• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 34
  • 22
  • 5
  • 4
  • 4
  • 4
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 90
  • 20
  • 16
  • 13
  • 11
  • 10
  • 8
  • 8
  • 8
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 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.
41

Climate and heat exchange in the oceanic region adjacent to Oregon

Lane, Robert Kenneth 20 April 1965 (has links)
The climate and the exchange of heat between atmosphere and ocean are examined in a region adjacent to Washington and Oregon, and in two sub-regions adjacent to Oregon. The sub-regions are chosen such that one contains the nearshore upwelling region and the other borders it on the seaward side. The data (ship weather observations, 1953 to 1962) reveal the general seasonal variation of climatic factors in the regions studied and the effects of the nearshore upwelling of cold water on the climate over the coastal ocean region and the adjacent coastal land mass. In the nearshore sub-region, summer values of temperature (air, wet bulb, and sea surface) are lower than those to seaward, but winter values are higher inshore than to seaward. The effects of these differences, and of other factors, on the heat exchange processes are examined with the use of empirical equations. It is seen that the processes of evaporation and conduction are suppressed considerably and net long wave radiation is slightly suppressed in the upwelling region during the summer. The effects of the reduction of heat loss to the atmosphere in the summer upwelling region on the climate of coastal Oregon are seen to be a slight reduction of air temperatures and, despite reduced evaporation, a very slight increase of relative humidity. Monthly means of daily net heat exchange between the sea and the atmosphere are examined and correlated with the difference between monthly means of the heat used per day in the oceanic evaporation process and the monthly means of daily totals of heat estimated to be used in the evaporation from a shallow pan under climatic conditions identical to those accompanying the net heat exchange and oceanic evaporation. / Graduation date: 1965
42

Ontologies of cree hydrography formalization and realization /

Wellen, Christopher. January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Geography. Title from title page of PDF (viewed 2008/12/10). Includes bibliographical references.
43

O papel dos comitês de bacias de Santa Catarina no sistema nacional e estadual de gerenciamento de recursos hídricos /

Madruga, Flávia do Nascimento. January 2007 (has links)
Orientador: Ana Tereza Caceres Cortez / Banca: Helmut Troppmair / Banca: Ricardo Wagner ad-Víncula Veado / Resumo: Os Comitês de Gerenciamento de Bacias Hidrograticas têm sido objeto de uma série de estudos de caso, que apresentam as particularidades da formação, representação e atuação destes Comitês sem situá-Ios em um contexto maior. Neste trabalho procura-se mostrar uma visão geral da importância dada aos problemas ambientais a partir das últimas décadas do século XX, e, em especial, a importância assumida pelas questões de manejo, recuperação e conservação dos recursos hídricos no Brasil. São apresentados de modo detalhado o Sistema de Gerenciamento de Recursos Hídricos do Brasil, de 1997, e de Santa Catarina, de 1994, a fim de mostrar o papel dos Comitês de Gerenciamento de Bacias Hidrográficas nestes Sistemas. Tratando de modo mais específico, foram apresentadas as potencialidades e as dificuldades da atuação e o trabalho dos 16 Comitês de Gerenciamento de Bacias Hidrográficas no Estado de Santa Catarina, dentro da metodologia do Sistema de Gerenciamento de Recursos Hídricos que as idealizou. Por fim, são apontadas as contribuições que a Geografia pode dar ao processo de gestão de recursos hídricos no Brasil. / Abstract: The Committees of Hydrographic Basins Management have been object of many case studies, witch show the particularities of formation, representation and actuation of these Committees, without pointing out them in a bigger context. In this work the aim is to display a general view of the importance concerning to the enviromental questions from the last decades of the XX century and, specially, the value assumed by the hydrical resources' management, recovering and conservation issues in Brazil. It's detailed Brazil's (1997) and Santa Catarina's (1994) Hydric Resource Management Systems, intending to reveal the role of the committees of hydrographic basins in those Systems. More specifically, have been presented potentialities and difficulties in the actuation and the work of the 16 Committees of Management of Hydrographic Basins in the State of Santa Catarina, within the methodology of the Hydric Resources Management System that idealized them. To conclude, have been pointed out the contributions with which Geography can suply the process of hydrical resources management in Brazil. / Mestre
44

Hidrografía urbana de Bahía Blanca

Zapperi, Paula Andrea 23 October 2012 (has links)
La ciudad de Bahía Blanca se emplaza en la cuenca inferior del arroyo Napostá cuyo curso atraviesa el interior de la misma. Esta posición contribuye a que reciba el escurrimiento generado aguas arriba además de aumentar el peligro de inundación por sus crecidas. Sin embargo, distintas obras hidráulicas disminuyeron la ocurrencia de este tipo de problemáticas. El principal efecto de las precipitaciones intensas en la ciudad es el anegamiento en zonas de menor pendiente. En las zonas de mayor altitud el escurrimiento del agua erosiona las calles sin pavimentar y el material socavado es depositado en niveles inferiores. Conforme a lo expresado el objetivo general de la investigación fue el estudio de la hidrografía urbana aplicado a la solución de los problemas hidro-ambientales en la ciudad de Bahía Blanca. Los objetivos específicos fueron: caracterizar el comportamiento del escurrimiento superficial en la ciudad, determinar las modificaciones que se realizaron sobre las condiciones naturales del drenaje, conocer el comportamiento de los parámetros meteorológicos que definen el clima del área, caracterizar el comportamiento de las precipitaciones en el área, medir el valor de pH del agua de lluvia y analizar su distribución espacial, establecer los efectos de las precipitaciones intensas sobre la ciudad, identificar los sectores que actualmente presentan riesgo de inundación, analizar la dinámica del crecimiento urbano de la ciudad y establecer propuestas de ordenamiento que eviten el desarrollo de problemas hidro-ambientales. En la presente tesis se utilizó información altimétrica obtenida de cartografía topográfica e imágenes satelitales para combinarse con datos diversos a través de la aplicación de la tecnología de los Sistemas de Información Geográfica (SIG). Se incorporó una capa temática con la sistematización de las observaciones realizadas en el trabajo de campo y se digitalizaron los tendidos de desagües pluviales. El estudio conjunto de estos factores permitió reconocer la superposición de la red de drenaje natural con el parcelamiento, vías de circulación y diferentes tipos de cobertura. La información generada mostró la reconfiguración del patrón de escurrimiento que tomó características correspondientes con el diseño subdendrítico. Los montos acumulados de precipitación de distintos puntos de la ciudad expusieron una diferenciación que supera los 100 mm. Los mayores registros se han dado en el sector sur, donde se presentan dificultades para el escurrimiento y en el noreste de la ciudad, donde se han reconocido procesos erosivos. Los valores de pH del agua de lluvia registrados mostraron un leve aumento en comparación con los de la década del ochenta por lo que se advirtió un incremento en la condición de alcalinidad. La localización de los diferentes procesos derivados de las precipitaciones permitió definir la influencia de las condiciones naturales y de aquellas derivadas del proceso de urbanización. La forma dispersa en que se extiende la ciudad encarece el tendido de servicios y mantenimiento de las vías de circulación favoreciendo el surgimiento de estas problemáticas. Se presentaron distintas propuestas para que desde la planificación urbana se logre una gestión del drenaje que minimice el impacto hidrológico del crecimiento de la ciudad. / Bahia Blanca city is located in the lower basin of the Napostá creek. This location contributes to receive the runoff that is generated upstream and increases the flooding risk. However, different hydraulic constructions decreased the occurrence of this type of problem. The main effect of intense rainfalls over the city is the flooding in areas of lower slope. Moreover, at higher ground altitude water runoff causes two problems: the erosion of unpaved streets and the deposit the material eroded at lower levels Therefore, the general aim was to study the urban hydrography applied to the solution of environmental problems in the city of Bahia Blanca. The specific aims were: to characterize the surface runoff behavior, to define the changes that were made on natural drainage conditions, to analyze the meteorological parameters that determinate the area's climate, to characterize the rainfall behavior in the city, to measure the rainwate pH values and their spatial distribution, to define the incidente of intense precipitations over the city, to analyze the places that are currently at flooding risk, to understand the urban growth dynamics and to propose specific solutions to avoid the development of hydro-environmental problems. The present thesis used information obtained from topographic mapping altimetry and satellite images to be combined with with a variety of information through the application of the technology of Geographic Information Systems (GIS). A thematic layer was incorporated with the field observations systematization and the urban drainage ducts were digitalized. The joint study of these factors helped to identify the overlapping natural drainage network with the urban parceling, roads and different types of coverage. The information generated allow to identified a reconfiguration of the runoff pattern design. Cumulative rainfall amounts from different city places showed a difference of over 100 mm. The higer records were registered in the south, where the runoff has difficulties to flow and in the northeast, where erosion processes has been recognized. The rainwater pH values of rainfall showed a slight increase compared to the records measured in the eighties. The location of the different processes generated by rainfalls helped to define the influence of natural conditions and those derived from the urbanization process. The dispersed way that the city is expanding urges the laying and maintenance of service roads favoring the emergence of these problems. Different proposals were presented to be implemented by the urban planning to achieve a drainage management that minimizes the hydrological impact of city growth.
45

USING ADVANCED DEEP LEARNING TECHNIQUES TO IDENTIFY DRAINAGE CROSSING FEATURES

Edidem, Michael Isaiah 01 August 2024 (has links) (PDF)
High-resolution digital elevation models (HRDEMs) enable precise mapping of hydrographic features. However, the absence of drainage crossings underpassing roads or bridges hinders accurate delineation of stream networks. Traditional methods such as on-screen digitization and field surveys for locating these crossings are time-consuming and expensive for extensive areas. This study investigates the effectiveness of deep learning models for automated drainage crossing detection using HRDEMs. The study also explores the performance of advanced classification algorithm such as EfficientNetV2 model using various co-registered HRDRM-derived geomorphological features, such as positive openness, geometric curvature, and topographic position index (TPI) variants, for drainage crossings classification. The results reveal that individual layers, particularly HRDEM and TPI21, achieve the best performance, while combining all five layers doesn't improve accuracy. Hence, effective feature screening is crucial, as eliminating less informative features enhances the F1 score. For drainage crossing detection, this study develops and trains deep learning models, Faster R-CNN and YOLOv5 object detectors, using HRDEM tiles and ground truth labels. These models achieve an average F1-score of 0.78 in Nebraska watershed and demonstrate successful transferability to other watersheds. This spatial object detection approach offers a promising avenue for automated, large-scale drainage crossing detection, facilitating the integration of these features into HRDEMs and improving the accuracy of hydrographic network delineation.
46

Diagnóstico hidroambiental da microbacia do córrego "Novo Rincão" - Rincão/SP /

Barbosa, Flavia Darre. January 2012 (has links)
Orientador: Antonio Carlos Tavares / Banca: Adler Guilherme Viadana / Banca: André Luiz Pinto / Resumo: Este trabalho trata da realização do diagnóstico hidroambiental da microbacia do Córrego Nova Rincão, no município de Rincão, localizado no estado de São Paulo, para comprovar que as áreas urbana e rural desse município estão interferindo na qualidade hídrica da bacia em questão. Para corroborar essa hipótese, foi realizada a análise da qualidade de água em diversos pontos inseridos na microbacia, bem como construção de perfis transversais, cálculo de vazão e observação do uso do solo, utilizando diversas técnicas e metodologias. Todos os resultados que propiciaram o diagnóstico foram comparados com as exigências que o CONAMA estabelece para classificação de corpos de água doce no estado de São Paulo através da resolução nº 357 de 2005. Após essa comparação, os pontos analisados foram classificados como poluídos. Unindo essa classificação às observações feitas em campo, foi construído um perfil longitudinal para a realização do diagnóstico hidroambiental. As principais conclusões foram que, os pontos localizados na área rural estão poluídos por conta da plantação de cana - deaçúcar, principal cultura do município, sobretudo por conta dos fertilizantes e uso do solo que acaba provocando o assoreamento. Após atravessar a área urbana, os pontos analisados se apresentam poluídos por conta do lançamento de esgotos domésticos. De forma geral a microbacia apresentou-se em desacordo com as leis de proteção para áreas de mananciais, APP e ocupação das margens / Abstract: This paper deals with the realization of a diagnosis of hidroambiental watershed Nova Rincão stream in the town of Rincão, located in the state of São Paulo, to demonstrate that the urban and rural areas of the municipality are interfering in the water quality of the watershed. To corroborate this hypothesis, we performed the analysis of water quality at various points entered in the watershed, as well as construction of transverse profiles, flow calculation and observation of land use, using various techniques and methodologies. All results that led to the diagnosis were compared with the requirements for establishing that CONAMA classification of bodies of freshwater in the state of São Paulo by Resolution No. 357 of 2005. After this comparison, the points analyzed were classified as polluted. Joining this classification to the observations made in the field, we built a longitudinal profile for the diagnosis hidroambiental. The main conclusions were that the points located in rural areas are polluted due to the planting of sugar cane - sugar cane, the main culture of the city, mainly due to use of fertilizers and soil that ends up causing siltation. After crossing the urban area, the points analyzed are presented polluted due to the release of domestic sewage. Generally the watershed appeared at odds with the laws of protection to watershed areas, APP and occupation of margins / Mestre
47

Impacts of basin-scale forcing on the circulation of the Faroe-Shetland Channel

Walicka, Kamila January 2019 (has links)
The investigation of the role of basin-scale forcing on the circulation of the Faroe-Shetland Channel (FSC) is important to further understanding of the inter-annual variability of the Atlantic water (AW) fluxes in this region. The FSC plays a key role in the transfer of warm and saline AW towards the Nordic Seas that is an integral part of the Atlantic Meridional Overturning Circulation which is projected to decline over the twenty-first century and might reduce the oceanic heat and salt transports towards the Arctic. So far little attention has been paid to the mechanisms driving the AW fluxes in the FSC, reliable estimates of AW temperature and salt transports time series are lacking. This study presents a new time series of the AW fluxes based on the combination of hydrography and altimetry data. The mechanisms involved in driving the variability of AW fluxes are considered based on observational data and the output from a high-resolution ocean model (VIKING20). The hydrographic observations from 1993 to 2015 show an increase in temperature and salinity of AW. However, there is no evidence of trends in AW volume, temperature or salt transports during the observed period. This analysis confirms that the amount of heat and salt transported through the FSC is dominated by the volume transport. Moreover, this study identifies a bias in the standard deviation of the geostrophic velocity at a depth associated with referencing the geostrophic calculations to the sea surface geostrophic velocity from satellite altimetry. This finding does not strongly influence the AW volume transports in the AW layer, however, it has important implications for estimates of the geostrophic volume transport at depth. This study shows that the Ekman driven up/downwelling and the differential Ekman pumping mechanisms driven by the local wind forcing may influence sea surface height (SSH) and the displacement of isopycnals in the channel, leading to AW volume transport variabilit However, due to the large associated error bars on the surface and subsurface parameters, there is no clear evidence that these mechanisms are significantly responsible for the AW volume transport variability in the FSC. Lagrangian trajectories show evidence of two pathways from the North Atlantic to the FSC that may explain AW variability in the FSC: one pathway involves the flow of warm and saline waters from the Rockall Trough that corresponds to high temperatures and low AW volume transport in the channel, and the other pathway involves the flow of relatively cooler and less saline waters from the Iceland Basin that is linked to low temperatures and stronger volume transport in the FSC. Moreover, we show that the first (second) pathway is associated with the negative (positive) phases of the North Atlantic Oscillation (NAO) and the ocean gyre contraction (expansion). The changes of the NAO index phases explain 26 % of the AW volume transport variance in the FSC. Another important mechanism that leads to stronger (weaker) AW volume transport is stronger (weaker) pressure gradient across the Greenland-Scotland Ridge, reflected by the SSH changes. This mechanism explains 29 % of AW volume transport variance in the FSC.
48

Grundstötning? : En kvalitativ undersökning om sjökortets tillförlitlighet

Kärnebro, Per January 2008 (has links)
<p>Arbetet handlar om sjömätning, både hur det går till i dag och hur det gick till förr. Jag har också forskat i alternativa metoder som skulle kunna komplettera konventionell sjömätning.</p><p>Syftet med mitt arbete var att ta reda på hur många oupptäckta grund det finns kvar i den Svenska skärgården.</p><p>Metoden för att få fram bra och trovärdiga uppgifter har varit att intervjua personer som på ett eller annat sätt sysslar med sjömätning. För att kunna beskriva sjömätningens historia har jag tagit hjälp av litteratur.</p><p>Resultatet av min undersökning är att sjökortet i huvudsak stämmer någorlunda med verkligheten. Det finns dock vissa undantag, ofta stämmer sjökortet sämre i skärgårdar där få yrkesfartyg opererar.</p> / <p>This essay is about hydrography, I will investigate how it is done, both today and from a historic perspective. I have also done some research in alternative methods that may complete conventional hydrography. The purpose with this essay was to investigate how many unknown dangerous shoals there is left in the Swedish archipelago.</p><p>The method to receive good and trustworthy information has been to do some interviews to people that in one way or another are practising hydrography.</p><p>To be able to describe the history of hydrography I have had some literature as an aid.</p><p>The result of my investigation is that the nautical chart is mainly comparable to the reality; however, there are some exceptions. The nautical charts is often less reliable in archipelagos were professional shipping is unusual.</p>
49

Grundstötning? : En kvalitativ undersökning om sjökortets tillförlitlighet

Kärnebro, Per January 2008 (has links)
Arbetet handlar om sjömätning, både hur det går till i dag och hur det gick till förr. Jag har också forskat i alternativa metoder som skulle kunna komplettera konventionell sjömätning. Syftet med mitt arbete var att ta reda på hur många oupptäckta grund det finns kvar i den Svenska skärgården. Metoden för att få fram bra och trovärdiga uppgifter har varit att intervjua personer som på ett eller annat sätt sysslar med sjömätning. För att kunna beskriva sjömätningens historia har jag tagit hjälp av litteratur. Resultatet av min undersökning är att sjökortet i huvudsak stämmer någorlunda med verkligheten. Det finns dock vissa undantag, ofta stämmer sjökortet sämre i skärgårdar där få yrkesfartyg opererar. / This essay is about hydrography, I will investigate how it is done, both today and from a historic perspective. I have also done some research in alternative methods that may complete conventional hydrography. The purpose with this essay was to investigate how many unknown dangerous shoals there is left in the Swedish archipelago. The method to receive good and trustworthy information has been to do some interviews to people that in one way or another are practising hydrography. To be able to describe the history of hydrography I have had some literature as an aid. The result of my investigation is that the nautical chart is mainly comparable to the reality; however, there are some exceptions. The nautical charts is often less reliable in archipelagos were professional shipping is unusual.
50

Variation in the prey field of North Atlantic right whales (Eubalaena glacialis) in Roseway Basin

Davies, Kimberley 08 August 2012 (has links)
‘Critical Habitat’ is the habitat required to close the life history of an endangered species and is a fundamental requirement for species recovery for two reasons; the role of habitat in population limitation and viability must be determined, and the habitat must be protected. The North Atlantic right whale is an endangered species that annually migrates to the Grand Manan Basin and Roseway Basin Critical Habitats to feed on diapausing calanoid copepods that are typically aggregated at depths of 100 to 150 m. In this thesis I quantify spatial and temporal variation in the copepod prey field and occupancy of right whales in Roseway Basin, and use this information to identify the location and extent of right whale Critical Habitat. To accomplish this, I measured copepod abundance and energy density (kJ m-3) using optical, acoustic and net collection methods during 2007 to 2009. Oceanographic processes that affect variation in the copepod prey field include slope water intrusions, water mass density, gyre-like circulation and frontal features. Aggregations of diapausing copepods are maintained on the southern slope of Roseway Basin by cross-isobath tidal advection, and are advected along-isobath by the residual flow. Tidal advection at a front, coupled with along-isobath advection and shear in the horizontal currents serve to accumulate copepods along the slope where aggregations are maintained for at least 7 days. The abundance, stage-structure, species composition and aggregation locations of copepods, as well as the hydrography and circulation, were variable among the three years of the study. A 20 year time series of right whales, copepods and hydrography revealed that interannual whale occupancy in the Critical Habitats is variable and can be explained by prey field variation only in Roseway Basin. Factors other than the local prey field affect the number of whales that occupy Grand Manan Basin. Variation in the right whale prey field could not be explained by temperature and phytoplankton-dependent growth in the Scotia - Fundy -Gulf of Maine region. The results of this thesis assisted in establishing the Roseway Basin right whale Critical Habitat in 2008, and the cross-disciplinary nature of the study also provides new insights into the relationships between biology and physics in Scotian Shelf - Gulf of Maine basins.

Page generated in 0.0779 seconds