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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.
11

Estimating Impervious Surface Cover in Flathead County, Montana

Skeen, James Andrew 22 June 2017 (has links)
Northwest Montana has seen a significant increase in its population in the past twenty years. The increase in population, and associated development, is thought to be associated with "amenity migration"; people moving to an area to exploit the recreational opportunities that are unique to that area. Impervious surfaces can serve as a suitable proxy for tracking the spread of various anthropogenic influences on an ecosystem; it impacts groundwater recharge, increases overall surface runoff as well as pollution and sediment load, and fragments landscapes. In this study, an Artificial Neural Network model was developed to update NLCD impervious surface product (2011) in Flathead County, Montana. Four Landsat 8 images from 2015 and 2016 were used to characterize imperviousness. This multi-temporal analytical method was designed to reduce the spectral confusion between impervious surface and soil/agricultural lands. We compared the neural network-predicted impervious surface maps with 2011 NLCD. When all four neural network prediction images agreed with a change of 50% or more from the 2011 NLCD map, the average of those four images replaced that pixel from the 2011 imperviousness map. Compared to the ground truth, the method used showed significant promise, with an R2 of 0.73 and RMSE of 0.123. A comparison of the artificial neural network model results and the 2011 NLCD data showed a continuation of urbanization trends; the urban cores of towns in the study remain static while the majority of impervious surface development takes place along the perimeter of urban areas. / Master of Science
12

A Method for the Determination of Design Discharges for Urban Stream Restoration Projects in Northern Virginia

Petrey, Scott Raymond 24 May 2011 (has links)
It is well documented that urbanization changes the hydrology of watersheds (Hammer 1972; Booth 1991; Rose and Peters 2001). Increases in runoff volume and velocity from urbanization result in stream channel degradation (Hammer 1972; Henshaw and Booth 2000; Walsh et al. 2005; Leopold et al. 2005a; Poff et al. 2006). While stormwater management measures may be implemented to reduce the impact of stormwater runoff on streams, these practices do not reverse stream channel degradation that has already occurred. Stream restoration utilizing Natural Channel Stream Design (NCD) techniques is an effective way to reverse the effects of urbanization and return natural function to a stream. The design (bankfull) discharge for an NCD stream restoration project is the cornerstone of a restoration design. Existing methodologies for determining design discharges, such as hydrologic modeling and bankfull identification, have not worked well for NCD stream restoration projects in urban watersheds. The use of hydraulic geometry relationships serves as an alternative method for determining design discharge, but the required information is not generally available for urban Northern Virginia streams. However, rural regional curves developed for the Maryland piedmont, adjusted for watershed impervious area, provide a means to determine design discharges for urban stream restoration projects in Northern Virginia. / Master of Science
13

Investigation of Correlation between Remotely Sensed Impervious Surfaces and Chloride Concentrations

Amirsalari, Faranak January 2007 (has links)
Water quality and nonpoint source (NPS) pollution are important issues in many areas of the world, including the Greater Toronto Area where urban development is changing formerly rural watersheds into impervious surfaces. Impervious surfaces (i.e. roads, sidewalks, parking lots, strip malls, building rooftops, etc.) made out of impenetrable materials directly impact hydrological attributes of a watershed. Therefore, understanding the degree and spatial distribution of impervious surfaces in a watershed is an important component of overall watershed management. According to Environment Canada’s estimates, road salts, also considered nonpoint source pollutants, represent the largest chemical loading to Canadian surface waters. The main objective of this study is to verify the often assumed correlation between impervious surfaces and chlorides that result from the application of road salts, focusing on a case study in the selected six major watersheds within the Greater Toronto Area. In this study, Landsat-5 TM images from 1990, 1995, 2000, and 2005 were used in mapping urban impervious surface changes within the study area. Pixel-based unsupervised classification technique was utilized in estimation of percentage impervious surface coverage for each watershed. Chloride concentrations collected at Water Quality Monitoring Stations within the watersheds were then mapped against impervious surface estimates and their spatiotemporal distribution was assessed. In a GIS environment, remotely sensed impervious surface maps and chloride maps were overlaid for the investigation of their potential correlation. The main findings of this research demonstrate an average of 12.9% increase in impervious surface areas as well as a three-fold increase in chloride concentrations between 1990 and 2005. Water quality monitoring stations exhibiting the highest amounts of chloride concentrations correspond with the most impervious parts of the watersheds. The results also show a correlation (coefficient of determination of 0.82) between impervious surfaces and chloride concentrations. The findings demonstrate that the increase in imperviousness do generate higher chloride concentrations. Correspondingly, the higher levels of chloride can potentially degrade quality of surface waters in the region. Through an innovative integrated remote sensing approach, the study was successful in identifying areas most vulnerable to surface water quality degradation by road salts.
14

Investigation of Correlation between Remotely Sensed Impervious Surfaces and Chloride Concentrations

Amirsalari, Faranak January 2007 (has links)
Water quality and nonpoint source (NPS) pollution are important issues in many areas of the world, including the Greater Toronto Area where urban development is changing formerly rural watersheds into impervious surfaces. Impervious surfaces (i.e. roads, sidewalks, parking lots, strip malls, building rooftops, etc.) made out of impenetrable materials directly impact hydrological attributes of a watershed. Therefore, understanding the degree and spatial distribution of impervious surfaces in a watershed is an important component of overall watershed management. According to Environment Canada’s estimates, road salts, also considered nonpoint source pollutants, represent the largest chemical loading to Canadian surface waters. The main objective of this study is to verify the often assumed correlation between impervious surfaces and chlorides that result from the application of road salts, focusing on a case study in the selected six major watersheds within the Greater Toronto Area. In this study, Landsat-5 TM images from 1990, 1995, 2000, and 2005 were used in mapping urban impervious surface changes within the study area. Pixel-based unsupervised classification technique was utilized in estimation of percentage impervious surface coverage for each watershed. Chloride concentrations collected at Water Quality Monitoring Stations within the watersheds were then mapped against impervious surface estimates and their spatiotemporal distribution was assessed. In a GIS environment, remotely sensed impervious surface maps and chloride maps were overlaid for the investigation of their potential correlation. The main findings of this research demonstrate an average of 12.9% increase in impervious surface areas as well as a three-fold increase in chloride concentrations between 1990 and 2005. Water quality monitoring stations exhibiting the highest amounts of chloride concentrations correspond with the most impervious parts of the watersheds. The results also show a correlation (coefficient of determination of 0.82) between impervious surfaces and chloride concentrations. The findings demonstrate that the increase in imperviousness do generate higher chloride concentrations. Correspondingly, the higher levels of chloride can potentially degrade quality of surface waters in the region. Through an innovative integrated remote sensing approach, the study was successful in identifying areas most vulnerable to surface water quality degradation by road salts.
15

Ecological Diversity in Hillsborough County, Florida: Correlations between Landscape Metrics and Socio-demographic Variables

Godfrey, David 01 January 2013 (has links)
Landscape metrics, a means of quantifying landscape attributes, are frequently used in landscape ecology to describe the spatial characteristics of a landscape, but they have been less often used in anthropology. Using geographic information system (GIS) software, this study tests a method that investigates statistical correlations between groundcover landscape metrics and socio-demographic variables in Hillsborough County, Florida. Statistically significant correlations were found, illustrating the potential utility of this exploratory method. Wealthier areas with fewer ethnic minorities tend to be more fragmented and diverse in terms of groundcover; these areas also tend to have a lower percentage of impervious surfaces. The method of analysis is critiqued and applications for the results are discussed with the hope that they might help guide municipal planners in designing better urban communities.
16

Evaluating the Effects of Green Roofs as Tools for Stormwater Management in an Urban Metropolis

Polinsky, Robyn R. 01 December 2009 (has links)
Stormwater management is an essential aspect of urban hydrology. Urbanized areas have large amounts of impervious surface cover (ISC) and well developed sewer and drainage networks which rapidly channel water and pollutants off of streets and into local streams. This research evaluates the use of vegetated roofs as mechanisms to reduce ISC and stormwater runoff in downtown Atlanta. A 3-D model of the study site was created so that runoff rates could be measured for various rooftop scenarios under different size storm events. The results revealed a reduction in peak runoff and an increase in both the lag time and duration of response time. The results were most significant for the smallest storm event with 2/3 of the rooftops vegetated. As these experiments use a scale model for a section of downtown Atlanta, results are likely to be applicable to similar urban environments and may provide guidance for stormwater engineers.
17

Kinematic wave modelling of surface runoff quantity and quality for small urban catchments in Sydney

Cheah, Chin Hong, Civil & Environmental Engineering, Faculty of Engineering, UNSW January 2009 (has links)
Extensive research has been undertaken to improve the robustness of runoff quantity predictions for urban catchments. However, equally robust predictions for runoff quality have yet to be attained. Past studies addressing this issue have typically been confined to the use of simple conceptual or empirical models which forgo the tedious steps of providing a physical representation of the actual system to be modelled. Consequently, even if the modelling results for the test catchments are satisfactory, the reliability and applicability of these models for other catchments remain uncertain. It is deemed that by employing process-based, deterministic models, many of these uncertainties can be eliminated. A lack of understanding of the hydrological processes occurring during storm events and the absence of good calibration data, however, hamper the advancement of such models and limit their use in the field. This research proposes that the development of a hydrologic model based on the kinematic wave equations linked to an advection-dispersion model that simulates pollutant detachment and transport will improve both runoff quantity and quality simulations and enhance the robustness of the predictions. At the very worst, a model of this type could still highlight the underlying issues that inhibit models from reproducing the recorded historical hydrographs and pollutographs. In actual fact, this approach has already been applied by various modellers to simulate the entrainment of pollutants from urban catchments. Also, the paradigm shift to using the Water Sensitive Urban Design (WSUD) approach in designing urban stormwater systems has prompted the need to differentiate the various sources of pollutants in urban catchments such as roads, roofs and other impervious surfaces. The primary objective of the study reported herein is to model runoff quantity and quality from small urban catchments, facilitated by the procurement of the necessary field data to calibrate and validate the model via implementation of a comprehensive field exercise based in Sydney. From a water quality perspective, trace metals were selected as the foci. The study outcomes include the formulation of a linkage of models capable of providing accurate and reliable runoff quantity and quality predictions for the study catchments by taking into consideration: - The different availability of pollutants from urban catchments, i.e. roads vs. roofs; - The build-up characteristics of pollutants on the distinct urban surfaces and their spatial distribution; - The contribution of rainwater to urban runoff pollution; - The partitioning of pollutants according to particulate bound and dissolved phases; - The respective role of rainfall and runoff in the detachment and entrainment of pollutants; - The influence of particle properties such as particle size distribution and density on pollutant transport; and - The relationship associating particulate bound metals to suspended solids. The simulation results obtained using the proposed model were found to be suitable for modelling the detachment and transport of pollutants for small urban catchments. Interpretation of these results reveals several key findings which could help to rectify shortcomings of existing modelling approaches. Even though the robustness of the model presented here may not translate into a significant improvement in the overall robustness of model predictions, the physical basis on which this process-based model was developed nevertheless provides the flexibility necessary for implementation at alternative sites. It is also shown that the availability of reliable runoff data is essential for implementation of the model for other similar urban catchments. In conclusion, the proposed model in this study will serve as a worthy tool in future urban catchment management studies.
18

Urbanization and flooding in Accra, Ghana

Afeku, Kizito. January 2005 (has links)
Thesis (M.A.)--Miami University, Dept. of Geography, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], v, 53 p. : ill. Includes bibliographical references (p. 50-53).
19

A scientific communicator's internship at Hollings Marine Laboratory

Ferrigan, Mollie. January 2005 (has links)
Thesis (M.T.S.C.)--Miami University, Dept. of English, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], vi, 64, [2] p. : ill. Includes bibliographical references (p. 32).
20

A necessidade da reserva de área para o armazenamento de água no início do crescimento urbano

Juchem, José Ricardo January 2002 (has links)
Atualmente, o desenho urbano tem sido realizado dentro de um âmbito restrito do conhecimento. Este não tem considerado aspectos de drenagem da água que trazem grandes transtornos e custos para a sociedade e o ambiente. O desenvolvimento urbano brasileiro tem produzido um aumento significativo na freqüência de inundações, na produção de sedimentos e na deterioração da qualidade da água. Tal situação é decorrente, na maioria dos casos, da ocupação intensiva do solo urbano. Assim, essa abordagem demonstra, inicialmente, uma visão sobre o desenho urbano e suas interfaces; particularmente as relacionadas com a geografia, o ambiente natural e o construído. Na seqüência, pretendendo atingir o enfoque interdisciplinar, aponta vínculos entre o desenho urbano e a hidrologia através de uma análise ambiental de bairros dos municípios de Porto Alegre e Lindolfo Collor, de modo a identificar relações com a utilização de uma variável - a superfície impermeável, procurando descrever o comportamento ambiental de bacias hidrográficas urbanizadas bem como mostrar a necessidade da reserva de área para armazenar água no início do crescimento urbano. Finalizando, apresenta os principais parâmetros ou características de desenho que deverão garantir a sustentabilidade urbana e hidrológica. Apesar de prematuro, pode-se afirmar que existem indícios para que a dissertação venha suprir algumas deficiências existentes no planejamento urbano-ambientalatualmente adotado. / Actually, the urban design has been realized in the restrict scope of knowledge. It hasn't considered drainage aspects that provide large disturbances and difficulties to society and the environment. The Brazilian urban development has produced significant increase in the flooding frequency, in the sediments produce and water quality. This situation result from, in the majority of cases, the intensive occupation of urban ground. Therefore this subject show the vision about urban design and the interfaces: specially the relation between geography, natural environmental and builded environmental. In the next time, intending to affect the interdisciplinary subject, show bonds between urban design and hydrology through design study in Porto Alegre City and Lindolfo CollorCity to identifythe relationwith a variable- impervious surface, looking for describe the environmental behavior from watershed and show the necessity of water reserve in the beginning urban development. Finally, shows a proposal of sustainability urban design that integrate urban planning and hydrology. Represent a new aspect to come providing some definitions actually adopted in the urban environmental planning.

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