acase@tulane.edu / Recent work demonstrates differences between channelized topography and resulting stratigraphic surfaces at various spatial resolutions, however, at present we lack a description of how channel mobility influences this architecture. Our goal is to develop a quantitative understanding of how information pertaining to paleo-topography and morphodynamics is stored in stratigraphy. To better understand the role of channel mobility in transferring topographic information into stratigraphy we examine three physical deltaic experiments, a key difference between each being the inclusion and amount of a polymer. The polymer enhances sediment cohesion and promotes channelization from subcritical Froude number flows. To quantitatively compare topographic and stratigraphic surfaces, we measure the decay of mean absolute surface slope as a function of measurement window. In all experiments we observe steeper average slopes in the stratigraphy compared to the topography over length scales less than a channel width. The difference between stratigraphic and topographic average mean slope is the least pronounced in the weakly cohesive experiment, which is associated with the highest channel mobility. As cohesion increases and channel mobility decreases, the difference between the slopes increases. In all experiments, stratigraphic and topographic statistics converge at a length scale approximately equal to one channel width. These results suggest that channel mobility, influenced by sediment cohesion, strongly influences the storage of paleo-topographic information in stratigraphy. Specifically, we predict that systems with low channel mobility, such as vegetated river deltas, have the greatest difference in topographic and stratigraphic statistics, while this difference is minimized in high mobility systems, such as alluvial fans. / 1 / William Matthew Benson

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 99-118).

Thesis (Ph. D.)--University of British Columbia, 1972. / Vita. Includes bibliographical references (leaves 211-221).

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A research program was undertaken to quantify the effect of flow induced erosion on the stability of natural river banks along the Red River in Winnipeg, Manitoba. The study correlated the percent decrease in factor of safety to intensity of river flow and duration. Two methods to quantify flow induced erosion were assessed, the first method based on observed erosion and the second on theoretically calculated erosion. The first method involved aligning annual historical river bank cross-sections and measuring the distance between cross-sections to represent the erosion induced from the flow year between successive cross-sections. Due to the fact there are no sites along the Red River regularly surveyed, the analysis did not provide for a correlation between erosion from a specific flow event to percent decrease in factor of safety. The second part involved the use of theoretical equations to quantify erosion given the river elevation of a specific flow year. The study showed a 1% to 8% decrease in factor of safety from low to high intensity flows and as high as 14.5% for high intensity flows of long duration. Additionally, the evolutionary stability of the riverbank was generated showing the percent decrease each year in factor of safety due to erosion and the years during which failure occurs. The results correlated well to the previous analysis showing a 1% to 5% decrease for low to high intensity flows respectively and as high as 10% for high intensities of long duration. / October 2007

In this study the stabili ty and stress distribution of anisotropic jointed rock slopes under external loading were examined. The influence of joint orientation and mechanical characteristics on the engineering behaviour of jointed rock slopes were included in the investigation. A total of four physical models were developed by using blocks of light-weight concrete and gypsum mortar to simulate intact rocks and joints respectively. The models were built within a confining frame such that plane strain conditions were maintained throughout the experiments. The stress-strain relationship and the strength of the model blocks were determined from laboratory tests. An empirical equation was established to represent the strength envelope of the model material and rocks in general. The normal and shear properties of the model rock JOints were examined, and were described by mathematical expressions in order to facilitate the numerical studies. Results from the physical modelling studies showed that localised failure regions were induced and three types of failure modes were identified. The stability and stress distribution wi thin the models were found to be significantly influenced by the properties and system of the jointing. Two computer programs were developed based on the Finite Element Method and Coupled Finite-Boundary Element Method in order to simulate the behaviour of jointed rock masses and assessments of their application were made in comparison with the physical modelling results. A special finite joint element was developed to incorporate the non-linearity and anisotropy behaviour of rock joints. The finite element program was successfully executed and gave reasonable results in which the principal stress distributions were generally in agreement with those obtained from the physical models. The finite-boundary element program on the other hand introduced boundary incompatibility in the system and therefore led to divergency.

A research program was undertaken to quantify the effect of flow induced erosion on the stability of natural river banks along the Red River in Winnipeg, Manitoba. The study correlated the percent decrease in factor of safety to intensity of river flow and duration. Two methods to quantify flow induced erosion were assessed, the first method based on observed erosion and the second on theoretically calculated erosion. The first method involved aligning annual historical river bank cross-sections and measuring the distance between cross-sections to represent the erosion induced from the flow year between successive cross-sections. Due to the fact there are no sites along the Red River regularly surveyed, the analysis did not provide for a correlation between erosion from a specific flow event to percent decrease in factor of safety. The second part involved the use of theoretical equations to quantify erosion given the river elevation of a specific flow year. The study showed a 1% to 8% decrease in factor of safety from low to high intensity flows and as high as 14.5% for high intensity flows of long duration. Additionally, the evolutionary stability of the riverbank was generated showing the percent decrease each year in factor of safety due to erosion and the years during which failure occurs. The results correlated well to the previous analysis showing a 1% to 5% decrease for low to high intensity flows respectively and as high as 10% for high intensities of long duration.

A research program was undertaken to quantify the effect of flow induced erosion on the stability of natural river banks along the Red River in Winnipeg, Manitoba. The study correlated the percent decrease in factor of safety to intensity of river flow and duration. Two methods to quantify flow induced erosion were assessed, the first method based on observed erosion and the second on theoretically calculated erosion. The first method involved aligning annual historical river bank cross-sections and measuring the distance between cross-sections to represent the erosion induced from the flow year between successive cross-sections. Due to the fact there are no sites along the Red River regularly surveyed, the analysis did not provide for a correlation between erosion from a specific flow event to percent decrease in factor of safety. The second part involved the use of theoretical equations to quantify erosion given the river elevation of a specific flow year. The study showed a 1% to 8% decrease in factor of safety from low to high intensity flows and as high as 14.5% for high intensity flows of long duration. Additionally, the evolutionary stability of the riverbank was generated showing the percent decrease each year in factor of safety due to erosion and the years during which failure occurs. The results correlated well to the previous analysis showing a 1% to 5% decrease for low to high intensity flows respectively and as high as 10% for high intensities of long duration.