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The sedimentology of bedforms to barforms within tidally-influenced fluvial zones (TIFZx): lower Columbia River, OR/WA, USA, and the lower Chehalis River, WA, USA
Get PDFThe tidally-influenced fluvial zone (TIFZ), or ‘fluvial-tidal’ transition, is an environment characterized by unidirectional fluvial, bidirectional tidal, and oceanic oscillatory currents. TIFZ environments (i.e., deltas to estuaries) occur everywhere rivers meet ocean basins, and thus are important to understand from a geomorphological, morphodynamic and sedimentological perspective. However, most of the few existing studies of modern TIFZs have investigated a single region within a TIFZ, or relied heavily upon sediment cores and/or trenches. A large percentage of current knowledge of TIFZs thus comes from ancient outcrop studies, where the boundary conditions of the environments being studied are unknown. Therefore, most sedimentological models of TIFZs are built upon interpretations and qualitative discussions, and not via direct observations. There is thus a need to systematically investigate modern TIFZs using geophysical data collection techniques beyond sediment cores and/or trenches, in order to refine current sedimentological models with observations made within the context of known boundary conditions. The aim of this research is therefore to integrate a number of geophysical datasets collected within two modern TIFZ environments: (a) the single-threaded lower Chehalis River, Washington, USA, and (b) the multi-threaded lower Columbia River (LCR), Oregon/Washington, USA, in order to characterize the morphology, sedimentology, and internal sedimentary architecture of the bedforms and barforms in these systems. These results will be used to further the current understanding, and sedimentological models, of single- and multi- threaded TIFZs.
New data are presented defining the large-scale TIFZ hydraulic environments along the lower Chehalis River using Power Spectral Density (PSD) and wavelet transform analyses of water elevation time series data. These findings were used to provide a large-scale hydraulic context for sedimentological results/interpretations gained from (a) Ground Penetrating Radar (GPR), (b) Parametric echosounding (PES) sub-bottom profiling, (c) shallow (≤ 5m in depth) vibracores, and (d) time series of aerial imagery of point-bar deposits across the lower Chehalis River TIFZ. These results show that point-bars located within the fully-fluvial to mixed tidal-fluvial regimes undergo relatively rapid laterally-oriented migration (> 1.5 myr-1), and possess an internal alluvial architecture consisting of lateral-accretion packages composed of continuous vertically-stacked sets of parallel strata. However, point-bars located within the tidally-dominated, fluvially-influenced regime experience relatively slow laterally-oriented migration (< 1.5 myr-1), and possess an internal alluvial architecture consisting of lateral-accretion packages composed of discontinuous- or chaotically- bedded vertically-stacked sets of strata. These vertically-stacked discontinuous strata are the product of bidirectional tidal-current reworking of initially deposited parallel strata.
The large-scale geomorphic/morphodynamic evolution of barforms within the multi-threaded LCR TIFZ from the mid-Holocene to present was investigated via shallow vibracores, deep sediment cores (≥ 10m depth), and optically stimulated luminescence (OSL) dating. This study demonstrates that the large-scale geomorphic state of the mid-Holocene to present-day LCR TIFZ is that of an ‘entrenched’ tidally-modified fluvial-deltaic environment, and not a pure estuarine basin or a late-Holocene ‘bay-head delta’ prograding into an unfilled estuary. This new LCR TIFZ geomorphic/morphodynamic model was then utilized as the context to examine the morphological variations of dunes within the LCR TIFZ thalweg, and the sedimentology and internal alluvial architecture of mid-channel barforms. Analysis of National Oceanic and Atmospheric Administration (NOAA) multibeam echo sounding (MBES) surveys of the main LCR navigation channel bed, reveals that in the mixed tidal-fluvial regime, dune morphology drastically changes from tidally-reversing 2-2.5D bedforms possessing heights < 1m, to 3D dunes that are downstream-migrating with heights between ~ 2-3m. This change in dune morphology marks the upstream-most point of intense flood tidal-current (landward-oriented) bedload transport, and the switch to strong downstream-oriented bedload transport. Lastly, the sedimentology/internal alluvial architecture of LCR TIFZ mid-channel bars were investigated using GPR, PES and coring. These results show that LCR mid-channel bars formed within the TIFZ fluvially-dominated, tidally-influenced hydraulic regime, possess an internal alluvial architecture and sedimentology indistinguishable from that of fully-fluvial braid-bars. Here, bars are mainly constructed from vertically-stacked (~ 10m thick) dune to unit-bar scale trough-cross and cross-bed sets. Thus, tidal hydraulic processes such as twice daily bar submergence/emergence, and ‘slackwater’ intervals, play no pivotal role in modifying the small- to large- scale sedimentology of these bars. In addition, within the LCR TIFZ mixed tidal-fluvial hydraulic regime, the internal alluvial architecture of mid-channel bars transition to bar cores, which are ~ 2-3m thick, consisting of vertically-stacked trough- and planar- cross-sets overlain by low-angle dipping (generally < 5°) longitudinally- and laterally- oriented accretion sets up to 5m in thickness. These low-angle dipping accretion-sets are interpreted as the product of the reworking of stacked dune to unit-bar scale cross-sets into stacked-beds of ripple-scale cross-laminae via the combined effects of flood-tidal currents and intrabasinal wind-waves. Vibracores taken from two mixed tidal-fluvial mid-channel bars have vertical grain size trends displaying coarsening-upwards sequences towards the bar-tops, where the bar-top medium sands become very-well sorted. This coarsening-upwards in bars in the mixed tidal-fluvial regime is reasoned the product of the winnowing of clays to fine sands via tidal-currents in conjunction with intrabasinal wind-waves, which cause the preferential preservation of coarser sediments. Importantly, these results illuminate the importance of intrabasinal wind-waves in playing a major role in the sedimentological products of the TIFZ, which is typically ignored in previous models of the fluvial-tidal transition.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-08-01The student, Eric Prokocki, accepted the attached license on 2017-07-12 at 23:18.The student, Eric Prokocki, submitted this Dissertation for approval on 2017-07-12 at 23:29.This Dissertation was approved for publication on 2017-07-14 at 12:11.DSpace SAF Submission Ingestion Package generated from Vireo submission #11442 on 2018-03-02 at 13:01:51Made available in DSpace on 2018-03-02T19:59:38Z (GMT). No. of bitstreams: 3
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The sedimentology of bedforms to barforms within tidally-influenced fluvial zones (TIFZx): lower Columbia River, OR/WA, USA, and the lower Chehalis River, WA, USA
No full textThe tidally-influenced fluvial zone (TIFZ), or ‘fluvial-tidal’ transition, is an environment characterized by unidirectional fluvial, bidirectional tidal, and oceanic oscillatory currents. TIFZ environments (i.e., deltas to estuaries) occur everywhere rivers meet ocean basins, and thus are important to understand from a geomorphological, morphodynamic and sedimentological perspective. However, most of the few existing studies of modern TIFZs have investigated a single region within a TIFZ, or relied heavily upon sediment cores and/or trenches. A large percentage of current knowledge of TIFZs thus comes from ancient outcrop studies, where the boundary conditions of the environments being studied are unknown. Therefore, most sedimentological models of TIFZs are built upon interpretations and qualitative discussions, and not via direct observations. There is thus a need to systematically investigate modern TIFZs using geophysical data collection techniques beyond sediment cores and/or trenches, in order to refine current sedimentological models with observations made within the context of known boundary conditions. The aim of this research is therefore to integrate a number of geophysical datasets collected within two modern TIFZ environments: (a) the single-threaded lower Chehalis River, Washington, USA, and (b) the multi-threaded lower Columbia River (LCR), Oregon/Washington, USA, in order to characterize the morphology, sedimentology, and internal sedimentary architecture of the bedforms and barforms in these systems. These results will be used to further the current understanding, and sedimentological models, of single- and multi- threaded TIFZs.
New data are presented defining the large-scale TIFZ hydraulic environments along the lower Chehalis River using Power Spectral Density (PSD) and wavelet transform analyses of water elevation time series data. These findings were used to provide a large-scale hydraulic context for sedimentological results/interpretations gained from (a) Ground Penetrating Radar (GPR), (b) Parametric echosounding (PES) sub-bottom profiling, (c) shallow (≤ 5m in depth) vibracores, and (d) time series of aerial imagery of point-bar deposits across the lower Chehalis River TIFZ. These results show that point-bars located within the fully-fluvial to mixed tidal-fluvial regimes undergo relatively rapid laterally-oriented migration (> 1.5 myr-1), and possess an internal alluvial architecture consisting of lateral-accretion packages composed of continuous vertically-stacked sets of parallel strata. However, point-bars located within the tidally-dominated, fluvially-influenced regime experience relatively slow laterally-oriented migration (< 1.5 myr-1), and possess an internal alluvial architecture consisting of lateral-accretion packages composed of discontinuous- or chaotically- bedded vertically-stacked sets of strata. These vertically-stacked discontinuous strata are the product of bidirectional tidal-current reworking of initially deposited parallel strata.
The large-scale geomorphic/morphodynamic evolution of barforms within the multi-threaded LCR TIFZ from the mid-Holocene to present was investigated via shallow vibracores, deep sediment cores (≥ 10m depth), and optically stimulated luminescence (OSL) dating. This study demonstrates that the large-scale geomorphic state of the mid-Holocene to present-day LCR TIFZ is that of an ‘entrenched’ tidally-modified fluvial-deltaic environment, and not a pure estuarine basin or a late-Holocene ‘bay-head delta’ prograding into an unfilled estuary. This new LCR TIFZ geomorphic/morphodynamic model was then utilized as the context to examine the morphological variations of dunes within the LCR TIFZ thalweg, and the sedimentology and internal alluvial architecture of mid-channel barforms. Analysis of National Oceanic and Atmospheric Administration (NOAA) multibeam echo sounding (MBES) surveys of the main LCR navigation channel bed, reveals that in the mixed tidal-fluvial regime, dune morphology drastically changes from tidally-reversing 2-2.5D bedforms possessing heights < 1m, to 3D dunes that are downstream-migrating with heights between ~ 2-3m. This change in dune morphology marks the upstream-most point of intense flood tidal-current (landward-oriented) bedload transport, and the switch to strong downstream-oriented bedload transport. Lastly, the sedimentology/internal alluvial architecture of LCR TIFZ mid-channel bars were investigated using GPR, PES and coring. These results show that LCR mid-channel bars formed within the TIFZ fluvially-dominated, tidally-influenced hydraulic regime, possess an internal alluvial architecture and sedimentology indistinguishable from that of fully-fluvial braid-bars. Here, bars are mainly constructed from vertically-stacked (~ 10m thick) dune to unit-bar scale trough-cross and cross-bed sets. Thus, tidal hydraulic processes such as twice daily bar submergence/emergence, and ‘slackwater’ intervals, play no pivotal role in modifying the small- to large- scale sedimentology of these bars. In addition, within the LCR TIFZ mixed tidal-fluvial hydraulic regime, the internal alluvial architecture of mid-channel bars transition to bar cores, which are ~ 2-3m thick, consisting of vertically-stacked trough- and planar- cross-sets overlain by low-angle dipping (generally < 5°) longitudinally- and laterally- oriented accretion sets up to 5m in thickness. These low-angle dipping accretion-sets are interpreted as the product of the reworking of stacked dune to unit-bar scale cross-sets into stacked-beds of ripple-scale cross-laminae via the combined effects of flood-tidal currents and intrabasinal wind-waves. Vibracores taken from two mixed tidal-fluvial mid-channel bars have vertical grain size trends displaying coarsening-upwards sequences towards the bar-tops, where the bar-top medium sands become very-well sorted. This coarsening-upwards in bars in the mixed tidal-fluvial regime is reasoned the product of the winnowing of clays to fine sands via tidal-currents in conjunction with intrabasinal wind-waves, which cause the preferential preservation of coarser sediments. Importantly, these results illuminate the importance of intrabasinal wind-waves in playing a major role in the sedimentological products of the TIFZ, which is typically ignored in previous models of the fluvial-tidal transition
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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