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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
701

Development and application of plant macrofossils for paleolimnological reconstructions in the Slave River Delta, N.W.T.

Adam, Margaret E. January 2007 (has links)
This thesis combines detailed analyses of living plant communities with paleolimnological methods to develop the use of plant macrofossils as an effective tool to track hydroecological changes in ponds of the Slave River Delta (SRD), N.W.T. Several approaches were used to develop an understanding of the relationships between hydrolimnological conditions, living plant communities, and the composition of sedimentary macrofossil remains across spatial and temporal scales. A spatial survey approach was used to assess the relationships between the composition of plant macrofossil assemblages contained in the surface sediments and the hydrological and limnological conditions of 40 SRD basins that span a broad range of hydrological settings in the delta. Results show that there are strong relationships between the prevailing hydrolimnological conditions in the SRD and the composition of sedimentary macrofossil remains, and subsequently indicator macrofossil taxa were identified to distinguish between sites with high river influence (flood-dominated sites: ostracode shells, Daphnia ephippia, Chara oospores; exchange-dominated sites: Myriophyllum winter-bud scales, Daphnia ephippia) and sites with low river influence (evaporation-dominated: Ceratophyllum leaves, Lemna leaves, Drepanocladus leaves). In light of the strong connection between spring flood events and the hydrolimnological conditions of SRD ponds, and growing concerns that the frequency of spring floods have declined in recent decades, paleolimnological investigations were initiated at a pond (SD2) adjacent to the Slave River to construct a record of flood events in the SRD. Prior to analysis of macrofossil assemblages from sediment cores, a detailed study of the living plant community was conducted at SD2, and results were compared to the distributions of surficial sedimentary plant macrofossil assemblages to assess how representative surficial sediment assemblages are of the living plant community. This study indicates distinct patch-scale (or quadrat-scale)similarity between the living vegetation and sedimentary remains in the central basin, as well as distinct similarity between the living aquatic macrophytes and sedimentary remains at a pond-scale, suggesting there is excellent potential to track changes in the composition and percent cover of aquatic macrophytes in pond sediment cores using plant macrofossil assemblages. Additionally, this study indicates that influence of long-distance transport of macrofossils during the 2005 flood event was minor at this pond, and may not be an important factor affecting paleolimnological reconstructions of plant communities. With contemporary studies as a framework, an ~90-year record of ice-jam flood frequency was reconstructed from a sediment core collected from pond SD2. Multi-proxy analyses indicated decadal-scale oscillations in flood frequency at this site, with at least three multi-year periods of low river influence. Beginning in ~1943, an 18-year period of particularly low river influence and greatly reduced water levels was indicated by abundant macrofossils of Sagittaria cuneata and represents the driest period over the past ~90-years. Similarities between the flood history of SD2 and upstream sites in the Peace-Athabasca Delta suggest that spring discharge generated from headwaters and major contributing rivers plays a key role in the frequency and magnitude of spring flood events of both deltas.
702

Sensitivity of Field Data and Field Protocols in One-Dimensional Hydraulic Modelling

Kuta, Robert Matthew William January 2008 (has links)
Over one million simulations were conducted using the Hec-Ras4b (US Army Corps of Engineers, 2004) model to evaluate the sensitivity of model predictions to field data accuracy, density and estimation techniques and provide guidance towards balancing human resource allocation with model accuracy. Notable differences were identified in model accuracy if a project is concerned with river processes occurring within the limits of the bankfull channel versus floodplain regions. Increased cross section discretization, bankfull channel detail and main channel roughness were of greatest field survey and measurement importance when processes relevant to the bankfull channel are of concern (i.e. geomorphic processes or sediment transport). Conversely, where flood conditions are of highest consideration, estimates of floodplain roughness dominate the accuracy of the results of computed water surface elevations. Results for this case study also demonstrate that higher orders of total station field surveys provide little additional accuracy in final predicted water surface elevations, relative to proper estimates of in-channel and floodplain roughness. As long as drift in field surveys has been accounted for during or subsequent to total station surveys, survey techniques such as hangers can be readily employed with very little increase in final model prediction error, while improving field data acquisition efficiency.
703

The State in the Indus River Valley

Green, Adam 11 September 2006 (has links)
This thesis examines the concept of the state in the context of the Indus River Valley, located in northwest India and Pakistan. In the first section, I synthesize several popular trends in state discussion from both inside and outside of archaeological theory. I then apply my synthesized approach to state definition to the archaeological record from the Indus River Valley. The resulting work visits both the concept of the state and the rich cultural history of the Indus Civilization. I determine that there was a state in the Indus River Valley, but that the Indus state was very different from others scholars have identified in the archaeological record.
704

River resources towards Sustainable Development of Tanzania. : A contribution of Hydropower tothe energy security in Tanzania: Case study, Rufiji River basin

Kiwia, Janbert January 2013 (has links)
This paper sets out: How river resources can be used towards a sustainable development of Tanzania, the case ofthe Rufiji River Basin. The study focuses on the role of hydropower at present and in the future, in the context ofeconomic growth and sustainability and meeting the energy demand in Tanzania.Take into consideration that hydropower is still the major source of electricity that Tanzania relies on. Tanzaniahas been struggling with one of the lowest electricity rates in sub-Saharan Africa where on average less than 15percent of the Tanzanian population has access to electricity.Tanzania faces a major challenge to provide more than 85 percent of the remaining population with electricity,which will require big investment and expertise. Electricity and energy in general seem to take fore debate andnews spots in the country because it reaches a point where even those accessing electricity still suffer withsevere energy rationing. In this project, different development implications regarding hydropower production inthe country were addressed through in depth literature review from different academic sources, and a surveywhich was conducted through questionnaires, a field trip and interviews to identify not only people’s opinionsand feelings concerning the situation, but also to find out if they propose any optimal sustainable solution forremedying the problem, which hinders the socio-economic development of the country. The analysis shows thatTanzania can produce enough hydropower to meet the energy demand if hydropower was improved as one of thesources of energy. The clear picture shows that the potential of the Rufiji River basin is not fully exploited due tothe lack of an integrated approach on achieving the best solutions for Tanzanian energy, inappropriatetechnology and poor allocation of funds.Moreover the indication illustrates that hydropower has an important role to play in the future if the potentialtapped in an area was endowed with considerable benefits to an integrated electric system. For that case, thepaper attributes that hydropower production can contribute to the energy security in Tanzania. On the other handthe paper argues that other renewable options such as solar and wind power in a country like Tanzania shouldn’tbe separated but rather go hand in hand in research and consideration. The theory derived in this project statesthat ‘‘River Basins remain a largely untapped resource for poverty alleviation in Tanzania’’.
705

The Devonian of the Bear River Range, Utah

Cooley, I. Lavell 01 January 1928 (has links)
The geological column in northern Utah has had very little detailed study. Those who have made reports on this section have done so only in a very general way, making no detailed sections of any part of the column, excepting that of the Cambrian made by Walcott. Other work has been done by Mansfield in southeastern Idaho and a general section of the Devonian made in Green Canyon, Bear River Range, Utah by Kindle. Due to the lack of any detailed work of this nature being done in the Bear River Range, suggested the matter of making a section and describing the Devonian System of this range, because, probably less is known of this system than of any other one. Stratigraphic relations were studied in several sections where outcrops were good. Conditions for the study of these outcrops are very favorable, because, within a very short distance of 6 or 7 miles there are 6 canyons cutting the range at approximately right angles to the general trend of the structure, giving satisfactory sections of the greater part of the Paleozoic Era. Blacksmith Fork Canyon gives the best section of the Devonian System in the area studied. Because of easy access and good exposures, this canyon was chosen for a graphic section. Another section was made in Logan Canyon as a matter of comparison.
706

Sensitivity of Field Data and Field Protocols in One-Dimensional Hydraulic Modelling

Kuta, Robert Matthew William January 2008 (has links)
Over one million simulations were conducted using the Hec-Ras4b (US Army Corps of Engineers, 2004) model to evaluate the sensitivity of model predictions to field data accuracy, density and estimation techniques and provide guidance towards balancing human resource allocation with model accuracy. Notable differences were identified in model accuracy if a project is concerned with river processes occurring within the limits of the bankfull channel versus floodplain regions. Increased cross section discretization, bankfull channel detail and main channel roughness were of greatest field survey and measurement importance when processes relevant to the bankfull channel are of concern (i.e. geomorphic processes or sediment transport). Conversely, where flood conditions are of highest consideration, estimates of floodplain roughness dominate the accuracy of the results of computed water surface elevations. Results for this case study also demonstrate that higher orders of total station field surveys provide little additional accuracy in final predicted water surface elevations, relative to proper estimates of in-channel and floodplain roughness. As long as drift in field surveys has been accounted for during or subsequent to total station surveys, survey techniques such as hangers can be readily employed with very little increase in final model prediction error, while improving field data acquisition efficiency.
707

The role of submersed macrophytes in river eutrophication and biogeochemical nutrient cycling

Hood, Jennifer Lynne Alice January 2012 (has links)
The goal of this work is to contribute to the understanding eutrophication in large rivers with a detailed study of the Grand River, an impacted river in highly agricultural and urbanized Southern Ontario. It focuses on the role of nitrogen (N) and phosphorus (P) in the distribution and abundance of benthic submersed macrophytes, which are important actors in river N and P cycles. Chapter 1 uses data from the Provincial Water Quality Monitoring Network to examine seasonal, long term and spatial patterns in total P (TP), soluble reactive P (SRP), nitrate and nitrite (NO3- + NO2-) and ammonium (NH4+). The monitoring of many sites in the Grand River began in 1965, and I examine data from the period from 1965 to 2009. The monitoring program began prior to the Canada-USA ban on the use of phosphate in detergents, which came into effect in 1973, and also before major improvements to municipal waste water treatment. The phosphate ban is analyzed as an example of a whole-system nutrient manipulation experiment, and the seasonal and long term response of the river system, from headwaters to mouth, is examined. TP and SRP declined over the monitoring period, with the greatest response found in TP, which declined by 120 µg/l/y immediately downstream of the of the watershed’s largest treatment plant in the years 1972-1975. Thereafter, TP and SRP continued to decline over most of the lower river, with rates of decline in nutrient concentration accelerating with distance from the wastewater treatment plants (WWTPs). NO3+NO2 increased during the monitoring period in the upper portion of the river with the highest increase of 158 µg-N/l/y observed in the 10 year period of 1975-1985. It did not change in response to WWTP upgrades that occurred in the early 1970s. WWTPs were a clear source of TP, SRP and NH4+ to the river system, but not NO3 +NO2 , and the continual increase in NO3 +NO2 was due to increases in diffuse sources. The seasonal and spatial data suggest that non-point sources of N and P dominate in the Grand River watershed. However, the largest WWTP in the region at Kitchener is an important source of nutrients, and was an especially large source of P prior to changes in detergent standards and wastewater treatment. The submersed macrophyte biomass in the Grand River was examined as a function of proximity to WWTPs in chapter 2. Spatial surveys were conducted in 2007 and 2009 on three reaches of approximately 10 km in length each, with two reaches having an upstream and downstream section, separated by a WWTP. Macrophyte patches were mapped, biomass was estimated, and plants were analyzed for N and P. Tissue N and P were compared to published thresholds for evidence of nutrient limitation. Biomass was greater downstream of the WWTPs than upstream in both reaches and both years, indicating that nutrient loading leads to increased biomass downstream, evidence that even in a heavily agricultural watershed, point sources have a demonstrable effect on macrophyte biomass. Depth was important in explaining some of the variation, while river width and orientation were not important. Even though macrophyte biomass was elevated downstream of the WWTPs, there was no strong evidence of N or P limitation upstream based on tissue concentrations and a laboratory determined critical nutrient threshold, and I hypothesize that the nutrient limitation affecting biomass occurs earlier in the growing season, before peak biomass. This suggests that the eutrophication process in rivers is distinct from that in lakes, and future work should view eutrophication in rivers in the context of seasonal succession. Drivers of seasonal and inter-annual variability in submersed macrophyte biomass were examined in chapter 3 with a multi-year, reach-scale spatial survey of three reaches near the WWTPs of Waterloo and Kitchener. Biomass differed among reaches, years and sites, and showed distinct seasonal patterns. The reach downstream of the WWTPs had the highest biomass, and peak biomass came soonest in the growing season, while the upstream reach had the smallest and latest peak biomass. Weather was significantly correlated to both the quantity and the time of the peak biomass, with higher temperatures associated with larger and earlier peak biomass and precipitation and higher flow associated with later and lower peak biomass. Therefore, the eutrophication response in rivers can depend on weather, and these drivers of variation should be accounted for when forecasting responses to future changes in nutrient loading. The effect of nitrogen discharged by WWTPs on the riverine submersed macrophyte community, and the suitability of macrophyte tissues as indicators of point source impact, were quantified in chapter 4 using δ15N as a tracer of WWTP effluent impact. Macrophytes and water for NO3- and NH4+ concentration and isotope analysis was collected by canoe along two 10 km reaches of the river, up and downstream of two WWTPs. Macrophytes incorporated effluent nitrogen into their tissues downstream of the WWTPs, using effluent NH4+ rather than NO3-. Impacts of the effluent on macrophytes can be traced as far as 10 km downstream, while daytime chemical evidence of the plume disappeared much sooner. The δ15N-NH4+ value rapidly increased downstream of the WWTP, changing in one instance from +13‰ to +31‰ over 1 km, with macrophyte δ15N values changing from +6‰ to +24‰ over 5 km, while δ15N- NO3- values showed no such change. These data lead to the conclusion that riverine submersed macrophytes record the influence of WWTP effluent, specifically effluent NH4+, but that using two end-member mixing models to determine N sources would be inappropriate in such dynamic environments. Nitrogen cycle processes such as nitrification and denitrification are influenced by dissolved oxygen (DO) and rapid transformations occur in environments with strong DO gradients. Because development of dense macrophyte beds in eutrophic rivers has the potential to greatly alter daily oxygen cycling, producing strong redox potentials, macrophytes could influence microbial nitrogen cycling. In Chapter 5, nitrogen uptake by macrophytes using a 15N-NH4+ tracer and N2O production was investigated using in situ chamber incubations upstream and downstream of a WWTP. NH4+ uptake occurred in chambers, while measurable net N2O production occurred in some chambers only. Neither N2O production nor NH4+ uptake differed between chambers with and without PO43- addition, nor did they differ between light and dark treatments. NH4+ uptake was higher at the upstream site, indicating that above the WWTP there was NH4+ demand in the macrophyte community. NH4+ uptake was a hyperbolic function of mean chamber NH4+ concentration. Turnover time for the macrophyte N pool due to NH4+ uptake was as long as 47 d, while the turnover of the dissolved NH4+ pool was as rapid as 14 h. Because net uptake was a small fraction of gross uptake, calculated release rates were almost as high as uptake rates, again indicating rapid NH4+ cycling. Eutrophication of rivers has elements that make it a process distinct from that in lakes. I showed that, in the Grand River, N and P were both high in concentration throughout the river, with a distinct increase downstream of the largest WWTPs in the watershed. The biomass of benthic submersed macrophytes was elevated below the WWTPs, but there was no evidence of nutrient limitation upstream during the time of peak biomass. Macrophyte biomass development followed a seasonal pattern, but was also influenced by seasonal temperature and precipitation patterns. Thus, the riverine eutrophication process has an important seasonal component, much as the plants themselves do, peaking in the summer and senescing in the fall. As part of the eutrophication response, macrophytes altered the chemical cycles of nutrients that fuel their growth. Though changes in benthic biomass themselves are part of riverine eutrophication, this thesis provides evidence that changes in macrophyte biomass produces chemical and ecological changes that are characteristic of increased trophic conditions.
708

The Lost White Settlers in Michael Crummey's River Thieves

Zhang, Lu January 2011 (has links)
In River Thieves, the white settlers are responsible for the vanishing of the Beothuk which reflects the spiritural loss of the white settlers. The major themes of truth, regret and guilt are discussed in the novel.
709

"Crossing the River" : the complexity of colonialism and slavery

Bakkenberg, Mikael January 2011 (has links)
Caryl Phillips’s novel Crossing the River deals with European colonialism and the consequences of it. Crossing the River is a novel which embraces characters from colonized cultures as well as characters from colonizing cultures. Following a timeline that begins in 1752 and ends in 1963, the novel shows slavery in progress as well as what transpires in the aftermath of slavery        In this essay I will argue that Caryl Phillips demonstrates the complexity of colonialism and slavery in his novel Crossing the River; he approaches the two concepts from different perspectives and shows us that colonialism and slavery are complicated concepts. Caryl Phillips uses narrative to demonstrate the negative sides of colonialism and slavery, to show that the negative aspects of the two concepts can affect not only the colonized people but also the colonizing people.        Colonialism, in its traditional sense, is present in some of the novel’s episodes but slavery, in different forms, appears in all episodes. Nevertheless, all episodes in Crossing the River have a common origin; which Phillips reminds us about by using the relationship between plot and story. Diversity is an important theme in the novel. From a narrative perspective, Crossing the River has a diversity of narrators who tell their stories as well as other persons’ stories. There are female narrators as well as male ones; some narrators are known while other narrators are unknown. The ways the episodes are told are diversified. Some of the episodes follow a chronological line (“The Pagan Coast” and “Crossing the River”) while other episodes jump back and forth in time (“West” and “Somewhere in England”). The forms of narration are diversified, not only between the individual episodes but also within some of the episodes. Crossing the River plays with diversity in several layers. The structure of the novel is as diversified as the number of narrators, a diversity of ways of dealing with the main themes results in a diversity of fates for Phillips’s characters. Caryl Phillips combines structure with content to demonstrate that colonialism and slavery are problematic concepts: the negative consequences of the two concepts can, in different ways and in different degrees, affect colonized people as well as those responsible for colonialism.
710

Biosphere-Atmopshere Interaction over the Congo Basin and its Influence on the Regional Hydrological Cycle

Shem, Willis Otieno 07 July 2006 (has links)
A comprehensive hydrological study of large watersheds in Africa e.g. the Congo basin and the Nile basin has not been vigorously pursued for various reasons. One of the major reasons is the lack of adequate modeling tools that would not be very demanding in terms of input data needs and yet inclusive enough to cover such wide extents (over 3 million square kilometers for the Congo basin). Using a coupled run of the Community Atmospheric model (CAM3) and Community Land Model (CLM3) components of the Community Climate System of Models (CCSM), this study looks into the spatial and temporal variation of precipitation and river runoff in the Congo basin in the light of increasing trends in deforestation of the tropical forests. The effect of deforestation on precipitation and runoff is investigated by changing the land cover-type from the current configuration of broadleaf evergreen/deciduous, non-Artic grass and corn to a mostly grass type of vegetation. Discharge simulation for the river Congo is centered at the point of entrance to the Atlantic Ocean. Although the CLM3 does not presently simulate the observed river runoff to within at least one standard deviation it gives an opportunity to iteratively improve on the land surface parameterization with a possibility of future accurate prediction of mean monthly river runoffs under varying climate scenarios and land use practices. When forced with the National Center for Environment and Prediction (NCEP) re-analysis data the CLM3 runoff simulation results are relatively more stable and much closer to the observed. An improved CLM3 when coupled to CAM3 or other Global Climate Models is definitely a better tool for investigative studies on the regional hydrological cycle in comparison to the traditional methods. There was a slight reduction in rainfall in the first experiment which mimicked a severe form of deforestation and a slight increase in rainfall following low level of deforestation. These changes in rainfall were however statistically insignificant when compared to the control simulation. There was notable heterogeneity in the spatial distribution of the changes in rainfall following deforestation.

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