• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 212
  • 52
  • 26
  • 25
  • 12
  • 5
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • Tagged with
  • 470
  • 470
  • 175
  • 121
  • 120
  • 66
  • 56
  • 45
  • 43
  • 42
  • 41
  • 35
  • 33
  • 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.
51

Analysis of coastal erosion on Martha's Vineyard, Massachusetts a paraglacial island /

Brouillette-Jacobson, Denise, January 2008 (has links)
Thesis (M.S.)--University of Massachusetts Amherst, 2008. / Includes bibliographical references (p. 392-481).
52

An Enhanced Inventory of Global Dams and Reservoirs and Their Contribution to Sea Level

Walter, Blake January 1900 (has links)
Master of Arts / Department of Geography / Jida Wang / In the 1950s-60s, the world was experiencing a dramatic increase in artificial water impoundments in an unprecedented effort to eliminate spatial and temporal variations in water accessibility. Dam construction has since decreased, but recently, efforts to supply water and power to a booming world population may once again spark another dam construction boom. Water supplies in some regions are already highly stressed in an effort to satisfy the ever-growing water demand for agriculture, industrial, and domestic uses. With nearly 30% of the world’s population living in water-scarce regions, an improved understanding of total stored surface water has never been more needed. Yet, a complete and spatially-explicit, worldwide inventory of such storage capabilities is lacking. Using several open-source dam registries and high-resolution global lake mapping datasets extracted from thousands of Landsat images, we here aim to provide an updated and spatially-explicit inventory of dams and artificial reservoirs across the world. The following research uses novel techniques to merge 5 authoritative, open-source dam registries into a single dam and reservoir dataset, which we deemed as the Global Dam and Reservoir Inventory (GDRI). In total, GDRI documents 89,500 dams and 83,767 reservoirs for a total capacity of 8,492km3 and total surface area of 754,551km2. Reservoirs account for approximately 2.5% of the Earth’s terrestrial water. In other words, 1 unit of water for every 40 units has been artificially created. Further downscaling of the non-geocoded records provided by the International Commission of Large Dams (ICOLD) using similar geocoding methods allowed for the thorough use of all available ICOLD records. Additional capacity estimates from downscaled ICOLD records increased the GDRI capacity documentation to 8,603km3 and surface area documentation to 859,271km2. Compared to its counterpart, the Global Reservoir and Dam dataset (GRanD), GDRI increased the number of dams documented by 1204%, reservoirs by 1127%, total capacity by 37%, and total surface area by 68%. Initial water impoundment from dam construction activities can lower sea level by permanently trapping water storage on land. Dam construction resulted in an equivalent sea level drop (SLD) of 23.4mm or 0.08mm/yr. Since the dam construction boom of the 1950s-1960s, yearly SLD increased to 0.27mm/yr. By considering the hydrological characteristics of dam location, in terms of endorheic and exorheic basins, we found that exclusion of endorheic located dams decreases the overall effect on SLD by 5.47% or 1.28mm. Failure to consider the hydrologic characteristic of dam location can result in the overestimation of dam-induced SLD. After the dam construction boom of the 1950s-1960s, the world has seen a decreasing trend in dam construction, but developing countries (China, Brazil, India) are still actively pursuing dam projects that are larger and more ambitious than ever before. We see less developed countries often lack the capabilities for dam construction possibly increasing stress on natural water supplies in those regions. The datasets produced are by no means perfect. Overall, the described procedures should be considered a heuristic model, where fastidious quality assurance and automated procedures work to thoroughly eliminate many of the issues encountered with the dataset production, but errors may still exist. However, duplication between the contributing dam datasets, spatial limitations of the lake datasets, imperfect geocoding procedures, and inclusion of more dam datasets provide opportunity for future refinement and improvement of the datasets. This research contributes vital information about anthropogenic water resources that incrementally enhances our knowledge of global hydrology and the interactions taking place between different water entities.
53

Geochemical consequences of Cretaceous sea level rise

Bata, Timothy Peter January 2016 (has links)
During the Cretaceous, the CO2 content of the global atmosphere increased in response to the volcanism associated with the disintegration of the former continents. This led to a considerable rise in global temperatures, leading to a significant rise in the global sea level and the landward movement of coastlines. Cretaceous marine strata transgressed directly on the underlying basement or much older sedimentary strata. Extreme environmental conditions in the Cretaceous involved a possibly more acidic and chemically destructive atmosphere than at present, which favoured widespread deep weathering at that time. The extensive Cretaceous palaeo-seaways played a vital role in transporting and depositing the huge volume of sediments generated during the weathering events, which included economically important placer deposits (e.g., gold, diamond and platinum). A direct consequence of the extreme Cretaceous global warmth was the widespread development of Cretaceous silcretes. Much of the world's heavy oil occurs in Cretaceous reservoir sands. The geological processes responsible for the widespread occurrence of the Cretaceous oil sands can also be traced back to the unique Cretaceous greenhouse climatic condition. The warm climatic conditions imply a higher heat flow regime in the subsurface, which contributed to the thermal maturation of the organic rich sediments that are closely associated with the Cretaceous transgressive sands. The oils were generated as conventional light oil, which later degraded into heavy oils, rather than thermally cracked oils from over-matured source rocks. Oils migrated into shallow warm reservoir sands that were favourable for microbial activities. All the studied Cretaceous oil sands show evidence of hopane degradation without the formation of 25-norhopanes despite diasterane degradation in some of the samples. This strongly implies that biodegradation in these studied Cretaceous oil sands occurred at shallow depths. Pyrite precipitated from an open system by means of microbial sulfate reduction as part of the biodegradation process.
54

On the horizon: Creating a contextual refuge on the shifting Louisiana coast

January 2014 (has links)
Climate change and sea level rise are making it more dangerous to live in coastal towns and cities. Communities in these areas must learn how to become more disaster resilient and adaptive by creating more connected and educated populations. In places devastated by natural disasters, the most vulnerable populations are the ones who are left behind. Climate refuges will become more and more common as people are forced to move from the places they call home due to inhabitable conditions. It would be beneficial for these populations to move before a large scale disaster forces them to leave. As the Louisiana coast subsides and is flooded by rising sea levels, the area is becoming more vulnerable to intense floods and storms. While there is a levee surrounding the New Orleans metropolitan area, the communities outside of the levee's protection are exposed to the elements. In these neighborhoods, the frequent damage by storms and rising flood insurance rates are making it too expensive to stay. St. Bernard and Plaquemines parishes are the areas that will lose the most land and where the land is vital to the local and national economy. An environmentally and contextually sensitive infrastructure will initiate the relocation of these populations, allowing them to remain in their communities while preserving their lifestyle and quality of life. To combat the dispersion of a strong community, I propose a system that allows the communities outside the levee walls to form new town centers within the flood protection. Specifically in St. Bernard Parish, a central hub would be built on the edge of the levee protection to attract people to move to a safer area. The town center is near the most southeastern part if the levee along Louisiana 46. The center will provide support for the intended increase in population as the area fills in with relocating residents. The center will increase the disaster resilience by providing spaces that can educate the public about climate change, facilitating movement to outside the levee with a boat and automobile transit hub, provide economic support through agriculture and fishing, and help the elderly population stay connected with their community. With the creation of this new town center, the residents that are threatened with sea level rise and flooding will be able to remain connected to their land, their communities, and their livelihoods while reducing their risk. / 0 / SPK / specialcollections@tulane.edu
55

Resiliency revised: Remediation and recreation in New Orleans water systems

January 2016 (has links)
In environmental terms, New Orleans is a city that should not exist. With the Mississippi River eager to escape its engineered confinement, the topography of the city sinking slowly due to subsidence, and the steady rise of sea level partnered with wetland and coastal erosion, the future of New Orleans is wet and it is fast approaching. Initial settlers built on the naturally elevated sediment deposits of the Mississippi River, but over time and as the city grew, swamps were drained and occupation spread into lower, more saturated ground. For over two hundred years, humans have interfered with water's natural authority over this area. We have contained, diverted, drained, and regulated rivers, lakes, and swamps to maintain a constructed version of the ground plane that subverts natural processes to the regions' detriment. Plans for the future of New Orleans have been debated since Hurricane Katrina served as an expose to our synthesized and extremely fragile system. From the Dutch Dialogues, a comprehensive u an redevelopment plan, to smaller scale water management studies such as the Mirabeau Water Gardens, the drawing board has rarely been empty. Proposals have met resistance from the community, and ten years after the disaster, no coherent plan has been outlined. New Orleans isn't the only city searching for answers; delta and coastal cities the world over are recognizing the need to rethink resiliency and sustainability in light of global environmental changes. This project proposes neighborhood-scale interventions that bring previously concealed water processes to light by exhibiting them in a sustainable community-centered resource. Rather than altering existing infrastructure, this strategy would utilize current neutral ground conditions in order to take pressure off the City's drainage network. By accepting and accommodating water within the urban fabric, New Orleans can address the deficiencies in defensive water infrastructure to define a new resilience. / 0 / SPK / specialcollections@tulane.edu
56

INVESTIGATING THE EFFECTS OF SEA-LEVEL RISE AND INCREASED SALINITY ON PEAT SOILS OF THE EVERGLADES (FLORIDA): IMPLICATIONS FOR CHANGES IN BIOGENIC GAS DYNAMICS AND PEAT COLLAPSE

Unknown Date (has links)
While repeated transgressive and regressive sea level cycles have shaped south Florida throughout geological history, modern rates of sea level rise pose a significant risk to the structure and function of the freshwater wetland ecosystems throughout the low-lying Everglades region. Current regionally corrected sea level projections for south Florida indicate a rise of 0.42m by 2050 and 1.15m by 2100, suggesting the salinization of previously freshwater areas of the Everglades is conceivable. As freshwater areas become increasingly exposed to saltwater they experience shifts in vegetation composition, soil microbial populations, plant productivity, and physical soil properties that ultimately result in a phenomenon called peat collapse. Recent work in the Everglades has sought to further explain the mechanisms of peat collapse, however the physical changes to the peat matrix induced by saltwater intrusion are still uncertain. Moreover, the combination of physical alterations to the peat matrix associated with peat collapse and shifts in wetland salinity regimes will also likely disrupt the current carbon gas dynamics of the Everglades. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection
57

Rising Seas: Cataloging Architectural Response in the Conch Republic

Sima, Christine 25 May 2022 (has links)
No description available.
58

Components of ocean sea-level pressure and their relationship with rainfall over Southern Africa

Howes, Carolann 07 August 2015 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, for the degree of Master of Science. Johannesburg, 1980 / Monthly mean s e a - l e v e l p r e s s u r e ove r th e o c ea nic areas a d j a c e n t t o t h e Kepublic o f South A f r i c a i s an aly s e d . R ela t i o n s h i p s between t h e oceanic p r e s s u r e and r a i n f a l l over t h i s p a r t o f t h e c o n t i n e n t a re d i s c u s s e d . P r i n c i p a l compon e n ts a n a l y s i s is used t o d e r i v e u n c o r r e l a t e d f u n c t i o n s of th e o r i g i n a l p r e s s u r e v a r i a b l e s . Three major p r e s s u r e f i e l d s were i d e n t i f i e d , termed a g e n e r a l , a l o n g i t u d i n a l and a l a t i t u d i n a l p r e s s u r e f i e l d . The r e l a t i o n s h i p s between p r e s s u r e and r a i n f a l l a re a s s e s s e d by r e g r e s s i n g monthly r a i n f a l l on t h e p r i n c i p a l comnonent s c o r e s . R a i n f a l l in w in te r maxima a r e a s appears t o be d i r e c t l y r e l a t e d t o oceanic s e a - l e v e l p r e s s u r e s i t u a t i o n s , whereas the r e s t o f th e country shows an o u t - o f - s e a s o n r e l a t i o n s h i p between r a i n f a l l and p r e s s u r e over n o n - c o n t i n e n t a l a r e a s .
59

Spatial Implications of Flood Exposure and Relocation Attitudes among Older Populations in Hampton Roads, VA

Campbell, Jarek 07 February 2023 (has links)
Coastal communities along the eastern seaboard are continuously exposed to flooding and related impacts, compromising the health and safety of their residents and especially of more vulnerable older populations. In cases where structural protection and floodproofing measures may not protect households from all types of flooding, relocation may represent the most effective long-term adaptation option. However, the extent to which older residents in Hampton Roads, Virginia are exposed to such flooding is not well understood, nor are the factors influencing their relocation attitudes. Thus, the main objective of this research is to understand both the exposure to flooding and evaluate attitudes towards relocation among older residents in Hampton Roads. This study uses a mixed methods approach to analyze flood exposure and attitudes towards relocation among older adults living in this area. First, a geospatial analysis was conducted to assess the change in flood risk in Hampton Roads over a period of 60 years and exposure to older populations, aged 60 and over. Then the survey data were used to conduct a correlation analysis to examine the relationship between survey responses and respondents' willingness to consider relocation. The geospatial analysis showed that flood exposure in this area does not increase linearly with time, with several block groups experiencing accelerated levels of flood increases from 2000-2060. Most of the municipalities which experience high overlap between flood extent and older population percentages are urban and see dramatic increases in flood exposure from 2000-2060. The statistical results show that willingness to consider relocation is correlated to several variables measuring sociodemographic characteristics, place attachment, and flood exposure, and less to other considerations influencing the decision to permanently relocate. The most influential factors driving relocation attitudes are financial, where residents would consider relocation if compensated or offered similar housing elsewhere. Finally, a large proportion of respondents (40.28%) would prefer to permanently move to either a different region or different state should flooding continue in their community. The results of this study can help community leaders and policymakers to better understand the flood outcomes and assistance needs of their older populations living in flood-prone areas. / Master of Science / Coastal communities along the Eastern United States are constantly exposed to flooding and related impacts. Hampton Roads, Virginia is experiencing higher-than-average sea level rise, which is increasing flooding and its impacts. This area is also a preferred retirement region, where older populations prefer to move. Older populations are more negatively affected by these impacts due to chronic health conditions like diabetes and hypertension, which require easy access to health care services, as well as mobility constraints. The objective of this research is to identify areas within Hampton Roads that have a significant overlap between flooding and older populations and to understand what factors are affecting older residents' attitudes towards relocation. This study answers the following questions regarding the overall objective: 1) What is the exposure to coastal flooding of older populations living in urban areas in Hampton Roads? and 2) Which aspects of socioeconomic circumstances, experiences with flooding, and flood-related concerns affect attitudes about permanent relocation among older coastal residents? To answer these questions, a geospatial analysis was conducted, followed by a survey analysis. There are high levels of overlap between older populations and flooding in urban municipalities, and flood exposure is expected to dramatically increase between the years 2000 and 2060. From the survey, older respondents favor monetary incentives for relocation as opposed to other factors. The results from this study should be used by local policymakers for more well-informed decisions that incorporate community members in the planning and relocation process.
60

Radial orbit error reduction and sea surface topography determination using satellite altimetry /

Engelis, Theodossios January 1987 (has links)
No description available.

Page generated in 0.043 seconds