Graduation date: 1982

Thesis (M.S.)--Oregon State University, 1993. / Typescript (photocopy). Includes bibliographical references (leaves 104-111). Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 1996. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

As fluvial, riparian and floodplain ecosystem functions are recognised for their role supporting fisheries and ecological values, recovery of streamside vegetation is increasingly important in river 'restoration'. Fluvial geomorphology and hydraulic engineering do not yet account well for the role of vegetation in fluvial processes. This research addresses the need for greater understanding of woody riparian vegetation influences on the hydraulics of overbank flow and floodplains sedimentation. Original hypotheses, research design, and data collection were generated by the student to address this gap in knowledge. A soil bioengineering design was constructed on the Mattole River, California, to revegetate the floodplain for better fish rearing habitat. Field data collection was carried out on this unregulated river for two flood events. The sediment samples resulting from a 1.25-year flow permitted the field testing of an hydraulic flume model of vegetation trapping efficiency. From velocity profiles measured during a I5-year storm event, the bed shear stress reduction caused by the vegetation was computed to be approximately 70-90%. A survey conducted in the UK and internationally evaluated from literature, hydraulic researchers and practitioners of river revegetation, the extent of and gaps in knowledge with regard to river bank stabilisation using live vegetation. A flume flow visualisation study simulated the hydraulic behaviour observed on the Mattole floodplain, which enabled characterisation of flow behaviour through a porous filter medium. Results of this research indicate that flexible woody stems have a profound 'calming' effect on overbank flow. These effects are propagated in the downstream direction at least five and as much as ten times the width of the baffle, much further than previously indicated. This research suggests that flexible vegetation is extremely effective in trapping fine (clay) sediments, contrary to general understanding and of importance for fish habitat. For hydraulic reasons, constructed zones of shrubs, such as the siltation baffle, could be spaced further apart than current design practise indicates.

Thesis (M.S.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 64-68). Also available online.

Thesis (Ph. D.)--University of Rhode Island, 2004. / Typescript. Includes bibliographical references (leaves 217-223).

Thesis (Ph. D.)--Oregon State University, 2000. / Typescript (photocopy). Includes bibliographical references (leaves 119-125). Also available online.

Thesis (M.S. in civil engineering)--Washington State University, December 2006. / Includes bibliographical references (p. 198-208).

Meandering rivers provide fresh water and important aquatic ecosystem services, yet at the same time induce flood and erosion hazards. In the face of ongoing development pressure and changing climate, growing concern for meandering rivers has increased the demand to model accurately the flow and predict the sediment transport in a meandering river channel. Calibration and validation of these models based on comparable field-based data, as opposed to laboratory-scale experimental data, may decrease uncertainty and improve understanding of complex flow structures in natural meandering rivers. In this thesis, spatially intensive field data are utilized to develop appropriate calibration and validation methods for 3D meandering river models. Validated models are then applied to the study of morphodynamic processes and the influence of channel change on fish habitat availability in meandering rivers. This study presents a novel methodology for use of three-dimensional (3D) velocity for improved calibration of a 3D hydro-morphodynamic model. A natural tortuously meandering river was simulated using the Delft3D hydrodynamic model. A spatially intensive acoustic Doppler current profiler (ADCP) survey was conducted throughout the study river, providing fully 3D distributed velocities for model calibration. For accurate and realistic comparison of the fully 3D predicted and measured velocities, an algorithm was developed to match the location of each ADCP bin with 3D model grid points. The results suggest that different calibration approaches can result in different calibration parameterizations whose simulated results can differ significantly. It is shown that the model which was calibrated based on the proposed 3D calibration approach had the best model performance. Depending upon the nature and objectives of the numerical modelling exercise, the results demonstrate the importance of model calibration with spatially intensive field data. Given the importance of pressure gradients in driving secondary flow, it is worth studying how the modelled flow structures in a natural river bend can be impacted by the assumption of hydrodynamic pressure. Accordingly, the performance of hydrostatic versus non-hydrostatic pressure assumption in the Delft3D hydrodynamic modelling of a tortuously meandering river was studied. An Acoustic Doppler Velocimeter (ADV) was employed to measure the 3D flow field at a section in a sharp bend of the simulated river at two different flow stages. The field-based ADV data were employed to validate the simulated hydrodynamic models. The results indicate the surprisingly superior performance of the hydrostatic over non-hydrostatic Delft3D modelling of the secondary flow. It was determined that the non-hydrostatic routine employed in Delft3D was not mass conservative, which diminished model accuracy. Despite several decades of intensive study of the morphological changes in meandering rivers, less attention has been paid to confined meanders. This thesis includes a study of the meandering behavior of a semi-alluvial cohesive bed river over a 10-year period. We employed a paired sub-reach study approach, wherein one sub-reach is freely meandering and the second adjacent sub-reach is confined by a railway embankment. Channel migration and morphological changes of the channel banks along each of these sub-reaches were analyzed by comparing the historical aerial photography, light detection and ranging (LIDAR) data, bathymetric data obtained from a total station survey, and field examination. Moreover, two different spatially intensive ADCP surveys were conducted in the study area to find the linkage between the hydrodynamics and morphological changes in the two different sub-reaches. The unconfined sub-reach displayed a typical channel migration pattern with deposition on the inner bank and erosion on the outer bank of the meander bend. On the other hand, the confined sub-reach showed greater bank instabilities than the unconfined sub-reach. In the confined sub-reach, an irregular meandering pattern occurred by the evolution of a concave-bank bench, which was caused by reverse flow eddies. The results of this study could shed light on the potential impacts of channel confinement on bank retreat and river migration in comparable case studies. It is reasonable to expect that hydro-morphodynamic processes in rivers can affect fish habitat availability and quality, but the impact of river morphological changes on fish habitat is not well studied. Herein, we investigate the impact of morphological development of a cohesive meandering creek on the quality of fish habitat available for juvenile yellow perch (Perca flavescens) and white sucker (Catostomus commersonii). A 3D morphodynamic model was first developed to simulate the hydro-morphodynamics of the study creek over a 1-year period. Total station topographic surveys were conducted to provide bathymetric change data for calibration of the morphodynamic module. Successful calibration efforts indicated that the developed model could be reasonably employed to predict the hydro-morphodynamics of the study creek. Two fish sampling surveys were carried out at the beginning and the end of the study period to determine habitat utilization of each fish species in the study reach. ANOVA multiple comparison tests indicate that morphological development of the river was a significant factor for the habitat utilization of juvenile yellow perch, whereas juvenile white sucker habitat utilization was not significantly impacted by the changes in the creek morphology. It is shown that flow depth, depth-averaged velocity, and suspended sediment transport also significantly influenced presence of the juvenile yellow perch at the 5% significant level. As for the juvenile white sucker, the only significant factor was the depth-averaged velocity. The results of the developed 3D hydro-morphodynamic model were fed into a fish habitat model. Comparison of the predicted fish habitat map of the juvenile yellow perch with the results of fish sampling surveys confirms that the habitat quality was better predicted when the impact of morphological changes was taken into account in the fish habitat modelling. The results of the proposed methodology could provide some insights into the impact of sediment transport processes on the fish community. This has important implications for effective river management.