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1
MacDonald, Ryan J., and University of Lethbridge Faculty of Arts and Science. "Modelling the potential impacts of climate change on snowpack in the St. Mary River watershed, Montana." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Geography, c2008, 2008. http://hdl.handle.net/10133/2511.
Full textAbstract:
Climate change poses significant threats to mountain ecosystems in North America (Barnett et al., 2005) and will subsequently impact water supply for human and ecosystem use. To assess these threats, we must have an understanding of the local variability in hydrometeorological conditions over the mountains. This thesis describes the continued development and application of a fine scale spatial hydrometeorological model, GENESYS (GENerate Earth SYstems Science input). The GENESYS model successfully simulated daily snowpack values for a 10 year trial period and annual runoff volumes for a thirty year period. Based on the results of these simulations the model was applied to estimate potential changes in snowpack over the St. Mary River watershed, Montana. GCM derived future climate scenarios were applied, representing a range of emissions controls and applied to perturb the 1961-90 climate record using the “delta” downscaling technique. The effects of these changes in climate were assessed for thirty year time slices centered on 2020s, 2050s, and 2080s. The GENESYS simulations of future climate showed that mountain snowpack was highly vulnerable to changes in temperature and to a lesser degree precipitation. A seasonal shift to an earlier onset of spring melt and an increase in the ratio of rain to snow occurred under all climate change scenarios. Results of mean and maximum snowpack were more variable and appeared to be highly dependent on scenario selection. The results demonstrated that although annual volume of available water from snowpack may increase, the seasonal distribution of available water may be significantly altered.viii, 93 leaves ; 29 cm
2
Stewart-Koster, Ben Donald. "Modelling Multiscale Relationships in Riverine Landscapes: Putting the "Riverscape" into Statistical Models for River Ecology and Management." Thesis, Griffith University, 2011. http://hdl.handle.net/10072/367114.
Full textAbstract:
Many questions in ecology involve exploring the environmental processes that influence
species’ distributions and abundances in both space and time. Such environmental
processes are rarely independent, and generally operate across many scales. This is
particularly relevant to riverine systems, where the nested hierarchical structure of the
riverscape means fine-scale processes are strongly influenced by processes operating
across larger scales. Recent research has identified some key advantages in applying
Bayesian hierarchical models to hierarchical ecological problems such as identifying
relationships between species’ abundances and environmental predictor variables across
multiple scales. This thesis focuses on applying Bayesian hierarchical models to
multiscale datasets for freshwater fishes and aquatic macrophyte cover in South-East
Queensland, Australia, to address two key aspects of applied river ecology and
management. Firstly, it examines multiscale species-environment relationships for
freshwater fishes. This involves developing Bayesian hierarchical models that reflect the
structure of a conceptual model of fish species’ distribution and abundance. Secondly,
this thesis examines methods to integrate such multiscale relationships into models for
river management and restoration using Bayesian networks with an emphasis on the
management of aquatic macrophytes (BNs). Novel statistical methods such as Bayesian
hierarchical models and BNs have the potential to advance our understanding of
multiscale abiotic drivers of ecosystem structure and function across the riverscape.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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3
Larson, Robert, and University of Lethbridge Faculty of Arts and Science. "Modelling climate change impacts on mountain snow hydrology, Montana-Alberta." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2008, 2008. http://hdl.handle.net/10133/669.
Full textAbstract:
A modelling approach focused on snow hydrology was developed and applied to project
future changes in spring streamflow volumes in the St. Mary River headwaters basin,
Montana. A spatially distributed, physically-based, hydrometeorological and snow mass
balance model was refined and used to produce snow water equivalent (SWE) and
rainfall surfaces for the study watershed. Snowmelt runoff (SR) and effective rainfall
runoff (RR) volumes were compiled for the 1961-2004 historical period. A statistical
regression model was developed linking spring streamflow volume (QS) at Babb,
Montana to the SR and RR modelled data. The modelling results indicated that SR
explained 70% of the variability in QS while RR explained another 9%.
The model was applied to climate change scenarios representing the expected range of
future change to produce annual QS for the period 2010-2099. Compared to the base
period (1961-1990), average QS change ranged from -3% to -12% for the 2020s period.
Percent changes increased to between -25% and -32% for the 2050s, and -38% and -55%
for the 2080s. Decreases in QS also accompanied substantial advances in the onset of
spring snowmelt. Whereas the spring pulse onset on average occurred on April 8 for the
base period, it occurred 36 to 50 days earlier during the 2080s. The findings suggest that
increasing precipitation will not compensate for the effects of increasing temperature in
watershed SWE and associated spring runoff generation. There are implications for
stakeholder interests related to ecosystems, the irrigation industry, and recreation.xii, 136 leaves : ill. ; 28 cm. --
4
McKenny, Claire, and n/a. "The Diversity of Macroinvertebrate Grazers in Streams: Relationships With the Productivity and Composition of Benthic Algae." Griffith University. Australian School of Environmental Studies, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060308.131239.
Full textAbstract:
There has been much interest in the last decade concerning the factors that influence diversity, especially how diversity and ecosystem processes may be linked. This study was based in small, cobble streams in South East Queensland. Its aim was to determine how the diversity and composition of consumers (the grazer guild) is influenced by both the production and composition of benthic algae, at different spatial scales. It also aimed to ascertain whether this response differs among grazer sub guilds with different dispersal capabilities. Ten sites in the Upper Brisbane and Mary catchments were sampled. The sites were selected to provide a range of productivity and composition. Grazers from these sites included snails and elmids, and larval mayflies, moths, and caddisflies. Grazer diversity and composition appeared to be structured by catchment scale influences, but environmental variables also affected which animals colonised patches and microhabitats (cobbles) within catchments. Primary productivity and algal composition could not be separated, with highly productive reaches also having a high cover of filamentous algal taxa. Grazer diversity displayed strongly positive, linear relationships with algal variables at the reach scale. It had a negative relationship with filamentous algae at the cobble scale, and a non-significant hump-shaped relationship with primary productivity. Survey data alone could not separate whether grazers were responding to habitat or food-related drivers, or to variations in productivity. Experimental manipulation of algal variables at the patch scale, using light and nutrients, also could not clearly uncouple the relationship between primary productivity and filamentous algal cover. Once reach scale variation was removed, grazer diversity displayed hump-shaped relationships with algal variables, including algal diversity. Much of this variation was due to patterns in mobile grazers, as sedentary grazers did not respond to algal variation at this scale. The density of the more mobile taxa showed similar patterns to those at the cobble scale (hump-shaped). A second field experiment was carried out in order to further investigate the responses of invertebrates to algal community composition at the cobble scale. Data from all three chapters suggested that as sites shifted to a dominance of filamentous algae, often with an associated increase in GPP, there was also a shift in the grazer community towards more sedentary grazers and away from the more mobile taxa. This also occurred at the cobble scale in the second experiment. The gut analysis and diet studies in the third chapter indicated that while many grazers consumed filamentous algae, it was not assimilated. This suggests that the preferences for sedentary taxa for cobbles and reaches dominated by filamentous algae are likely to be due to some other, possibly habitat-related, factor such as flow or predation refuge. The study provides a rare examination of relationships between primary productivity and consumer diversity in freshwater streams, and finds support for the pattern found in other systems of monotonic relationships of these two variables at large scales and hump-shaped relationships at smaller scales. It emphasises the importance of understanding other, potentially confounding, aspects of communities of producers, and investigates the possible roles of the most important of these (community composition) in structuring consumer communities in the small cobble streams of South-East Queensland.
5
McKenny, Claire. "The Diversity of Macroinvertebrate Grazers in Streams: Relationships With the Productivity and Composition of Benthic Algae." Thesis, Griffith University, 2005. http://hdl.handle.net/10072/368092.
Full textAbstract:
There has been much interest in the last decade concerning the factors that influence diversity, especially how diversity and ecosystem processes may be linked. This study was based in small, cobble streams in South East Queensland. Its aim was to determine how the diversity and composition of consumers (the grazer guild) is influenced by both the production and composition of benthic algae, at different spatial scales. It also aimed to ascertain whether this response differs among grazer sub guilds with different dispersal capabilities. Ten sites in the Upper Brisbane and Mary catchments were sampled. The sites were selected to provide a range of productivity and composition. Grazers from these sites included snails and elmids, and larval mayflies, moths, and caddisflies. Grazer diversity and composition appeared to be structured by catchment scale influences, but environmental variables also affected which animals colonised patches and microhabitats (cobbles) within catchments. Primary productivity and algal composition could not be separated, with highly productive reaches also having a high cover of filamentous algal taxa. Grazer diversity displayed strongly positive, linear relationships with algal variables at the reach scale. It had a negative relationship with filamentous algae at the cobble scale, and a non-significant hump-shaped relationship with primary productivity. Survey data alone could not separate whether grazers were responding to habitat or food-related drivers, or to variations in productivity. Experimental manipulation of algal variables at the patch scale, using light and nutrients, also could not clearly uncouple the relationship between primary productivity and filamentous algal cover. Once reach scale variation was removed, grazer diversity displayed hump-shaped relationships with algal variables, including algal diversity. Much of this variation was due to patterns in mobile grazers, as sedentary grazers did not respond to algal variation at this scale. The density of the more mobile taxa showed similar patterns to those at the cobble scale (hump-shaped). A second field experiment was carried out in order to further investigate the responses of invertebrates to algal community composition at the cobble scale. Data from all three chapters suggested that as sites shifted to a dominance of filamentous algae, often with an associated increase in GPP, there was also a shift in the grazer community towards more sedentary grazers and away from the more mobile taxa. This also occurred at the cobble scale in the second experiment. The gut analysis and diet studies in the third chapter indicated that while many grazers consumed filamentous algae, it was not assimilated. This suggests that the preferences for sedentary taxa for cobbles and reaches dominated by filamentous algae are likely to be due to some other, possibly habitat-related, factor such as flow or predation refuge. The study provides a rare examination of relationships between primary productivity and consumer diversity in freshwater streams, and finds support for the pattern found in other systems of monotonic relationships of these two variables at large scales and hump-shaped relationships at smaller scales. It emphasises the importance of understanding other, potentially confounding, aspects of communities of producers, and investigates the possible roles of the most important of these (community composition) in structuring consumer communities in the small cobble streams of South-East Queensland.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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6
Henderson, Amanda Olivia. "Low-Shield Volcanism: A Comparison of Volcanoes on Syria Planum, Mars and Snake River Plain, Idaho." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6138.
Full textAbstract:
Volcanoes are key indicators of a planet's internal structure, mechanics, and evolutionary history. Consequently, understanding the types and ages of volcanoes on a planet's surface is an important endeavor. In an attempt to better understand the relationship between morphometry and volcanic processes, we compared low-shield volcanoes on Syria Planum, Mars, with basaltic shields of the eastern Snake River Plain. We used 133 volcanoes on Syria Planum that are covered by Mars Orbiting Laser Altimeter (MOLA) and High Resolution Stereo Camera (HRSC) elevation data and 246 eSRP shields covered by the National Elevation Dataset (NED) for this comparison. Shields on Syria Planum average 191 +/- 88 m tall, 12 +/- 6 km in diameter, 16 +/- 28 km3 in volume, and have 1.7° +/- 0.8 flank slopes. eSRP shields average 83 +/- 44 m tall, 4 +/- 3 km in diameter, 0.8 +/- 2 km3 in volume, and have 2.5° +/- 1 flank slopes. Bivariate plots of morphometric characteristics show that Syria Planum and Snake River Plain low shields form the extremes of the same morphospace shared with some Icelandic olivine tholeiite shields, but are generally distinct from other terrestrial volcanoes. Cluster analysis of Syria Planum and Snake River Plain shields with other terrestrial volcanoes separates these volcanoes into one cluster and the majority of them into the same sub-cluster that is distinct from other terrestrial volcanoes. Principal component and cluster analysis of Syria Planum and Snake River Plain shields using height, area, volume, slope, and eccentricity shows that Syria Planum and Snake River Plain low-shields are similar in shape (slope and eccentricity). Apparently, these low shields formed by similar processes involving Hawaiian-type eruptions of low viscosity (mafic) lavas with fissure controlled eruptions, narrowing to central vents. Initially high eruption rates and long, tube-fed lava flows shifted to the development of small lava lakes that repeatedly overflowed, and on some with late fountaining to form steeper spatter ramparts. However, Syria Planum shields are systematically larger than those on the eastern Snake River Plain. The larger size of Syria Planum shields is likely due to the smaller gravity of Mars, requiring larger magma batches to generate sufficient buoyant force to overcome the strength of rocks in the lithosphere and rise to the surface. Thus, Syria Planum lavas erupt in larger volumes and at higher rates generating larger volcanoes with slightly smaller slopes.
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Crues, Tomas Enrique. "The river and the margins : marginality and escclusion in mark twain's old south." reponame:Repositório Institucional da UFSC, 1998. http://repositorio.ufsc.br/xmlui/handle/123456789/77838.
Full textAbstract:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e ExpressãoMade available in DSpace on 2012-10-17T07:58:03Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-09T00:30:10Z : No. of bitstreams: 1 149150.pdf: 2615219 bytes, checksum: 94ba9a448de8327b3d0c0d044d40beaa (MD5)
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Goodwin, Kevin R. "American Eel Subpopulation Characteristics in the Potomac River Drainage, Virginia." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/34036.
Full textAbstract:
The demographic characteristics of American eels (Anguilla rostrata) are believed to vary with latitude and distance inland from the ocean; eels are generally thought to increase in length, age, and the proportion of females in inland and more northerly areas. Understanding this variation is necessary for the sound management of eels, but investigations into characteristics on a broad scale within drainages are scarce. Eels in the Potomac River drainage, Virginia, were sampled over a two-year period in both near-coastal and inland areas to describe characteristics in each area as well as to understand drainage-wide patterns. Inland data resulted from sampling in the Shenandoah River drainage and near-coastal data resulted from sampling tributaries to the lower Potomac River. Movement and growth were also investigated in inland areas.
Eels from the Shenandoah River drainage were significantly longer (median = 763 mm TL) and older (median = 11.5) than those found in the Potomac River tributary sites (median = 142 mm TL; median = 2.0, respectively). Both total length and age increased with increasing distance inland and sex ratio shifted from varying ratios of males:females in Potomac River tributaries to all females in the Shenandoah River drainage. Movements confirmed through mark-recapture over periods ranging up to one year were short, generally <100 m, with the longest detected movement being 1.5 km. Recapture rates were low and may be due either to low sampling efficiency, long-distance movements, or a combination of these factors. Growth and 95% confidence interval from five eels recaptured after approximately one year was 43.0 +/- 29.7 mm/year. CPUE decreased with increasing distance inland, confirming information reported by others for Virginia streams.Master of Science
9
Viviers, Joanita. "Seasonal migration and reproductive behaviour of the Common River Frog (Amietia quecketti) / Joanita Viviers." Thesis, North-West University, 2013. http://hdl.handle.net/10394/10212.
Full textAbstract:
The Common River Frog Amietia quecketti is a well-known and widely distributed species in southern Africa. Despite the fact that it is a common species and quite prevalent in urban areas little is known about its behaviour. The North-West University Botanical Gardens was selected as study area as it supports a healthy population of Common River Frogs at a series of 18 water bodies. Each pond in the Garden was assigned a reference number and the surface area, depth and vegetation were noted. Frogs were located with the aid of strong flashlights. Specimens were caught by hand and transferred to clear plastic bags. Frogs were sexed and their mass and their snout-vent length (SVL) were determined. Frogs were subsequently individually marked by means of injecting a micro-transponder (pit-tag) subcutaneously.
Field observations were conducted over two consecutive evenings every two weeks for a period of one year. On the first night all sites were visited and all frogs were scanned and their position, orientation and activity were noted. During the second night focus was on Pond 6 as it sustained the biggest population. Observation started at 19:15 and continued until 02:30. All frogs in and around the pond were scanned and detailed notes were taken, focusing on their orientation, behaviour, calling activity and distance to the nearest other frog.
Results showed that limited movement between ponds in the Garden does occur. A number of individuals were recorded regularly. Some males had preferred call sites, and clear circadian and seasonal patterns with regards to males and females exist. The complex call structure consist of a chuck and a whine and then a combination of the two.MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2013
10
Musoke, Elizabeth. "Understanding the adoption of soil and water conservation practices: the role of social capital." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38221.
Full textAbstract:
Doctor of PhilosophyEnvironmental Design and Planning
Timothy D. Keane
Kenya has been adversely affected by soil erosion due to population growth, changes in land use and land cover, and unsustainable agricultural practices. Issues related to land degradation cost the Kenyan government approximately $390 million or 3 percent of the country’s GDP yearly (Government of Kenya, 2013). Despite extensive land degradation, many attempts to encourage the use of soil and water conservation (SWC) practices have been unsuccessful. The study focuses on Merigi Ward, Kenya. Merigi Ward lies within the Mara River Basin (MRB), an ecologically and economically important river basin that has experienced extensive erosion problems. Increased agricultural activities driven by population growth in the area and changes in land use and land cover have degraded the landscape. SWC practices are greatly needed to mitigate the effects of erosion and conserve the natural resources within the MRB. Past studies suggest that social capital may increase the adoption of SWC practices (Knowler & Bradshaw, 2007; Nyangena, 2008). This study defines social capital as the groups and networks, trust and reciprocity, formal and informal rules, and information that informs the interactions among persons that lead to collective action. Twenty-five smallholder farmers within Merigi Ward were interviewed and the relationship between the adoption of SWC practices and social capital was explored through a qualitative analysis. Additionally, the MRB is home to the Mau Mara Serengeti Sustainable Water Initiative (MaMaSe). The MaMaSe initiative is a public private partnership (P3) with the goal to promote sustainable water use, economic growth, and environmental conservation within the basin. The effect the MaMaSe initiative had on the level of social capital amongst the study participants was also investigated. Findings suggest that social capital is an important aspect of SWC adoption in Merigi Ward. Groups and networks provide farmers with implementation support and information. Particularly, the local farmers’ cooperative provides farmers with implementation assistance and links (bridging capital) to experts at the MaMaSe initiative and the Ministry of Agriculture. Strong bonding capital works in the favor of this community allowing for high levels of trust. Thus, farmers collaborate to help one another implement practices and exchange information, materials, and experiences. In general, social capital has helped facilitate better environmental conservation awareness and the use of SWC practices. The largest impact the MaMaSe initiative had on the community’s social capital was expanding networks (particularly bridging and linking capital) and providing in depth information and guidelines for SWC practice use. The P3 has also helped the farmers integrate environmental conservation into their daily lives and has helped promote a shared understanding of the importance of conservation. The findings of this study will help environmental conservation professionals understand how to use social capital to strengthen natural resource management.
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Mwangi, Hosea M., Padia Lariu, Stefan Julich, Sopan D. Patil, Morag A. McDonald, and Karl-Heinz Feger. "Characterizing the Intensity and Dynamics of Land-Use Change in the Mara River Basin, East Africa." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233450.
Full textAbstract:
The objective of this study was to analyze patterns, dynamics and processes of land-use/cover changes in the transboundary Mara River Basin in East Africa. We specifically focused on deforestation and expansion of agriculture in the watershed. The intensity analysis approach was used to analyze data from satellite imagery-derived land-use/cover maps. Results indicate that swap change accounted for more than 50% of the overall change, which shows a very dynamic landscape transformation. Transition from closed forest to open forest was found to be a dominant landscape change, as opposed to a random change. Similarly, transition from open forest to small-scale agriculture was also found to be a dominant transition. This suggests a trend (pathway) of deforestation from closed forest to small-scale agriculture, with open forest as a transitional land cover. The observed deforestation may be attributed to continuous encroachment and a series of excisions of the forest reserve. Transition from rangeland to mechanized agriculture was found to be a dominant land-use change, which was attributed to change in land tenure. These findings are crucial for designing strategies and integrated watershed management policies to arrest further deforestation in the forest reserves as well as to sustainably control expansion of agriculture.
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Mwangi, Hosea M., Stefan Julich, Sopan D. Patil, Morag A. McDonald, and Karl-Heinz Feger. "Relative contribution of land use change and climate variability on discharge of upper Mara River, Kenya." Elsevier, 2016. https://tud.qucosa.de/id/qucosa%3A30418.
Full textAbstract:
Study region
Nyangores River watershed, headwater catchment of Mara River basin in Kenya.
Study focus
Climate variability and human activities are the main drivers of change of watershed hydrology. The contribution of climate variability and land use change to change in streamflow of Nyangores River, was investigated. Mann Kendall and sequential Mann Kendall tests were used to investigate the presence and breakpoint of a trend in discharge data (1965–2007) respectively. The Budyko framework was used to separate the respective contribution of drivers to change in discharge. Future response of the watershed to climate change was predicted using the runoff sensitivity equation developed.
New hydrological insights for the region
There was a significant increasing trend in the discharge with a breakpoint in 1977. Land use change was found to be the main driver of change in discharge accounting for 97.5% of the change. Climate variability only caused a net increase of the remaining 2.5% of the change; which was caused by counter impacts on discharge of increase in rainfall (increased discharge by 24%) and increase in potential evapotranspiration (decreased discharge by 21.5%). Climate change was predicted to cause a moderate 16% and 15% increase in streamflow in the next 20 and 50 years respectively. Change in discharge was specifically attributed to deforestation at the headwaters of the watershed.
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Mwangi, Hosea M., Padia Lariu, Stefan Julich, Sopan D. Patil, Morag A. McDonald, and Karl-Heinz Feger. "Characterizing the Intensity and Dynamics of Land-Use Change in the Mara River Basin, East Africa." Molecular Diversity Preservation International MDPI, 2017. https://tud.qucosa.de/id/qucosa%3A30819.
Full textAbstract:
The objective of this study was to analyze patterns, dynamics and processes of land-use/cover changes in the transboundary Mara River Basin in East Africa. We specifically focused on deforestation and expansion of agriculture in the watershed. The intensity analysis approach was used to analyze data from satellite imagery-derived land-use/cover maps. Results indicate that swap change accounted for more than 50% of the overall change, which shows a very dynamic landscape transformation. Transition from closed forest to open forest was found to be a dominant landscape change, as opposed to a random change. Similarly, transition from open forest to small-scale agriculture was also found to be a dominant transition. This suggests a trend (pathway) of deforestation from closed forest to small-scale agriculture, with open forest as a transitional land cover. The observed deforestation may be attributed to continuous encroachment and a series of excisions of the forest reserve. Transition from rangeland to mechanized agriculture was found to be a dominant land-use change, which was attributed to change in land tenure. These findings are crucial for designing strategies and integrated watershed management policies to arrest further deforestation in the forest reserves as well as to sustainably control expansion of agriculture.
14
Mwangi, Hosea M., Stefan Julich, Sopan D. Patil, Morag A. McDonald, and Karl-Heinz Feger. "Relative contribution of land use change and climate variability on discharge of upper Mara River, Kenya." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-227067.
Full textAbstract:
Study region
Nyangores River watershed, headwater catchment of Mara River basin in Kenya.
Study focus
Climate variability and human activities are the main drivers of change of watershed hydrology. The contribution of climate variability and land use change to change in streamflow of Nyangores River, was investigated. Mann Kendall and sequential Mann Kendall tests were used to investigate the presence and breakpoint of a trend in discharge data (1965–2007) respectively. The Budyko framework was used to separate the respective contribution of drivers to change in discharge. Future response of the watershed to climate change was predicted using the runoff sensitivity equation developed.
New hydrological insights for the region
There was a significant increasing trend in the discharge with a breakpoint in 1977. Land use change was found to be the main driver of change in discharge accounting for 97.5% of the change. Climate variability only caused a net increase of the remaining 2.5% of the change; which was caused by counter impacts on discharge of increase in rainfall (increased discharge by 24%) and increase in potential evapotranspiration (decreased discharge by 21.5%). Climate change was predicted to cause a moderate 16% and 15% increase in streamflow in the next 20 and 50 years respectively. Change in discharge was specifically attributed to deforestation at the headwaters of the watershed.
15
Mango, Liya M. "Modeling the Effect of Land Use and Climate Change Scenarios on the Water Flux of the Upper Mara River Flow, Kenya." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/159.
Full textAbstract:
Increasingly erratic flow in the upper reaches of the Mara River, has directed attention to land use change as the major cause of this problem. The semi-distributed hydrological model SWAT and Landsat imagery were utilized in order to 1) map existing land use practices, 2) determine the impacts of land use change on water flux; and 3) determine the impacts of climate change scenarios on the water flux of the upper Mara River. This study found that land use change scenarios resulted in more erratic discharge while climate change scenarios had a more predictable impact on the discharge and water balance components. The model results showed the flow was more sensitive to the rainfall changes than land use changes but land use changes reduce dry season flows which is a major problem in the basin. Deforestation increased the peak flows which translated to increased sediment loading in the Mara River.
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Atisa, George. "Economic assessment of best management practices in the Mara River Basin : toward implementing payment for watershed services." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/1333.
Full textAbstract:
The Mara River in East Africa is currently experiencing poor water quality and increased fluctuations in seasonal flow. This study investigated technically effective and economically viable Best Management Practices for adoption in the Mara River Basin of Kenya that can stop further water resources degradation.
A survey of 155 farmers was conducted in the upper catchment of the Kenyan side of the river basin. Farmers provided their assessment of BMPs that would best suit their farm in terms of water quality improvement, economic feasibility, and technicalsuitability. Cost data on different practices from farmers and published literature was collected. The results indicated that erosion control structures and runoff management practices were most suitable for adoption. The study estimated the total area that would be improved to restore water quality and reduce further water resources degradation. Farmers were found to incur losses from adopting new practices and would therefore require monetary support.
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com, aeveraardt@hotmail, and Annika Everaardt. "The impact of fire on the honey possum Tarsipes rostratus in the Fitzgerald River National Park, Western Australia." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040611.105120.
Full textAbstract:
The honey possum Tarsipes rostratus is a tiny (7 - 12 g) highly specialised flower-feeding marsupial endemic to the south-western corner of Australia. The impact of fire on this small mammal was studied, over a 19-year period, in the Fitzgerald River National Park, a large (330,000 ha) area of relatively undisturbed heathland/shrubland, rich in the proteaceous and myrtaceous plants upon which the honey possum appears to rely for food. The honey possum is the most abundant and widespread mammal in this Park.
Capture rates of honey possums were significantly related to the years since the vegetation was last burnt, annual rainfall in the preceding (but not the current) year, the season when trapping occurred, and the trapping grid operated. Capture rates declined markedly after fire and remained low (less than one third of those in long unburnt vegetation) for about 4 - 5 years following a fire. Rates of capture then increased steadily over the next 20 - 25 years, with maximal abundance recorded about 30 years after fire. Thereafter, there appeared to be a slight decline in capture rates, but even in the vegetation unburnt for longest (> 50 years since fire), honey possum abundance was substantial and relatively stable. In contrast to these changes in abundance, the structure of the honey possum population, with 79 % adults and 57 % males, appeared little influenced by fire history, annual rainfall, season or grid.
The increase in the rates of capture of honey possums following fire paralleled the pattern of availability of cover in the vertical and, to a lesser extent, horizontal plane. Indeed, projective foliage cover took around 20 years after fire to reach levels similar to those available in areas unburnt for even longer. The trend in capture rates was also congruent with the maturation of the most frequently visited foodplants of honey possums, particularly Banksia nutans (summer flowering) and B. baueri (winter flowering). Areas long unburnt still contained shelter and foodplants adequate for honey possums even 50 years or more after fire, with only slight evidence of senescence.
Pollen loads indicated that honey possums caught in burnt areas, where their preferred foodplants were absent, continued to feed on these favoured foodplants (Banksia and Dryandra spp.) at nearby unburnt areas. In addition, they also fed, in both burnt and long unburnt areas, upon a suite of other plant species that regenerated more rapidly from lignotubers and epicormic buds, as well as from seeds (e.g. Eucalyptus and Calothamnus spp.). Thus, honey possums appeared to persist with their preferences for feeding from a limited number of flowering plants despite some of these species not being available in recently burnt areas for many years. Nearby patches of unburnt vegetation can clearly be important refuges, feeding grounds and shelter for the few honey possums that visit recently burnt areas, and appear to be the source of honey possum colonists in the years following a fire.
Capture rates were also greater following years when rainfall was higher than average. Indeed, rainfall had as great an influence upon capture rates as time since fire. Capture rates were also consistently higher over winter, and to a lesser extent over summer, than in either autumn or spring. Individual grids, even those close together in apparently similar vegetation with a similar fire history, still differed significantly overall in their capture rates of honey possums. This last finding has implications for the use of chronosequences in the study of post-fire changes in biota.
Although not the primary focus of the study, data on the limited suite of other, far less abundant, small mammals present indicated that house mouse Mus musculus domesticus numbers peak soon after fire (about two years after fire), grey-bellied dunnart Sminthopsis griseoventer numbers somewhat later (about eight years after fire) and that southern bush rats Rattus fuscipes fiuscipes, like honey possums, are later successional species. Most species were present in vegetation over a range of post-fire ages, with data consistent with models based on sequential changes in relative abundance.
Like many Australian mammals, the range of the honey possum has contracted substantially over the last 200 years and the coastal heathlands of the south-west are its last stronghold. In terms of its conservation, this study indicates that, if possible, management burns in these heathlands should be separated by intervals of at least 20 years between successive burns, and preferably even longer. If burns are required more frequently to meet other management priorities, it is highly preferable that they are small and patchy, rather than large scale. Such practices may help ensure the long-term survival of this unique, highly specialised and endemic marsupial.
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Mwangi, Hosea Munge. "Impact of Land Use Change and Climate Variability on Watershed Hydrology in the Mara River Basin, East Africa." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-209530.
Full textAbstract:
Land use change and climate variability are the main drivers of watershed hydrological processes. The main objective of this study was to assess the impact of land use change and climate variability on hydrology of the Mara River Basin in East Africa. Land use maps generated from satellite images were analyzed using the intensity analysis approach to determine the patterns, dynamics and intensity of land use change. Changes in measured streamflow caused separately by land use change and climate variability were separated using the catchment water-energy budget based approach of Budyko framework. The information on past impact of climate variability on streamflow was used to develop a runoff sensitivity equation which was then used to predict the future impact of climate change on streamflow. Finally, the impact of agroforestry on watershed water balance was predicted using SWAT (Soil and Water Assessment Tool) model. Deforestation and expansion of agriculture were found to be dominant and intensive land use changes in the watershed. The deforestation was attributed to illegal encroachment and excision of the forest reserve. The deforested land was mainly converted to small scale agriculture particularly in the headwaters of the watershed. There was intensive conversion of rangeland to largescale mechanized agriculture which accelerated with change of land tenure (privatization). The watershed has a very dynamic land use change as depicted by swap change (simultaneous equal loss and gains of a particular land use/cover) which accounted for more than half of the overall change. This implies that reporting only net change in land use (of MRB) underestimates the total land use change.
The results show that streamflow of Nyangores River (a headwater tributary of the Mara River) significantly increased over the last 50 years. Land use change (particularly deforestation) contributed 97.5% of change in streamflow while the rest of the change (2.5%) was caused by climate variability. It was predicted that climate change would cause a moderate 15% increase in streamflow in the next 50 years. SWAT model simulations suggested that implementation of agroforestry in the watershed would reduce surface runoff, mainly due expected improvement of soil infiltration. Baseflow and total water yield would also decrease while evapotranspiration would increase. The changes in baseflow (reduction) and evapotranspiration (increase) were attributed to increased water extraction from the soil and groundwater by trees in agroforestry systems. The impact of agroforestry on water balance (surface runoff, baseflow, water yield and evapotranspiration) was proportional to increase in size of the watershed simulated with agroforestry.
Modelling results also suggested that climate variability within the watershed has a profound effect on the change of water balance caused by implementation of agroforestry. It is recommended that authorities should pay more attention to land use change as the main driver of change in watershed hydrology of the basin. More effort should be focused on prevention of further deforestation and agroforestry may be considered as a practical management strategy to reverse/reduce degradation on the deforested parts of the watershed currently under intensive cultivation.
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Whitlock, Rebecca Eleanor. "Applying Bayesian mark-recapture and decision analysis methods to evaluate fisheries management options for Fraser River white sturgeon." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542935.
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Mwangi, Hosea Munge. "Impact of land use change and climate variability on watershed hydrology in the Mara River Basin, East Africa." Thesis, Bangor University, 2016. https://research.bangor.ac.uk/portal/en/theses/impact-of-land-use-change-and-climate-variability-on-watershed-hydrology-in-the-mara-river-basin-east-africa(54692d94-33ee-40a5-9475-d5f1f7148be3).html.
Full textAbstract:
Land use change and climate variability are the main drivers of watershed hydrological processes. The main objective of this study was to assess the impact of land use change and climate variability on hydrology of the Mara River Basin in East Africa. Land use maps generated from satellite images were analyzed using the intensity analysis approach to determine the patterns, dynamics and intensity of land use change. Changes in measured streamflow caused separately by land use change and climate variability were separated using the catchment water-energy budget based approach of Budyko framework. The information on past impact of climate variability on streamflow was used to develop a runoff sensitivity equation which was then used to predict the future impact of climate change on streamflow. Finally, the impact of agroforestry on watershed water balance was predicted using SWAT (Soil and Water Assessment Tool) model. Deforestation and expansion of agriculture were found to be dominant and intensive land use changes in the watershed. The deforestation was attributed to illegal encroachment and excision of the forest reserve. The deforested land was mainly converted to small scale agriculture particularly in the headwaters of the watershed. There was intensive conversion of rangeland to largescale mechanized agriculture which accelerated with change of land tenure (privatization). The watershed has a very dynamic land use change as depicted by swap change (simultaneous equal loss and gains of a particular land use/cover) which accounted for more than half of the overall change. This implies that reporting only net change in land use (of MRB) underestimates the total land use change. The results show that streamflow of Nyangores River (a headwater tributary of the Mara River) significantly increased over the last 50 years. Land use change (particularly deforestation) contributed 97.5% of change in streamflow while the rest of the change (2.5%) was caused by climate variability. It was predicted that climate change would cause a moderate 15% increase in streamflow in the next 50 years. SWAT model simulations suggested that implementation of agroforestry in the watershed would reduce surface runoff, mainly due expected improvement of soil infiltration. Baseflow and total water yield would also decrease while evapotranspiration would increase. The changes in baseflow (reduction) and evapotranspiration (increase) were attributed to increased water extraction from the soil and groundwater by trees in agroforestry systems. The impact of agroforestry on water balance (surface runoff, baseflow, water yield and evapotranspiration) was proportional to increase in size of the watershed simulated with agroforestry. Modelling results also suggested that climate variability within the watershed has a profound effect on the change of water balance caused by implementation of agroforestry. It is recommended that authorities should pay more attention to land use change as the main driver of change in watershed hydrology of the basin. More effort should be focused on prevention of further deforestation and agroforestry may be considered as a practical management strategy to reverse/reduce degradation on the deforested parts of the watershed currently under intensive cultivation.
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Sousa, Magda Catarina Ferreira de. "Modelling the Minho river plume intrusion into the rias baixas." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12276.
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Doutoramento em Ciências do Mar e do AmbienteThe Minho River, situated 30 km south of the Rias Baixas is the most important freshwater source flowing into the Western Galician Coast (NW of the Iberian Peninsula). This discharge is important to determine the hydrological patterns adjacent to its mouth, particularly close to the Galician coastal region. The buoyancy generated by the Minho plume can flood the Rias Baixas for long periods, reversing the normal estuarine density gradients. Thus, it becomes important to analyse its dynamics as well as the thermohaline patterns of the areas affected by the freshwater spreading. Thus, the main aim of this work was to study the propagation of the Minho estuarine plume to the Rias Baixas, establishing the conditions in which this plume affects the circulation and hydrographic features of these coastal systems, through the development and application of the numerical model MOHID. For this purpose, the hydrographic features of the Rias Baixas mouths were studied. It was observed that at the northern mouths, due to their shallowness, the heat fluxes between the atmosphere and ocean are the major forcing, influencing the water temperature, while at the southern mouths the influence of the upwelling events and the Minho River discharge were more frequent. The salinity increases from south to north, revealing that the observed low values may be caused by the Minho River freshwater discharge. An assessment of wind data along the Galician coast was carried out, in order to evaluate the applicability of the study to the dispersal of the Minho estuarine plume. Firstly, a comparative analysis between winds obtained from land meteorological stations and offshore QuikSCAT satellite were performed. This comparison revealed that satellite data constitute a good approach to study wind induced coastal phenomena. However, since the numerical model MOHID requires wind data with high spatial and temporal resolution close to the coast, results of the forecasted model WRF were added to the previous study. The analyses revealed that the WRF model data is a consistent tool to obtain representative wind data near the coast, showing good results when comparing with in situ wind observations from oceanographic buoys. To study the influence of the Minho buoyant discharge influence on the Rias Baixas, a set of three one-way nested models was developed and implemented, using the numerical model MOHID. The first model domain is a barotropic model and includes the whole Iberian Peninsula coast. The second and third domains are baroclinic models, where the second domain is a coarse representation of the Rias Baixas and adjacent coastal area, while the third includes the same area with a higher resolution. A bi-dimensional model was also implemented in the Minho estuary, in order to quantify the flow (and its properties) that the estuary injects into the ocean. The chosen period for the Minho estuarine plume propagation validation was the spring of 1998, since a high Minho River discharge was reported, as well as favourable wind patterns to advect the estuarine plume towards the Rias Baixas, and there was field data available to compare with the model predictions. The obtained results show that the adopted nesting methodology was successful implemented. Model predictions reproduce accurately the hydrodynamics and thermohaline patterns on the Minho estuary and Rias Baixas. The importance of the Minho river discharge and the wind forcing in the event of May 1998 was also studied. The model results showed that a continuous moderate Minho River discharge combined with southerly winds is enough to reverse the Rias Baixas circulation pattern, reducing the importance of the occurrence of specific events of high runoff values. The conditions in which the estuarine plume Minho affects circulation and hydrography of the Rias Baixas were evaluated. The numerical results revealed that the Minho estuarine plume responds rapidly to wind variations and is also influenced by the bathymetry and morphology of the coastline. Without wind forcing, the plume expands offshore, creating a bulge in front of the river mouth. When the wind blows southwards, the main feature is the offshore extension of the plume. Otherwise, northward wind spreads the river plume towards the Rias Baixas. The plume is confined close to the coast, reaching the Rias Baixas after 1.5 days. However, for Minho River discharges higher than 800 m3 s-1, the Minho estuarine plume reverses the circulation patterns in the Rias Baixas. It was also observed that the wind stress and Minho River discharge are the most important factors influencing the size and shape of the Minho estuarine plume. Under the same conditions, the water exchange between Rias Baixas was analysed following the trajectories particles released close to the Minho River mouth. Over 5 days, under Minho River discharges higher than 2100 m3 s-1 combined with southerly winds of 6 m s-1, an intense water exchange between Rias was observed. However, only 20% of the particles found in Ria de Pontevedra come directly from the Minho River. In summary, the model application developed in this study contributed to the characterization and understanding of the influence of the Minho River on the Rias Baixas circulation and hydrography, highlighting that this methodology can be replicated to other coastal systems.
O Rio Minho, situado a 30 km a sul das Rias Baixas, é o rio mais importante que desagua na costa ocidental Galega (NO da Península Ibérica). A descarga da água doce proveniente deste rio é importante para a determinação dos padrões hidrológicos adjacentes à sua foz, particularmente perto das regiões costeiras galegas. Esta água doce pode inundar as Rias Baixas por períodos prolongados, invertendo a distribuição normal de densidade. Deste modo, é fundamental caracterizar a dinâmica da pluma do Rio Minho, assim como os padrões termohalinos das áreas afetadas pela sua dispersão. Assim, os principais objetivos deste trabalho consistiram no estudo da propagação da pluma estuarina do Minho em direção às Rias Baixas, e na deteção das condições nas quais esta afeta a circulação e as características hidrográficas destes sistemas costeiros, através do desenvolvimento e aplicação do modelo numérico MOHID. Com este propósito avaliaram-se inicialmente as características hidrográficas das embocaduras das Rias Baixas. Verificou-se então que, no caso das embocaduras norte, devido à sua reduzida profundidade, os fluxos de calor entre a atmosfera e o oceano são o forçamento principal que determina a temperatura da agua, enquanto que nas embocaduras sul os eventos de afloramento costeiro e a descarga de água doce são os fatores determinantes mais frequentes. Observou-se ainda um aumento de salinidade de sul para norte, o que indica que os menores valores detetados poderão ser explicados pela descarga de água doce proveniente do Rio Minho. Seguidamente efetuou-se uma avaliação de dados de vento na costa Galega, com o objetivo de verificar a sua aplicabilidade no estudo da dispersão da pluma estuarina do Minho. Inicialmente compararam-se ventos medidos ao longo da costa em estações meteorológicas terrestres, com ventos medidos ao largo pelo satélite QuikSCAT. Esta análise permitiu estabelecer que os dados do satélite são uma boa aproximação no estudo de fenómenos costeiros induzidos pelo vento. No entanto, visto que para forçar o modelo numérico MOHID são necessários dados de vento com grande resolução espácio-temporal perto da costa, acrescentou-se ao estudo anterior dados resultantes de simulações de um modelo de previsão (WRF). Da comparação com os dados provenientes de boias oceanográficas, conclui-se que a melhor base de dados para representação do vento perto da costa provém do modelo WRF. Para efetuar o estudo da influência da pluma estuarina do Minho nas Rias Baixas, foi desenvolvido e implementado um sistema de modelação integrado de três níveis encaixados, baseado na utilização do modelo numérico MOHID. O primeiro domínio é um modelo de maré barotrópico, englobando toda a costa da Península Ibérica. O segundo e o terceiro domínios são modelos baroclínicos tridimensionais, sendo o segundo uma representação grosseira das Rias Baixas e da costa adjacente, enquanto que o terceiro domínio inclui a mesma área com maior resolução. Neste âmbito, foi também implementado em modo 2D um modelo para o estuário do Minho, de forma a quantificar o fluxo (e as suas propriedades) que o estuário injeta no oceano. Devido à disponibilidade de dados foi escolhido o período de maio de 1998 para a validação da implementação numérica desenvolvida, efetuando a simulação da propagação da pluma estuarina do Minho para este período. Note-se que durante esta época foi detetada uma descarga elevada do Rio Minho, bem como ventos favoráveis à dispersão da pluma em direção as Rias Baixas. Os resultados obtidos mostraram que a metodologia de modelos encaixados foi implementada com sucesso, uma vez que os modelos reproduzem com precisão aceitável os padrões hidrodinâmicos e termohalinos do estuário do Minho e das Rias Baixas. Também foi avaliada a importância da descarga do Rio Minho e do vento no evento de maio de 1998. Os resultados revelaram que uma descarga moderada e contínua combinada com ventos de sul é suficiente para inverter o padrão de circulação das Rias Baixas, reduzindo a importância da existência de eventos específicos de elevado caudal. No âmbito do objetivo princial deste estudo, foram avaliadas as condições nas quais a pluma estuarina do Minho afeta a circulação e hidrografia das Rias Baixas. Os resultados numéricos indicaram que a dispersão da pluma estuarina do Minho responde rapidamente as variações do vento e às variações de batimetria e morfologia da linha de costa. Sem vento, a pluma expande-se para o largo, criando um bojo em frente da embocadura do rio. Sob condições de vento de norte, a pluma estende-se numa maior dimensão para o largo. Por outro lado, sob condições de vento de sul, a pluma fica confinada junto à costa, chegando às Rias Baixas ao fim de um dia e meio. No entanto, para descargas do Rio Minho superiores a 800 m3 s-1, a pluma estuarina do Minho inverte os padrões de circulação das Rias Baixas. Verificou-se também que a variabilidade do vento e da descarga do Rio Minho são os fatores que mais influenciam o tamanho e forma da pluma. Sob as mesmas condições analisou-se a troca de água nas Rias Baixas seguindo a trajetória de partículas lancadas perto da embocadura do estuário do Minho. Para descargas do Rio Minho superiores a 2100 m3 s-1 combinadas com ventos de sul de 6 m s-1 e numa escala superior a cinco dias, observou-se uma intensa troca de água entre as Rias. Cerca de 20% das partículas detetadas na Ria de Pontevedra provêm diretamente do Rio Minho. Em suma, a aplicação do modelo desenvolvido neste trabalho contribuiu para o conhecimento da influencia do Rio Minho na circulação e hidrografia das Rias Baixas, evidenciando que esta metodologia também pode ser replicada para outros sistemas costeiros.
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McMahon, William. "Pre-vegetation alluvium : geological evidence for river behaviour in the absence of land plants." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/276277.
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Pre-vegetation alluvium is unique; at the present day, plants affect multiple aspects of river functioning and deposition and so those rivers that operated before the evolution of land plants largely lack modern sedimentological analogue. However, such rivers were the norm for the first 90% of Earth history and so a better understanding of their sedimentary product enables insight into both the fundamental underlying mechanisms of river behaviour and the ways in which fluvial processes operated on ancient Earth and other rocky planets. This study presents five original fieldwork based case studies and an analysis of a holistic database of all of Earth’s pre-vegetation alluvium. Together these research strands offer perspectives on the sedimentological characteristics and stratigraphic trends of pre-vegetation alluvium and the behaviour and functioning of pre-vegetation rivers. Results show that, in pre-vegetation alluvial settings: 1) a variety of fluvial styles are represented, but diminished in comparison with syn-vegetation alluvium; 2) ‘sheet-braided’ architectures are common but may record a variety of fluvial planforms; 3) meandering planforms were less frequent, particularly in small- to moderate-sized river systems; 4) mudrock is on average 1.4 orders of magnitude less common than it is in syn-vegetation alluvium; and 5) microbial matgrounds were present, but had negligible effect on preserved architecture and facies. This thesis demonstrates that whilst the physical laws governing fluvial fluid-sediment interaction have not changed, the theatre in which they operated irrevocably evolved with the greening of the continents.
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Defersha, Mengistu Balew. "A multi-scale and multi-approach investigation of sediment yield and runoff flux in the Mara River basin, Kenya." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/2762.
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The purposes of this study were to identify the current potential sediment source areas and quantify rate of erosion and runoff. Runoff plots were established at three sites and the Water Erosion Prediction Project (WEPP) and Erosion 3D models were applied at watershed scale. The highest total sediment yield was observed on cultivated land (162.38 g/m2) in the Nyangores sub-watershed and the lowest sediment yield (29.95 g/m2) was observed on grassland, in Amala downstream. The model evaluation indicated that both of the models perform well in estimation of runoff, however, the WEPP model performs better than Erosion 3D in estimation of erosion. At watershed scale, the simulation result indicated that average erosion in cultivated land was about 120 tons/ha/year and the lowest erosion rate was estimated on bush lands and grass lands, which may indicate change in land use has significant impact on soil erosion in the Mara River basin
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ZHANG, HENG. "A Journey of Racial Neutrality : the symbolic meaning of the Mississippi in The Adventures of Huckleberry Finn." Thesis, Högskolan Kristianstad, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-5894.
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Bitencourt, Diego Mello. "Descrição pontual de maré, perfil de correntes e suas inter-relações em um ponto do estuário do Rio Mearim, São Luis, Maranhão." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/142122.
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Este estudo visa à descrição pontual do comportamento hidrodinâmico do estuário do Rio Mearim, analisando os padrões de corrente de maré, do registro de marés e das possíveis relações entre eles. Durante novembro e dezembro de 2012 um ADCP foi fundeado no canal do estuário, onde coletou dados por 31 dias. Os dados foram qualificados e processados para futura análise e inter-relações. Foi observado que a coluna de água estuarina no ponto de medição move-se como uma coluna de água homogênea com fluxo bidirecional no eixo NE-SW. As medições ocorreram no período de baixo índice de pluviosidade. O espectro de energia de velocidade de correntes indicou contribuições parciais dos harmônicos M2, M4, M6 e M8 no padrão de correntes encontrados. Defasagens no tempo entre os picos de máxima velocidade de corrente durante enchente e vazante mostraram a dominância do processo de maré vazante sobre a enchente no estuário. A análise integrada apresentada permitiu uma melhor compreensão no entendimento do comportamento das correntes forçadas pela maré, as chamadas correntes de maré, no estuário do Rio Mearim.This study aim to describe the punctual hydrodynamic behavior of Mearim River estuary, analyzing the pattern of the tidal current, the tidal data and possible relationship between them. During 2012 november and december an ADCP was deployed in the estuary channel, where it collected data for 31 days. The data were qualified and processed for further analysis and inter-comparisons. It was observed the estuarine water column in the point of deployment moved as a homogeneous water column with bidirectional flux in axis NE-SW. The deployment was made in a period of low pluviosity index. The energy spectrum of current velocity indicated partial contribution of harmonics M2, M4, M6 e M8 in the current pattern found. Delays between the maximum velocity during flood and ebb conditions, showed the dominance of the edd process over the flood in the estuary. An analysis integrated presented on this paper allowed a better understanding of the behavior of the current forced by tides, called the tidal current in the Mearim River estuary.
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Roberts, James H. "Factors Influencing Darter Dispersal Patterns in the Upper Roanoke River Watershed, Virginia." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34967.
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Effective delineation and management of stream fish populations requires a thorough knowledge of dispersal patterns, because these patterns affect a number of other demographic rates such as population growth, reproduction, survival, and gene flow. Previous studies of stream fish dispersal patterns have generally established species- and stream-specific home ranges and movement rates, but have largely failed to account for the environmental variables that may cause these parameters to vary. Many fishes occupy a variety of streams across a broad spectrum of ecological conditions, and movement rates (and thus population dynamics) may respond to these environmental gradients. Furthermore, enhanced understanding of the ecological features that induce or impede dispersal will help guide future management of stream channels for population connectivity.
To determine the instream features that influence the dispersal patterns of darters, I conducted a spatially intensive mark/recapture study of three darter species in the upper Roanoke River watershed. Logistic regression was used to relate observed inter-riffle movements to gradients in riffle and corridor attributes. During the first study period, habitat area loss and habitat spacing drove dispersal patterns. However, a model developed from these data transferred poorly to the second study period, in which density dependence was a more effective predictor of dispersal. Individual size did not seem to influence the probability of emigration, but did influence the distance traveled following emigration, particularly for the two more specialist species. This finding suggests a size-based dominance hierarchy for habitat selection and occupancy in darters. Predation threat had only a minor effect on the probability of traversing inhospitable corridors, but experimentally introduced structural cover significantly elevated dispersal rates through such corridors. Taken together, results of this study indicate that a complex array of ecological features interact to produce heterogeneity in dispersal rates across the stream landscape. Knowledge of these influences can be used to manage stream channels for dispersal permeability.
In addition to field studies, laboratory studies were undertaken to determine the efficacy of visible implant elastomer (VIE) and injectable photonic dye (IPD) for marking darters. No previous studies have rigorously evaluated these marks in darters, and comparisons of the two technologies in any taxa are few. Results of the laboratory study indicated that VIE is preferable to IPD for marking darters, particularly when mark longevity greater than 80 days is desired. Individuals marked with VIE exhibited higher survival and mark retention rates than did individuals marked with IPD. Additionally, VIE mark retention was more consistent across body locations. Retention of both marking technologies was biased by color. My study indicates that the results of tagging efficiency studies are not applicable across taxa, and that pilot studies are necessary prior to field use of marks in previously untested species.Master of Science
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Dessu, Shimelis B. "Water Demand and Allocation in the Mara River Basin, Kenya/Tanzania in the Face of Land Use Dynamics and Climate Variability." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/861.
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The Mara River Basin (MRB) is endowed with pristine biodiversity, socio-cultural heritage and natural resources. The purpose of my study is to develop and apply an integrated water resource allocation framework for the MRB based on the hydrological processes, water demand and economic factors. The basin was partitioned into twelve sub-basins and the rainfall runoff processes was modeled using the Soil and Water Assessment Tool (SWAT) after satisfactory Nash-Sutcliff efficiency of 0.68 for calibration and 0.43 for validation at Mara Mines station. The impact and uncertainty of climate change on the hydrology of the MRB was assessed using SWAT and three scenarios of statistically downscaled outputs from twenty Global Circulation Models. Results predicted the wet season getting more wet and the dry season getting drier, with a general increasing trend of annual rainfall through 2050. Three blocks of water demand (environmental, normal and flood) were estimated from consumptive water use by human, wildlife, livestock, tourism, irrigation and industry. Water demand projections suggest human consumption is expected to surpass irrigation as the highest water demand sector by 2030. Monthly volume of water was estimated in three blocks of current minimum reliability, reserve (>95%), normal (80–95%) and flood (40%) for more than 5 months in a year. The assessment of water price and marginal productivity showed that current water use hardly responds to a change in price or productivity of water. Finally, a water allocation model was developed and applied to investigate the optimum monthly allocation among sectors and sub-basins by maximizing the use value and hydrological reliability of water. Model results demonstrated that the status on reserve and normal volumes can be improved to ‘low’ or ‘moderate’ by updating the existing reliability to meet prevailing demand. Flow volumes and rates for four scenarios of reliability were presented. Results showed that the water allocation framework can be used as comprehensive tool in the management of MRB, and possibly be extended similar watersheds.
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Barendregt, Bart A. "From the realm of many rivers : memory, places and notions of home in the southern Sumatran highlands /." [S.l. : s.n], 2005. http://catalogue.bnf.fr/ark:/12148/cb40235154v.
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Garavanta, Carolyn A. M. "A mark-recapture study of the social organisation of the honey possum Tarsipes rostratus in the Fitzgerald River National Park, Western Australia." Thesis, Garavanta, Carolyn A. M. (1997) A mark-recapture study of the social organisation of the honey possum Tarsipes rostratus in the Fitzgerald River National Park, Western Australia. PhD thesis, Murdoch University, 1997. https://researchrepository.murdoch.edu.au/id/eprint/52134/.
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The honey possum Tarsipes rostratus is a small (7-12g) diprotodont marsupial found only in south-western Australia, mainly in sandplain heathlands. Tarsipes, the only non-flying mammal that feeds exclusively on nectar and pollen, shows considerable morphological and physiological adaptation to this specialised diet. Their anatomy, diet and reproduction have been comprehensively described but with the exception of one field study near Albany (Wooller et al. 1981) and a detailed study of the behaviour of captive animals (Russell 1986), little has been published on the spatial and temporal patterns of activity of honey possums. A series of mark-recapture studies were started in the Fitzgerald River National Park in 1984 and this thesis describes some of the results.
From February 1984 to April 1996, honey possums were caught in grids of 10x10 pitfall traps in the Fitzgerald River National Park on the south coast of Western Australia. The 72 trapping sessions resulted in 8 044 captures of honey possums from a total of 110 859 trapnights in vegetation long unburnt, an overall trapping success of 7.3%. Overall, highest capture rates of honey possums were in winter when nectar levels were high and lowest in spring when nectar was most scarce. Significantly more males than females were caught but this was not due to an unequal sex ratio but rather because males were more active. Females carrying pouch young were caught in all seasons, although autumn usually had fewest breeding females. Free-living young were also caught in each season. The maximum life span recorded for honey possums in the field was about two years, but very few individuals were recaptured after only one year.
The distance moved by honey possums between successive captures varied greatly but most moved less than 30m. Significantly more males (30%) than females (22%) moved more than 30m within a three day trapping session; however, the difference between the sexes was not significant between trapping sessions one to three months apart. The distances moved by honey possums did not differ significantly either seasonally or over increasing intervals between trapping sessions.
Home ranges, estimated by the minimum area method for individuals caught six or more times, varied from 1 50m2 to 3494m2, with a mean of 1 277m2 (0.1 3ha) for 30 males, and from 112m2 to 2212m2, with a mean of 701m2 (0.07ha) for 20 females. Males had significantly larger home ranges than females but neither sex appeared to be territorial. Honey possums are sexually dimorphic in size, with many more females than males reaching a large size. On the basis of home range overlap, it is suggested that honey possums may have a promiscuous or polyandrous mating system. A promiscuous mating system is more likely, with males travelling longer distances looking for females as well as food.
Interception lines were erected around one grid in order to detect dispersal from this grid. Very little evidence of dispersal was obtained, so that disappearance of marked individuals from the population was probably due to their death. There was some suggestion that all honey possums move farther in spring, when nectar is scarce in the Fitzgerald River National Park, but the low numbers in spring make this difficult to confirm.
Of 23 male and 18 female honey possums tracked using the spool-and-line technique, 9 males and 9 females could be followed for at least 10m. On average, about 75% of each of these trails were along runways on the ground. Eleven individuals were tracked to feeding sites on Banksia, Dryandra or Calothamnus flowers. Over 116 hours of field observations, only 30 honey possums were observed, usually only fleetingly. However, five of these were observed feeding for a total of ten minutes. Honey possums appear to be trap-line foragers, utilising a specific foraging path over sequential nights.
Comparison of the social organisation of the honey possum with other small mammals and other small nectarivores suggests that Tarsipes rostratus is widely separated from phylogenetically related small mammals and has no real ecological counterpart anywhere in the world.
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Garcia, Rivera Mariel Anel [Verfasser], and Mark [Akademischer Betreuer] Brönstrup. "Antibiotic uptake in Pseudomonas aeruginosa and its consequences on the metabolome / Mariel Anel Garcia Rivera ; Betreuer: Mark Brönstrup." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://d-nb.info/122961494X/34.
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Carey, Caitlin. "An Evaluation of Population Restoration and Monitoring Techniques for Freshwater Mussels in the Upper Clinch River, Virginia, and Refinement of Culture Methods for Laboratory-Propagated Juveniles." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/24450.
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From 2006-2011, four population reintroduction techniques were applied to three sites within a reach of the upper Clinch River in Virginia designated suitable for population restoration of the federally endangered oyster mussel (Epioblasma capsaeformis). These techniques were: 1) translocation of adults (Site 1), 2) release of laboratory-propagated sub-adults (Site 1), 3) release of 8-week old laboratory-propagated juveniles (Site 2), and 4) release of stream-side infested host fishes (Site 3). Demographic data were collected in 2011 and 2012 by systematic quadrat and capture-mark-recapture sampling to assess reintroduction success, evaluate reintroduction techniques, and compare survey approaches for monitoring freshwater mussels. Estimates of abundance and density of translocated adults ranged from 450-577 individuals and 0.09-0.11/m2 in 2011, and 371-645 individuals and 0.07-0.13/m2 in 2012. Estimates of abundance and density of laboratory-propagated sub-adults ranged from 1,678-1,943 individuals and 0.33-0.38/m2 in 2011, and 1,389-1,700 individuals and 0.27-0.33/m2 in 2012. Additionally, three recruits were collected at Site 1. No E. capsaeformis were collected at Sites 2 and 3. Capture-mark-recapture sampling produced similar mean point estimates as systematic quadrat sampling, but with typically more precision. My results indicated that the release of larger individuals (>10 mm) is the most effective technique for restoring populations of E. capsaeformis, and that systematic quadrat and capture-mark-recapture sampling have useful applications in population monitoring that are dependent on project objectives. Systematic quadrat sampling is recommended when the objective is to simply estimate and detect trends in population size for species of moderate to larger densities (>0.2/m2). Capture-mark-recapture sampling should be used when objectives include assessing a reintroduced population of endangered species or at low density, obtaining precise estimates of population demographic parameters, or estimating population size for established species of low to moderate density (0.1-0.2/m2).
The ability to grow endangered juveniles to larger sizes in captivity requires improving grow-out culture methods of laboratory-propagated individuals. A laboratory experiment was conducted to investigate the effects of temperature (20-28 C) on growth and survival of laboratory-propagated juveniles of the Cumberlandian combshell (Epioblasma brevidens), E. capsaeformis, and the wavyrayed lampmussel (Lampsilis fasciola) in captivity. Results indicated that 26 C is the optimum temperature to maximize growth of laboratory-propagated juveniles in small water-recirculating aquaculture systems. Growing endangered juveniles to larger sizes will improve survival in captivity and after release into the wild. As a result, hatcheries can reduce the time that juveniles spend in captivity and thus increase their overall production and enhance the likelihood of success of mussel population recovery efforts by federal and state agencies, and other partners.Master of Science
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Johnson, James Matthew. "Demography and Behavior of Western Sandpipers (Calidris mauri) Breeding on the Yukon-Kuskokwim River Delta, Alaska." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28903.
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I conducted demographic and behavioral studies of Western Sandpipers (Calidris mauri) breeding on the Yukon-Kuskokwim River Delta, Alaska (1998-2005). In chapter one, I estimated apparent annual survival (product of true survival and site fidelity) while correcting for the probability of encounter for 237 males and 296 females. Overall return rates (individual returned to the site in a subsequent season) were lower for females (40%) than males (65%), as was apparent annual survival (± SE, females = 0.65 ± 0.05, males = 0.78 ± 0.03), and encounter rate (females = 0.51 ± 0.07, males = 0.74 ± 0.04). In chapter two, I examined the effects of mate and site fidelity on nesting success (N = 430 nests). Annual divorce rate ranged between 37-83%, with 17-63% of pairs reuniting annually. Reuniting pairs initiated clutches earlier than newly formed pairs, and clutches that were initiated early in the season had higher nest success rates compared to late-season nests. When I controlled for clutch-initiation date, nests tended by individuals with prior breeding-site experience had higher daily survival rates compared to birds breeding at the site for the first time. The effect of site experience was greater for males than females. In chapter 3, I reported that Western Sandpipers exhibited aggregated breeding behavior on a 36 ha plot. Breeding aggregations occurred when dominant and/or older individuals excluded younger, subordinate individuals from preferred habitat. The pattern of habitat occupancy conformed to an ideal despotic distribution with aggregated nesting birds in less preferred habitat experiencing lower reproductive success. In chapter 4, I described and demonstrated the form and function of parent-chick communication in the Western Sandpiper. Through experimental playback of adult vocalizations to chicks in the field, I demonstrated: (1) chicks respond to the alarm call by vocalizing relatively less often and moving away from the signal source, (2) chicks respond to the gather call by vocalizing relatively more often and moving toward the signal source, (3) and chicks respond to the freeze call by vocalizing relatively less often and crouching motionless on the substrate for extended periods of time. I also describe two distinct chick vocalizations (chick-contact and chick-alarm calls).Ph. D.
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Burfeid, Castellanos Andrea Montserrat. "Ecological factors and diatom diversity at rivers of the iberian mediterranean river basins: macro-scale, meso-scale and micro-scale = Factores ecológicos y diversidad de diatomeas en los ríos de las cuencas hidrográficas del Mediterráneo ibérico: maro-escala, meso-escala y micro-escala." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663475.
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Benthic diatoms, photoautotrophic, silicate plated, single-celled aquatic organisms dwelling on substrates, have been used in bioindication, since they are good indicators of ecological water state. In this thesis, we have used a multi-scalar approach to observe how diatoms from Spanish Mediterranean rivers are affected by the characteristics of the habitats they live in. These organisms were observed under a taxonomic-indicative, functional-grouped and morphometric prism.
The samples stem from Mediterranean rivers pertaining to either the Ebro Basin, or jurisdictions of the Catalan rivers or the Júcar authorities. Ebro samples have a fundamental importance, due to their temporal frame of 10 years, which has permitted the establishment and observation of changes in diatom communities and their characteristics. Two experimental setups, comparing differing water compositions and hydrological characteristics, were made in the other basins. The structure of this thesis takes a gradual decrease in observation range.
The macro-scale: chapter studied benthic diatom communities from the Ebro River Basin taxonomically, based on samplings ranging 10 years. We studied if diatom communities were maintained in time, or what parameters could help to the establishment of ecoregions. This study showed that the ecotype division of rivers established by the Water Framework Directive (WFD) did not reflect diatom assemblages well. A double approach of physico- chemical and diatom-sociological aggregation can create a better mirror of diatom communities, thus improving ecoregions for diatoms.
The meso-scale chapter investigated the Segre, Ebro tributary, observing the relationship between land use and diatom assemblages and indicator values. Land uses have a direct effect on river water composition. Thus, a link between upstream land cover and diatom assemblages was expected. The results show that only the predominant covers affect both the composition of the diatom community and indicator values. Structural Equation Modelling comparisons have established changes in the importance of physicochemical parameters through time and depending on diatom community structure. Diversity indices and bioindicator values were affected mostly by physicochemical composition, and tangentially by land cover.
In the micro-scale chapter, the reaction of diatoms at each site was studied. To do this, we parted the chapter in three sections, two life form experiments to observe how physicochemical composition and hydrology affect life forms, and how morphometry can be affected through abiotic parameter variation in time. The first, made in the Llobregat Basin, was an experimental approach to ascertain the effect of intrinsically different sites on diatom life forms and ecological guilds and the change when these communities are translocated. This showed that, although the physicochemical parameters seemed to favour functional groups, changing the community into a different site could still maintain some of the characteristic life forms.
Then, a comparison of functional structure of the diatom community in temporary rivers (that lose part or the totality of its surface water) of Mediterranean basins along the northeast coast was made. It showed that the hydrological regime (connectedness of the stream in total) had a bigger impact than aquatic state (water quantity
present at time of sampling). The disconnection of streams also affected the use of conventional diatom bioindicators that will be addressed in the future.
Finally, in this microscale prism, we automatically photographed samples from the Ebro River to extract diatom morphometry features. Relating these to physicochemical parameters of each site and their temporal variability, we saw that diatom sizes are affected by water composition. The surface-to-volume ratio (S/V) was highly correlated. An up to now neglected parameter, diatom width, was highly affected by physicochemical parameters.
This thesis attempted to establish how diatoms and their traits are affected by their surroundings, observing the effect of abiotic parameters, such as physicochemical composition, land use, and substrate characteristics.Las diatomeas bentónicas son organismos fotoautotróficos unicelulares, acuáticos y colonizadores de sustratos, que se han usado en bioindicación por ser buenas indicadoras del estado ecológico del agua. En esta tesis hemos estudiado cómo las diatomeas de ríos ibéricos mediterráneos se ven afectadas por la ecología del medio donde habitan, a diversas escalas. Estos organismos se estudiaron a nivel taxonómico e indicativo, funcional y morfométrico. La estructura de esta tesis sigue una aproximación a la reducción de escala de trabajo. El capítulo de macro-escala se basó en una investigación de las comunidades bentónicas epilíticas de las diatomeas del río Ebro, en base a muestreos realizados a lo largo de 10 años. Este estudio se ha demostrado que la división en ecotipos fluviales establecida para el seguimiento de la Directiva Marco del Agua (DMA) no coincide con la diversificación delascomunidades deestosorganismos. Nuestrosresultados apuntanqueunaaproximacióndoble (composición físico-química y estructura de la comunidad) puede reflejar mejor la realidad para las diatomeas. En el capítulo de meso-escala se investigó el río Segre con la finalidad de establecer las relaciones entre los usos del suelo y las comunidades de diatomeas y valores de los índices de diatomeas. Los usos del suelo afectan directamente a la composición del agua fluvial. Por ello, se esperaba una correlación entre el uso del suelo aguas arriba de las comunidadesde diatomeas estudiadas. Los resultados muestranque únicamentelos usos mayoritarios afectan la composición las comunidades de diatomeas y los valores de los índices diatómicos. En el capítulo de microescala se estudió la reacción de las diatomeas en cada punto. Para ello el capítulo se dividió en tres secciones. Un experimento observó el efecto de puntos intrínsecamente diferenciales sobre las formas de vida, y cambios de estas tras su translocación. La otra sección comparó la composición funcional de la comunidad de diatomeas en ríos temporales, que sufren pérdida parcial o total del agua superficial. Finalmente, aún en microescala, se fotografiaron automáticamente muestras de diatomeas del río Ebro para calcular sus características morfométricas. Estas se relacionaron con los parámetros fisicoquímicos de cada punto y con su variabilidad temporal. El resultado fue una clara afectación de tamaños valvares según la composición del agua. La relación superficie-volumen estaba altamente correlacionada y la anchura valvar, obviada hasta ahora, se vio afectada por los parámetros fisicoquímicos.
Les diatomees bentòniques, organismes fotoautotròfics unicel·lulars, aquàtics i colonitzadors de substrats, que s’han utilitzat a la bioindicació per ser bones indicadores del estat ecològic de l’aigua. En aquesta tesi hem estudiat com les diatomees de rius ibèrics mediterranis es veuen afectades per l’ecologia del medi al que habiten a diverses escales. Aquests organismes es varen observar a nivell taxonòmic-indicatiu, funcional i morfomètric. L’estructura d’aquesta tesi segueix una aproximació a la reducció d’escala de treball. El capítol de macro-escala es basà en una investigació taxonòmica de les comunitats bentòniques epilítiques de diatomees del riu Ebre, basat en mostrejos realitzats al llarg de 10 anys. Aquest estudi ha mostrat que la divisió d’ecotips fluvials establerta per a el seguiment de la Directiva Marc de l’Aigua (DMA) no coincideix amb la diversificació de les comunitats d’aquests organismes. Els resultats assenyalen que una aproximació doble (composició fisicoquímica i estructura comunitària) podria reflectir millor la realitat per a les diatomees. Al capítol de meso-escala s’estudià el Segre per tal d’establir les relacions entre els usos del sòl, les comunitats de diatomees i els seus valors indicadors. Els usos del sòl afecten directament a la composició de l’aigua fluvial. Per això, s’esperava una correlació entre els usos del sòl aigües amunt de les comunitats de diatomees estudiades. Els resultats mostren que únicament els usos majoritaris afecten els la composició de les comunitats de diatomees els i valors dels índexs diatòmics. El capítol de micro-escala investigà la reacció de les diatomees a cada punt. Per això, el capítol es dividí en tres seccions. Un experiment observà l’efecte de punts intrínsecament diferencials sobre les formes de vida i canvis d’aquests després de la translocació. L’altra secció comparà la composició funcional de la comunitat de diatomees a rius temporals, que pateixen la pèrdua total o parcial de l’aigua superficial. Finalment, seguint a la micro-escala, es fotografiaren les mostres del riu Ebre automàticament per calcular les seves característiques morfomètriques. Aquestes es relacionaren amb els paràmetres fisicoquímics de cada punt i la seva variabilitat temporal. El resultat fou una clara afectació de mides valvars segons la composició de l’aigua. La relació superfície-volum estava altament correlacionada amb les variacions fisicoquímiques i l’amplada valvar, obviada fins ara, era afectada pels paràmetres fisicoquímics.
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Ribeiro, Cristina Ramalho. "Processos de alterações da maré astronômica na desembocadura da Lagoa dos Patos." reponame:Repositório Institucional da FURG, 2008. http://repositorio.furg.br/handle/1/3521.
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Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia Oceânica, Escola de Engenharia, 2008.Submitted by Lilian M. Silva (lilianmadeirasilva@hotmail.com) on 2013-04-23T20:01:48Z No. of bitstreams: 1 Processos de Alterações Da Maré Astronômica Na Desembocadura da Lagoa Dos Patos.pdf: 5559394 bytes, checksum: d5348a72601c4539f3d215ebe5cbad74 (MD5)
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Made available in DSpace on 2013-06-13T17:34:41Z (GMT). No. of bitstreams: 1 Processos de Alterações Da Maré Astronômica Na Desembocadura da Lagoa Dos Patos.pdf: 5559394 bytes, checksum: d5348a72601c4539f3d215ebe5cbad74 (MD5) Previous issue date: 2008
Diversos estudos têm sido realizados sobre a circulação estuarina da Lagoa dos Patos. Devido a menor importância das marés, a maioria dos trabalhos têm se concentrado nos efeitos que o vento e a descarga fluvial exercem sobre a hidrodinâmica da lagoa e, embora o efeito da maré seja secundário na circulação estuarina, existe uma complexa interação entre as marés, a descarga fluvial e os ventos. A Lagoa dos Patos está localizada na planície costeira do Estado do Rio Grande do Sul, entre as latitudes de 30° S e 32° S. Este estudo está baseado na análise estatística dos dados, principalmente de séries temporais de nível das águas registradas na desembocadura da Lagoa dos Patos e na aplicação de técnicas de modelagem numérica. Para se verificar os efeitos do vento e da descarga fluvial na variabilidade das constantes harmônicas da região, são usados como referência, séries de velocidade e direção do vento e dados de descarga fluvial dos principais afluentes da Lagoa dos Patos. Os componentes harmônicos caracterizam a maré de um determinado local e, por isso, é necessário o estudo dos constituintes a fim de analisar as oscilações existentes. A previsão das séries está diretamente relacionada a esta variabilidade e, devido a este motivo, são testadas diferentes séries para se obter uma previsão mais eficaz. O modelo TELEMAC é utilizado para simular os componentes harmônicos O1, K1, M2 e S2. As análises mostraram que os ventos e a descarga fluvial, influenciam nas variações que ocorrem nas amplitudes dos componentes harmônicos estudados (O1, K1, M2 e S2).
Several studies have been conducted on the movement of estuarine of Patos Lagoon. Due to the minor importance of the tides, most of the previous studies carried out in the area focused on the effect of wind and river discharge carry on the hydrodynamics of the lagoon, and although the effect of the tide is secondary in estuarine hydrodynamics, there is a complex interaction between the tides, river discharge and the winds. The Patos Lagoon is located in the coastal plain of the State of the Rio Grande do Sul, between latitudes 30 ° S and 32 ° S. This study is based on analysis of data, particularly of time series of water levels recorded in the entrance of Patos Lagoon and the analysis of the results of a numerical model adapted to the conditions of the lagoon. To ascertain the effects of wind and river discharge in the variability of harmonics in the region, are used as reference, data sets of speed and direction of wind and river discharge data of the main tributaries of Patos Lagoon. The harmonic components characterize the tide of a particular place and therefore it is necessary to study their constituents to analyze existing fluctuations. The forecast of the series is directly related to this variability, and because of this reason, are tested different series for a more effective forecasting. Model TELEMAC is used to simulate the behavior of the harmonic components O1, K1, M2 and S2 under different wind and river discharge regimes. The analyses had shown that to the winds and the river discharge, influence in the variations that occur in the amplitude of the studied harmonic components (O1, K1, M2 e S2).
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Ermak, Jessica Lea. "The Social Structure and Mating Strategies of Bottlenose Dolphins (Tursiops truncatus) in the St. Johns River." UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/533.
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Across populations, bottlenose dolphins (Tursiops sp.) exhibit a fission-fusion pattern of associations, in which group size and composition change fluidly throughout the day. Beneath this seemingly ephemeral social structure, considerable variation exists across study sites. While females typically have moderate bonds with one another within a large social network, male-male bonds are variable, though males typically take one of two strategies; some males encounter females individually for opportunities to breed while others cooperate within a first-order alliance to collectively herd females. In addition, multi-tiered alliances in which two first-order alliances cooperate to defend or assist in the theft of a female have been documented within Shark Bay, Australia. However, these patterns do not apply to all study sites, as intersexual bonds are strong within several bottlenose dolphin populations. Given the variation in the presence and complexity of male alliances, greater documentation of social structure and male mating strategies across study sites is needed to draw conclusions as to the ultimate factors behind alliance formation. As such, chapter one documents the inclusion of a new study site in the St. Johns River (SJR) in Northeast Florida where males form first and second-order alliances. In addition, variables from the SJR are included within a meta-analysis in chapter two, the first systematic examination of what variables correlate with alliance presence and complexity, with the conclusion that male-male competition best describes the patterns seen in male alliance formation. Chapter three builds upon this conclusion by examining seasonal trends in tooth rake marks, a proxy for aggression, across the sexes and males of two different mating strategies, ultimately highlighting the potential for non-reproductive aggression. Together, this work provides greater insight as to the social structure and mating patterns of bottlenose dolphins, as well as to the ecological pressures that result in complex sociality.
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Kirkland, Graham. "From Rivers to Gardens: The Ambivalent Role of Nature in My Ántonia, O Pioneers!, and Death Comes to the Archbishop." Digital Archive @ GSU, 2010. http://digitalarchive.gsu.edu/english_theses/78.
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Though her early writing owes much to nineteenth-century American Realism, Willa Cather experiments with male and female literary traditions while finding her own modern literary voice. In the process Cather gives nature an ambivalent role in My Ántonia, O Pioneers!, and Death Comes to the Archbishop. She produces a tension between rivers and gardens, places where nature and culture converge. Like Mary Austin and Sarah Orne Jewett, Willa Cather confronts the boundaries between humans and nature.
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Silva, Elaine Rosangela Leutwiler di Giacomo. "Associação da variabilidade climática dos oceanos com a vazão de rios da Região Norte do Brasil." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-30072013-102659/.
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O objetivo desta pesquisa foi investigar a relação linear existente entre a Temperatura de Superfície do Mar (TSM) dos oceanos Pacífico e Atlântico e a vazão do rio Madeira, localizado na parte sul da região Norte do Brasil. A investigação foi feita nas escalas mensal, sazonal e anual, para o período de 1968 a 2009. A hipótese de que alterações climáticas na região Norte do Brasil estariam associadas a episódios de aquecimento e resfriamento dos oceanos globais, já que quando ocorrem têm o potencial de modificar o padrão de precipitação em áreas remotas do globo, foi a motivação central da pesquisa. A pesquisa foi desenvolvida com base em análises estatísticas para os dados de TSM, índices climáticos e a vazão do rio Madeira. Observou-se que a vazão mensal do rio Madeira apresenta correlação linear significativa com áreas específicas dos oceanos Atlântico e Pacífico. No Oceano Atlântico Norte, são significativas as correlações obtidas nos setores tropical (área AT3) e norte (área AT1). O setor subtropical do Atlântico Norte (AT2) apresenta correlações lineares não tão expressivas como suas áreas tropical e norte. O Atlântico Sul não apresenta áreas com correlações lineares significativas com a vazão. As áreas com correlação significativa do Atlântico Norte (AT1) apresentam valores negativos máximos entre -0,6 e -0,4. Os valores de correlação linear entre a vazão mensal do rio Madeira e a TSM do Atlântico (AT2) apresentam um pequeno aumento para os cálculos realizados com defasagem temporal de até nove meses, entre 0,3 a 0,4 para 5 meses de defasagem entre a vazão e a TSM. A TSM do setor oeste do Pacífico tropical apresenta fortes valores negativos de correlação linear com a vazão do rio Madeira, com valores máximos que variam entre -0,7 e -0,4. Tal qual acontece para o Atlântico, as águas superficiais do Pacífico tropical oeste apresentam um pequeno aumento dos valores de correlação linear para defasagens maiores entre a TSM e a vazão. As áreas com forte correlação negativa no setor oeste do Pacífico tropical foram denominadas PA1, no norte, e PA3, no sul. Uma pequena área com correlação significativa e positiva a leste da bacia do Pacífico, junto à costa do Chile, foi denominada PA2. Nesta área os valores máximos de correlação linear entre a vazão mensal e a TSM variam entre 0,2 e 0,4. A análise de correlação linear entre a vazão anual do rio Madeira e índices climáticos indicam que os índices ODP, MEI e OAN são os mais bem correlacionados com a vazão, apresentando valores iguais a 0,89, 0,86 e 0,85, respectivamente. Com base na TSM das áreas bem correlacionadas com a vazão do rio Madeira e nos índices climáticos considerados, foi desenvolvido um modelo estocástico de regressão linear múltipla para a previsão da vazão trimestral com antecedência de um trimestre. A TSM das áreas do setor oeste do Pacífico tropical, PA1, e do Atlântico Norte tropical, AT3, constituíram as variáveis selecionadas para a elaboração do modelo estocástico. O modelo estocástico foi desenvolvido para o início da série temporal considerada, de 1968 a 1988, e apresentou um ajuste linear com coeficiente de determinação igual a 78%. A verificação do modelo foi feita para o final da série, de 1989 a 2009. O erro médio normalizado calculado pela diferença entre os valores de vazão previstos pelo modelo e os observados foi igual a 40%. Desta forma, conclui-se que a vazão trimestral do setor sul da região Norte do Brasil é uma variável que pode ser prevista com base na variabilidade da temperatura das águas superficiais dos oceanos Pacífico e Atlântico. A análise do comportamento atmosférico com base em períodos específicos de anomalias de TSM no Atlântico Norte tropical indica que a ocorrência de TSMs mais altas (baixas) que o normal foram acompanhadas por ventos de leste mais fracos (fortes). Foram analisados os campos atmosféricos médios para os meses chuvosos de novembro a março para as variáveis Velocidade Vertical (Omega) em 500 e 850 hPa, divergência e vorticidade do vento. Os resultados obtidos demonstram que em média, a variabilidade atmosférica foi determinante no que se refere às anomalias apresentadas pela vazão.The objective of this research was to investigate the linear relation between the sea surface temperature (SST) over Pacific and Atlantic oceans and the outflow of the Madeira river, located at the southern part of the Northern region of Brazil. The investigation considered monthly, seasonal and annual scales, to the period between 1968 to 2009. The consideration about the influence of heating and cooling of oceanic areas over climate around the world constitutes the main hypothesis taken in account in the study. The research was developed based on statistical analysis considering SST, climatic indexes and river outflow data. The monthly outflow for Madeira River shows significant linear correlation to SST at specific areas over Atlantic and Pacific. Over North Atlantic, the linear correlation values are significant at the tropical and north sectors, namely AT3 and AT1, respectively. The subtropical sector of North Atlantic presents positive correlation but not too expressive as the tropical and north areas of Atlantic. South Atlantic does not present significant values of linear correlation with the river outflow. The area with significant correlation over North Atlantic (AT1) presents maximum negative values ranging between -0,6 and -0,4. In general, the greater the interval between river outflow and SST data, greater is the linear correlation values. SST data from the western sector of tropical Pacific presents strong negative correlation with Madeira River outflow data, and shows maximum values ranging between -0,7 and -0,4. The areas to the West of Pacific showing high negative correlation were named PA1 and PA3, to northern and southern sectors, respectively. A small area that shows significant positive linear correlation to the river outflow data, PA2, is located over the eastern side of Pacific basin, very closed to the coast of Chile. In this area, the linear maximum correlation values range between 0,2 and 0,4. Linear correlation analysis between annual river outflow data and climatic indices indicates that PDO, MEI and NAO are those more correlated with the river outflow data, presenting values equal to 0,89, 0,86 e 0,85, respectively. Based on averaged SST and climatic indices well correlated to the Madeira River outflow data, a stochastic model was developed in order to forecast the river outflow in seasonal scale. SST from west of tropical Pacific, PA1, and from tropical North Atlantic, AT3, were selected to build up the stochastic model. The stochastic model was developed considering the first half of the total series, between 1968 and 1988, while the last period was used to validate the model, between 1989 and 2009. The linear adjusting over the first period reach a determining coefficient equal to 78% and the normalized mean error obtained for the second period was equal to 40%. Thus, we conclude that the seasonal outflow for Madeira River is a climatic variable that can be forecast based on the SST variability over specific areas on Pacific and Atlantic oceans. The analysis of atmospheric behavior based on specific periods of SST anomalies in the tropical North Atlantic indicates that the occurrence of SSTs higher (lower) than normal was accompanied by easterly winds weak (strong). We analyzed the average atmospheric fields for the rainy months from November to March for variables Vertical Speed (Omega) at 500 and 850 hPa, divergence and vorticity of the wind. The results show that approximately the atmospheric variability was decisive with regard to the deficiencies presented by the ouflow.
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Graham, Philip Mark. "Modelling the water quality in dams within the Umgeni Water operational area with emphasis on algal relations / Philip Mark Graham." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1022.
Full textAbstract:
Based on many years of water quality (including algal) and water treatment cost data,
available at Umgeni Water, a study was undertaken to better understand the water
quality relationships in man made lakes within the company's operational area, and
to investigate how water quality affected the cost of treating water from these lakes.
The broad aims to the study were to:
identify the key environmental variables that were affecting algal populations
in lakes; and if these were significant to
establish predictive models relating algae to the water quality; and to
develop models relating the water quality in lakes to the cost of treating water
from the lakes.
Semi-quantitative models were developed relating algal abundances with important
environmental variables. In most cases, the models developed were related to algal
populations that were known to adversely affect water treatment. Direct algal impact
on water treatment processes was through the production of either taste and odour
forming compounds (requiring advanced water treatment, such as use of activated
carbon), or their ability to clog sand filters and so reduce filter run times (requiring
more frequent backwashing of filters).
Thereafter lake water quality parameters (which included water physico-chemistry
and algae) were investigated to determine which factors were most significantly
impacting on water treatment and hence treatment costs at selected water works
(WW) within the Umgeni Water operational area. Models were developed relating
raw water quality entering respective water works with costs incurred in treating that
water. The models allowed simulations to be developed illustrating how changes in
water quality might impact on water treatment costs. The impact of eutrophication
and contamination of rivers and lakes, and its subsequent impact on surface water
resources, was quantified.Thesis (Ph.D. (Botany))--North-West University, Potchefstroom Campus, 2004.
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Neves, Fernanda Volpon. "Análise morfológica da evolução da captura do rio Guaratuba (Bertioga-SP) através da técnica de datação por luminescência opticamente estimulada (LOE)." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-08012013-125447/.
Full textAbstract:
A Serra do Mar pertence ao complexo litorâneo brasileiro, preenchendo todo o litoral desde Santa Catarina até o Rio de Janeiro. As feições de seu relevo são peculiares, resultantes de um tectonismo recente com acelerado processo de intemperismo, que acarreta em feições distintas ao longo de todo o complexo da Serra do Mar. A evolução deste relevo tem como fator resultante a adequação da drenagem às falhas e rupturas presentes nas rochas. Desta forma a evolução da Serra do Mar e compreensão das anomalias de drenagem, tal como a Captura Fluvial do alto rio Guaratuba, passa a ser ponto de investigação desta pesquisa, utilizando datação por Luminescência Opticamente Estimulada (LOE). Para o desenvolvimento da pesquisa foi proposta uma divisão do relevo em três compartimentos geomorfológicos (Planalto, Planície do alto rio Guaratuba, Bordas e escarpa da Serra). A compartimentação foi elaborada respeitando as morfologias e a drenagem local, baseada na teoria de AbSaber (1969) sobre a forma de se estudar o Quaternário. Foram elaboradas cartas temáticas (declividade, hipsometria, orientação das vertentes, etc.) para um embasamento visual da teoria discutida no trabalho, vinculando a elas os pontos de coleta das amostras. A partir da compartimentação do relevo desenvolveu-se atividade de campo para coleta de material sedimentar de possíveis trechos do antigo leito fluvial. As amostras coletadas foram trabalhadas em laboratório por datação através da técnica de LOE, utilizando-se o protocolo de alíquota única (SAR). As amostras foram trabalhadas quimicamente para que se obtivesse o grão de quartzo na sua forma mais pura. A partir dos dados adquiridos através da IX datação, as informações foram trabalhadas em planilhas e softwares voltados para a interpretação dos dados. Os valores alcançados foram discutidos ao longo da pesquisa, justificando-se os apontamentos positivos e negativos das amostras. Os dados obtidos concordam com a literatura abordada sobre a evolução geomorfológica da Serra do Mar.The Serra do Mar mountain range belongs to the Brazilian coastal complex which runs from the state of Santa Catarina to Rio de Janeiro. Its relief has peculiar features, derived from a recent tectonism with accelerated weathering process, which leads to distinct features throughout the complex of the Serra do Mar. The evolution of this relief results in the drainage adequacy to the failures and disruptions found in the rocks. Therefore, the evolution of the Serra do Mar and understanding of drainage anomalies, such as the Guaratuba upper river fluvial capture, becomes the point of investigation in this research, using Optically Stimulated Luminescence (OSL) for dating. For the development of the research, the relief was divided into three geomorphologic compartments (Plateau, Guaratuba upper river plain, Borders and Scarp of the Serra do Mar). The compartmentation was developed in compliance with the morphologies and local drainage, based on the Ab\'Saber Theory (1969) on how to study the Quaternary. Thematic maps were drawn (slope, hypsometry, orientation of the strands, etc.) for a visual basis of the theory discussed in the thesis, linking them to the points of sample collection. From the relief compartmentation a field activity was carried out for the collection of sedimentary material of possible sections of the old riverbed. The samples were processed in the laboratory through the technique of dating OSL, using the single-aliquot regenerative-dose (SAR). Samples were chemically worked out to obtain the quartz grain in its pure form. From the data acquired through dating, the information was analyzed on spreadsheets and software focused on the interpretation of data. The values achieved were discussed throughout the thesis research to explain any positive XI and negative results of the samples. The data obtained agree with the literature on the geomorphological evolution of the Serra do Mar that is presented in the thesis.
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Hua, Dan. "Propagation and monitoring of freshwater mussels released into the Clinch and Powell rivers, Virginia and Tennessee." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51755.
Full textAbstract:
Freshwater mussels (Unionidae) in the United States have experienced dramatic declines, and 25% species are listed as federally endangered. Hence, recovery plans for endangered species proposed a strategy of propagation of young mussels for release to natal rivers to augment declining populations. In this study, I conducted laboratory experiments, assessed site suitability for mussel restoration, and evaluated survival and growth rates of released mussels to meet the requirements of recovery plan.
I conducted multiple experiments to develop an improved protocol for juvenile mussel propagation and culture. Significantly greater survival and growth rates were found in newly metamorphosed juveniles of the rainbow mussel (Villosa iris) reared in a substrate of fine sediment and one-month-old juveniles of wavy-rayed lampmussel (Lampsilis fasciola) fed on natural food in pond water. Bio-filter media greatly increased water quality by reducing the concentration of ammonia and nitrite. The negative impacts of flatworm predation and filamentous algae in juvenile culture were controlled, and juvenile escapement was prevented. Juvenile mussels were successfully produced and cultured to stockable size (>15 mm) for release.
I released laboratory-propagated mussels at three historically important sites in Clinch and Powell rivers for the assessment of site suitability. Use of cages was the most effective method to determine site suitability because the free-released mussels (untagged, tagged) had low catchability. Mussels released at Horton Ford, Clinch River, exhibited significantly faster growth. Horton Ford is the most suitable site, while environmental conditions at Fugate Ford, Powell River, are deemed unsuitable for mussel restoration and recovery.
To facilitate the detection of released mussels, I applied Passive Integrated Transponder tags to laboratory-produced juveniles of the endangered Cumberlandian combshell (Epioblasma brevidens) and released them near Brooks Bridge, Powell River. The detection probability increased above 98%. I developed a set of hierarchical Bayesian models incorporating individual variations, seasonal variations, periodic growth stages and growth cessation to estimate survival, detection probability and growth of released mussels in a changing environment. Mussels of E. brevidens exhibited great survival (> 99% per month) and growth, indicating suitable conditions for recovery of this endangered species at this site.Ph. D.
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Dmitrieva, Tatiana. "Perceptions, réglementations et mesures de la qualité des eaux de surface en France, 1854-1964. Le cas des eaux de la ville de Versailles." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066341/document.
Full textAbstract:
La dégradation de la qualité de l’eau de la Seine à Paris et dans sa banlieue depuis la deuxième moitié du XIXe siècle a fait l’objet de plusieurs études. Rares sont les études qui confrontent les perceptions de médecins, d’ingénieurs, d’hygiénistes ou d’administrateurs sur la qualité des eaux des rivières et l’évolution de leur état. Cette confrontation permet d’analyser sur la longue durée l’efficacité des réponses apportées pour améliorer la qualité, ce que nous avons réalisé ici pour la ville de Versailles et ses eaux. La première partie du mémoire décrit les perceptions de la qualité des eaux des rivières par des experts entre 1854 et 1964 sur la base de l’analyse de revues d’hygiène et d’assainissement urbain, montrant l’évolution des indicateurs de qualité et de la réglementation. Versailles a pour particularité d’être, au XIXe siècle, essentiellement alimentée par de l’eau de Seine grâce à la machine de Marly, par le biais d’un Service dépendant directement de l’Etat, conséquences de son passé royal. Mais la qualité de l’eau du fleuve se dégradant à cause des rejets des égouts de Paris, les différentes administrations, locales et nationales, doivent résoudre la question d’approvisionnement en eau alimentaire et recourent à l’aide d’experts pour s’assurer de sa qualité. Les analyses chimiques et bactériologiques effectuées sur les eaux conduisent à l’abandon de l’eau de la Seine en 1894 au profit des eaux de la nappe de Marly-Croissy. En même temps, Versailles rejetait ses eaux usées dans des cours d’eau à faible débit : le ru de Marivel et le ru de Gally. Epidémies et plaintes accompagnent la dégradation de leur état. Les nombreuses expertises menées témoignent de l’intérêt pour la qualité des eaux de surface et en même temps de l’absence de la volonté politique et des limites techniques pour l’améliorer, conduisant à leur sacrifice pendant plus de 100 ansThe Seine River pollution both in Paris and its suburbs has been already the subject of several studies. Few studies compare perceptions that physicians, engineers, hygienists or managers might have of the quality of water resources, and the evolution of their state. This confrontation makes it possible to analyze over the long term the effectiveness of the responses made to improve quality. We have achieved this here for the city of Versailles and its waters. The first part of this work describes perceptions of river water quality by experts between 1854 and 1964 based on an analysis of hygiene and urban sanitation reviews, showing the evolution of quality indicators and of regulations. In the 19th century, Versailles has the peculiarity of being essentially fed by water from the Seine thanks to the Marly machine, through a service directly dependent on the State, consequences of its royal past. But as the water quality of the Seine River deteriorates because of the discharges from the Paris sewers, the various administrations, local and national, have to solve the question of water supply and asked for the help of experts to ensure its quality. The chemical and bacteriological analyzes carried out on waters lead to stopping the use of the Seine waters in 1894 in favor of the Marly-Croissy water table. At the same time, Versailles rejected its wastewater into two low-flowing streams: Marivel and Gally. Epidemics and complaints accompany the deterioration of their state. The numerous experiments carried out show the interest in the quality of surface water and at the same time the absence of the political will and the technical limits to improve it, leading to their sacrifice for more than 100 years
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Reig, Alejandro. "When the forest world is not wide enough we open up many clearings : the making of landscape, place and people among the Shitari Yanomami of the upper Ocamo basin, Venezuela." Thesis, University of Oxford, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669819.
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Roghair, Craig N. "Recovery From and Effects of a Catastrophic Flood and Debris Flow on the Brook Trout (Salvelinus fontinalis) Population and Instream Habitat of the Staunton River, Shenandoah National Park, VA." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/34286.
Full textAbstract:
The Staunton River is a high gradient, second order stream approximately 6 km in length located on the eastern slope of the Blue Ridge Mountains in Shenandoah National Park, VA. In June 1995, a catastrophic flood and debris flow altered the instream habitat and Salvelinus fontinalis population of the Staunton River. The debris flow scoured the streambed, deposited new substrate materials, removed trees from the riparian zone, and eliminated fish from a 1.9km section of the stream. By June 1998, both young-of-year (YOY) and age 1+ S. fontinalis had recolonized the debris flow affected area. The event provided a rare opportunity to examine recovery of the S. fontinalis population and instream habitat in addition to addressing potential effects of the debris flow on movement, activity, and growth of fish in the debris flow affected and unaffected areas of the stream.
Post-recolonization movement and activity were monitored using two-way fish traps (weirs), mark-recapture techniques, and radio telemetry. The weirs failed to produce any movement data. Most fish (91%) in the mark-recapture study had range sizes less than 100m, however biases common to mark-recapture study designs (low recapture rate, flawed logic, etc.) hampered interpretation of results. For example, subsequent recapture of individually marked fish indicated that as many as 54% of marked fish confirmed to have been alive at the time of a recapture session were not recaptured.
Radio telemetry provided information on S. fontinalis movement and activity at seasonal and diel scales during summer and fall. Differences in movement and activity between the debris flow affected and unaffected areas were minimal when compared to seasonal variations. During summer, range sizes were near 0m and crepuscular activity patterns were observed. During the fall range size increased and diel activity was concentrated in the mid-afternoon with a much higher peak than during summer.
Basin-wide visual estimation technique (BVET) fish population surveys performed each spring and fall from 1993 = 1999 provided pre- and post-event fish population abundance and density estimates. Post-event fish growth in the debris flow affected and unaffected areas was monitored using mark-recapture techniques. Abundance and density of both YOY and age 1+ S. fontinalis exceeded pre-event levels within 2-3 years. Growth of YOY and age 1+ fish was significantly greater in the debris flow affected area until spring 1999. Population density appeared to have a strong negative influence on growth. The observed changes in fish growth and differences in fish size associated with population density would be of minimal importance to the typical angler but may suggest a mechanism by which S. fontinalis populations can quickly recover from catastrophic events.
BVET habitat surveys provided information on total stream area, number of pools and riffles, pool and riffle surface area and depth, substrate composition, and large woody debris (LWD) before (1993), immediately following (1995), and four years post-event (1999). Immediately following the debris flow, the stream channel was highly disordered which resulted in an increase in the total number of habitat units and a decrease in average habitat unit surface area, total stream area, and average depth when compared with pre-event conditions. In addition, substrate composition had shifted from small to large diameter particles and LWD loading had increased in both debris flow affected and unaffected areas. Four years after the event, the total number of habitat units, average habitat unit surface area, total stream area, and average depth had all returned to near pre-debris flow levels and substrate composition had begun to shift towards smaller particle sizes. Changes in LWD loading from 1995-1999 reflected changes in the riparian zone following the debris flow. In the unaffected area, where riparian trees remained intact, LWD loading increased, whereas in the debris flow affected area, where riparian trees were eliminated, LWD loading decreased.
For the most part the effects of the debris flow, although immediately dramatic, were in the long term minimal. The debris flow affected area was recolonized rapidly and abundance and density quickly rebounded past pre-event levels. Differences in fish growth between the affected and unaffected area were short lived. Any effect the debris flow affected area may have had on movement or activity was minimal when compared with seasonal variations. Most habitat characteristics reverted to near pre-event levels just four years after the flood and debris flow. Although a number of factors will influence recovery time from such events, these results indicate that immediate management action, such as stocking or habitat modifications, are not necessary in all cases.Master of Science
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Mwangi, Hosea Munge [Verfasser], Karl-Heinz [Akademischer Betreuer] Feger, Morag [Akademischer Betreuer] McDonald, Karl-Heinz [Gutachter] Feger, and Martin [Gutachter] Volk. "Impact of Land Use Change and Climate Variability on Watershed Hydrology in the Mara River Basin, East Africa / Hosea Munge Mwangi ; Gutachter: Karl-Heinz Feger, Martin Volk ; Karl-Heinz Feger, Morag McDonald." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://d-nb.info/1150309458/34.
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Costa, Karine Mirieli dos Santos. "Variabilidade oceânica associada à variabilidade climática da vazão na bacia do rio São Francisco." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-17072012-161148/.
Full textAbstract:
Esta pesquisa tem como objetivo avaliar a relação existente entre o comportamento anual dos oceanos e o da vazão na Bacia do Rio São Francisco, Brasil, para o período de 1968 a 2004. Foram construídos modelos de regressão linear múltipla para simular o valor da vazão anual em Ponte da Taquara, Alto São Francisco, com base em índices climáticos e no valor médio da Temperatura da Superfície do Mar (TSM) em áreas específicas dos oceanos Pacífico e Atlântico. Os índices climáticos considerados foram a Oscilação Decadal do Pacífico (ODP), Indice de Oscilação Sul (IOS) e anomalias de TSM nas regiões de Niño. Os padrões oceânicos de correlação linear entre a TSM do Pacífico e a vazão dos postos do Alto São Francisco e o Médio São Francisco, indicam valores positivos em toda a costa oeste da América do Norte e do Sul e região equatorial e fortes sinais negativos na costa leste da Ásia e Austrália. Este padrão é bastante semelhante ao padrão espacial do primeiro modo obtido pela aplicação de análise multivariada à TSM no Oceano Pacífico, que é associado à Oscilação Multidecadal do Pacífico. A consideração de defasagem mensal no cálculo do coeficiente de correlação linear entre os valores de vazão e TSM indicam que a TSM dos meses mais próximos ao da vazão têm maior potencial para serem considerados como seus preditores. Observa-se a diminuição da correlação linear entre TSM do Pacífico e a vazão dos postos do Médio e Baixo São Francisco em relação aos postos do Alto São Francisco. O que sugere que o Oceano Pacífico apresenta maior influência na variabilidade da vazão nos postos localizados mais ao sul da Bacia do São Francisco. Por outro lado, observa-se o aumento dos valores do coeficiente de correlação linear no Atlântico Sul principalmente para a vazão dos postos do Médio e Sub-Médio, indicando possivelmente a maior influência do Oceano Atlântico na vazão de postos localizados mais a nordeste da bacia hidrográfica considerada. O padrão oceânico indicado pelos valores de correlação linear entre a TSM e os postos do Sub- Médio São Francisco indica a presença de um dipolo meridional, com anomalias negativas e positivas na bacia do Atlântico Sul tropical e subtropical. O IOS e ODP apresentam maior valor de correlação para a vazão observada no Alto e Médio São Francisco. As regiões selecionadas nos oceanos Pacífico, Atlântico e Índico e os índices Niño1+2, Niño 3 e Niño 4 para a construção do modelo linear para a simulação da vazão anual suavizada explicam 96% da variância total da vazão. No caso da vazão sem suavização as variáveis selecionadas pelo modelo elaborado explicam 52% da variância total. O padrão atmosférico anômalo associado aos dois primeiros subperíodos da vazão em Ponte da Taquara, de 1968 a 1978 e de 1979 a 1988, caracterizados em média por anomalias negativas e positivas, respectivamente, apresenta condições atmosféricas específicas às anomalias observadas da vazão. Em geral, anomalias negativas (positivas) de vazão em Ponte da Taquara são acompanhadas por ODP negativa, com anomalias negativas (positivas) de TSM no Pacífico Equatorial.This research concerned to propose a valuation about the relationship between annual oceanic behavior and river outflow at São Francisco Hydrographic Basin, in Brazil, for the period from 1968 to 2004. Linear model based on multiple regression were built for annual river outflow at Ponte da Taquara, located at High São Francisco sub-basin. Climatic indexes and Sea Surface Temperature (SST) averages for selected areas over Pacific and Atlantic oceans were taken as independent variables in the modeling. Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI) and SST anomalies at the Niño regions were also considered as independent variables in the modeling. The specific oceanic areas were selected through linear correlation calculation between river outflow at High São Francisco and SST. Oceanic patter represented by linear correlation between Pacific SST and river outflow at High São Francisco and Medium São Francisco shows positive values throughout the west coast of North and South America and the equatorial areas and, high negative values at oceanic areas to the east of Asia and Australia. This patter is quite similar to that obtained as the first mode of multivariate analysis applied over Pacific basin, and is related to the PDO. The consideration of temporal lag between SST river outflow monthly values showed that the smaller interval provide the best linear correlation. Linear correlation patter over Pacific is more significant for river outflow observed at the southern area of São Francisco Basin in relation to those located at northern areas. This aspect suggests that Pacific Ocean plays a more significant role to determination of river outflow observed at the south of the hydrographic basin. On the other hand, linear correlation values are greater at South Atlantic when river outflow for Sub-Medium São Francisco is considered. This result suggests that South Atlantic Ocean can play a greater role for the determination for climatic variability for river outflow observed at northern areas of São Francisco Basin. The oceanic correlation pattern for South Atlantic Ocean also shows a dipole mode, between tropical and subtropical latitudes, for fluvial stations located at the northern areas of the hydrographic basin. SOI and PDO present greater correlation values for river outflow observed at High and Medium São Francisco Basin. Ocean Pacific, Atlantic and Indian and the indexes Niño1+2, Niño 3 e Niño 4 variables, selected for the linear model elaboration to river outflow simulation, explain 96% of the total variance. In the case of not smoothed data, the variance explained by the linear model is equal to 52%. The atmospheric averaged patterns for the considered two first subperiods, from 1968 to 1978 and from 1979 to 1988, that are characterized by negative and positive river outflow anomalies at High São Francisco, present atmospheric conditions closely related to the observed river outflow anomalies. In general, river outflow negative (positive) anomalies at High São Francisco are related to negative PDO and SST negative anomalies (positive) at equatorial Pacific.
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Oliveira, Déborah de. "A captura do Alto Rio Guaratuba: uma proposta metodológica para o estudo da evolução do relevo na Serra do Mar, Boracéia - SP." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-05052004-134328/.
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Este trabalho trata da captura da bacia do Alto Guaratuba, devido ao recuo da Escarpa da Serra do Mar na região de Boracéia-SP. A bacia do Alto Guaratuba localiza-se no reverso imediato da Escarpa da Serra do Mar, a aproximadamente 45056 e 45052 de longitude oeste e 23038 e 23042 de latitude sul, onde situa-se a Estação Biológica de Boracéia (USP), A Serra do Mar corresponde a um conjunto de escarpas festonadas com cerca de 1.000km de extensão, que vai de Santa Catarina ao Rio de Janeiro. Sua origem está relacionada a processos tectônicos de movimentação vertical realizadas no Cenozóico. A observação de imagem LANDSAT TM 7 permitiu uma primeira aproximação do delineamento estrutural (linhas de falhas, fraturas, etc) da área de estudo. O emprego do programa ILWIS, no tratamento das cartas topográficas 1:10.000 permitiu, por seu lado, confirmar aquelas direções estruturais, de sentido geral NE-SW, bem como mostrar a presença de compartimentos escalonados do relevo, a partir da borda da Escarpa para o interior. A fotointerpretação na escala 1:25.000 revelou a presença de uma drenagem direcionada a NE-SW, seguindo os alinhamentos estruturais que já haviam sido assinalados. Revelou também a mudança de direção do Rio Guaratuba, formando um cotovelo, próximo à borda da Escarpa, descendo-a na direção N-S. Algumas evidências de campo mostram o Rio Guaratuba, em seu cotovelo de captura, descendo oblíquo às estruturas do gnaisse até posicionar-se perpendicularmente a elas ao descer a Escarpa. O conjunto desses dados indica a importância da tectônica na formação do relevo da área, originando os patamares escalonados, entre os quais instalou-se a drenagem. Por outro lado, a erosão regressiva na Escarpa foi responsável pela captura do Alto Guaratuba, gerando um grande anfiteatro. Assim, foi possível propor uma história prognóstica de evolução da Escarpa, sob a ação erosiva, aproveitando as linhas estruturais, podendo ocasionar novas capturas. Dessa maneira, seria necessário estudar os altos cursos dos rios que deságuam no litoral a partir de suas cabeceiras no Planalto, além de verificar de que maneira eles correm atualmente na direção que correm.This assignment is about the capture of the Alto Guaratuba basin, due to the retrocession of Serra do Mars scarp in Boracéias area. The Alto Guaratuba basin is located near to Serra do Mar scarp, approximately at 45º56and 45º52 of longitude west and 23º38and 23º42of latitude south, where Estação Biológica de Boracéia is located. The Serra do Mar corresponds to a whole of festooned scarps with about 1000km of area that is situated from Santa Catarina to Rio de Janeiro. Its origin is related to tectonic process of vertical movements that happened in Cenozoic. The observation of image LANDSAT TM 7, permitted the first approach to the structural delineation (fault lines, fractures, etc) of study area. The use of the program ILWIS, in topographic maps treatment, allowed the confirmation of structural directions, in a general meaning NE-SW, and also shows the presence of compartments that have the form of a stair in the relief, from the Scarps edge towards interior. The photo interpretation in 1:25.000 scale revealed the presence of drainage directed towards NE-SW, following the structural lineaments that had already been shown. It revealed, the changes of Guaratubas direction, forming an elbow, near the Scarps edge, going in the direction of N to S. Some evidence shows the Guaratuba River, in its elbow of capture, going down oblique to the gneiss structures until being positioned perpendicularly to them while going down the Scarp. All of these details indicate the importance of the tectonics in the areas relief formation, leading to landing steps. However, the regressive erosion in the Scarp was responsible for the capture of Alto Guaratuba, creating a big amphitheater. Though, it was responsible to make a prognostic history of the Scarps evolution, with the erosive action, taking advantage of the structural lines that can make new captures. So, it would be necessary to study the high water courses that flow to the coast, from their headwaters in plateau, and also to check in what manner they flow nowadays in the direction they flow.
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Magris, Rafael Almeida. "Variabilidade Interanual e Sazonal na Comunidade de Copepoda Relacionada ao Regime de Marés em um Estuário Tropical (Rio Mucuri, Brasil)." Universidade Federal do Espírito Santo, 2008. http://repositorio.ufes.br/handle/10/5721.
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Previous issue date: 2008-03-24A variabilidade interanual, sazonal e entre as fases da maré da comunidade de Copepoda no estuário do rio Mucuri (Bahia, Brasil) foi estudada. Foram coletadas amostras de plâncton em cada estação do ano por um período de cinco anos (2002-2006) em três pontos de amostragem; sendo que em um deles, as amostragens aconteceram de acordo com o ciclo de marés (duas na enchente e duas na vazante). Dados de temperatura, salinidade, pluviosidade e vazão do rio foram obtidos. O inverno e o verão se destacaram por representarem o período seco e o chuvoso, respectivamente. A representatividade de Copepoda na comunidade zooplanctônica variou entre 40 e 63% da abundância total de espécies, e foi composta por 46 taxa, sendo dominada por espécies comuns nos ecossistemas estuarinos (Temora turbinata, Parvocalanus crassirostris, Acartia lilljeborgi, Oithona hebes, dentre outras). Foram encontrados indivíduos em todos os estágios do ciclo de vida, exemplificando o papel do estuário na reprodução e crescimento das espécies. Para espécies estenohalinas (e.g. Notodiaptomus sp. e Thermocyclops minutus), as variações interanuais e sazonais parecem ser mais importantes enquanto as espécies eurihalinas (a maioria das espécies dominantes) tiveram suas densidades controladas pela variabilidade entre as fases de maré.
Copepod community variability among years, seasons and tidal fluctuations at the Mucuri River estuary (Bahia, Brasil) were studied. Zooplankton samples were collected in each season for a period of five years (2002-2006) at three sampling stations; with one of the stations sampled at each tidal cycle (two neap and two flood tides). Temperature, salinity, river flow and rainfall data were obtained. Winter and summer represented the dry and wet seasons, respectively. Copepods abundance ranged from 40 to 63% of the total zooplankton community and was composed of 46 taxa, dominated by common estuarine species such as Temora turbinata, Parvocalanus crassirostris, Acartia lilljeborgi, Oithona hebes, among others). Individuals in all of the life stages were found, exemplifying the role of the estuary in the reproduction and growth of several species. For the stenohaline species (e.g. Notodiaptomus sp. and Thermocyclops minutus), interannual and seasonal variations seems to be more important while for the euryhaline species (the majority of the dominant ones) had their densities controlled by tidal variability.
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Presado, Patrícia Valente. ""Distribuição, abundância e estrutura dimensional das espécies exóticas Blackfordia virginica (Mayer, 1910) e Corbicula fluminea (Müller, 1774) no estuário do Mira"." Master's thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/15927.
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O cnidário Blackfordia virginica e o bivalve Corbicula fluminea são duas espécies exóticas muito abundantes no estuário do Mira, pelo que este trabalho teve como principais objectivos determinar a distribuição espacial e o estado das suas populações.
B. virginica foi registada em salinidades entre 7 e 32 e verificou-se que a fase medusa se desloca com a massa de água ao longo do ciclo de maré, atingindo densidades superiores a 370 indivíduos/m3. Os indivíduos de maior diâmetro encontram-se em salinidades mais elevadas e os mais pequenos em salinidade inferiores. Amostragens efectuadas ao longo de um ciclo de maré indicaram a realização de migrações verticais, que serão um possível mecanismo de retenção das medusas no interior do estuário.
C. fluminea ocorreu em salinidades inferiores a 15, atingindo densidades superiores a 4000 indivíduos/m2, sendo em algumas épocas a espécie macrobentónica dominante. Dados recolhidos em anos e épocas diferentes indicaram uma elevada variabilidade espacial e temporal; ABSTRACT: The cnidarian Blackfordia virginica and the bivalve Corbicula fluminea are the two most abundant exotic species in the Mira estuary. The major objectives of this study were to determine the spatial distribution and the population state of these species.
The medusae stage of B. virginica occurred in salinities between 7 and 32 and moved with the water column along the tidal cycle, with densities over 370 specimens/m3 at some locations. Bigger specimens were found in higher salinities while smaller specimens occurred in lower salinities. Surveys conducted along a tidal cycle indicated the occurrence of vertical migrations, most likely used by the medusae as retention mechanism to avoid being flushed out of the estuary.
C. fluminea occurred in salinities lower than 15 and, at some locations and periods, it was the dominant benthic invertebrate species, with densities higher than 4000 specimens/m2. Data collected at different years and seasons indicated a high spatial and temporal variability.
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Delacroix, Barbara. "De brignatium à gesoriacum : les amers, les navires et les ports en mare externum sous l'empire Romain." Thesis, Lille 3, 2016. http://www.theses.fr/2016LIL30044.
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La navigation sur l’arc atlantique à l’époque romaine est un sujet immense qui pâtit encore trop souvent de l’avis sceptique de chercheurs obnubilés par la Méditerranée. Il a donc fallu détricoter le mythe de l’océan infranchissable par l’étude approfondie des éléments interdépendants constitutifs de la navigation fluvio-maritime et moteurs de l’économie de l’arc atlantique, à savoir : l’amer, le navire et le port. Aussi l’étude de l’organisation du commerce atlantique sur les voies fluviales et maritimes, de La Corogne à Boulogne-sur-Mer, a-t-elle abouti à l’établissement d’une typologie « atlantique » tripartiteNavigation in the Atlantic arc – enlarged to the English Channel and the North Sea – in Roman period, is a vast topic that, too often, still suffers from the sceptical opinion of researchers obsessed with the Mediterranean. It has been necessary to unravel the myth of the impassable Ocean, by means of a deep study of the mutually dependent elements forming the maritime and fluvial navigation and driving force of the Atlantic arc economy: the landmark, the vessel and the harbour. Moreover, the study of the organization of the Atlantic trade through the maritime and fluvial routes, from A Coruña to Boulogne-sur-Mer, have result in the establishment of a three-party ‘Atlantic’ typology
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TAVARES, Daniela Passos Simões de Almeida. "Fluidodinâmica da dispersão de óleo a partir de vazamento em Riser Submarino tipo Catenária: análise de plumas multifásicas." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/280.
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DANIELA PASSOS SIMÕES DE ALMEIDA TAVARES - TESE PPGEQ 2016..pdf: 15494076 bytes, checksum: 86040371b4c9f0e560658409f7d3b95d (MD5)Made available in DSpace on 2018-03-12T15:40:08Z (GMT). No. of bitstreams: 1 DANIELA PASSOS SIMÕES DE ALMEIDA TAVARES - TESE PPGEQ 2016..pdf: 15494076 bytes, checksum: 86040371b4c9f0e560658409f7d3b95d (MD5) Previous issue date: 2016-08-18
Capes
O vazamento de fluidos tóxicos em tubulações submarinas devido à corrosão, erosão ou falhas na estrutura, geralmente conduzem a danos extensivos à vida marinha, saúde humana e recursos naturais. Quando um vazamento acidental ocorre, uma resposta rápida e adequada é necessária para reduzir as consequências ambientais. Logo, compreender, por exemplo, o comportamento da pluma de óleo vazado possibilita a determinação do percurso da pluma de óleo e a dispersão da mesma na correnteza marítima e, assim, propor técnicas e/ou tecnologias para eliminar ou minimizar os danos causados pelo vazamento. Neste sentido, foi realizado um estudo do comportamento da pluma e sua dispersão, adotando-se uma abordagem Euleriana-Euleriana. Foi utilizado um modelo matemático representativo da fluidodinâmica de uma pluma de óleo originada do vazamento em um riser tipo catenária. Adotou-se um escoamento bifásico (Modelo de Superfície Livre), isotérmico e turbulento (modelo k-ε padrão) para se resolver as equações de conservação de massa e momento linear utilizando ANSYS CFX® v.15. Os resultados dos campos de pressão, velocidade e fração volumétrica, além dos perfis de fração volumétrica possibilitaram a avaliação do comportamento da pluma e de sua dispersão no mar. Observou-se que a pluma atingiu a superfície marítima quando adotado altas velocidades de vazamento de óleo e baixas velocidades da correnteza marítima. Para os casos em que a densidade do óleo é maior, houve espalhamento lateral subsuperfície. Para os casos com maior velocidade do jato de óleo e menor velocidade da água do mar, na chegada do óleo à superfície observou-se que houve espalhamento horizontal a montante e a jusante do sentido de escoamento. A depender das condições de velocidade de vazamento, da correnteza marítima e da diferença de densidade percebeu-se uma tendência da pluma não atingir a superfície marítima.
The leak of toxic fluids in submarine pipes due to corrosion, erosion or failures in the structure, generally lead to extensive damage to marine life, human health and natural resources. When occurs an accidental leak, a quick and adequate response is needed to reduce the environmental consequences. Therefore, understand, for example, the behavior of leaked oil plume enables the determination of the oil plume path and the dispersion of the same in the sea current and like this propose techniques and/or technologies to eliminate or minimize the damage caused by the leak. In this sense, it was proposed a study of the behavior of plume and its dispersion, adopting an EulerianEulerian approach. It was used a representative mathematical model of the fluid dynamics of an oil plume originated from leak at riser in catenary format. It was adopted a two-phase flow (Free Surface Model), isothermal and turbulent (k-ε standard model) to solve the mass and momentum conservation equations using ANSYS CFX® v.15. The results of the pressure, velocity and volumetric fraction fields, and the volumetric fraction profiles allowed the plume behavior assessment and dispersal at sea. Also it was observed that the plume reaches the sea surface when adopted high velocities of oil leak and low velocities of sea current. For the cases in which the oil density is higher, there was lateral subsurface scattering. For the cases with higher velocity of the oil jet and lower velocity of the sea water, in the arrival of the oil to the surface it was observed that there was horizontal scattering upstream and downstream of the direction of flow. Moreover, depending on conditions of the leak velocity, of the sea current and of the density difference was noticed a tendency of the plume not reach the sea surface.