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1
Jose, Paul V. "The hydrochemistry of backwaters and dead zones." Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/33160.
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This thesis investigates the inter-relationship between hydrological and water quality variations with reference to backwaters and dead zones in rivers. The examination of a series of controlled reservoir releases to an upland channel in Wales showed "in-channel" dead zones were important solute source and storage areas. Physico-chemical data have been presented to show the influence of main channel flow and quality variations on the hydrochemistry of a range of seven backwaters within the Trent basin. The hydrological regime of the mainstream seasonally modified backwater quality. The degree of main-flow influence declined with decreasing hydrological connectivity of the backwater environments with the mainstream. Furthermore other hydrological, biological and biogeochemical factors influenced backwater physico-chemistry. A generalised typology of permanent floodplain water bodies in the R. Trent catchment based upon water chemistry was established. An applied study examined the effect of reservoir cleaning/emptying operations and flood events on backwater hydrochemistry on the French Upper River Rhone. The simultaneous occurrence of decreasing mainstream discharge with the passage of the sediment laden release wave reduced its impact on backwater environments. Anthropogenic influences on riverine systems as a result of intensification of agriculture and urbanisation (e.g. nitrate pollution and river regulation) have influenced the hydrological and physico-chemical functioning of fluvial hydrosystems. In view of rising nitrate levels in many British rivers, trends within the Trent basin have been investigated. Rates of increase in concentration of 0.06 mg.l-1 N yr-1 were typical of rural catchments, whilst rates of up to 0.20 mg.l-1 N yr-1 were recorded in urbanised tributaries. Furthermore the impact of rising nitrate levels in the Trent catchment and river regulation on backwater hydrochemistry and ecology have been examined.
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Csoboth, Laura A. "Early life history of fishes in restored and unrestored backwaters /." Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1240695551&sid=15&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Taylor, Ritchie Don. "Water Quality Aspects of an Intermittent Stream and Backwaters in an Urban North Texas Watershed." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3206/.
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Pecan Creek flows southeast through the City of Denton, Texas. Characterized as an urban watershed, the basin covers approximately 63.5 km2. Pecan Creek is an intermittent stream that receives nonpoint runoff from urban landuses, and the City of Denton's wastewater treatment plant, Pecan Creek Water Reclamation Plant, discharges effluent to the stream. Downstream from the City of Denton and the wastewater treatment plant, Pecan Creek flows about 6,000 m through agricultural, pasture, and forested landscapes into Copas Cove of Lake Lewisville, creating backwater conditions. Pecan Creek water quality and chemistry were monitored from August 1997 to October 2001. Water quality was influenced by seasonal, spatial, climatic, and diurnal dynamics. Wastewater effluent discharged from the Pecan Creek Water Reclamation Plant had the greatest influence on water quality of the stream and backwaters. Water quality monitoring of Pecan Creek demonstrated that dissolved oxygen standards for the protection of aquatic life were being achieved. Water quality modeling of Pecan Creek was completed to assess future increases in effluent flow from the Pecan Creek Water Reclamation Plant. Water quality modeling indicated that dissolved oxygen standards would not be achieved at the future effluent flow of 21 MGD and at NPDES permitted loadings. Model results with application of a safety factor indicated that the maximum allowable concentrations for a 21 MGD discharge would be 2.3 mg/L of ammonia and 7.0 mg/L of biochemical oxygen demand at summer conditions. Drought conditions that occurred from 1998 to 2001 reduced water levels in Lake Lewisville and impacted dissolved oxygen water quality in Pecan Creek. Water quality observations made during the period of drought allowed for the development of a model to estimate the zone of the dissolved oxygen sag in Pecan Creek based on reservoir elevation. Finally, monitoring results were analyzed with nonparametric statistical procedures to detect water quality changes in the backwater area of Pecan Creek, as influenced by storm events.
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Scott, Mark Thomas. "Larval fish abundance and habitat associations in backwaters and main channel borders of the Kanawha River." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45967.
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Larval fish distributions were determined in the lower Winfield Pool, Kanawha River, West 85, Virginia, using a 0.5-m plankton net and a 1-m2 dropbox. Five habitats were sampled with the plankton net, 3 habitats with the dropbox. The 5 deep water water habitats, greater than 1.5-m in depth, sampled by the plankton net included surface tows in Bill's Creek backwater, main channel border upstream and downstream of Little Guano backwater, and Little Guano Creek backwater, where deep tows (1.5 m deep) were also taken. The 3 shallow water habitats, less than 1 m in depth, sampled by the dropbox included open water over silt substrate, open water over a sand substrate, and emergent vegetation. Lepomis species, emerald shiners (Notropis atherinoides), and gizzard shad (Dorosoma cepedianum) were the dominant taxa. The emerald shiner taxa could also have included some larvae of Notropis species which are also present in the Kanawha River but whose larvae have not been described. Overall, the mean total larval density did not differ between the backwater or the main channel borders but the species associated with each habitat differed greatly.
The Lepomis larvae were found predominantly in backwater areas. These areas provide suitable spawning sites for many centrarchids of this river. Upon leaving the nest, the Lepomis larvae moved into the deeper open water areas within the backwater. After reaching the juvenile stage, these same larvae returned to the shallow water habitats where they inhabited vegetated areas. Emerald shiner larvae, while present in both backwater and main channel habitats, were most abundant in the main channel borders. This is probably a result of their parent's pelagic spawning strategy. In all habitats, emerald shiner larvae predominated in the upper 1 m of water. Upon becoming larger, the emerald shiner larvae appeared in the backwaters. This increase in numbers could be due to movement, differential mortality, or higher growth rates. Other cyprinids (excluding emerald shiners and carp) were equally abundant in both backwater and main channel areas. These other cyprinid larvae were also distributed equally, Gizzard shad larvae were found predominantly in the main channel borders. Presumably, these higher densities were the result of main channel spawning. The gizzard shad larvae present in the backwater areas were distributed evenly throughout the water column. Overall, the backwaters were important for the nest-building species found in the river and also for the larger larvae of the pelagic species, and thus acts as a nursery area for these species. Therefore, the backwaters do seem to be important for the fishery of the Kanawha River.Master of Science
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Balfour, Christopher. "The design of a backwater wave free electron laser." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263764.
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W, Schultz Douglas. "Quantifying fish movement between the Illinois River and an associated backwater /." Available to subscribers only, 2006. http://proquest.umi.com/pqdweb?did=1136077881&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Britsch, Louis D. "Geomorphic History of the Atchafalaya Backwater Area: Upper Deltaic Plain Development." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/637.
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Earlier researchers have produced conceptual models of Mississippi River delta plain development which divide the deltaic plain into upper and lower reaches. The upper deltaic plain has been described as an area composed mainly of lacustrine, lacustrine delta, backswamp, and crevasse channels, with minimal distributary development. The lower deltaic plain is characterized by numerous distributaries forming distributary systems and lobes. Detailed geomorphic mapping and chronologic reconstruction within the Atchafalaya Backwater Area of the upper deltaic plain of the Mississippi River has led to the recognition of a complex network of distributary development related to three distinct distributary systems that formed in the upper deltaic plain over the past 2500 years. These systems do not fit previous models of upper deltaic plain development. The East Atchafalaya Basin Protection Levee blocked Atchafalaya River water and sediment from entering the study area and burying these older distributary systems, preserving their surface expression and allowing their identification. Results show that distributary systems can be a major contributor to upper deltaic plain development and that these systems are not always related to the lower delta plain delta switching process. A stable Mississippi River position and a favorable gradient in the study area over the past 4,000 years appear to be responsible for the geomorphic development of the study area.
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Ransley, Jessica. "The backwater boats of Kerala : identity, place and the world of Munruthuruthu." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/361340/.
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Schubert, Michael Andrew Weber Larry Joseph Young Nathan C. "Computational fluid dynamics applications for nitrate removal in an upper Mississippi River backwater." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/431.
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Wear, Andrew. "High-tech hot spot or sleepy backwater? : innovation and the importance of networks /." Connect to thesis, 2008. http://repository.unimelb.edu.au/10187/5741.
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This paper draws on evidence from Victoria to examine why more innovation takes place in some areas than in others. In so doing, it explores the relationship between innovation and networks.Despite a large number of recent government policy statements on innovation, there has been very little attention paid to the spatial dimensions of innovation.
The literature on innovation increasingly points to the important role played by local and regional networks in driving innovation. Innovation is the result of the production, use and diffusion of knowledge, and this demands collaboration involving networks of individuals, organisations and institutions.
To test the theory of a connection between networks and innovation across regional Victoria, patent data is used as a proxy measure for innovation. This data is then cross-referenced with various social and economic data sets.
The analysis reveals that innovation in Victoria is substantially concentrated in ‘hot spots’ such as inner Melbourne. In some parts of Victoria very little innovation takes place at all.
This research has found that all things being equal, more innovation will take place in those areas in which there is a greater density of informal networks. However, not all types of networks are positive, and they are more important in provincial areas than in big cities. Innovation clearly has a spatial aspect, and innovation policy needs to give particular attention to the requirements of provincial areas.
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Jackson, Ashley James Walker. "Watershed in a colonial backwater? The Bechuanaland Protectorate during the Second World War." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321629.
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Schubert, Michael Andrew. "Computational fluid dynamics applications for nitrate removal in an upper Mississippi River backwater." Thesis, University of Iowa, 2009. https://ir.uiowa.edu/etd/431.
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This thesis details the work completed in order to develop a hydrodynamic and nitrate transport and reaction model for Round Lake, a backwater on UMR Pool 8. This work begins with investigating the fundamentals of nitrogen removal in aquatic ecosystems and reviewing other combined hydrodynamic and nutrient modeling efforts. Field data were gathered to determine model boundary conditions and provide a basis for calibration and validation. Using this data, the flow regime in Round Lake was simulated. CFD applications to model particle residence times and species transport and reaction were used to analyze the effects local hydraulics have on nitrogen removal in the lake. Results demonstrated an ability for CFD to predict spatial variation of nitrate with this ecosystem.
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Bramsäter, Jenny, and Kajsa Lundgren. "Study on the Dynamic Control of Dam Operating Water Levels of Yayangshan Dam in Flood Season." Thesis, KTH, Industriell ekologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174877.
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Water levels up- and downstream of dams are strongly affected by water levels in the reservoir as well as the discharge of the dam. To ensure that no harm comes to buildings, bridges or agricultural land it is important to ensure that the water level in the reservoir is adjusted to handle large floods. This report studies within what range the water level in the reservoir of the Yayangshan dam, located in Lixian River, can vary without causing any flooding downstream the dam or at the Old and New Babian Bridge located upstream the dam. By calculation of the designed flood, flood routing- and backwater computation, initial water level ranges in the reservoir have been set for the pre-flood, main flood and latter flood season for damages to be avoided. Due to the far distance between the dam site and the bridges, backwater effects had no influence on the limitations of the initial water level in the reservoir.
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Lyle, Beverley Nicola. "Peripheral backwater or innovative upland? : patterns of Franciscan patronage in Renaissance Perugia, c.1390-1527." Thesis, Oxford Brookes University, 2008. https://radar.brookes.ac.uk/radar/items/e2e5200e-c292-437d-a5d9-86d8ca901ae7/1.
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In 1400, Perugia had little home-grown artistic talent and relied upon foreign painters to provide its major altarpieces. A century later, this situation had been reversed with Perugino, Pintoricchio and Raphael all active in the city. By investigating commissioning patterns III Franciscan establishments in Perugia from 1390 to c.1527, this thesis identifies the circumstances leading to this change. It argues that artistic innovation in such peripheral places is often undervalued or automatically attributed to external factors. Focusing upon five Minorite establishments, the importance of local religious, familial and notarial networks on patronal decisions is newly evaluated. Geography-based models of the introduction and spread of ideas, particularly theories of centre-periphery and cultural exchange, are considered as a means of explaining Perugia's changing artistic status. The introduction analyses theories regarding the autonomy of peripheral patrons, the innovative potential of the periphery and the repetition of paradigms. It finds that existing models fail fully to acknowledge the periphery's contribution to artistic development which should be reappraised. Chapters 1 and 2 chart Perugian patrons' shifting preference from foreign to local painters and attribute this to changes in training, political stability, increased civic identity, and an aspirational humanist court. Chapters 3 and 4 assess the dominance of the Peruginesque style. They propose that Raphael's early success lay in his perfection of this aesthetic, along with female Baglioni/Oddi and Franciscan patronal support. This occurred in a temporary competitive vacuum, characteristic of places beyond the centre. In conclusion, some current theories undervalue the contribution of local patrons and fail to accommodate the innovative potential of peripheral places like Perugia. Ideas are generated in both places and influences flow between them through processes of exchange involving painters and patrons. Local patronal networks provide a matrix within which valid tastes are promoted independently of external pressures.
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Usher, Mark Peter. "Government of water, circulation and the city : transforming Singapore from tropical 'backwater' to global 'hydrohub'." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/government-of-water-circulation-and-the-city-transforming-singapore-from-tropical-backwater-to-global-hydrohub(85ab4081-be00-4d17-a6ae-401ca854ab26).html.
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This thesis will revisit Michel Foucault's original arguments on the ‘urban problem’ and the concomitant question of circulation, which I contend has been disassociated from more general renderings of his concept of governmentality. Throughout the 1970s, and particularly during his lectures at the Collège de France, Foucault would regularly return to the problem of urban circulation; how it has been conceived, calculated and distributed. Foucault would ponder the ways that material infrastructures have canalised people and resources, and naturalised their complex coexistence, in the interests of urban economic restructuring and state aggrandisement. Here, the ‘question of water’ was not only incidental to Foucault’s analytics of government but absolutely integral. Indeed, according to Foucault, whether flowing through rivers, canals, pipes, pumps, sewers or fountains, or stagnating in swamps, marshes and ditches, water has required the especial attention of town planners attempting to optimise the contentious process of urbanisation. Using Singapore as a case study, I will consider how the circulation of water has been administered under the three technologies of power identified by Foucault, with the greater emphasis put on discipline and security. The overarching argument will be that the modern state was consolidated and subsequently decentralised through the material configuration of drainage infrastructure, reservoirs and distribution systems, where governmental programmes have been co-produced with the technological networks of water circulation. Although disciplinary techniques had initially been found effective in terms of pollution control and flood alleviation, counterproductive consequences of concrete modernism quickly emerged requiring a greater uptake of security mechanisms, where government would be increasingly exercised through practices of exposure rather than enclosure. Mosquitoes were now thriving in the subterranean network of drains, valuable land was being wastefully converted into dormant storm canals, whilst people had become socially and emotionally disconnected from water. Released and revalorised, water now serves as a mobile technology of government which can penetrate and pervade the urban form and the everyday life of its inhabitants, centrifugally unleashing the potency of water flows and human desire whilst facilitating Singapore’s transformation into a global city. With its methodological nominalism and commitment to concrete practices, I argue that once reoriented around the urban problem, Foucault’s analytics can advance environmental politics debates by demonstrating that government is a mundanely material process orchestrated through the everyday infrastructure of water management. In so doing, I also shift the emphasis from the urbanisation of nature to the naturalisation of the urban, of circulation and the art of government itself.
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Clark, Andrew Francis. "From frontier to backwater : economy and society in the upper Senegal valley (West Africa), 1850-1920 /." Lanham (Md.) : University press of America, 1999. http://catalogue.bnf.fr/ark:/12148/cb375642092.
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Hansson, Mattis. "Rating of discharge at monitoring station affected by backwater effects - El Deim station in the Blue Nile." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-206149.
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On the Blue Nile in Sudan, near the Ethiopian border, there is a measurement station named El Deim. The discharge assessments carried out at this station are crucial for the water resource management in Sudan. Due to changed conditions, caused by a heightening of the downstream-located Roseires dam, new methods for discharge assessment are needed. The objective of the present study was to examine possibilities and methodologies to assess the discharge at this station. The flow dynamics was examined through steady state as well as dynamic hydraulic modeling by use of the Mike 11 modeling software package. By simulating possible future scenarios, in the aspect of discharge variations in the Blue Nile and water level variations in the reservoir, the effects from the raised dam on El Deim could be studied. The model was based on bathymetrical data in form of cross sections. As boundary conditions for the simulation, measured and synthetic data series of discharge and water levels were used. The known measured water levels at El Deim were compared with the simulated water levels at El Deim for the same discharge scenarios. The modeled value corresponds well to the measured values. The existing discrepancies between the simulated and measured values are likely caused by insufficient bathymetrical data. Simulation results show that the flow dynamics at El Deim are highly dependent on the water level of the reservoir and the discharge’s rate of variation. Accordingly, rating curves were created for a range of water levels at the reservoir. With the use of these curves, and tables/equations based on them, the discharge can be rated by knowing the water level at the Roseires dam and El Deim. However, the results from this study are more a description of the principles of how the discharge ratings could be performed. If the methodology and rating tools from this study are planned to be implemented the model must be improved with more bathymetrical data. The improvements are needed to create more accurate curves, tables and equations for discharge rating. Discharge ratings can then be produced and enable better operation of Roseires dam and a more efficient use of the valuable water resources in Sudan. In order to test the applicability of the created model and produced rating tools they should be compared with new measurement data from El Deim with the heightened Roseires dam fully implemented. It is possible to assess the discharge at El Deim even when backwater effects affect the station. The methodology developed in this thesis would be applicable for similar studies at other locations.
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Quarderer, Nathan Anderson. "Sediment-size analysis, nitrate monitoring, bathymetric mapping and construction of a two-dimensional hydrodynamic model of a backwater region of the Upper Mississippi River System 2008-2009." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/728.
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In April 2008, the non-profit organization Living Lands & Waters (LL&W) approached IIHR-Hydroscience and Engineering to assist with the preliminary scoping and assessment for the proposed dredging and restoration of the backwater region located near the confluence of the Iowa and Mississippi Rivers, commonly referred to as Boston Bay. IIHR was responsible for the measurement and analysis of relevant physical and chemical parameters including particle-size analysis of sediment cores; real-time monitoring of nitrate-nitrogen concentration of agricultural runoff entering Boston Bay; bathymetric surveying; as well as the development of a two-dimensional hydrodynamic capable of simulating the proposed dredging activity.
Particle-size analysis was achieved using the hydrometer method of sedimentation to determine the distribution of fine particles (silt and clay) while traditional sieving techniques were employed to establish the proportions of sand-sized particles. Results indicate that the sediment contained in Boston Bay consists primarily of particles with diameters in the range of 2-50 µm, what the USDA considers silt, and clay.
A real-time nitrate-nitrogen sensor was deployed at the Bay Island Drainage & Levee District pump intake from October 2008, through June 2009. The data collected, coupled with the daily maintenance logs from the pumping station, allow one to estimate that roughly 800 tons of nitrate-nitrogen were pumped into Boston Bay from the drainage district during the time period that the nitrate sensor was deployed in the field.
Bathymetric surveying took place in March, 2009. Survey results indicate that the average elevation of Boston Bay is 531.9 feet above sea level (MSL, 1912). Overall, the bay is very flat with little topographic relief except in the areas of Bell's Pocket and the pond where the drainage district pumps discharge. These areas are much deeper than other areas of the bay, with elevations as low as 508 feet above sea level in the deepest regions.
A two-dimensional hydrodynamic model of the bay (pre- and post-dredge) was constructed using the US Bureau of Reclamation's SRH-W modeling package. Initial results indicate that dredging Boston Bay does not appear to have detrimental impacts on the existing hydrology of the study area. Model outputs reveal that dredging will create greater availability of deep-water regions, with increased areas of faster moving current. The total area of inundation will also be affected by dredging, perhaps creating ideal habitat for hardwood tree species in portions of the study area that would otherwise be wet under existing conditions. Further studies should be conducted to couple the data obtained during particle-size analysis, with the model results to help estimate the feasibility of the proposed dredging activity and lifetime of the excavated channels.
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Hellmers, Sandra [Verfasser], and Peter [Akademischer Betreuer] Fröhle. "Integrating local scale drainage measures in meso scale hydrological modelling of backwater affected catchments / Sandra Hellmers ; Betreuer: Peter Fröhle." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2020. http://d-nb.info/1206245980/34.
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Jensen, Alexandria Kosoma. "HIGH RESOLUTION SENSING OF NITRATE DYNAMICS IN A MIXED-USE APPALACHIAN WATERSHED: QUANTIFYING NITRATE FATE AND TRANSPORT AS INFLUENCED BY A BACKWATER RIPARIAN WETLAND." UKnowledge, 2018. https://uknowledge.uky.edu/bae_etds/59.
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As harmful algal blooms begin to appear in unexpected places such as rivers in predominantly forested systems, a better understanding of the nutrient processes within these contributing watersheds is necessary. However, these systems remain understudied. Utilization of high-resolution water quality data applied to deterministic numerical modeling has shown that a 0.42% watershed area backwater riparian wetland along the Ohio River floodplain can attenuate 18.1% of nitrate discharged from local mixed-use watersheds and improves in performance during high loading times due to coinciding increased hydrological connectivity and residence times of water in these wetlands. Loading from the Fourpole Creek watershed was typical for mixed-use systems at 3.3 kgN/ha/yr. The high-resolution data were used to improve boundary condition parameterization, elucidate shortcomings in the model structure, and reduce posterior solution uncertainty. Using high resolution data to explicitly inform the modeling process is infrequently applied in the literature. Use of these data significantly improves the modeling process, parameterization, and reduces uncertainty in a way that would not have been possible with a traditional grab sampling approach.
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Yassin, Menna. "Steady State Hydroplaning Risk Analysis and Evaluation of Unsteady State Effects." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7990.
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Hydroplaning is a major concern on high speed roadways during heavy rainfall events. Hydroplaning tools are widely used by designers to reduce their roadway’s hydroplaning potential, therefore reducing the possibilities of severe crashes. This dissertation presents two methodologies for improving the prediction of hydroplaning potential.
The first phase focused on improving an existing widely used software called PAVDRN. Using multiple datasets from the Florida Department of Transportation, the author filtered the data using specific criteria to leave only truly dynamic hydroplaning crashes. The author then evaluated PAVDRN’s prediction capabilities and assessed its reliability in predicting a hydroplaning crash. Using past accident statistics, the author accounted for extraneous factors that are difficult to capture, such as driver behavior, and obtained probability factors for a more realistic estimate of hydroplaning risk on roadways. The second phase focused on improving the modeling technique used in hydroplaning prediction tools. Currently when assessing a roadway’s hydroplaning potential, the roadside drainage is not considered in the analysis. The author modeled a combined pavement-drainage system using a 1D/2D method to better capture the effects of roadside drainage, especially in the events of flooding. The methodology used in modeling successfully captures the backwater effects that are caused under critical flooding conditions. Lastly the author created a new tool (MY-PAVDTCH) to provide design engineers with updated waterfilm thickness values under roadside drainage flooded conditions.
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Snyder, Katie May. "Quantitative analysis in energy loss and vertical mass transport of various channel restoration structures using physical based modeling." Thesis, University of Iowa, 2016. https://ir.uiowa.edu/etd/2144.
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Physical based modeling was conducted to improve channel restoration efforts through direct comparison of submerged structures of various design and orientations. In-stream structure technologies studied are used to provide bank stabilization, flow control, scour and sediment control, as well as ecological enhancement through turbulent dispersion and vertical mass transport. Quantitative analysis evaluates flow effects induced by common channel restoration structures in their ability to provide mixing in our streams and rivers without significant impacts on flooding through excessive energy loss and backwater effect. Physical, fixed-bed flume experiments were performed under high-Reynolds number subcritical steady-state flow conditions. Theoretical energy loss relationships were developed, compared, and evaluated experimentally for stream barbs, spurs, submerged vanes, blocks and boulders. Extensive surface dye-trace experiments were performed to determine centerline mixing and vertical mass transport produced by stream barbs, vanes and boulders. The research presented in this thesis illustrates that the use of dispersion relationships to assess length of vertical mass transport based on the change in energy slope, and estimated shear velocity, of the channel does not properly correct for boundary layer formation and advection or angular motion produced by channel restoration structures. Submerged vanes were found to provide efficient vertical mixing with minimal energy loss or flood risk, as compared to stream barbs, spurs, blocks, and boulders. The deterioration of water quality and the need to provide bank stabilization with limited flood risk require updated NRCS and ASCE design standards and selection tools for vertical mass transport and energy loss relationships of channel restoration structures. The research conducted in these two studies have provided data for a select number of such structures.
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Keruzoré, Antoine. "Aquatic vegetation processes in a floodplain-river system and the influence of lateral dynamics and connectivity." Thesis, University of Stirling, 2012. http://hdl.handle.net/1893/7677.
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In river ecology the description and understanding of near-natural ecosystem functionality is a difficult task to achieve as the majority of river floodplains have been intensively impacted by human activities. This work addresses ecological functionality of a relatively unimpacted large river system, focussing on the lateral dynamic and connectivity mechanisms driving aquatic vegetation processes. Macrophytes were found to be very patchily distributed at the riverscape scale, being mainly confined to low energy lateral habitats in the floodplain, such as backwaters. Backwaters provided favourable conditions for plants to colonise and recruit and contributed highly to species diversity and productivity at the floodplain scale. Differences between backwaters were attributed to the frequency of connectivity with the main channel during flood events. Nevertheless, the ecological mechanism driving diversity through flooding appears not to be related to flow disturbance. Biomass produced in backwaters was found to remain stable after potentially scouring floods. Therefore the hypothesis that flood disturbances promote species diversity through the removal and destruction of biomass and rejuvenate communities such that species coexistence is increased was rejected. Rather, it appears that diversity in backwaters increases along a temporal gradient as a response to the input of colonists and their accumulation overtime through successive flood inputs. Despite the apparently non-destructive effect of floods on macrophyte biomass, backwaters appear to have a significant role in exporting large amounts of plant propagules from the site of production. Backwaters represented a net source of propagules which highly enriched the main channel pool of potential colonists. However, whereas propagules could be dispersed for long distances in flood flows the probability for them to reach a suitable downstream habitat was extremely low. This work showed that dispersal at baseflow and entry to backwaters through the downstream end after short dispersal drift provided a greater chance of successful colonisation despite the individually much shorter distance moved. Backwaters were demonstrated to be rather isolated aquatic habitats, even though they experience hydrological connectivity, suggesting that primary colonisation of these sites is a limiting step. Instead, colonisation was shown to rely primarily on propagules generated internally by established plants. Whereas colonisation could occur via internal re-organisation of existing plant propagules, the backwater seed bank could also contribute to the macrophytes species established in backwaters. Such contribution was consistently low to medium along a gradient of disturbances and connectivity and showed independence from such river flow processes. Species richness was found to be higher in the established species than in the seed bank, suggesting that asexual reproduction is prioritised by aquatic vegetation in riverine backwaters. The occurrence or persistence of macrophyte species in backwaters depends upon rhizome and plant shoot regeneration. The lack of influence of connectivity revealed that plants may originate from both in situ and externally waterborne vegetative propagules derived from other upstream backwaters. This research demonstrated that the lateral dynamic and associated connectivity are major components of river floodplain ecology which generate a wide spectrum of habitats and have a controlling effect on vegetation processes. Therefore a naturally dynamic ecological state is required to support ecosystem functionality in large river floodplains and especially to maintain a high level of species diversity, productivity and colonisation of backwaters by macrophytes.
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Åkesson, Anna. "Peakflow response of stream networks : implications of physical descriptions of streams and temporal change." Doctoral thesis, KTH, Vattendragsteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172939.
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Through distributed stream network routing, it has quantitatively been shown that the relationship between flow travel time and discharge varies strongly nonlinearly with stream stage and with catchment-specific properties. Physically derived distributions of water travel times through a stream network were successfully used to parameterise the streamflow response function of a compartmental hydrological model. Predictions were found to improve compared to conventional statistically based parameterisation schemes, for most of the modelled scenarios, particularly for peakflow conditions. A Fourier spectral analysis of 55-110 years of daily discharge time series from 79 unregulated catchments in Sweden revealed that the discharge power spectral slope has gradually increased over time, with significant increases for 58 catchments. The results indicated that the catchment scaling function power spectrum had steepened in most of the catchments for which historical precipitation series were available. These results suggest that (local) land-use changes within the catchments may affect the discharge power spectra more significantly than changes in precipitation (climate change). A case study from an agriculturally intense catchment using historical (from the 1880s) and modern stream network maps revealed that the average stream network flow distance as well as average water levels were substantially diminished over the past century, while average bottom slopes increased. The study verifies the hypothesis that anthropogenic changes (determined through scenario modelling using a 1D distributed routing model) of stream network properties can have a substantial influence on the travel times through the stream networks and thus on the discharge hydrographs. The findings stress the need for a more hydrodynamically based approach to adequately describe the variation of streamflow response, especially for predictions of higher discharges. An increased physical basis of response functions can be beneficial in improving discharge predictions during conditions in which conventional parameterisation based on historical flow patterns may not be possible - for example, for extreme peak flows and during periods of nonstationary conditions, such as during periods of climate and/or land use change.QC 20150903
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Marek, Vít. "Protipovodňová ochrana obce Želešice na tocích Bobrava a Hajanský potok." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226143.
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This thesis is a study of flood protection in the community Želešice, Brno-venkov. The theoretical part deals with: the causes of flooding, their dividing and deals with options, how to protect endangered area. Main part includes calculations of the amount of sediment in the river Bobrava and the Hajanský stream, analysis of risks by quantitative expression, suggests to complete the flood plan of the community and a list of designed flood control measures with own technical suggestion. The last point is to consider, whether is the community threatened by backwater from the river Svratka, which the river Bobrava flows into.
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Isel, Sandra. "Développement de méthodologies et d'outils numériques pour l'évaluation du débit en réseau hydraulique à surface libre." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAD008/document.
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L’évaluation du débit en réseaux hydrauliques à surface libre est une problématique actuelle sur le plan scientifique, à forts enjeux technologiques, économiques et écologiques. Dans cette thèse, de nouvelles méthodologies d’instrumentation, basées sur une synergie entre mesures non intrusives de hauteur d’eau et modélisation numérique ont été développées. Celles-ci s’appliquent d’une part à des collecteurs dont le fonctionnement hydraulique est complexe et, d’autre part, à des ouvrages non-standard (Venturi, déversoirs d’orage). Ce travail de thèse multidisciplinaire vise une meilleure compréhension de l’écoulement pour en déduire des relations Q=f(hi) plus robustes, spécifiques à chaque site et associées à leurs incertitudes; mais également l’identification de possibles modifications du site de mesure afin d’améliorer l’estimation du débit. Au final, l’applicabilité des méthodologies développées a été éprouvée au travers de plusieurs études sur sites réelsThe evaluation of the flow rate in free surface water systems is a current scientific problem, related to high technological, economical and ecological issues. In this study, new methods of instrumentation based on a synergy between non-intrusive water level measurements and numerical modeling have been developed. These methods are applied first to sewer pipes with complex hydraulic conditions then to non-standard hydraulic structures (Venturi flumes, Combined Sewer Overflows). This multidisciplinary work aims at a better understanding of the flow to identify more robust site-specific Q=f(hi) relationships related to their uncertainties. It also aims at the identification of possible modification of the measurement site in order to improve the flow rate evaluation. Finally, the applicability of the developed methodologies has been tested through several real site studies
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Khalil, Kamal. "Water surface profile modelling for Pinjarra flood diversion channel and economic evaluation." Curtin University of Technology, Department of Civil Engineering, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=17589.
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Shire of Murray has concerns regarding the negative impact that a 100 year flood could have on existing structures built before 1997. The increase cost in construction due to landfill has an adverse effect on development in Pinjarra. Feasibility of constructing a diversion channel at upstream of Murray River to attenuate the flood level from 1 in 100 year ARI to 1 in 50 year ARI, was investigated by Kiong (2003). The Murray River Water Surface Profile along three kilometres south of Greenlands Road was modelled. Flood damages on each flood occurrence were assessed and Average Annual Damage (AAD) was calculated. The AAD is used to estimate the monetary benefit against the construction cost of the diversion channel. Groundwater along Greenlands and Fauntleroy Drains was also modelled to determine the viable depth of the designed channel, as well as the analysis of backwater. The proposed channel is designed at different scenarios (invert level at breakout point, culvert or causeway design, and diversion channel variations). The benefit cost ratio of the proposed diversion channel is calculated. Other mitigation options are suggested including detention basins for structural measure, or building a new flood-proof township for non-structural measure.
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"Backwater rise due to a submerged spur." Thesis, 1992. http://hdl.handle.net/10388/etd-01312011-131519.
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A spur is an earth or rock fill embankment which projects into a stream channel from the bank. The spur is usually a low height structure and therefore it may be overtopped during flood events. Prediction of the backwater rise upstream of the overtopped spur, given the downstream stage-discharge curve and the geometry of the channel and the spur, is a new area of study and was the main objective of this thesis.
Overtopping or submergence of a spur is an example of 'over and around' flow. 'Over and around' flow is a complicated case of rapidly varied non-uniform flow through a non-prismatic cross section. 'Around only' flow such as flow past bridge piers, and 'over only' flow such as flow over weirs, represent simpler cases of rapidly varied nonuniform flow, and have been studied by previous researchers. Before studying 'over and around' flows, 'over only' flows and 'around only' flows were also studied in order to confirm that the instrumentation and methodology were satisfactory for the present study. Design charts were developed to compare the results of this study with those of previous researchers, and also some new charts were developed. The 'over and around' flows were studied in detail and new design charts were developed to predict the backwater rise due to a submerged spur.
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DVOŘÁKOVÁ, Olga. "Biodiverzita a ekologie makrofyt vybraných stojatých vod v aluviu horního toku Lužnice." Master's thesis, 2008. http://www.nusl.cz/ntk/nusl-48863.
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This is a field study describing seven backwaters in the floodplain of the Luznice river. The backwaters include alluvial pools, river arms and oxbows which differ in their genesis, morfology, hydrological régime, macrophyte vegetation and chemistry of water and sediments. This study was carried out in the Trebonsko - Protected Landscape Area and Biosphere Reserve, South Bohemia, Czech Republic. The data of species composition of the vegetation on transects of the backwaters are supplemented by water and sedimet analyses.
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Graham, Robert Alan. "Routing procedures for multiple reservoirs with backwater-affected outlet structures." 1996. http://hdl.handle.net/1993/19139.
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Liu, Yu-Chi, and 劉有棋. "The linearized analytical approach in a regular channelwhere backwater occurs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/80485722664011521261.
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碩士淡江大學
水資源及環境工程學系碩士班
98
The objective of this study is to develop a linearly analytical solution for simulating unsteady open channel flow in various shapes of the cross sections, such as rectangular and trapezoidal cross sections, where the significant backwater effect from downstream is existed. And comparing with the numerical method and the normalized analytical solution. Neglecting the inertia terms in the Saint-Venant momentum equation to obtain the linearization of the Saint-Venant equation by the method of small perturbation. And obtaining the normalized analytical model by dividing the discharge, length and time by the individual characteristics of constant. The nonlinear dynamic-wave model is solved by an explicit finite difference method which calculating the discharge and area of cross section by using the central grid method, forward difference method and Lax-Wendroff method. Approaching downstream of channel the more effect by the backwater. And the impact area is about several hundred meters. In the hydrograph of different pitch selection, it is hard to do observation and might lead to differences on results. After normalization, the discharge and time could be fitted in the range between 0 and 1. The analytical solution expressed obvious relationship between discharge and time. And the normalized analytical model could be applied to concentration routing problem.
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Hsu, Tung-Fu, and 許冬福. "Analytical and Numerical Solution of Circular Flow where Backwater Occurs." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/83297006151997207194.
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碩士淡江大學
水資源及環境工程學系碩士班
98
At present when solves mighty current of calculation problems which unsteady circular flow, the major method is using the coverall software or the numerical methods which be used by the momentum equation in the unsteady open channel flow in the inertia item to be ignored, and make the equation linearization, and the results is almost the same to complete dynamic wave model . But therefore in the computational process, because of its abbreviation inertia item, utilizes in the circular channel or the downstream which the backwater occurred. It often makes a little difference with the actual situation, and is not enough to satisfy project of engineering, therefore the present paper use the preliminary linear analytical solution and the one dimension Saint-Venant equation with numerical solution does by the circular flow compares. On the other way, regarding that downstream boundary condition with backwater effect, as soon as whether between both to have bigger errors to do compares. By the results may know that the numerical solution has the counting error which bigger than the analytic solution, and then analytical solution is closer to genuine solution, and its computation and application is more convenience, therefore analytical solution may be understood that is simple ,economic, effectiveness, the accurate project use value.
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Yen, Sen Lin, and 顏森霖. "Backwater effect on water surface profile and bed deformation in channel bend." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/15821341570186407862.
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碩士國立成功大學
水利及海洋工程學系
87
As water flows into a curved alluvial channel, or a channel bend, centrifugal acceleration of water column produces water surface super-elevation and forms a helical flow pattern. Bed material tends to be eroded from the outer bank region and deposits at the inner bank region. If a structure, such as a weir or jetty, is constructed downstream the bend for bank protection or some other reason. Backwater rises water level in the bend and may vary the bed topography. Aims of this study are to examine these backwater effects that are aroused from a dam constructed at various distances downstream an 1800 constant-radius channel. Eight experiments are conducted and bed topography, water surface profile are measured. Surface velocities in the bend are also obtained for two of the experiments by a flow visualization technique. Froude numbers of these experiments are between 0.1 to 0.5. As one expected, the existence of a dam downstream the channel bend changes flow pattern and bed topography dramatically. Backwater changes the bed roughness and the bed form in the bend can be dune or plane type. An empirical equation based on local Froude number Fr, , is proposed to classify the bed form type and the corresponding Manning's coefficient. Manning's coefficient modification through this approach improves greatly the water surface profile computation using the standard step method.
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Theis, Lindsay J. "Post-impoundment sedimentation in the backwater swamps of Bagley Bottoms, Pool Ten, Upper Mississippi River." 2002. http://catalog.hathitrust.org/api/volumes/oclc/50148193.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 2002.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 56-59).
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Jeena, T. S. "Economic and Institutional factors in the use and management of Wetlands: A case study of the cochin backwater, Kerala." Thesis, 2002. http://hdl.handle.net/2009/2979.
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