• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 271
  • 51
  • 21
  • 6
  • 4
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 405
  • 405
  • 142
  • 73
  • 73
  • 65
  • 60
  • 52
  • 45
  • 43
  • 42
  • 36
  • 35
  • 31
  • 31
  • 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.
201

River basin administration and the Colorado: past practices and future alternatives

Kenney, Douglas S.,1964- January 1993 (has links)
The vast majority of large river systems in the United States cross (or comprise) one or more state lines, creating numerous administrative challenges. Addressing these multijurisdictional challenges in an efficient and equitable manner often requires the development of sophisticated institutional arrangements. Several types of "regional organizations" have been created for this purpose, including compact commissions, interstate councils, basin interagency committees, interagency-interstate commissions, federal-interstate compact commissions, federal regional agencies, and the single federal administrator format. These organizations feature a wide variety of authorities and responsibilities; what they inevitably share in common is a hostile political environment, a consequence of political geography and bureaucratic entrenchment. In this study, the challenges associated with the governance, administration, and management of interstate water resources are examined, using the Colorado River Basin as a case study. The Colorado is the only major river in the United States utilizing the "single federal administrator" format, an institutional arrangement that is often criticized for its subordination of the states and its concentration of policy-making authorities in the hands of administrators. When evaluated against carefully defined normative criteria, the Colorado is shown to feature many institutional deficiencies that are, in part, derivative of the Colorado's unique institutional arrangements. The primary objective of this study is to determine if the governance and management of the Colorado could be improved by the establishment of an alternative form of regional water organization. It is concluded that a type of federal-interstate compact commission, if carefully tailored to the political realities of the region, could improve many of the observed institutional deficiencies. This study also presents a widely-applicable methodology for the description and evaluation of institutional arrangements.
202

The water war debate : swimming upstream or downstream in the Okavango and the Nile?

Jacobs, Inga 12 1900 (has links)
Thesis (MA (Political Science))--University of Stellenbosch, 2006. / Water is a vital resource essential to human survival and for which there is no substitute. Additionally, whilst water is still seen as a ‘renewable resource,’ reality seems to dictate that there is only a finite quantity of water available in water-scarce regions. As a result, ‘water’ and ‘war’ are two topics that have begun to be assessed together with increasing frequency. Water disputes have indeed been labelled as one of the “New Wars” in Africa, comparing it to the likes of other resource wars such as those over oil and diamonds. Placing water discourse within a theoretical framework of International Relations, this thesis attempts to ground the water war debate in the Fourth Great Debate of rationalism (downstream) and reflectivism (upstream), through a comparative analysis of Anthony Turton’s positivist approach, and Larry Swatuk and Peter Vale’s post-positivist sentiments embedded in reflectivism. The research aim can, therefore, be phrased as: to examine the debate surrounding the inevitability or impossibility of water wars by means of a comparative analysis of the works of Turton and Swatuk/Vale, as applied to the case study of the Okavango River basin and a tentative assessment of the Nile River basin. This study hypothesises that whether you swim upstream or downstream, a water war erupting in the Okavango River basin is never inevitable and quite implausible as argued by both theoretical perspectives. A bridge-building exercise is therefore conducted in an attempt to find commonalities between the two supposedly incommensurable perspectives of Turton and Swatuk/Vale. Furthermore, based on the tentative assessment of the Nile River Basin, this thesis also postulates that while the potential for water conflict is greater in this region, it is unlikely that a full-scale water war will erupt. Indeed, contrary to what doomsday soothsayers predict, interstate cooperation of shared water resources, such as the shared river basins of the Okavango and the Nile rivers, is more prevalent than conflictive situations.
203

The avian community characteristics of constructed treatment wetlands of South Florida

Unknown Date (has links)
This study compared the avian communities of treatment wetlands in South Florida called Stormwater Treatment Wetlands (STAs) to those in natural marshes and crop lands, and examined factors that influenced the size and structure of the avian communities within the STAs. The STAs contained a more abundant, rich and distinct avian community compared to reference land types. The STAs were dominated by wintering waterfowl, and therefore community patterns fluctuated more seasonally other land types. Within the STAs, density and richness in the fall and winter were much greater in the submerged aquatic vegetation than in the mixed emergent vegetation when waterfowl were present. The STAs maintain two vegetation treatments which enhanced their biodiversity value by supporting distinct avian communities with different migratory strategies This suggests the increase in treatment wetlands could partially offset the loss of natural wetlands, but avian communities in treatment wetlands are not surrogates for natural wetlands. / by Tyler J. Beck. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
204

MATHEMATICAL SYSTEM THEORY AND THE ECOSYSTEM CONCEPT, AN APPROACH TO MODELLING WATERSHED BEHAVIOR

Rogers, James Joseph 06 1900 (has links)
This study explores the possible role of mathematical system theory in integrating existing ecological knowledge within the existing concepts of the structure of the biosphere. The objective of this integration is a theory of ecosystems which must include interactions. The basic unit of the biosphere is the biogeocoenose; similar to the ecosystem, but homogeneous with respect to topographic, microclimatic, vegetation, animal, pedalogical, hydrological and geochemical conditions. The role of the biogeocoenose in a theory of ecosystems based on system theory is discussed. The biogeocoenose may serve as the building block for modeling watersheds as ecosystems. The fundamentals of system theory are reviewed. As an example, an analysis and synthesis of the arid zone water balance follows. The water balance is resolved into twenty components which represent the water balance of (1) the canopy, (2) the mulch, (3) the soil surface, (4) the soil, and (5) the plant, including interactions. The twenty components were modeled as separate systems which were later coupled into one overall, complex, well defined ecosystem water balance system. The example illustrates the role of system theory in integrating ecological knowledge. Further discussion indicates the need for explicitly including plant behavior in the water balance model.
205

OPTIMAL WATER QUALITY MANAGEMENT STRATEGIES FOR URBAN WATERSHEDS USING MACRO-LEVEL SIMULATION MODELS LINKED WITH EVOLUTIONARY ALGORITHMS

Tufail, Mohammad 01 January 2006 (has links)
Urban watershed management poses a very challenging problem due to the varioussources of pollution and there is a need to develop optimal management models that canfacilitate the process of identifying optimal water quality management strategies. Ascreening level, comprehensive, and integrated computational methodology is developedfor the management of point and non-point sources of pollution in urban watersheds. Themethodology is based on linking macro-level water quality simulation models withefficient nonlinear constrained optimization methods for urban watershed management.The use of macro-level simulation models in lieu of the traditional and complexdeductive simulation models is investigated in the optimal management framework forurban watersheds. Two different types of macro-level simulation models are investigatedfor application to watershed pollution problems namely explicit inductive models andsimplified deductive models. Three different types of inductive modeling techniques areused to develop macro-level simulation models ranging from simple regression methodsto more complex and nonlinear methods such as artificial neural networks and geneticfunctions. A new genetic algorithm (GA) based technique of inductive modelconstruction called Fixed Functional Set Genetic Algorithm (FFSGA) is developed andused in the development of macro-level simulation models. A novel simplified deductivemodel approach is developed for modeling the response of dissolved oxygen in urbanstreams impaired by point and non-point sources of pollution. The utility of this inverseloading model in an optimal management framework for urban watersheds isinvestigated.In the context of the optimization methods, the research investigated the use of parallelmethods of optimization for use in the optimal management formulation. These includedan evolutionary computing method called genetic optimization and a modified version ofthe direct search method of optimization called the Shuffled Box Complex method ofconstrained optimization. The resulting optimal management model obtained by linkingmacro-level simulation models with efficient optimization models is capable ofidentifying optimal management strategies for an urban watershed to satisfy waterquality and economic related objectives. Finally, the optimal management model isapplied to a real world urban watershed to evaluate management strategies for waterquality management leading to the selection of near-optimal strategies.
206

Water management in the Colorado River Basin : an application of nonlinear transportation algorithms

Boles, Keith Edwin. January 1980 (has links)
Water management models have evolved through three basic stages. The earliest models dealt with the problem of getting water to where it was needed. Adequate supplies of sufficiently high cudlity were assumed to exist, and thus these models attempted to determine optimal distribution networks. In 1966 J.A. Dracup developed a model of this form to explore alternate sources of supply to meet industrial and municipal demands, agricultural demand, and demand for water to provide artificial recharge of groundwater aquifers. The next developments in water management were due to the emerging awareness of the environmental impacts of water use. These models were primarily concerned with maintaining certain quality levels within the natural water system (rivers, streams, estuaries). They tended to ignore the quantity of water within the system, being concerned with optimizing over the distribution system and quality control through the use of by-pass piping, on-site and regionalized treatment plants. The final category of models is one in which both quality and quantity considerations are allowed to enter as decision variables. The most general model of this type was developed by D.E. Pingry and T.L. Shaftel in 1979. This model allows for any configuration of sources, users, piping, disposal areas, and treatment plants. Thus the problem of distribution and quality control are both handled. This model also employs realistic nonlinear cost functions through economies of scale in treatment, and diseconomies of scale in treatment efficiency. The major limitation of their model, and others of the same type, is that they have been applied only to closed water systems which do not include rivers, streams, etc., and therefore ignore the environmental impacts of the water development on the complete natural water systems (e.g., a river basin). The Pingry-Shaftel model has been expanded to allow for the integration of a river system into an optimization model where the distribution system, quality control, source development, recycling of wastewater, and other management strategy alternatives are all allowed to enter as decision variables. At the same time the quantity requirements and quality standards are being monitored in order to analyze their impacts on cost. Decomposing the problem and making use of a large-scale transportation algorithm permit a solution to be obtained in an efficient manner. The model has sufficient flexibility to permit the comparison of impacts of various natural, technological, economic, and legal constraints. The model has been applied to the Colorado River Basin under varying assumptions in order to determine the economic and environmental implications of various water supply allocations and salinity treatment strategies.
207

SIMULATION OF NUTRIENT AND HEAVY METAL TRANSPORT CAPACITY OF SUSPENDED SEDIMENT.

Gabbert, William Andrew. January 1982 (has links)
No description available.
208

New insights for the future of Lake Champlain: Practical approaches and useful tools for grappling with uncertainty and weighing trade-offs in watershed management.

Halteman, Philip 01 January 2015 (has links)
The effective management of non-point source nutrient pollution continues to prove elusive. Though the scientific literature is unequivocal that all anthropogenic land uses contribute to non-point source (NPS) pollution, variable levels of contribution over time and across location and complex relationships between cost and effect make finding technologically effective management solutions difficult. In addition, these solutions are implemented in a world of scarce resources, diverse and often competing concerns and values, and intense public scrutiny. Clearly, making the best possible decision about how to manage NPS pollution under these conditions is not simple. My overarching goal was to develop and test several practical approaches that provide insight into the implications of management decisions and the trade-offs facing water quality managers using the challenges of restoring Lake Champlain as a test case. I first demonstrate a simple spreadsheet-based method for (1) identifying the areas of greatest potential for further phosphorus reductions, (2) estimating the potential scale of those reductions, and (3) identifying the severe tradeoffs that exist between cost and effectiveness at high levels of management. Results of this method suggest that better and more extensive management of developed impervious surfaces and annual cropland and hayland represent the greatest potential for phosphorus reductions. Farmstead management, combined sewer overflows, and wastewater treatment present little opportunity under the current regulatory environment. Results also suggest that due to order-of-magnitude differences in cost-effectiveness between management practices for developed and agricultural lands, substantial tradeoffs exist between cost-efficiency and equity in the distribution of responsibility for management. Second, in an effort to quantify the variability of NPS contributions over time and space, I developed and applied a Bayesian hierarchical modeling approach to incorporate annual hydrologic variability and uncertainty about land use areas into estimates of land-use specific phosphorus loading rates and watershed-scale residual loading. The model was able to replicate both average load and the variability around that average with an acceptable degree of precision. The results of this approach suggest that for some watersheds, unmanageable sources of phosphorus are dominant. Third, I applied a Bayes network to predict the effects of alternative management scenarios on phosphorus loads. Using evolutionary optimization and a multiple-criteria decision analysis, I explored the tradeoffs between cost, effectiveness, and distributional equity in the burden of management. Results of this study indicate that the probability that phosphorus loads will comply with regulatory targets is, in some watersheds, small under any management scenario. More interestingly, it also appears that there are large differences between watersheds in the ability of management actions to raise those probabilities, and the significant and non-linear tradeoffs between cost, effectiveness, and equity will make decision-making - and achieving restoration targets - difficult. Together, these approaches provide a foundation for a fuller and more completely informed decision-making process that incorporates uncertainty and identifies key trade-offs for the State of Vermont as it implements a new management plan for Lake Champlain.
209

Alternativas de restauração de florestas ripárias para o fornecimento de serviços ecossistêmicos. / Riparian forest restoration alternatives for the provision of ecosystem services.

Machado, Aline Ribeiro 26 May 2017 (has links)
Mais da metade da vegetação nativa no Brasil ocorrem em propriedades privadas, por isso a importância da compatibilização das atividades agropecuárias com a conservação dos recursos naturais. Os benefícios gerados pelos ecossistemas para os seres humanos são definidos como serviços ecossistêmicos, que podem ser pagos para incentivar a manutenção e restauração da vegetação nativa nas propriedades rurais, com os chamados programas de Pagamento por Serviços Ambientais (PSA). A metodologia proposta neste estudo proporciona um avanço no sentido do planejamento espacial da paisagem em propriedades privadas, a fim de aumentar o fornecimento de serviços ecossistêmicos, levando em conta a percepção dos tomadores de decisão no manejo do uso do solo, por meio de Análise de Decisão Multicritérios (MCDA). A metodologia foi testada na microbacia do córrego Cavalheiro, que é afetada pela fragmentação do habitat e conversão de terras para fins agrícolas. Os resultados mostraram que para os serviços ecossistêmicos hidrológicos, utilizados pelos programas de PSA brasileiros, deve existir uma ponderação entre a regulação do regime hidrológico com a consequente diminuição da vazão anual esperada devido ao incremento da área florestada. Em um dos cenários de uso e ocupação do solo, no qual se propôs a ocupação de 51,8 % da microbacia por vegetação nativa, houve uma diminuição de 81,25 % no escoamento superficial e de 32,2 % no escoamento de base. Entretanto, este aumento da cobertura vegetal provou ter a função de regulação hídrica, aumentando de 68 % para 87 % a contribuição da vazão de base no escoamento total da microbacia. Isso mostra que a decisão quanto ao tamanho das áreas de vegetação nativa deve ficar por conta das funções ecológicas mais exigentes, que para o caso da área de estudo mostrou ser o suporte à biodiversidade. O uso da ponderação dos critérios para a análise de decisão multicritério (MCDA) mostrou que os tomadores de decisão da microbacia estão interessados em novas formas de manejo de uso do solo, visando a regulação do regime hidrológico, aumento do suporte à biodiversidade e paisagens que tragam maior potencial às atividades de ecoturismo. Assim, os cenários com maiores áreas de vegetação nativa (cenários 6 e 8) foram classificados em primeiro lugar, uma vez que contribuíram de forma significativa com os serviços ecossistêmicos analisados. Portanto, a metodologia utilizada contribuiu com informações essenciais para a fase de diagnóstico e análise da elaboração de programas de Pagamento por Serviços Ambientais (PSA) para microbacias. / More than half of the native vegetation in Brazil occurs in private properties, this demonstrates the importance of the compatibilization of agricultural activities with the conservation of natural resources. The benefits generated by ecosystems for humans are defined as ecosystem services, which can be paid to encourage the maintenance and restoration of native vegetation on farms, with so-called Payment for Environmental Services (PES) programs. The methodology proposed in this study provides a step towards the spatial planning of the landscape in private properties, in order to increase the supply of ecosystem services, taking into account the perception of the decision makers in the land use management, through Multicriteria Decision Analysis (MCDA). The methodology was tested in the Cavalheiro stream microbasin, which is affected by habitat fragmentation and land conversion for agricultural purposes. The results showed that for hydrological ecosystem services, used by Brazilian PES programs, there should be a weighting between the regulation of the hydrological regime and the consequent decrease in the expected annual flow due to the increase of the forested area. In one of the land use and occupation scenarios, in which 51.8% of the microbasin was occupied by native vegetation, there was a decrease of 81.25% in surface runoff and 32.2% decrease in base runoff. However, this increase in vegetation cover proved to have the function of water regulation, increasing the contribution of the base flow to the total runoff of the watershed from 68% to 87%. This shows that the decision on the size of native vegetation areas must be based on the most demanding ecological functions, which for the case of the study area has been shown to be the support for biodiversity. The use of criteria weighting for multicriteria decision analysis (MCDA) has shown that microbasin decision makers are interested in new forms of land use management, aiming at regulating the hydrological regime, increasing support for biodiversity and landscapes that Bring greater potential to ecotourism activities. Thus, scenarios with larger areas of native vegetation (scenarios 6 and 8) were ranked first, since they contributed significantly to the ecosystem services analyzed. Therefore, the methodology used contributed with essential information for the diagnostic and analysis phase of the elaboration of Environmental Services Payment (PSA) programs for the Cavalheiro stream microbasin.
210

"Compartilhando a gestão dos recursos hídricos: Joinville e o Rio Cubatão". / Sharing watershed management: Joinville and the Cubatão River case study

Pereira, Marina Eduarte 08 April 2005 (has links)
Joinville é uma cidade industrial catarinense que na década de 1990 viveu a polêmica acerca da instalação de uma usina hidrelétrica na cabeceira do Cubatão, rio que abastece 70% de sua população. Apesar de o governo municipal e estadual e grande parte do poder econômico da cidade estarem em favor da obra, e de esta ter obtido algumas licenças governamentais para a instalação, a população não se convenceu da segurança da obra e achou que o dano ambiental seria grande demais – e a usina não foi concretizada. Através da mobilização da comunidade, da convocação para a participação de entidades com mais poder técnico e político sobre a questão e da exigência por maior transparência e participação no processo, conseguiu-se impedir a consecução da obra – uma vez que esta não provou sua necessidade, viabilidade e a ausência de riscos decorrentes. Considerando o associativismo na cidade e a capacidade para a ação coletiva mostrada no caso, imaginamos que o comitê de bacia hidrográfica do rio Cubatão, criado no ano 2000, apresentasse um bom estoque de capital social, sinergia e desempenho institucional. Procedemos a aplicação de questionários utilizando perguntas referentes aos componentes do capital social e do desempenho institucional aos membros do comitê, e este se mostrou permeável à participação, capaz de mobilizar recursos, favorecer a comunicação, a confiança e a cooperação entre os membros dos diversos setores, melhorar o nível de informação de seus membros e arbitrar conflitos: apresentou-se como um organismo que dispõe de bom desempenho institucional relacionado ao capital social. O desempenho institucional depende também de outros fatores: o poder governamental deveria estar muito mais presente, principalmente através de órgãos municipais, que têm grande parte das vagas no comitê, mas sofrem com a falta de recursos financeiros e técnicos para a consecução de suas atividades. O capital social e a capacidade para a ação coletiva provaram ter resistido ao fim da mobilização em torno do debate sobre a usina, penetrado no comitê e continuado através e para além dele. Iniciativas locais para despoluição de rios e reconstituição de mata ciliar conjugadas com a preocupação com as condições socioeconômicas dos habitantes da bacia hidrográfica, construindo parcerias através do comitê, evidenciam que este funciona como uma arena mobilizadora de recursos sociais, constituindo um instrumento para o gerenciamento de recursos hídricos mais eficaz e justo e para a governança da água. / In the 1990´s, Joinville, an industrial city settled in the brazilian State of Santa Catarina, has watched a controversy about the installation of a hidroelectric plant near the source of Cubatao river – responsible for 70% of the city water supply. Despite of the fact that city and State government were favourable to the plant, and that it has obtained some of the environmental licences required to its installation, Joinville’s population was not sure about the absence of its risks, and concluded that the environmental costs would be too high – and the powerplant was never constructed. Making use of leadership, convoking organisms with more political and technical capabilites about the question and demanding for more transparency and participation in the decisory process, mobilization has managed to impeach the plant installation. Taking into consideration the partnership and the capacity of collective action showed in the mobilization, we presumed that the Cubatao River Watershed Committee, created in the year 2000, would have a good level of social capital, sinergy, and good institutional performance. A survey was conducted to assess social capital and institutional performance within the committee, and it showed permeability to social participation, capacity to mobilize resources, to enlarge communication and information between its members and ability in arbitrating conflicts – presenting institutional performance related to social capital. Institutional performance, however, depends also on other factors, such as more participation of government officials in the committee. Social capital and capacity for collective action was mobilized around Cubatao watershed, acting through and beyond the comitee. Local initiatives to revert pollution process and to make forestry recovering, combined with concerning about socioeconomical aspects within the comunity, has constructed partnerships and collaboration through the committee and proved that it works as a space for mobilizating social resources, improving watershed management and acting as a tool for a more efficient and fair political decisory process, as for water governance.

Page generated in 0.1035 seconds