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Thesis (M.S. - Geosciences)--University of Arizona, 1989. / Accompanied by folded map in pocket. Includes bibliographical references (leaves 36-41).

The water problem in the Sacramento Valley, prior to it occupation by the white race, is impossible to ascertain. The Indians, however, have a tradition of a great flood sometime in the early part of the nineteenth century, which inundated the whole valley and in which a great many lives were lost and villages destroyed. It forms an era in their calendar from which they date events. Again a great flood in the winter of 1825-26 is mentioned, through an Indian named Peter. He used to say that the trapping party he was with was compelled to camp in the Buttes on account of high water, and that those hills were full of grizzlies, elk, antelope, and smaller game that had taken refuge there.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 186-211).

Thesis (M.Eng.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 129-134. Also available online.

Thesis (D.P.A.)--University of Oklahoma, 1991. / Includes bibliographical references (leaves 294-300).

This study had three primary aims. Firstly, to establish the flow resistance characteristics of meandering channels in flood with different inner channel sinuosities and morphology. Secondly, to gain a better understanding of the coherent flow structures and energy loss mechanisms present within such flows. Third, to establish a link between the identified energy loss mechanisms and the flow resistance behaviour of channels with different geometry. The study begins with a review of current literature appertaining to three flow systems. These were; Inbank flow through meandering channels, overbank flow through channels comprising a straight channel with straight parallel floodplains, and meandering channels with floodplain flow. The available literature with regards to flooded meandering channels was limited to a handful of studies. It was clear there existed a deficiency in stage-discharge data over a range of inner channel sinuosities, and the flow descriptions given were limited to inner channels of relatively low sinuosity i.e. 1.25 - 1.3, rectangular or trapezoidal cross-section and unrealistically low width to depth (aspect) ratio. In addition, the influence of roughened floodplains also required further study. To address these needs, a small-scale laboratory investigation was undertaken at Aberdeen, together with a large-scale collaborative experimental study centred at the SERC Flood Channel Facility. These two experimental studies, in which two inner channels of sinuosity 1.4 and 2 were investigated in detail, are described. The experimental techniques and data collection procedures used are also described. The data types collected include: stage- discharge data, flow visualisation, flow velocity measurement, water surface profiles and bed shear stress analysis using an erodible bed. The stage-discharge data were used for the following; to establish the relationship between inner channel sinuosity and overall channel flow resistance; to establish the effect of inner channel morphology on overall channel resistance: and to assess the implications of roughened floodplains on resistance behaviour. The analysis of these data, together with existing related overbank data, yielded a number of conclusions; i). Overall flow resistance increases as inner channel sinuosity increases, ii). At deep floodplain flows, a floodplain comprising a trapezoidal inner channel was less efficient than one comprising a smaller natural inner channel, iii). Roughening the floodplains has a significant effect on channel resistance characteristics. The flow description data, of overbank flow, revealed the presence of coherent flow structures in flows over inner channels of sinuosity 1.4 and 2, and at a number of flow depths. It is suggested these coherent flow structures are a source of additional energy loss, and a link is proposed between the vigour and frequency of these structures for several flow conditions and channel geometries, and the overall resistance behaviour. Contour maps of water surface elevation are presented for several flow conditions and channel geometries. An increase in surface relief was observed as floodplain depth, and therefore velocity, increased. These maps and earlier related work were then discussed. Plots of near bed velocities, secondary circulation patterns and erodible bed observations strongly indicated a change in sediment erosion and deposition patterns, and thus a change in inner channel morphology during overbank flow. Implications of this change are proposed and discussed. Finally, suggestions for future work are presented. with particular emphasis on a 3-dimensional numerical model presently under development at the University of Aberdeen.

The main intention of the PhD project was to create a varve chronology for the Suigetsu Varves 2006' (SG06) composite profile from Lake Suigetsu (Japan) by thin section microscopy. The chronology was not only to provide an age-scale for the various palaeo-environmental proxies analysed within the SG06 project, but also and foremost to contribute, in combination with the SG06 14C chronology, to the international atmospheric radiocarbon calibration curve (IntCal). The SG06 14C data are based on terrestrial leaf fossils and therefore record atmospheric 14C values directly, avoiding the corrections necessary for the reservoir ages of the marine datasets, which are currently used beyond the tree-ring limit in the IntCal09 dataset (Reimer et al., 2009). The SG06 project is a follow up of the SG93 project (Kitagawa & van der Plicht, 2000), which aimed to produce an atmospheric calibration dataset, too, but suffered from incomplete core recovery and varve count uncertainties. For the SG06 project the complete Lake Suigetsu sediment sequence was recovered continuously, leaving the task to produce an improved varve count. Varve counting was carried out using a dual method approach utilizing thin section microscopy and micro X-Ray Fluorescence (µXRF). The latter was carried out by Dr. Michael Marshall in cooperation with the PhD candidate. The varve count covers 19 m of composite core, which corresponds to the time frame from ≈10 to ≈40 kyr BP. The count result showed that seasonal layers did not form in every year. Hence, the varve counts from either method were incomplete. This rather common problem in varve counting is usually solved by manual varve interpolation. But manual interpolation often suffers from subjectivity. Furthermore, sedimentation rate estimates (which are the basis for interpolation) are generally derived from neighbouring, well varved intervals. This assumes that the sedimentation rates in neighbouring intervals are identical to those in the incompletely varved section, which is not necessarily true. To overcome these problems a novel interpolation method was devised. It is computer based and automated (i.e. avoids subjectivity and ensures reproducibility) and derives the sedimentation rate estimate directly from the incompletely varved interval by statistically analysing distances between successive seasonal layers. Therefore, the interpolation approach is also suitable for sediments which do not contain well varved intervals. Another benefit of the novel method is that it provides objective interpolation error estimates. Interpolation results from the two counting methods were combined and the resulting chronology compared to the 14C chronology from Lake Suigetsu, calibrated with the tree-ring derived section of IntCal09 (which is considered accurate). The varve and 14C chronology showed a high degree of similarity, demonstrating that the novel interpolation method produces reliable results. In order to constrain the uncertainties of the varve chronology, especially the cumulative error estimates, U-Th dated speleothem data were used by linking the low frequency 14C signal of Lake Suigetsu and the speleothems, increasing the accuracy and precision of the Suigetsu calibration dataset. The resulting chronology also represents the age-scale for the various palaeo-environmental proxies analysed in the SG06 project. One proxy analysed within the PhD project was the distribution of event layers, which are often representatives of past floods or earthquakes. A detailed microfacies analysis revealed three different types of event layers, two of which are described here for the first time for the Suigetsu sediment. The types are: matrix supported layers produced as result of subaqueous slope failures, turbidites produced as result of landslides and turbidites produced as result of flood events. The former two are likely to have been triggered by earthquakes. The vast majority of event layers was related to floods (362 out of 369), which allowed the construction of a respective chronology for the last 40 kyr. Flood frequencies were highly variable, reaching their greatest values during the global sea level low-stand of the Glacial, their lowest values during Heinrich Event 1. Typhoons affecting the region represent the most likely control on the flood frequency, especially during the Glacial. However, also local, non-climatic controls are suggested by the data. In summary, the work presented here expands and revises knowledge on the Lake Suigetsu sediment and enabls the construction of a far more precise varve chronology. The 14C calibration dataset is the first such derived from lacustrine sediments to be included into the (next) IntCal dataset. References: Kitagawa & van der Plicht, 2000, Radiocarbon, Vol 42(3), 370-381 Reimer et al., 2009, Radiocarbon, Vol 51(4), 1111-1150 / Die Hauptzielsetzung der Doktorarbeit war die Erstellung einer Warvenchronologie für das Kompositprofil der "Suigetsu Varves 2006" (SG06) Sedimentbohrung vom Suigetsu See durch Dünnschliffmikroskopie. Die Chronologie soll dabei nicht nur als Altersskala für die unterschiedlichen Proxies, die im Rahmen des SG06 Projekts bearbeitet werden, dienen, sondern in Kombination mit der SG06 14C Chronologie auch zur Verbesserung der internationalen Radiokarbon Kalibrationskurve (IntCal) beitragen. Da die SG06 14C Daten aus fossilen, in den See eingewehten Blättern gewonnen wurden, geben sie den 14C Gehalt der Atmosphäre direkt wieder. Das heißt, dass Korrekturen entfallen, wie sie bei den derzeit im IntCal09 Datensatz (Reimer et al., 2009) genutzten marinen 14C Daten notwendig sind. Das SG06 Projekt ist ein Folgeprojekt des SG93 Projekts (Kitagawa & van der Plicht, 2000), welches ebenfalls die Erstellung eines Kalibrationsdatensatzes zur Zielsetzung hatte. Allerdings war das Sedimentprofil der SG93 Bohrung unvollständig und die Warvenchronologie unzureichend genau. Im Rahmen des SG06 Projekts wurde die komplette Sedimentabfolge des Sees erbohrt, so dass die Erstellung einer verbesserten Warvenchronologie als Aufgabe verblieb. Für die Erstellung der Warvenchronologie kam neben Dünnschliffmikroskopie eine zweite, unabhängige Zähltechnik zum Einsatz, die Mikro-Röntgenfluoresenz (µXRF) Daten nutzt. Diese Zählung wurde von Dr. Michael Marshall in Zusammenarbeit mit dem Doktoranden erstellt. Insgesamt wurden in 19 m des SG06 Sedimentprofils Warven gezählt, was dem Zeitabschnitt zwischen ≈10 und ≈40 ka BP entspricht. Die Warvenzählung zeigte, dass sich nicht jedes Jahr saisonale Lagen ausgebildet hatten und die Zählungen von beiden Techniken damit unvollständig waren. Dieses Problem tritt bei Warvenzählungen häufiger auf und wird in der Regel durch manuelle Interpolation der fehlenden Lagen gelöst. Allerdings hat der manuelle Ansatz Schwächen. Zum einen kann es zu subjektiven Ungenauigkeiten kommen, zum anderen wird die durchschnittliche Sedimentationsrate (welche die Grundlage der Interpolation ist) in der Regel aus benachbarten, gut warvierten Bereichen abgeleitet. Das setzt jedoch voraus, dass die Sedimentationsrate in den benachbarten Intervallen identisch mit der im zu interpolierenden Bereich ist, was nicht zwingend der Fall ist. Um diese Probleme zu umgehen wurde für die vorliegende Arbeit eine neuartige Interpolationsmethode entwickelt. Diese ist computergestützt und automatisiert und Ergebnisse daher objektiv und reproduzierbar. Weiterhin wird die Sedimentationsrate direkt aus dem zu interpolierenden Bereich bestimmt, indem die Abstände der auftretenden saisonalen Lagen statistisch ausgewertet werden. Daher kann die Methode auch für Profile ohne gut warvierte Bereiche eingesetzt werden. Ein weiterer Vorteil des neuen Interpolationsprogramms ist, dass ein objektiver Interpolationsfehlers berechnet wird. Die interpolierten Ergebnisse der beiden Zähltechniken wurden kombiniert und um nachzuweisen, dass es sich bei der resultierenden Chronologie um ein zuverlässiges Ergebnis handelt, wurde diese mit der mit IntCal09 kalibrierten 14C Chronologie vom Suigetsu See verglichen. Dabei wurde nur der Abschnitt berücksichtigt, in dem IntCal09 auf dendrologischen Daten beruht (bis 12,55 ka cal BP). Der Vergleich zeigte, dass die finale Warvenchronologie innerhalb des 68,2% Fehlerbereichs der 14C Datierungen lag. Das heißt, dass die Interpolationsmethode hinreichend genaue und zuverlässige Ergebnisse erzielt. Die Genauigkeit wurde weiter verbessert, indem die Chronologie mit U-Th Altern von Speläothemen modelliert wurde, wobei die tieffrequenten Signale der 14C Daten als Verbindung zwischen Suigetsu und den Speläothemen verwendet wurde, was die Konstruktion eines verbesserten Kalibrationdatensatzes erlaubte. Die modellierte Chronologie stellt dabei auch die Altersskale für die im SG06 Projekt analysierten Proxies dar. Ein Proxy der im Rahmen der Doktorarbeit untersucht wurde war die Verteilung von Ereignislagen. Diese sind in der Regel Anzeiger für Flutereignisse oder Erdbeben. Die mikrofazielle Untersuchung der Ereignislagen zeigte drei verschiedene Lagentypen auf, wobei zwei davon hier erstmals für den Suigetsu See beschrieben sind. Die Lagentypen sind: Matrix dominierte Lagen als Ergebnis von Seegrundrutschungen, Turbidite als Ergebnis von Hangrutschungen und Turbidite als Ergebnis von Flutereignissen. Die ersten beiden Lagentypen wurden vermutlich durch Erdbeben ausgelöst. Die große Mehrheit der Ereignislagen ist jedoch auf Flutereignisse zurückzuführen (362 von 369). Dies erlaubte die Rekonstruktion der Hochwasserhäufigkeit für die letzten 40 ka. Dabei zeigten sich starke Schwankungen über den analysierten Zeitraum. Die höchsten Werte wurden während des glazialen Meeresspiegelminimums erreicht während die niedrigsten Werte im Zusammenhang mit Heinrich Ereignis 1 auftraten, was vermutlich in erster Linie mit der Taifunhäufigkeit in der Region zusammenhängt. Allerdings zeigten die Daten auch Einflüsse von lokalen, nicht Klima getriebenen Prozessen. Zusammenfassend kann gesagt werden, dass die hier vorliegende Arbeit die Kenntnisse über die Sedimente des Suigetsu Sees deutlich erweitert hat und die Revidierung einiger älterer Interpretationen nahe legt. Die verbesserte Warvenchronologie trug zu einem deutlich verbesserten Kalibrationsdatensatz bei. Dieser ist der erste aus lakustrinen Daten gewonnen Datensatz, der in den (kommenden) IntCal Datensatz eingearbeitet werden wird. Quellennachweis: Kitagawa & van der Plicht, 2000, Radiocarbon, Vol 42(3), 370-381 Reimer et al., 2009, Radiocarbon, Vol 51(4), 1111-1150

Cottonwoods are poplar trees that are adapted to riparian zones that are naturally occasionally flooded. Like all Salicaceae, cottonwoods are dioecious and prior studies have indicated that males are more drought-tolerant than females and found more often in poorer, drier sites. We investigated sex differentiation of cottonwoods in response to the opposite water-stress, flood, and predicted that the increased water-stress tolerance of males in drought would also apply to flood-stress. Twenty-one clones of male and female narrowleaf cottonwoods (Populus angustifolia) were grown in a greenhouse along with three female clones of the hybrid native lanceleaf cottonwood (P. x acuminata) for comparison. It was anticipated that the hybrids would show the fastest growth owing to the genetic contribution from the P. deltoides parent and its rapid intrinsic growth rate. Flood reduced heights and the numbers and sizes of leaves and roots, and consequently dry weights, abaxial stomatal conductance and leaf chlorophyll. Inundation increased carbon:nitrogen, but did not alter stomatal density, leaf water potential, or δ13C. The hybrid saplings were much larger than the narrowleaf saplings but their proportional growth reduction with flooding was greater than in the female P. angustifolia, suggesting higher flood-tolerance of the narrowleaf cottonwood. P. angustifolia sexes performed similarly under reference conditions but the males were proportionally more inhibited by flood, suggesting sex differentiation in flood-tolerance. This study indicates that riparian cottonwoods are reasonably flood-tolerant but slight differences exist between the sexes and to a greater extent, across taxa. While prior studies have indicated males are apparently more tolerant of drought, females are probably more flood-tolerant. / xiii, 117 leaves : ill. ; 29 cm

No description available.