power among assorted actors. I adopted a qualitative case study methodology that involved triangulating interview transcripts, policy documents, and other data in the case study area of Prescott, Arizona. Across governance scales, my analysis found that informational and contentious interactions occur around water management plans, groundwater withdrawal fees, and growth debates due to the stipulations of Arizona’s Groundwater Management Act. Locally, municipalities in different groundwater basins coordinate by pooling resources for water development due to shared growth visions. However, municipalities within the same groundwater basin are divided in their pursuit of the state-mandated goal of safe yield due to discontent arising from differing growth visions, libertarian values of water control, and unequal responsibilities among actors in conserving water or monitoring use. Finally, local and state actors exercise power through litigation, legislation, and political processes to pursue their interests, thereby limiting coordination for water sustainability. My explicit analysis of power reveals that coordination occurs not just because of water policies but due to interest-based water narratives (growth and libertarian). The emphasis of growth proponents on supply augmentation and libertarian opposition to regulations pose significant barriers to water sustainability. Successful policy-based pursuits of water sustainability will, thus, require an acknowledgment of these management asymmetries and commitments to addressing them. / Dissertation/Thesis / Doctoral Dissertation Geography 2017
129

Novel Operation of Granular Activated Carbon Contactors for Removal of Disinfection Byproducts Precursors

January 2017 (has links)
abstract: Granular activated carbon (GAC) is effectively used to remove natural organic matter (NOM) and to assist in the removal of disinfection byproducts (DBPs) and their precursors. However, operation of GAC is cost- and labor-intensive due to frequent media replacement. Optimizing the use of GAC is necessary to ensure treatment efficiency while reducing costs. This dissertation presents four strategies to reduce improve GAC usage while reducing formation of DBPs. The first part of this work adopts Rapid Small Scale Tests (RSSCTs) to evaluate removal of molecular weight fractions of NOM, characterized using size exclusion chromatography (SECDOC). Total trihalomethanes (TTHM), haloacetic acids (HAA5) and haloacetonitriles (HAN) formation were quantified after treatment with GAC. Low MW NOM was removed preferentially in the early bed volumes, up until exhaustion of available adsorption sites. DBP formation potential lowered with DOC removal. Chlorination prior to GAC is investigated in the second part of this work as a strategy to increase removal of NOM and DBP precursors. Results showed lower TTHM formation in the effluent of the GAC treatment when pre-chlorination was adopted, meaning this strategy could help optimize and extend the bed life if GAC filters. The third part of this work investigates in-situ GAC regeneration as an alternative to recover adsorption capacity of field-spent GAC that could potentially offer new modes of operation for water treatment facilities while savng costs with reactivation of spent GAC in an external facility. Field-spent GACs were treated with different oxidant solutions and recovery in adsorption capacity was evaluated for NOM and for two micro pollutants. Recovery of GAC adsorption capacity was not satisfactory for most of conditions evaluated. This indicates that in-situ GAC regeneration could be more effective when the adsorbates are present at high concentrations. Lastly, this work investigates the impact of low molecular weight polyDADMAC on N-nitrosodimethylamine (NDMA) formation. Water treatment facilities rely on polyDADMAC as a coagulant aid to comply with NOM removal and turbidity requirements. Since polymer-derived NDMA precursors are not removed by GAC, it is essential to optimize the use and synthesis of polyDADMAC to reduce NDMA precursors during water treatment. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2017
130

Pegada hídrica da atividade suinícola na região do COREDE Serra

Carra, Sofia Helena Zanella 20 July 2015 (has links)
A atividade suinícola, assim como as demais atividades pecuárias, é diretamente dependente de recursos naturais e, portanto, a falta de conhecimento acerca do impacto sobre os recursos hídricos na atividade pecuária pode comprometer o crescimento do setor. Neste contexto, a pegada hídrica surge como um indicador abrangente do uso da água que permite avaliar qual é o consumo utilizado, direta ou indiretamente, para produzir um determinado produto ao longo de toda a cadeia produtiva. Este trabalho avaliou a pegada hídrica no desenvolvimento da atividade suinícola na região do Corede Serra, no Estado do Rio Grande do Sul, considerando os suínos abatidos no ano de 2014. O cálculo da pegada hídrica foi aplicado para o processo de produção das culturas de milho e soja, destinadas à alimentação dos suínos (pegada hídrica verde), para o processo de confinamento, onde foram considerados os volumes de água destinados a dessedentação animal, limpeza das áreas de criação e incorporação ao animal (pegada hídrica azul) e o volume de água necessário para diluir a carga de fósforo que lixivia em direção aos recursos hídricos a partir da aplicação dos dejetos com fertilizantes (pegada hídrica cinza). A pegada hídrica verde foi a mais significativa (59,35%), seguida pela pegada hídrica cinza (40,44%) e pela pegada hídrica azul (0,21%). Observa-se que o maior consumo de água está na produção das culturas de milho e soja, que são a base da alimentação dos animais e não na água associada ao processo de confinamento. Para reduzir a pegada hídrica verde é necessário aumentar a produtividade de milho e soja, através de investimentos em tecnologias e zoneamento, associado a programas e políticas públicas com vistas ao aumento da produtividade das culturas. Investir em modelos de bebedouros mais eficiente, que forneçam um volume adequado de água e atendam à fase de criação animal, apresenta-se como uma opção de baixo custo para a economia de água e consequente redução da pegada hídrica azul. A pegada hídrica cinza pode ser reduzida através do uso de tecnologias mais eficientes de tratamento dos dejetos suínos, de forma que o fósforo seja removido ou reduzido em baixas concentrações antes de ser aplicado no solo. Ao aplicar a metodologia da pegada hídrica em uma unidade de referência composta por trinta e um município, observou-se que o nível de detalhamento das informações necessárias para se obter um resultado compatível com a situação real, é um verdadeiro desafio. Os resultados obtidos a partir deste trabalho poderão ser utilizados no planejamento das atividades suinícolas no Corede Serra com vistas a gestão dos recursos hídricos. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-11-03T13:17:07Z No. of bitstreams: 1 Dissertacao Sofia Helena Zanella Carra.pdf: 2417844 bytes, checksum: e0f3bf41167f11500bf07b6843d7ca59 (MD5) / Made available in DSpace on 2015-11-03T13:17:07Z (GMT). No. of bitstreams: 1 Dissertacao Sofia Helena Zanella Carra.pdf: 2417844 bytes, checksum: e0f3bf41167f11500bf07b6843d7ca59 (MD5) / The pig activity, as well as other livestock activities, is directly dependent on natural resources. The lack of knowledge about the impact on water resources in the cattle industry can jeopardize the growth of the sector, highlighting the need for methodologies to assess the performance of the same. In this context, the water footprint comes as a comprehensive indicator of water use that evaluates what is the consumption used, directly or indirectly, to produce a particular product throughout the supply chain. Thus, this study aimed to evaluate the water footprint in the development of pig activity in the Corede Serra region, in the state of Rio Grande do Sul, considering the pigs slaughtered in the year 2014. The calculation of the water footprint was applied to the production process of corn and soybeans, aimed at feeding the pigs (green water footprint) and the confinement process, which were considered the volumes of water for animal watering, cleaning the areas of creation and incorporation into the animal (blue water footprint) and the volume of water needed to dilute the phosphorus load of bleach from the application of manure fertilizer and finds the water (gray water footprint). The green water footprint is the most significant (59.35%), followed by the gray water footprint (40.44%) and the blue water footprint (0.21%). It is observed that the highest water consumption is in the production of corn and soybean crops, which are the staple diet of the animals and not in the water associated with the confinement process. Reducing the green water footprint is necessary to increase the productivity of corn and soybeans, through investments in technologies and zoning, associated with programs and policies aimed at increasing crop productivity. Investing in more efficient models drinking fountains, giving an adequate volume of water and meet the phase of breeding, presents itself as a low-cost option for saving water and consequent reduction of the blue water footprint. The gray water footprint can be reduced through the use of more efficient technologies for processing of manure, so that phosphorus is removed or reduced to low levels before being applied to the soil. By applying the methodology of water footprint in a reference unit consisting of thirty-one municipalities, it was observed that the level of detail of the information required to obtain a result consistent with the actual situation, it is a real challenge. The results from this work will be used in the planning of pig activities in COREDE Serra with a view to managing water resources.

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