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O processo erosivo e o material hidro-transportado na bacia hidrográfica do rio Pinhal no Sudoeste do ParanáTomazoni, Julio Caetano 04 1900 (has links)
No description available.
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O processo erosivo e o material hidro-transportado na bacia hidrográfica do rio Pinhal no Sudoeste do ParanáTomazoni, Julio Caetano 04 1900 (has links)
No description available.
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Debris flow initiation by runoff in a recently burned basin: Is grain-by-grain sediment bulking or en masse failure to blame?McGuire, Luke A., Rengers, Francis K., Kean, Jason W., Staley, Dennis M. 28 July 2017 (has links)
Postwildfire debris flows are frequently triggered by runoff following high-intensity rainfall, but the physical mechanisms by which water-dominated flows transition to debris flows are poorly understood relative to debris flow initiation from shallow landslides. In this study, we combined a numerical model with high-resolution hydrologic and geomorphic data sets to test two different hypotheses for debris flow initiation during a rainfall event that produced numerous debris flows within a recently burned drainage basin. Based on simulations, large volumes of sediment eroded from the hillslopes were redeposited within the channel network throughout the storm, leading to the initiation of numerous debris flows as a result of the mass failure of sediment dams that built up within the channel. More generally, results provide a quantitative framework for assessing the potential of runoff-generated debris flows based on sediment supply and hydrologic conditions.
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Tracking Sediment Bypassing, Geomorphological Analysis, and Regional Sediment Management at Tidal InletsBeck, Tanya M. 01 July 2019 (has links)
Tidal inlets on sandy shorelines separate barrier islands and serve as a conduit for transport of sand and water between embayments and oceans, seas, or other tidally influenced waterbodies. Tides and waves induce currents along the coastline that transport sediment across-shore and alongshore. Coastal managers must optimize barrier-inlet system stability while conserving limited sediment resources, and often base management decisions and engineering design upon geomorphic and numerical models that predict the morphological behavior of tidal inlets on short-to-medium timescales (years to decades). The overall goal of this study was threefold. First, to provide science-based practical guidance for regional sediment management in the vicinity of tidal inlets. Secondly, to enhance the understanding of the temporal and spatial scales of sediment pathways in these regions through numerical simulation of traced sediment transport. And, third, to combine these lessons learned in both regional sediment management and analysis of morphodynamic and sediment bypassing pathways with application to a common practical management practice of inlet shoal mining and adjacent beach placement.
The temporal and spatial scales controlling the morphodynamics of barrier-inlet systems were reviewed within a regional sediment management context. Next, the application of regional sediment management methods to case studies of multiple barrier-inlet systems in West-Central Florida led to the development of a decision-support tool for regional sediment management (RSM) as applied to barrier-inlet systems. Connecting multiple barrier islands and inlets at appropriate spatio-temporal scales is critical in developing an appropriately scoped sediment management plan for a barrier-inlet system. Evaluating sediment bypassing capacity and overall inlet morphodynamics can better inform regional sand sharing along barrier-inlet coastlines; particularly where sediment resources are scarce and a close coupling between inlet dredging and beach placement is vital to long-term sustainable management. Continued sea-level rise and anthropogenic activities may intensify the need for investigating longer-term processes and expanding regional planning at a centennial timescale, and are acknowledged as challenging tasks for RSM studies going forward. A regionally focused, multi-inlet study was necessary to improve the management plans for the case study inlets (from north to south): John’s Pass, Blind Pass, Pass-a-Grille Inlet, and Bunces Pass. Key recommendations based on the case studies include: 1) allow the natural sediment bypassing to be re-established at Blind Pass inlet through reduced ebb-tidal delta mining, 2) reduce the interruption to sediment bypassing at John’s Pass and Pass-a-Grille inlets through an improved design of the dredged mining areas located along sediment bypassing pathways, 3) allow for continued natural sediment bypassing at Bunces Pass, and, 4) incorporate the cyclic sediment bypassing through swash-bar attachment into the management plan at Bunces Pass and adjacent barrier-islands. Similar systems in other regions may benefit from the lessons derived in this case study of an adaptively managed multi-inlet system.
A numerical model that computes hydrodynamics, sediment transport, and morphodynamics including bed layering was incorporated in this study to analyze sediment transport pathways between littoral sources from adjacent beaches and the geomorphic features of an idealized tidal inlet designed to imitate the John’s Pass tidal inlet in West-central Florida, USA. This study developed a methodology to numerically trace sediment transport, deposition and erosion. This method was applied to investigate sediment-bypassing pathways under varying temporal and spatial scales. The analyses of the adjacent beach’s contribution to tidal inlet sediment bypassing demonstrated variable temporal scales on sediment transport and exchange. High-energy wave events dominated the temporal scale for sand to be transported from the updrift beach to the ebb-tidal delta, whereas cyclical tidal processes had a significant influence on the spatial pattern of exchange between the shoals and channel features of the tidal inlet. The ability to simulate burial and erosion of tracers allowed identification of offshore sedimentation hotspots such as terminal lobe as well as zones of deposition and active transport in shallow water, such as the updrift channel margin linear bar and the downdrift platform of the ebb-tidal delta. The general sediment-bypassing pathway reflected a tidal-driven redistribution following event-driven pulses of wave-induced sediment mobilization. Sediment was transported along the beach during these energetic wave events. Flood- and ebb-tidal currents transported the sediment mobilized by high waves into the inlet channels. This was followed by subsequent gradual redistribution of the deposited channel sediments over the ebb-tidal delta features during fair-weather conditions.
The modeling methods were then applied to investigate the sediment pathways and bypassing processes for three validated numerical models of coastal tidal inlets that span a range of forcing conditions. The processes that influence sediment transport along various pathways between the several morphological features of each inlet and its adjacent beaches were examined. The sediment tracing methodology employed in this study allowed for an evaluation of the sediment transport pathways between the various morphologic features of a tidal inlet, as well as their respective processes that drive the exchange of sediments. Characterizing and correlating the sediment pathways between tidal inlet morphologic features can improve the inlet reservoir model, which is a predictive model of inlet shoal volumes based on empirical formulae. The results of this study illustrate the value of including sediment-tracking techniques in simulating sediment bypassing and the potential of this application to inform coastal engineering and design modifications to sediment reservoirs of tidal inlets.
And, finally, the spatial patterns of transport and erosion and deposition of traced, littoral source sediment, were investigated using the same modeling framework to evaluate the design of ebb-tidal delta mining on sediment bypassing dynamics of a tidal inlet system based on an idealized model of John’s Pass, Florida. Seven mining areas were simulated with traced sediment sources from the updrift beach, downdrift beach, and adjacent shoals. The tracers’ migration pattern and mining area infilling were analyzed to depict the sediment bypassing pathways and their contributions to mining area infilling. Mining area recovery rates were highest along the channel margin linear bar, and decrease offshore and downdrift. Updrift sand sources contributed more to mining area infilling than downdrift sand sources. The position of the mining area in relation to the updrift or downdrift morphological features dictates whether it will receive primarily updrift- or downdrift-originating littoral sediment from the beach. The source of sedimentation within the mining areas is a combination of inlet-ward transport of beach sediment and nearby shoal sediment. Proximity to the inlet channel determined the degree to which sedimentation had originated from longshore transported beach sediment. This methodology can improve confidence in management decisions concerned with the sand-sharing capacity of barrier-inlet systems in a local and regional context.
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Scouring Around Multiple Structures in Extreme Flow ConditionsApril LeQuéré, Philippe 20 April 2022 (has links)
As world population increases, coastal areas experience an increase in human occupancy. These community locations come with a greater risk of impacts due to extreme natural events. Tsunami, being one of the most unpredictable and most devastating types of extreme hydrodynamic events, received significant attention over the past decades due to the recent extreme events (2004 Indian Ocean, 2010 Chile, 2011 Japan, 2018 Indonesia). The focus of this thesis is on investigating scour around structures generated by tsunami. Scouring was found to be one of the greatest sources of building damage during the 2011 Tohoku Japan Tsunami and, at the date of the redaction of this thesis, this phenomenon is still little understood by the scientific community. The main objective of this thesis is to study the change in scouring when multiple buildings are constructed in close proximity, as opposed to individual elements such as in the case of all previous studies focussed on tsunami-induced scour. This topic was first investigated by the candidate with the use of a numerical model, FLOW-3D, using the large eddy simulation approach and the Nielsen (1992) bed load sediment transport model. The model results showed a significant increase in scouring when a second building was located along the same transversal plane as the building investigated. Then, three structure arrangements were investigated in a comprehensive physical experiment conducted in the new Dambreak Flume of Hydraulic Laboratory of the University of Ottawa, Canada, to study the effects of (1) upstream constriction, (2) lateral spacing and (3) sheltering on tsunami-induced scour. All three structure arrangements showed a significant effect on tsunami-induced scour. A secondary project was conducted in collaboration with the Technical University of Braunschweig, Germany, and the Leibniz University Hannover, Germany. This large-scale physical experiment, performed in the Large Wave Flume of the Leibniz Institute Hannover, Germany, was used to investigate three different research phenomenon that influence tsunami scouring: (1) the wave drawdown on scour around structures, (2) the evolution of flow eddies and (3) the change in the soil’s pore pressure.
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Morpho-sedimentary dynamics of pool-riffle sequences in a gravel-bed river : bedload transport reversal and pool-riffle maintenanceLatulippe, Christian. January 2006 (has links)
No description available.
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Sediment transport and channel adjustments associated with dam removalCheng, Fang 10 March 2005 (has links)
No description available.
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Auto-suspension of sediment : a test of the theory.Mackintosh, Michael Edward January 1975 (has links)
Thesis. 1975. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Bibliography: leaves 36-37. / M.S.
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Lunar seismology : the internal structure of the moon.Goins, Neal Rodney January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Science. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 313-331. / Ph.D.
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Investigation of the sediment transport capacity in vegetated open channel flowHuai, W.-X., Wang, X., Guo, Yakun, Sun, Z.H. 22 March 2022 (has links)
No / The suspended sediment transport capacity is important for estimating the suspended load concentration and the ecological environment of the river. So far, few studies have been conducted to investigate the suspended sediment transport capacity in the vegetated sediment-laden flow. In this study, a new formula is derived to predict the sediment transport capacity in a vegetated flow by considering the absolute value of the energy loss between the sediment-laden flow and the clear water flow. Finally, the formula is expressed in a practical form by using the logarithmic matching method.
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