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1
Norbiato, Daniele. "Regional analysis of flooding and flash flooding". Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425502.
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Improving the capacity to make predictions in ungauged basins is one of most difficult challenge for the scientific community (see for example the current initiative Prediction Ungaged Basins (PUB) launched by the International Association of Hydrological Sciences, IAHS). Whatever hydrological models are used, in view of the tremendous spatio-temporal heterogeneity of climatic and landscape properties, extrapolation of information, or knowledge, from gauged to ungauged basins remains fraught with considerable difficulties and uncertainties, especially in the light of the generally poor understanding of where water goes when it rains, what flow path it takes to the stream, and the age of the water that emerges in the channel.
The PUB problem is the key concept of this thesis and it is analysed from several point of view. Methodologies able to observe, model and predict the hydrological response at the regional scale are proposed.
2
Kasimbazi, Gloria. "POLYMER FLOODING". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25562.
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This thesis involves the investigation of the effects of POLYMER FLOODING for the purpose of enhancing oil recovery. Different simulations will be done using Petrel software with synthetic data. The aim is to examine the effects of polymer properties in different reservoir permeabilities in terms of oil recovery. The study focus is to determine results that will be considered as the screening criteria for polymer flooding project. Four cases with different permeability will be created with homogeneous and heterogeneous distribution. Examination of different polymer properties like adsorption, concentration (viscosity) etc., will be done similarly for all cases so as economical evaluation. The grids will be refined, local grid refinement (LGR) and full grid refinement for better approximation of simulation results.
3
Frick-Trzebitzky, Fanny. "Riskscapes of flooding". Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19225.
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Diese Arbeit zeigt die Reproduktion ungleicher Risikolandschaften von Überschwemmungen auf. Die fortschreitende Urbanisierung in den Küstenregionen der Welt ist mit zahlreichen unterschiedlichen Risiken verbunden, denen sozio-ökonomisch benachteiligte Gruppen in besonderem Grad ausgesetzt sind. Dennoch ist Wissen über soziale Dynamiken, die solch ungleichen Risikolandschaften zugrunde liegen, gegenwärtig begrenzt. Das Densu Delta, ein dynamisch urbanisierendes Feuchtgebiet westlich von Accra, dient hier als Fallstudie, die anhand von qualitativen Daten mit Methoden der Humangeographie untersucht wird. Die übergeordnete Forschungsfrage lautet: Was sind die Beziehungen und Dynamiken, die die Verteilung von Überschwemmungsrisiken gestalten, und wie verfestigen sich diese in den gegenwärtig stark ungleichen Mustern von Überschwemmungsrisiken rund um das Densu Delta? Das Konzept ‚Risikolandschaften‘ (‚riskscape‘) wird hier mit Sichtweisen des kritischen Institutionalismus und der Argumentation verbunden, um Prozesse zu analysieren, die eine ungleiche Verteilung von Vulnerabilität und Anpassungskapazität bedingen. Die Ergebnisse zeigen erstens, dass institutionelle und bio-physische Dynamiken eine vielfältige Landschaft von Vulnerabilität erzeugen. Zweitens wird Anpassungskapazität von dynamischen Autoritätsverhältnissen geprägt. Drittens erweitern Unterschiede in Policy-Argumenten auf verschiedenen Ebenen und in unterschiedlichen Sektoren die Implementierungslücke in der Anpassung an Überschwemmungen. Die Arbeit leistet einen Beitrag zur bestehenden Forschung, indem die Rollen von Schlüsselakteuren und von unsichtbaren Praktiken und Institutionen in der (Re-) Produktion von ungleichen Risikolandschaften betont werden. Diese werden hier am Beispiel von Überschwemmungen im Densu Delta in Accra aufgezeigt. Skalenübergreifende Interaktionen in Risikolandschaften und deren praktische Implikationen für die Minimierung von Überschwemmungsrisiken bedürfen der weiteren Forschung.The thesis shows how uneven landscapes of urban flood risk are (re)produced. Coastal urbanisation comes with multiple risks, to which the poor are particularly exposed. Social dynamics underlying uneven riskscapes are however poorly understood. The Densu delta in Accra, a dynamically urbanising wetland, is analysed as a case based on qualitative data with methods from human geography. The overall research question is: What are the relations and dynamics that shape the distribution of flood risks, and how are they materialised in the currently highly uneven patterns of flood risk around the Densu delta? The concept of ‘riskscape’ is applied through lenses of critical institutionalism and argumentation to analyse the processes behind uneven distribution of vulnerability and adaptive capacity. Findings are that firstly, institutional and bio-physical dynamics produce a diverse landscape of vulnerability. Secondly, dynamics of authority shape adaptive capacity. Thirdly, disparities in policy arguments widen implementation gaps in adaptation to flooding. The research contributes to the existing literature in highlighting the role of actors and underlying practices and institutions in shaping multiple uneven riskscapes. In the present research the reproduction of uneven riskscapes of flooding is shown for the Densu delta case. Further research ought to look at cross-scale interactions between riskscapes and their practical implications for flood risk reduction.
4
Engelke, Jennifer. "Wetlands: a flooding solution". Kansas State University, 2012. http://hdl.handle.net/2097/13691.
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Master of Landscape ArchitectureDepartment of Landscape Architecture/Regional and Community Planning
Tim Keane
Wildcat Creek in Riley County, KS has repeatedly flooded in the past 5 years causing significant damage to the watershed, private property, and community livelihood. Strategically placing wetlands throughout the watershed can help reduce stormwater runoff, increase infiltration, and increase wildlife habitat. A watershed assessment was completed to determine the best location for wetlands in the Wildcat Creek Basin. Two watershed-scale plans for wetlands were derived and evaluated based upon estimation of stormwater runoff and quality of wildlife habitat. Wetlands were then examined and incorporated into existing land cover and land uses at the site-scale for an existing golf course. Three proposals for the nine hole course (for best golf experience, wildlife habitat, and wetland creation) were developed to reflect expansion options from a Par 30 to a Par 34 or 35 course. Each proposal was evaluated based on wetland capacity from estimated stormwater runoff, quality of wildlife habitat, playability of the golf course for all skill levels, and cost of implementation. After this evaluation, the wetland proposal was moved forward and further developed into a proposal that is best suited for the site. Following wetland implementation, stormwater runoff can be collected on-site to prevent runoff and flooding at the golf course and downstream. In order to solve flooding problems in the Wildcat Creek watershed, a series of wetlands can be implemented at the smaller site scale, like the Wildcat Creek Golf Course site, throughout the watershed. Wetlands are one component of a larger stormwater management system that is needed to reduce flooding of the Wildcat Creek and the flood-prone area of Manhattan, KS.
5
Shiraishi, Tatsuya. "Flooding tolerance of rice". Thesis, Shiraishi, Tatsuya (1991) Flooding tolerance of rice. PhD thesis, Murdoch University, 1991. https://researchrepository.murdoch.edu.au/id/eprint/52562/.
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The possibility was examined that the flooding tolerance of (Oryza rice sativa L.) might be improved through use of somaclonal variants regenerated from callus cultures. The response was also studied of cell cultures to gaseous environments which mimic submergence conditions.
Scutellum callus was induced from a range of rice cultivars by placing seed for 2 weeks on MS medium supplemented with 2,4-D (10 µM), casein hydrolysate (3 gl-1) and sucrose (20 gl-1). The scutellum was then excised and further callus growth took place for 4 weeks on the same medium but with a lower 2,4-D (5 µM) concentration. Embryogenic callus was isolated under a dissection microscope and transferred to a regeneration medium. Callus production, growth, and regeneration ability was strongly affected by genotype. Regeneration was obtained on media with or without kinetin, but high levels of kinetin were toxic.
The immediate ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) was successfully used at 5 or 10 µM, as a plant growth regulator to stimulate regeneration of plantlets.
A technique which allowed callus to be exposed to gradually increasing levels of plant growth regulators was devised by inserting a silicone tubing well into the centre of the agar medium in a 90 mm plastic petri dish and adding filter sterilised plant growth regulators to the well.
A total of 503 regenerated plants (R1 generation) were potted out and their seed collected. Seedlings from each self-pollinated R1 plant (referred to as an R2 line) were germinated then placed on polystyrene "rafts" for testing for submergence tolerance in aquaria in a glasshouse. Conditions simulating flooding were achieved by use of appropriate nutrient solutions at 30°C, covering the tank with shade cloth to cut down the light intensity to 50 µmolm-2s-1 and submerging plantlets natural to 50 cm depth. The period of submergence for each line was that which was expected to kill 90% of the parent plants. Seedlings were then desubmerged and the rafts refloated on the nutrient medium to allow for plant recovery for 12 days. The R2 lines were assessed for submergence tolerance by the number of seedlings that survived, and chlorophyll contents of the third and/or fourth leaf. To determine if any lines had enhanced tolerance to flooding these data were compared with data for the parental lines which were also submerged at same time. A total of 231 lines of R2 and R3 generations seedlings have been screened and it was found that 74 lines (32.0%) were less tolerant of submergence than parents, 29 lines (12.6%) showed slightly better tolerance, and 7 lines (3.0 %) showed much better tolerance than their parents. The promising lines were sent to Thailand and IRRI for further research, and several of them proved their superiority in submergence tolerance in field testing.
Somaclonal variation in other morphological and physiological characterustcus was observed in the R1 plants but could not be followed through to the R2 generation as most of the plants were deliberately killed when submerged. One somaclone that may have commercial value is a white-seeded line of the submergence tolerant line FR 13A, which normally has a red seed coat.
The gaseous phase above cultured rice callus was studied by analysing carbon dioxide, ethanol, ethylene, and oxygen. An apparatus was developed whereby growing callus could be exposed to flowing sterile gas mixtures. When callus was exposed to a gas with composition similar to that found in submerged plants (2% (v/v) oxygen, 8% (v/v) carbon dioxide, and 10 ppm ethylene), callus from rice cultivars with low submergence tolerance grew more slowly, utilised more oxygen, produced more ethylene, and showed higher necrosis than callus lines from submergence tolerant rice.
Ethylene released from the callus during culture resulted in early necrosis of the callus in some submergence sensitive lines. This correlates with the difficulty of keeping callus in good condition during the sequence of subcultures necessary to induce regeneration.
6
Jiang, Long. "Numerical simulation of urban flooding". Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504497.
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McNeil, D. A. "Flooding in a vertical tube". Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381710.
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Porwal, Rupesh. "Adaptive Selective Flooding Qos Routing". Thesis, Indian Institute of Science, 2002. https://etd.iisc.ac.in/handle/2005/3924.
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The routing strategy used in today's Internet is best-effort service, where all data packets are treated equally. This type of service is not suited for applications such as video conferencing, and video on demand, that requires the availability of certain resources (such as bandwidth) to be guaranteed for them to function properly. The routing in this context, called Quality-of-Service (QoS) Routing, is the problem of finding suitable paths that meet the application's resource requirements.
The majority of proposed QoS routing schemes operate by maintaining the global state of the network, and using this knowledge to compute the QoS route. However, all these schemes suffer from the inherent drawback of scalability, because of the need for each node to collect state information about the complete network. The other type of QoS routing schemes do not maintain network state information, but instead flood the network with QoS connection establishment requests. This type of scheme suffers from excessive message overhead during QoS connection establishment.
In this thesis, we present a new QoS routing algorithm that is a combination of the above-mentioned two schemes (i.e., global state and flooding based). The algorithm aims at minimizing the message overhead associated with these two schemes and still maintaining the positive aspects of both of them. The basic idea of the algorithm is: to reach to a destination, the path(s) will always pass through a specific set of intermediate nodes. The algorithm discovers such intermediate nodes (limited by a hop count threshold value needed to reach there). When a QoS connection request arrives at a node, it selects the feasible path leading to the intermediate node for the requested destination. The QoS connection establishment message (or routing message) is forwarded along this path. When the message arrives at the intermediate node, the further path is decided through same logic. To decide the path that leads to the intermediate node, the algorithm maintains the link state related to these intermediate nodes, and link state updates are restricted only with regard to these intermediate nodes. Because of this restriction in link state updation, one has less message overhead, compared to the global state based routing scheme. Further, the algorithm tries to group these intermediate nodes in such a way that the routing message need be sent to only one of the grouped intermediate nodes, and still makes sure that all the possible paths are covered. Therefore, one has a reduced message overhead because of grouping.
9
Porwal, Rupesh. "Adaptive Selective Flooding Qos Routing". Thesis, Indian Institute of Science, 2002. http://hdl.handle.net/2005/51.
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The routing strategy used in today's Internet is best-effort service, where all data packets are treated equally. This type of service is not suited for applications such as video conferencing, and video on demand, that requires the availability of certain resources (such as bandwidth) to be guaranteed for them to function properly. The routing in this context, called Quality-of-Service (QoS) Routing, is the problem of finding suitable paths that meet the application's resource requirements.
The majority of proposed QoS routing schemes operate by maintaining the global state of the network, and using this knowledge to compute the QoS route. However, all these schemes suffer from the inherent drawback of scalability, because of the need for each node to collect state information about the complete network. The other type of QoS routing schemes do not maintain network state information, but instead flood the network with QoS connection establishment requests. This type of scheme suffers from excessive message overhead during QoS connection establishment.
In this thesis, we present a new QoS routing algorithm that is a combination of the above-mentioned two schemes (i.e., global state and flooding based). The algorithm aims at minimizing the message overhead associated with these two schemes and still maintaining the positive aspects of both of them. The basic idea of the algorithm is: to reach to a destination, the path(s) will always pass through a specific set of intermediate nodes. The algorithm discovers such intermediate nodes (limited by a hop count threshold value needed to reach there). When a QoS connection request arrives at a node, it selects the feasible path leading to the intermediate node for the requested destination. The QoS connection establishment message (or routing message) is forwarded along this path. When the message arrives at the intermediate node, the further path is decided through same logic. To decide the path that leads to the intermediate node, the algorithm maintains the link state related to these intermediate nodes, and link state updates are restricted only with regard to these intermediate nodes. Because of this restriction in link state updation, one has less message overhead, compared to the global state based routing scheme. Further, the algorithm tries to group these intermediate nodes in such a way that the routing message need be sent to only one of the grouped intermediate nodes, and still makes sure that all the possible paths are covered. Therefore, one has a reduced message overhead because of grouping.
10
Atthawutthisin, Natthaporn. "Numerical Simulation of Low Salinity Water Flooding Assisted with Chemical Flooding for Enhanced Oil Recovery". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19113.
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World proved oil reserve gradually decreases due to the increase production but decrease new field discovery. The focus on enhance oil recovery from the existing fields has become more interesting in the recent years. Since waterflooding has been used in practices in secondary recovery phase for long time ago, the low salinity waterflooding is possible to apply as tertiary recovery phase. Another effective enhance oil recovery method is chemical flooding especially, nowadays, when the price of chemical is not a big issue compared to oil price. Both low salinity and chemical flooding method have been trialed and success in laboratory studies and some field tests. Moreover the salinity sensitivity on chemical flooding has been studied and both positive and negative results were proposed. Because new technology has been developing day by day in order to get higher oil recovery, the new technology as the combination of low salinity waterflooding and chemical flooding has been studied in this report. In this thesis, the literature of low salinity water flooding, alkaline flooding, surfactant flooding, polymer flooding and alkaline-surfactant-polymer flooding (ASP) have been reviewed. The mechanisms of each method that affect to oil recovery and salinity sensitivity on each chemical flooding method have been summarized. All of those studies showed the benefit of chemical to the low salinity water flooding. the result of literature reviews has turned to the numerical simulation part.The simulation has been carried out on a 3 dimensional synthetic model by using Eclipse 100 as the simulator. The model is heterogeneous with patterns variation in permeability and porosity. The effect of low salinity in water flooding, alkaline flooding, surfactant flooding, polymer flooding and ASP flooding have been observed in many aspects.The main role of low salinity effect in water flooding is wettability changing from oil-wet to water-wet. The low salinity water in the first water flooding phase give the positive effect but not much different compared to overall recovery. The low salinity in chemical solution influences an additional oil recovery in all combinations. Mainly, low salinity increases polymer solution viscosity that can improve sweep efficiency of polymer flooding. In alkaline flooding and surfactant flooding, the salinity is need to be optimized to optimum salinity condition corresponding to optimum alkaline concentration and surfactant concentration, where creates the lowest IFT. The range of secondary flooding for alkaline and surfactant flooding is when they reach the optimum concentration. In case of polymer, the viscous polymer solution can impact longer as the polymer injection range. In term of low salinity in tertiary water flooding, it influences better oil recovery than high salinity water flooding. Therefore, it can be concluded that low salinity water flooding gives a positive effect to overall result when combined with chemical flooding. The recommendations are also available for further study.
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Afeku, Kizito. "Urbanization and Flooding in Accra,Ghana". Connect to this document online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1123271331.
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Thesis (M.A.)--Miami University, Dept. of Geography, 2005.Title from first page of PDF document. Document formatted into pages; contains [1], v, 53 p. : ill. Includes bibliographical references (p. 50-53).
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Nie, Linmei. "Flooding Analysis of Urban Drainage Systems". Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-308.
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- Description of the problems
Throughout history floods have been one of the most severe natural catastrophes, which brought about loss of lives and huge economic losses in addition to the influence on community activities and adverse effects on the environment. We have witnessed enormous flood events almost all over the world, even in the early years of 21st century. The cruel lesson learnt is that we have not coped well with floods.
Studying the risk of flooding is the goal of this thesis. The focus is given to flooding of urban drainage systems. Urban climate, human activities and land use vary quickly and greatly with time. These variations modify the features of both urban hydrology and hydraulics, and change the distribution of water. It may lead to dual adverse effects in one region: the severe water shortage in one period and the increasing risk of flooding in another period. Therefore, finding appropriate solutions for these problems has been being a great challenge for the whole world.
- Aims of this study
This study aims to contribute ideal approaches and models to understand deeply urban flooding problems, i.e. to find the causes of flooding, to analyze their propagations and on this basis to evaluate the risk of flooding, and finally to search for solutions for flood mitigation.
- Study contents and methodologies
Distinguishing the potential hazards of urban flooding, delineating the changes of urban lands, developing models to simulate flooding and examining different measures to mitigate the risk of flooding constitute the main contents of this study. It is carried out by both qualitative analysis and quantitative simulations in a stepwise manner. Regarding the stochastic characteristics of flooding, a risk analysis initiates the study, which aims to formulate flooding scenarios in general urban environment through procedures of system definition, hazard identification, causal analysis, frequency analysis, consequence estimation and mitigation. A Norwegian case study illustrates the whole process.
Following the risk analysis, GIS technology is introduced to delineate the variation of topography. GIS hydrological modeling is applied to delineate the basic hydrological elements from a Digital Elevation Model (DEM). The accuracy of grid DEM and the influence of buildings are studied.
Two urban flooding models, the "basin" model and the dual drainage model, are developed on the basis of the MOUSE program (DHI, 2000). The three models, i.e. the MOUSE model, the “basin” model and the dual drainage model, are examined through two case studies, and the flow capacities of the existing sewers in these two case studies are then checked. Following the flooding simulation, the effectiveness of four flooding mitigation measures is tested.
- Main results
Sixty-eight (68) potential flooding hazards are identified by risk analysis in Chapter three. In combination with Trondheim case study, the frequencies of several flooding scenarios are studied, and it is indicated that the flooding of urban drainage systems happens more frequently than river flooding. When it happens, urban flooding disturbs very much the activities in flooding areas. Therefore management attentions should be paid to urban flooding in addition to large river flooding.
GIS is used as a bridge between digital data and numerical flooding simulation. Two important hydrological elements, watersheds and surface stream networks, are derived from grid DEM in Chapter four. The preliminary flood risk zones are delineated in combination with two case studies. They provide useful information for flood management.
The three flooding models are calibrated through two case studies: Trondheim- Fredlybekken catchment in Norway and Beijing-Baiwanzhuang (BWZ) catchment in China. Flooding checking of the existing sewer systems in these two case studies indicates that the current flow capacities of sewers are less than the designed capacities. Consequently, flood mitigation measures are examined in the following Chapter six. The study indicates that the combination of structural and non-structural flood mitigation measures are regarded as the comprehensive solution for flood control.
- Restrictions of the developed models
The developed flood models are restricted to summer and autumn flooding situations. In other words, the snowmelt routine is not included in the hydrological model applied. However, if a hydrological model that is able to simulate snowmelt could be connected to the developed models, then the hydraulic analysis would be carried out similarly.
13
Zhu, Wanning. "Multipoint Relay flooding : Network coding improvements". Thesis, KTH, Kommunikationssystem, CoS, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91526.
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Network coding is a new research area with potential to reduce network resources. With network coding, intermediate nodes forward packets that are linear combinations of previously received packets. The type of networks we consider are vehicle mounted mobile tactical radio networks. Tactical communication may be required in areas where pre-deployed base stations are unavailable. Mobile ad hoc networks satisfy this requirement. Due to low antenna heights, network resources are scarce inmobile networks without base stations. Broadcast traffic, which disseminates information network-wide, is very important in tactical mobile networks. Multipoint relay flooding is a well-known technique for efficient distribution of broadcast traffic. It is therefore interesting to evaluate how much network coding can reduce the number of transmissions in a mobile ad hoc network. In this thesis we show that it is possible to further reduce the number of transmissions for Multipoints Relay flooding by using network coding. However, this improvement is largely theoretical - there has been no effort to evaluate this approach in practice.
14
Iu, Ming-Yee. "Selective Flooding in Ad Hoc Networks". Thesis, University of Waterloo, 2002. http://hdl.handle.net/10012/1152.
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An ad hoc network is a collection of mobile wireless devices that cooperate with each other to route packets amongst themselves. The main difficulty in designing routing algorithms for such a network is the large number of topology changes that the network undergoes due to device movement.
Selective flooding is a routing technique that is more resilient to topology changes than traditional algorithms but is more bandwidth efficient than pure flooding. An on-demand selective flooding algorithm has been designed and tested on the ns-2 simulator. In scenarios involving a large number of topology changes, selective flooding outperforms other ad hoc network routing techniques. Unfortunately, selective flooding is much more bandwidth hungry and is unable to scale to handle reasonable traffic loads.
Interestingly, the analysis of selective flooding reveals major problems with traditional ad hoc networking techniques. Many current algorithms demonstrate shortcomings when dealing with bursty traffic, and current wireless hardware cannot handle ad hoc networking traffic in an efficient manner. These issues need to be addressed before ad hoc networking technology can become feasible for widespread use.
15
McQuillan, K. W. "Flooding in annular two-phase flow". Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354843.
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Olayinka, Dupe Olayinka. "Modelling flooding in the Niger Delta". Thesis, Lancaster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658090.
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Research regarding anthropogenic effects on flood inundation and morphological/landscape change in the River Niger is presented in this thesis. Various anthropogenic effects are considered within the case study area. Effects of dam construction were numerically modelled using Dynamic Harmonic Regression (DHR) Model, Geographical Information System (GIS) and Cellular Automaton Evolutionary Slope And River model (CAESAR). CAESAR model was used to simulate different flood scenarios resulting from environmental change (climate and anthropogenic land cover change) on the River Niger. Most pm1s of the Niger River Basin lack spatially distributed hydrological data to facilitate efficient monitoring of anthropogenic effects on the river. The use of parsimonious models such as Dynamic Harmonic Regression models which require few spatially-distributed data are therefore suitable for simulating water stages behaviour/response to anthropogenic effects, in this case, the Kainji and Jebba Dam constructions. DHR routines were used to simulate the dynamics of pre- and post-dam constmction water stages within the River Niger Basin in Nigeria. The DHR model explicitly calculates the uncertainty in the estimated cycles and trends and thereby ensures that the data are not over-interpreted. Seasonal cycles and trend in water stage data across the Niger River Basin within Nigeria before and after Kainji and Jebba dams construction were captured using this model. It has robustly quantified a range of differences in the water stage regimes after the dam construction especially at the immediate downstream gauge station. These differences, however, dissipate further down the downstream catchment towards the Niger Delta.
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El-Feghi, Farag Abdulrazzak. "Miscible flooding in correlated random fields". Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1506.
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Subramanian, Jayashree Ph D. Massachusetts Institute of Technology. "Efficient flooding for wireless mesh networks". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/71490.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 113-116).
Flooding in wireless mesh networks involves distributing some data from one node to rest of the nodes in the network. This dissertation proposes UFlood, a flooding protocol for wireless mesh networks that targets large file transfers, such as software updates, where achieving high throughput (minimizing the time to complete the flood to all nodes) and low airtime (lower the time each node spends in transmitting packets, and thus lower the impact on other wireless traffic) are both important. The central challenge in good flooding performance is the choice of senders for each transmission opportunity. At each time during a flood, some parts of the network will have received more data than others. The set of best sending nodes lies along the boundaries between these regions, and evolves with time in ways that are difficult to predict. UFlood's key new idea is a distributed heuristic to dynamically choose the senders likely to lead to all nodes receiving the flooded data in the least time. The mechanism takes into account which data nearby receivers already have as well as inter-node channel quality. The mechanism includes a novel bit-rate selection algorithm that trades off the speed of high bit-rates against the larger number of nodes likely to receive low bit-rates. Unusually, UFlood uses both random network coding to increase the usefulness of each transmission and detailed feedback about what data each receiver already has; the feedback is critical in deciding which node's coded transmission will have the most benefit to receivers. The required feedback is potentially voluminous, but UFlood includes novel techniques to reduce its cost. The dissertation concludes that careful choice of senders allows UFlood to achieve 150% higher throughput than MORE, a known high-throughput flooding protocol, using 65% less time transmitting. UFlood uses 54% lower airtime than MNP, an existing flooding protocol to minimize airtime, and achieves 300% higher throughput.
by Jayashree Subramanian.
Ph.D.
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Gibson, Marc A. "THERMOSYPHON FLOODING IN REDUCED GRAVITY ENVIRONMENTS". Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1354132775.
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Kannan, Gangadharan. "Selective flooding for better QoS routing". Link to electronic version, 2000. http://www.wpi.edu/Pubs/ETD/Available/etd-0510100-143929/.
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Black, Andrew Roger. "Seasonality of flooding in Scottish rivers". Thesis, University of St Andrews, 1993. http://hdl.handle.net/10023/15201.
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The study considers the seasonal distribution of non-tidal peak flows on a large number of rivers draining varied catchments across Scotland and Northumberland. Peaks over threshold (POT) flood series from 156 gauging stations are used, and are subject to two quality control measures. Firstly, threshold values are standardised to give 45 peaks over a ten year period and secondly, records are adjusted to compensate for non-stationarity in the sampled data. The database assembled consists of 3458 station-years of record. A comprehensive description of the seasonal patterns found is presented, based on these quality-controlled data and utilising a number of methods of characterisation. Directional statistics are employed to indicate the central tendency of time-of-year values for each station, a six-season analysis gives more detailed information, and the seasonality of large peaks is compared with that of full POT series. Finally, a classification analysis is used to summarise these patterns. These patterns are related to five catchment characteristics: the seasonality of rainstorms; soil moisture deficit lengths; catchment size; lake storage and snowmelt, although the effect of the last of these is unclear as suitable data were not available for analysis. A discriminant analysis is employed to relate the five physical factors to flood seasonality. The study concludes with a discussion on the implications of its findings. A method of assessing seasonal flood risk using POT series is presented, offering an accurate means of relating flood magnitude to recurrence interval for any period of less than one year. The implications of seasonal heterogeneity, both within and between flood records, are also discussed. The suitability of the exponential model for use with POT records is questioned and it is suggested that explicit recognition of the seasonality of flooding may be necessary in order to make accurate design flood estimates.
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Thorstensson, Jonatan. "Genomgång av skyddsmetoder för TCP SYN flooding". Thesis, University of Skövde, School of Humanities and Informatics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-4103.
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Följande arbete behandlar möjliga lösningar för hantering av SYN flooding, en Denial-of-Service-attack mot tjänster som använder TCP för kommunikation över datanätverk. Ett flertal olika skyddsmetoder, med varierande ansatser, identifieras, beskrivs och undersöks. Även möjligheter att kombinera dessa analyseras. Det visas att genom att implementera existerande skydd, samt kombinera flera av dessa begränsas hotet från SYN flooding avsevärt. Rekommendationer presenteras dessutom för hur organisationer bör gå tillväga för att säkra tjänster som riskerar att utsättas för SYN flooding-attacker genom att implementera skydd nära tjänsten först samt därefter ytterligare lager allt längre ut i nätverket.
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Palomo, Isaac. "Implementing Green Infrastructure to Address Urban Flooding". The University of Arizona, 2017. http://hdl.handle.net/10150/626201.
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Farlow, Charles R. "Prepositioning for flooding in the Sacramento region". Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5721.
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Approved for public release; distribution is unlimited.The Sacramento region is prone to flooding disasters. This thesis uses an optimization model to recommend where to preposition and/or expand warehouses, health-care personnel, ramp space, and transportation vehicle capacity. Adequate prepositioning helps evacuate the emergency population (EP), supply commodities to affected population (AP) that stays back in the affected areas (AAs), and transport other displaced population (DP) to the relief locations (RLs) for shelter. The goal is to minimize the expected number of EP and AP casualties, and then to maximize the DP transported to RL shelters, both during the first 72 hours after a flood disaster. We model a network of eight AAs and ten RLs, four flooding scenarios of different severity, and several budget levels for expansion of the initially prepositioned resources. We find that the RLs that the Federal Emergency Relief Agency (FEMA) has already selected have enough warehouse space to support the AP. This model recommends minor investment in additional health-care providers and emergency rescue vehicles for the EP. On the other hand, we observe a shortfall in mass housing capacity for the DP, even after fully expanding the capacity of existing facilities.
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Wat, Rex Man Shing. "Experimental modelling studies of miscible flooding processes". Thesis, University of Exeter, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310076.
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During the tertiary stage of oil recovery, various chemicals and gases are injected into the reservoir. The success of these processes often depend on the ability of the injected chemicals/gases making contact with the residual hydrocarbon. The accessibility of the individual pore, where the hydrocarbon are trapped, to the injected fluid is therefore important. In many core flooding experiments which simulate such tertiary processes, the effluent profiles of the injected chemical often exhibit the capacitance effect of early breakthrough and long tails. These are mainly due to the fact that not all the pores are accessible to the displacing fluid. In this work, a mass transfer model, using physical meaningful parameters, has been set up to study the capacitance effect. The pore space are divided into a flowing fraction in which the bulk flow of the injected chemical takes place and a stagnant fraction where the chemical can only access by molecular diffusion. The significance and sensitivity of the five model parameters have been studied extensively using computer simulation. The extent of the mass transfer process is characterised by the different sets of family curves. A series of IPA/water miscible displacements using Clashach sandstone have been carried out to provide experimental data for model simulation. The assumption of the stagnant fraction in the form of dead end pores has been supported by the results of hexane/toluene displacements at connate water saturation. Some problems of history matching the experimental results by model simulation have been highlighted. This is mainly caused by the difficulty of establishing an analytical solution for the model equation and the need to optimise simultaneously the five model parameters. Various approach to overcome these problems have been successfully demonstrated in this work and further possible improvement has been identified. The source of numerical dispersion and the different corrective schemes proposed in various papers have been summarised and compared. One of these, the method of lines (MOL) has been used successfully in this work to minimise numerical dispersion. The understanding of the non-equilibrium capacitance effect in porous media is essential in order to interpret the production data and, in particular, laboratory core flooding results correctly. It is also important, for the mathematical model, to use parameters which are physically meaningful to the process itself. The work carried out in this research has provided a detailed study on this subject.
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Ullberg, Susann. "Watermarks : Urban Flooding and Memoryscape in Argentina". Doctoral thesis, Stockholms universitet, Socialantropologiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-89335.
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The relationship between social experience and action in the context of recurrent disasters is often thought of in terms of adaptation. This study problematises this assumption from an anthropological perspective by analysing the memoryscape that mediates past experiences of disasters. The inquiry is based on translocal and transtemporal ethnographic fieldwork conducted in 2004-2011 in the flood-prone city of Santa Fe in Argentina. The study examines how past flooding is remembered by flood victims in the middle- and low-income districts and by activists of the protest movement that emerged in the wake of the 2003 flood. It deals with flood memory in the local bureaucracy, in local historiography, myths and popular culture. The analysis reveals that the Santafesinian flood memoryscape is dynamically configured by evocative, reminiscent and commemorative modes of remembering, which are expressed in multiple forms, ranging from memorials and rituals to bureaucratic documents, infrastructure and everyday practices. The study addresses the relationship between memory, morality and social inequality and discusses the implications for questions regarding vulnerability, resilience and adaptation.
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Messham, Rebecca Louise. "Doing business underwater : flooding, entrepreneurship and resilience". Thesis, University of Hull, 2014. http://hydra.hull.ac.uk/resources/hull:11488.
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Small and Medium Sized Enterprises (SMEs) are extremely important to the health of the UK economy. Yet their continued survival is threatened by a plethora of risks on a daily basis. Floods affect more people and cause more economic losses than any other hazard in the UK. Accordingly, the aim of this thesis was to explore flood risk from the SME perspective by looking at case examples of Hull and Sheffield, two cities which were hit extremely hard during the summer 2007 floods. Through the conduction of 38 semi-structured interviews and the distribution of a postal questionnaire with a response rate of 8.7%, it was found that for SME owner/managers flooding is not a significant risk. It is one in a ‘package of disruptions’ which causes discontinuity to the ‘order of business’. These perceptions differ to those held by local regulatory bodies. It was revealed that the Environment Agency, Hull City Council and Sheffield City Council are at cross-purposes in regards to the resilience measures implemented to address flooding. This variation leads to the production of a ‘responsibility game’ scenario between SMEs and regulatory bodies, the catalyst for SMEs remaining vulnerable to the risk of flooding. The responsibility game develops due to limitations associated with regulatory body resilience measures. As regulatory body resilience measures are dictated by national policy, their shortcomings are attributed to constraints at a national level. Flooding has a ‘local profile’. Therefore it is recommended that flooding policies should be generated at a local scale on a place-by-place basis. Local characteristics can be taken into account and assistance can be provided by regulatory bodies which is tailored to those stakeholders in need. By doing so, it is predicted that SME vulnerability will reduce, and owner/managers will not spend a future “doing business underwater”.
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Brendel, Conrad. "Analysis, Modeling, and Forecasting Of Urban Flooding". Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/105131.
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As the world becomes more urbanized and heavy precipitation events increase in frequency and intensity, urban flooding is an emerging concern. Urban flooding is caused when heavy rainfall collects on the landscape, exceeding the capacity of drainage systems to effectively convey runoff. Unlike riverine and coastal flooding, urban flooding occurs frequently, and its risks and impacts are not restricted to areas within floodplains or near bodies of water. The objective of this dissertation is to improve our understanding of urban flooding and our capability to predict it through the development of tools and knowledge to assist with its analysis, modeling, and forecasting.
To do this, three research objectives were fulfilled. First, the Stream Hydrology And Rainfall Knowledge System (SHARKS) app was developed to improve upon existing real-time hydrologic and meteorological data retrieval/visualization platforms through the integration of analysis tools to study the hydrologic processes influencing urban flooding. Next, the ability to simulate the hydrologic response of urban watersheds with large storm sewer networks was compared between the fully distributed Gridded Surface/Subsurface Hydrologic Analysis (GSSHA) model and the semi-distributed Storm Water Management Model (SWMM). Finally, the Probabilistic Urban Flash Flood Information Nexus (PUFFIN) application was created to help users evaluate the probability of urban flash flooding and to identify specific infrastructure components at risk through the integration of high-resolution quantitative precipitation forecasting, ensemble forecasting, and hydrologic and hydraulic modeling.
The outcomes of this dissertation provide municipalities with tools and knowledge to assist them throughout the process of developing solutions to their site-specific urban flooding issues. Specifically, tools are provided to rapidly analyze and respond to rainfall and streamflow/depth information during intense rain events and to perform retrospective analysis of long-term hydrological processes. Evaluations are included to help guide the selection of hydrologic and hydraulic models for modeling urban flooding, and a new proactive paradigm of probabilistic flash flood guidance for urban areas is introduced. Finally, several potential directions for future work are recommended.Doctor of Philosophy
As the world becomes more urbanized and heavy precipitation events increase in frequency and intensity, urban flooding is an emerging concern. Urban flooding is caused when heavy rainfall collects on the landscape, exceeding the capacity of drainage systems to effectively convey runoff. Unlike riverine and coastal flooding, urban flooding occurs frequently, and its risks and impacts are not restricted to areas within floodplains or near bodies of water. The objective of this dissertation is to improve our understanding of urban flooding and our capability to predict it through the development of tools and knowledge to assist with its analysis, modeling, and forecasting. To do this, three research objectives were fulfilled. First, the Stream Hydrology And Rainfall Knowledge System (SHARKS) app was developed to improve upon existing real-time hydrologic and meteorological data retrieval/visualization platforms through the integration of analysis tools to study the hydrologic processes influencing urban flooding. Next, the ability to simulate the hydrologic response of urban watersheds with large storm sewer networks was compared between the fully distributed Gridded Surface/Subsurface Hydrologic Analysis (GSSHA) model and the semi-distributed Storm Water Management Model (SWMM). Finally, the Probabilistic Urban Flash Flood Information Nexus (PUFFIN) application was created to help users evaluate the probability of urban flash flooding and to identify specific infrastructure components at risk through the integration of high-resolution quantitative precipitation forecasting, ensemble forecasting, and hydrologic and hydraulic modeling. The outcomes of this dissertation provide municipalities with tools and knowledge to assist them throughout the process of developing solutions to their site-specific urban flooding issues. Specifically, tools are provided to rapidly analyze and respond to rainfall and streamflow/depth information during intense rain events and to perform retrospective analysis of long-term hydrological processes. Evaluations are included to help guide the selection of hydrologic and hydraulic models for modeling urban flooding, and a new proactive paradigm of probabilistic flash flood guidance for urban areas is introduced. Finally, several potential directions for future work are recommended.
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Lundberg, Ludvig. "Damage Assessment of Mozambique Flooding Using Sentinel". Thesis, KTH, Geoinformatik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-272396.
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In the past 40 years, floods have become a bane of Mozambique’s inhabitants and economy. The latest of them, caused by the cyclone Idai, has devastated the area resulting in loss of life and property. It was estimated that around 715 000 hectares of farmland was destroyed as a result of the cyclone. The main goal of this thesis was to assess the extent of the flooding and to determine the types of land cover that were affected. This was done in Google Earth Engine, using SAR change detection on Sentinel 1 data to create a mask for the flooded areas, followed by a supervised image classification on Sentinel 2 data to identify the types of land cover that were flooded. Two classifications were done, using imagery from early periods of the country’s plant growing season and later periods of the same season, respectively. The results of both classifications were below standard, with the main problems stemming from difficulties with differentiating between agriculture and roads along with agriculture and vegetation. Multiple ways to improve the results and avoid the errors in future similar projects were discussed, including using multi temporal data and utilizing a road map for the area to create a large amount of training points for the classification. In conclusion, while the results were not as good as was envisioned, the thesis provided ample opportunity to analyze errors and to theorize methods for improving future work.
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Dambe, Natalia. "Riverine flooding using GIS and remote sensing". Master's thesis, Faculty of Engineering and the Built Environment, 2020. https://hdl.handle.net/11427/31738.
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Floods are caused by extreme meteorological and hydrological changes that are influenced directly or indirectly by human activities within the environment. The flood trends show that floods will reoccur and shall continue to affect the livelihoods, property, agriculture and the surrounding environment. This research has analyzed the riverine flood by integrating remote sensing, Geographical Information Systems (GIS), and hydraulic and/or hydrological modeling, to develop informed flood mapping for flood risk management. The application of Hydrological Engineering Center River Analysis System (HEC RAS) and HEC HMS models, developed by the USA Hydrologic Engineering Center of the Army Corps of Engineers in a data-poor environment of a developing country were successful, as a flood modeling tools in early warning systems and land use planning. The methodology involved data collection, preparation, and model simulation using 30m Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) as a critical data input of HEC RAS model. The findings showed that modeling using HEC-RAS and HEC HMS models in a data-poor environment requires intensive data enhancements and adjustments; multiple utilization of open sources data; carrying out multiple model computation iterations and calibration; multiple field observation, which may be constrained with time and resources to get reasonable output.
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AlSofi, Abdulkareem Mohamad. "The simulation and design of polymer flooding". Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7031.
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Most polymers used in Enhanced Oil Recovery exhibit shear-thinning behaviour. An in-house streamline simulator was modified and used to study the effects of both shear-thinning and shear-thickening on oil recovery. First, we describe how to simulate Newtonian and non-Newtonian polymer flooding. In contrast to current simulators, our methodology: (1) implements an iterative approach to solve the pressure field opposed to the common approach where this viscosity-pressure interdependence is ignored, (2) defines non-Newtonian viscosities to be cell-centred while current simulators use a face-approach and (3) uses a physically-based rheological model where non-Newtonian viscosities in two-phase flow are those exhibited in single-phase flow at the same pressure gradient not the same flow rate. To validate the simulator, we constructed one-dimensional analytical solutions for waterflooding with a non-Newtonian fluid. We then compared our results to those from commercial simulators illustrating the significance of current assumptions and their effects on the simulation results as well as the design of polymer flooding. The simulator was also used to investigate non-Newtonian effects on sweep and recovery. The results of this work prove the importance of taking polymers’ non-Newtonian behaviour into account for the successful design and evaluation of polymer flooding projects. Shear-thinning impairs sweep through exacerbated fingering and channelling. Increased channelling is due both to an overall reduction in viscosity as well as local viscosity variations, the latter factor being less significant. In addition, our results illustrate the potential of using shear-thickening agents for channelling reduction. The numerical simulation of such processes is also a challenge as the solutions should minimise numerical dispersion. Traditional numerical simulations of polymer flooding give excessive front smearing compared to pure waterfloods, requiring many thousands of gridblocks in one dimension to resolve the fronts adequately and rendering the predictions from three-dimensional simulations dubious at best. Investigating numerical dispersion in simulations of polymer flooding, we showed that these erroneous predictions occur because of the coupling of compositional dispersion with fractional flow. Small errors in composition alter the fractional flow, causing the development of incorrect wavespeeds. Rather than implementing a higher-order discretisation method, we propose a simple scheme based on segregated-flow within a gridblock. Compared to current mixing schemes, it differs in that segregation not only affects fluid properties but the transport, too. The scheme was shown to reestablish self-sharpness across the trailing shock. After validating the approach in one dimension, we performed multi-dimensional simulations demonstrating that traditional simulation methods can vastly overestimate recovery, potentially leading to poor injection design and management decisions. Finally, we illustrated the extendibility of this technique to low-salinity flooding as well as compositional simulations of miscible and near-miscible gas injection processes. At the end, since one of the main purposes of reservoir simulation is to optimally design the exploitation and production of petroleum resources, we investigated various aspects of the design of polymer flooding processes. First, we investigated the design of such processes in terms of finding the optimal solution and the characteristics of optimal strategies. The results suggest that polymer-flooding design – in terms of concentration, slug size and initiation – is more intuitive than expected previously. In terms of optimisation, polymer flooding is unimodal. In terms of optimal design, we found that: (1) it is always beneficial to start polymer flooding as soon as possible preferably before any waterflooding; (2) optimal slugs are very close to being continuous and (3) shear-thinning floods require higher polymer concentrations to compensate for losses in mobility control. Second, we quantified the impact of uncertainty on both the optimal design and profitability. The uncertainty results provide a quantitative ranking of the various factors affecting polymer flooding. This serves as a guide to associated data-acquisition efforts. Pre-polymer flooding initiation efforts can be focused on reducing uncertainties of high impact factors, thereby increasing the probability of success. Finally, we investigated upscaling effects. The main limitation to the use of upscaled models was found to be injectivity-related. For cases where polymer-flooding injectivity was not a factor, the results illustrate the potential utility of upscaled models for the preliminary design of polymer floods in terms of optimal polymer concentrations. This is despite the significant mismatch in polymer flooding predictions obtained with the different upscaled models.
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Austin, Barney Nicolas. "Probable maximum flooding using quantitative weather radar". Thesis, University of Salford, 1995. http://usir.salford.ac.uk/43018/.
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Reservoir spillways are designed to pass extreme flood events without significant damage. For Category A dams in the UK (whereby a breach will endanger lives in a community), designs are based on the Probable Maximum Flood (PMF) arising from the critical duration Probable Maximum Precipitation (PMP). This may occur in the winter, coupled with snowmelt, or in the summer when more heat for convection is available. This thesis details an analysis of 20 extreme rainfall events which occurred in the UK in the past 15 years and were observed by radar. Storm efficiencies have been determined in a Lagrangian frame of reference for these events and used as input into a storm model to determine the corresponding PMP. Results show that while the peak rainfall rates are somewhat less with the storm model than suggested by the NERC FSR (current UK guidelines), the overall volume of rainfall is slightly greater resulting in differences in the maximum storage requirement of the reservoir.
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Grew, Helen Louise. "Temporal variability of flooding in Scottish rivers". Thesis, University of St Andrews, 1997. http://hdl.handle.net/10023/15203.
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Over fifty peaks-over-threshold flood records from across Scotland are analysed for temporal and spatial variability over two standard periods, 1954-92 and 1964-1992, using a number of time series statistical techniques. The results of this analysis demonstrate both clear temporal and spatial patterns in the frequency and magnitude of floods. The period 1964-73 is characterised by decreasing flood frequencies, with the early 1970s standing out as being "flood poor", particularly in the eastern regions of Scotland, whilst the 1950s and more recently, the late 1980s and early 1990s can be characterised as "flood rich". A broadly similar pattern is evident in many flood magnitude series. The influence of climatic variability upon flood records is also examined over the same periods of time, using a regional synoptic classification of daily weather types. The Westerly, Cyclonic and South-Westerly weather types are identified as important mechanisms in initiating Scottish flood events. These weather types also show a strong link with catchment location, with the Westerly type being important in the more westerly catchments, the South-Westerly type being important in the south-west and west whilst flood events in the more eastern catchments are often associated with the incidence of the Cyclonic weather type. The annual frequencies of these three key weather types also show clear patterns of temporal variability. However, a seasonal split of weather type frequencies also reveals some contrasting seasonal trends which are masked within the amalgamated annual series. The most dramatic variability is evident within the time series of the South-Westerly weather type, where frequencies have been increasing steadily since the mid 1970s in all seasons. Recent increases in the incidence of the most frequently occurring weather type - the Westerly - appear to be confined to the winter months (December to February). The relationship between temporal variability within flood series and the climate are tentatively explored through a simple comparison exercise using the two sets of time series plots, linked by information obtained on trigger weather types and dominant seasons of flooding. This process suggests that the relationship between flood series and the climate is a complex one which cannot be adequately explained using the results of this research. More likely other factors, such as precipitation variability, need to be introduced into the equation before a more complete picture is acquired. The possible consequences of the variability detected within flood series are highlighted with reference to flood frequency analysis, a technique which makes the assumption that flood records, and ultimately climatic records, are stationary through time. By splitting individual flood records into hydrologically similar sub-periods, it is revealed that frequency-magnitude relationships may vary considerably, depending upon the period of record used. It is recommended that, in future, hydrologists consider splitting flood series (into hydrologically similar sub-periods or in terms of the weather types linked to each flood) in order to examine the range of frequency-magnitude relationships which exist.
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Stolle, Jacob. "Debris Hazard Assessment in Extreme Flooding Events". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39621.
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Coastal areas are often important to economic, social, and environmental processes throughout the world. With changing climate and growing populations in these areas, coastal communities have become increasingly vulnerable to extreme flooding events, such as tsunami, storm surges, and flash floods. Within this new paradigm, there has been an effort to improve upon current methods of hazard assessment, particularly for tsunami. Recently, the American Society of Civil Engineers (ASCE) released the ASCE 7 Chapter 6 which was the world’s first standard, written in mandatory language, that addressed tsunami resilient design in a probabilistic manner for several of its prescriptions. While often the focus tends to be on mapping the hazards related to hydraulic loading conditions, post-tsunami field surveys from disaster-stricken coastal communities have also shown the importance of also considering the loads exerted by solid objects entrained within the inundating flows, commonly referred to as debris loading. Limited research has addressed debris hazard assessment in a comprehensive manner.
Debris loading can be generally divided into two categories: impact and damming. Debris impact loads are caused by the rapid strike of solid objects against a structure. Debris damming loads are the result of the accumulation of debris at the face of or around a structure, causing thus an obstruction to the flow. The primary difference between these loads is the time period over which they act. The rapid loading due to debris impacts requires structural properties be considered in assessing the associated loads whereas debris damming loads are generally considered in a quasi-static manner. In assessing the hazard associated with both impact and damming loading conditions, methodologies must be developed to consider the likelihood of the load occurring and the magnitude of that load.
The primary objective of this thesis was to develop a probabilistic framework for assessing debris hazards in extreme coastal flooding events. To achieve this objective, the components of the framework were split into three general categories: debris transport, debris damming, and debris impact. Several physical experimental studies were performed to address each of these components, representing the most comprehensive assessment of debris hazards in extreme flooding events to date.
Debris transport was addressed to estimate the likelihood of debris loading occurring on a structure. The studies presented herein examine the different parameters that must be considered in assessing the motion of debris with the flow. The studies showed that the initial configuration of the debris and hydrodynamic conditions were critical in determining the motion of the debris. The stochastic properties of the debris motion were also assessed. It was shown that the lateral displacement of the debris could be approximated by a Gaussian distribution and the debris velocity by a Kumaraswamy (1980) distribution. The study of debris impact was further used to develop the current models used in estimating the impact force. The rigid body impact model was compared to models where the structural response was considered. The analysis showed that the effective stiffness model proposed by Haehnel and Daly (2004) was best suited to provide a conservative estimation of the impact force. Additionally, the impact geometry was taken into consideration examining the influence of various parameters on the impact force. Furthermore, debris damming was examined for the first time in transient loading conditions. This particular study examined the influence of the transient wave condition on the debris dam formation as well as the influence of different debris geometries. The influence of the debris dam geometry was correlated to increases in loading and overtopping conditions at structures. The assessment of debris hazards is critical in the development of accurate design conditions. The probabilistic framework presented within this thesis is expected to provide a basis for estimating debris hazards and inform future studies in the development of hazard assessment models.
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Keef, Caroline. "Spatial dependence of river flooding and extreme rainfall". Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485231.
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The extent of spatial dependence of flooding and extreme rainfall in Britain is unknown. In this thesis we develop existing extreme value theory to study this phenomenon. It is important to know the level of spatial dependence of flooding because if a flood occurs at multiple sites at the same time the consequences for (for example) the emergency services and the insurance industry can be more severe than if these floods occurred at different times. There are various features of river flow and rainfall data that complicate the estimation of extremal dependence. The two main features are the presence of missing data and the temporal dependence of the individual time series. Heffernan and Tawn (2004) developed a flexible method for modelling multivariate extreme values that can be used for a large number of variables. In this thesis we develop and extend this method to handle the presence of missing data and temporal dependence. We apply this extended method separately to river flow and rainfall data to estimate the level of spatial dependence of flooding and extreme rainfall over Britain. We find that heterogeneous regions in terms of the geology and soil types show low levels of spatial dependence. As we would expect we also find that connected rivers show a high level of dependence between them. We also find that the upland regions of Britain have low levels of spatial dependence of extreme rainfall.
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Becker, Andrea. "Wood frame building response to rapid onset flooding". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2429.
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Floods are considered to be among of the deadliest, costliest and most common natural disasters. Rapid onset, catastrophic floods inundate the shore quickly and manifest as deep water with high velocities. The deep water and high velocities caused by these floods inflict great pressures and forces on the built and natural environments and pose a threat to human safety. Recent disasters such as Hurricane Katrina in the Southern United States and the Sumatra tsunami in the Indian Ocean have revealed that communities at risk require improved preparations for these types of dangerous events. Current building codes, design practices and disaster planning methods account for potential earthquake and wind loads on simple wood frame buildings typical of North American residential construction, however, flood impacts have not been considered in the same level of depth. The objectives of this research are to develop a theoretical model that describes flood impacts on wood frame residential buildings and relates building response to physical flood properties such as depth and velocity. This thesis provides a brief synopsis of previous approaches used to describe building response to flooding. An overview of the major loads caused by rapid onset flooding, along with a description of the structural system utilized in wood design to resist these forces is provided. The failure mechanisms considered and the model logic are described and applied to assess the response of a typical Canadian wood frame home to flood conditions that might be experienced in a rapid onset flood event like a tsunami. Building response results are discussed along with recommendations for future analysis and applications.
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Darch, Geoffrey. "Climate change and future flooding in the UK". Thesis, University of East Anglia, 2010. https://ueaeprints.uea.ac.uk/24510/.
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胡俊平 i Chun-ping Wu. "Tidal flooding and its research in Hong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B26823810.
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Raby, Alison Caroline. "Extreme waves, overtopping and flooding at sea defences". Thesis, University of Oxford, 2003. http://ora.ox.ac.uk/objects/uuid:82fcc770-8838-4f9b-9abe-32eecdd05f9a.
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This thesis describes experiments that were carried out using focused wave groups in the UK Coastal Research Facility (UKCRF). Considerable effort was put into calibrating the UKCRF to determine the relationship between the input signals sent to the paddles and the waves generated in the facility. Focused wave groups of various sizes and phases, based on NewWave theory were generated, and measurements were made of the resulting surface elevation data, water particle kinematics, wave runup and overtopping volumes. NewWave theory models the profile of extreme waves in a Gaussian (random) sea. The thesis describes the first time this model has been applied in the context of coastal wave transformation. A method for the separation of the underlying harmonic structure of a focused wave group is described and results presented. This technique has been used in relatively deep water but is shown to work successfully in the coastal zone until wave overturning. A method has been devised to provide a theoretical Stokes-like expansion of the free and bound waves to model the surface elevation and water particle kinematics of the focused wave groups. Satisfactory agreement is achieved between the theoretical predictions of UKCRF measurements. Suggestions are made for an improved model. The underlying harmonic structure of the focused wave groups is presented as stacked time histories that give insight into the wave transformation process from deep to shallow water. Particular attention is paid to the low frequency wave generated as the wave group interacts with the beach. This is compared to the low frequency wave that is generated by a solitary wave in the UKCRF. Runup and overtopping measurements are in reasonable agreement with predictions based on certain empirical formulae, but not others. These comparisons are useful in identifying those formulae able to predict runup and overtopping of extreme waves in the coastal zone.
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Alhdad, Gazala. "Responses of Suaeda maritima to flooding and salinity". Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/43812/.
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Suaeda maritima is an annual halophyte commonly found in salt-marshes. Its salt tolerance has been well studied, though there is little published on the effect of simultaneous waterlogging. The effects of saline waterlogging on growth, antioxidants (glutathione and total polyphenolic compounds, antioxidant activity) and oxidative damage were investigated with simulated tides in a controlled glasshouse and on plants collected from the field. Flooded shoots possessed higher levels of antioxidants than those from plants growing in well-drained situations, in the glasshouse and the field. The effects of hypoxia, (simulated in nutrient solution by flushing with nitrogen in a solution containing a low concentration of agar, which limits convection within the solution and so the transport of oxygen from the air) were determined on growth and trace metal concentrations, in plants grown in different concentrations of artificial seawater (100 and 350 mM Na+ at low pH, > pH 5.5), in sand/mud irrigated with halfstrength fresh seawater (at high pH, ca 7-8) and in different concentrations of manganese and iron in solution culture. High salt concentration reduced accumulation of trace metals in plants. Optimal growth occurred in 14 μM Fe and 1 mM Mn. Accumulation of trace metals was reduced at high pH, with more accumulating in the roots than the shoots. Hypoxia increased soluble sugars in shoots and roots, and this was affected by the salt concentration. Hypoxia also caused adventitious root development in hydroponic experiments, while in sand, adventitious root development was greater in drained than flooded conditions. Hypoxia significantly reduced shoot sodium concentration, sodium flux and bypass flow, at low and high salt concentrations. In high salt conditions, S. maritima reduced its transpiration rate and improved its water use efficiency. It was also shown that the roots contained high lactate concentrations under aerated and hypoxic conditions. S. maritima demonstrated many adaptations for tolerating extreme hypoxia.
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Farantatou, Eirini. "FLOODING THE CITY : CREATING DYNAMIC SPACES FOR WATER". Thesis, KTH, Stadsbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189039.
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This thesis focuses on areas prone to inland floods and more specifically on the municipality of Acharnes, Attica, Greece. Usually, flood risk management strategies are treated as an engineering problem. Here, the floodplains/wetlands are going to be addressed as an asset and reveal the role of the landscape as a dynamic way for climate change mitigation and adaptation. Furthermore, such an approach can also offer potentials not only for water quality and management but also for benefiting the public spaces and open a discussion concerning awareness and engagement. Within the context of Attica, flood prone areas are not only ecologically deprived but also places of inequalities and loose social capacities. Acharnes is not an exception. Thus, the vision of this thesis is to investigate an alternative way for flood resistance by incorporating tools and methods capable of strengthening local communities. The thesis will investigate the following questions: •How can cities adapt to water issues and how can public space be used towards this end? •Can design for flood management be incorporated into a greater strategy connected to building relations?
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You, Yonghua. "A defense framework for flooding-based DDoS attacks". Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/653.
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Kortekaas, Stella. "Tsunamis, storms and earthquakes : distinguishing coastal flooding events". Thesis, Coventry University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491429.
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Garcia, Quijada Marylena. "Optimization of a CO2 flood design Wesson Field - west Texas". Texas A&M University, 2005. http://hdl.handle.net/1969.1/4138.
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The Denver Unit of Wasson Field, located in Gaines and Yoakum Counties in west
Texas, produces oil from the San Andres dolomite at a depth of 5,000 ft. Wasson Field is
part of the Permian Basin and is one of the largest petroleum-producing basins in the
United States.
This research used a modeling approach to optimize the existing carbon dioxide (CO2)
flood in section 48 of the Denver Unit by improving the oil sweep efficiency of miscible
CO2 floods and enhancing the conformance control.
A full compositional simulation model using a detailed geologic characterization was
built to optimize the injection pattern of section 48 of Denver Unit. The model is a
quarter of an inverted nine-spot and covers 20 acres in San Andres Formation of Wasson
Field. The Peng-Robinson equation of state (EOS) was chosen to describe the phase
behavior during the CO2 flooding. An existenting geologic description was used to
construct the simulation grid. Simulation layers represent actual flow units and resemble
the large variation of reservoir properties. A 34-year history match was performed to
validate the model. Several sensitivity runs were made to improve the CO2 sweep
efficiency and increase the oil recovery.
During this study I found that the optimum CO2 injection rate for San Andres Formation
in the section 48 of the Denver Unit is approximately 300 res bbl (762 Mscf/D) of
carbon dioxide. Simulation results also indicate that a water-alternating-gas (WAG) ratio
of 1:1 along with an ultimate CO2 slug of 100% hydrocarbon pore volume (HCPV) willallow an incremental oil recovery of 18%. The additional recovery increases to 34% if a
polymer is injected as a conformance control agent during the course of the WAG
process at a ratio of 1:1. According to the results, a pattern reconfiguration change from
the typical Denver Unit inverted nine spot to staggered line drive would represent an
incremental oil recovery of 26%.
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Papathoma, Maria. "Tsunami vulnerability assessment using a geographical information system with special reference to Greece". Thesis, Coventry University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251854.
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Tsunami are rare geological phenomena but their impacts are frequently catastrophic. Greece is the European country that has been affected most frequently by tsunami. Whilst tsunami hazard and risk within Greece have been studied, tsunami vulnerability has not. Previous studies and hazard mapping of tsunami flood prone areas around the world imply that populations, buildings and infrastructure within a potential inundation zone are uniformly vulnerable to impact. However, vulnerability is a dynamic factor and is a function of a number of parameters, since vulnerability of any physical, structural or socio-economic element is the probability of it being damaged, destroyed or lost. This dissertation identifies two coastal segments within Greece known to be at risk from tsunami flooding; reviews the historical record of events and determines a worse case tsunami event for both locations. A new methodology for assessing vulnerability of these coastal communities is then developed and applied to each location. The methodology incorporates multiple parameters that contribute to tsunami vulnerability and identifies and demonstrates the vulnerability of different components of the community (human, economic and the built environment). Using a Multi Criteria Evaluation Method the vulnerability of individual buildings and open spaces within the potential inundation zone are assessed and the results are displayed in map form with the aid of a Geographical Information System (GIS). The primary database may be used by various end-users, such as emergency planners, insurance companies, individuals, local authorities and scientists, in order to produce maps that could enable them to make recommendations regarding response plans or mitigation measures. Finally, a framework for Tsunami Vulnerability Assessment is introduced which integrates this vulnerability assessment methodology. Through this framework, the Greek Civil Protection system is outlined, its weaknesses are discussed and recommendations are made.
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Spooner, Jake. "Flow structures in a compound meandering channel with flat and natural bedforms". Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/6825.
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Detailed experiments were conducted on a meandering compound channel, with a sinuosity of 1.384, in a 13m long 2.4m wide flume. Two cases were examined, where the main channel contained flat and natural bedforms. Measurements recorded include stage-discharge, sediment transport and bed shear stress. A three-component Laser Doppler Anemometer measured the velocity and turbulence in the flow and the bedform was measured using Digital Photogrammetry. It was found from the stage-discharge data that at most depths the effect of the bedforms is to reduce the discharge capacity of the channel. The maximum reduction in the discharge capacity was at the bankfull flow depth where the discharge was reduced by thirty percent. The sediment transport rate was found to decrease at relative overbank flow depths of 0.2-0.3. The velocity and turbulence measurements were used to examine the flow structure. It was found that the formation of bedforms in the main channel significantly affects the flow structure of the flow in the main channel, although the flow on the floodplain is similar. Significant secondary flow circulations were found in the natural bed case, particularly at higher flow depths. The secondary circulations are caused by centrifugal force, flow entering the main channel from the floodplain and reverse flows as the flow passes over ridges in the natural bed case. A new method for predicting velocity and discharge in meandering channels has been introduced based on the two-dimensional curvilinear equations for strearnwise motion. The turbulence terms were found to be insignificant and the method was applied to data sets at different scales.
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Asal, Fahmy F. "Airborne remote sensing for landscape modelling". Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275311.
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Anderson, Thomas J. "Development of a SIMSMART based, progressive flooding design tool". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA361627.
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Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, March 1999."March 1999". Thesis advisor(s): Charles N. Calvano, Fotis Papoulias. Includes bibliographical references (p. 141). Also available online.
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Ehsan, Saqib. "Evaluation of life safety risks related to severe flooding". Stuttgart Inst. für Wasserbau, 2009. http://d-nb.info/996795944/34.
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Badaru, Akintunde A. "Flooding mitigation in a microjet based PEM fuel cell". Tallahassee, Florida : Florida State University, 2010. http://etd.lib.fsu.edu/theses/available/etd-01272010-133631/.
Pełny tekst źródłaStreszczenie:
Thesis (M.S.)--Florida State University, 2010.Advisor: Anjaneyulu Krothapalli, Florida State University, College of Engineering, Dept. of Mechanical Engineering. Title and description from dissertation home page (viewed on July 15, 2010). Document formatted into pages; contains x, 95 pages. Includes bibliographical references.