Thesis (M.S.) -- University of Tennessee, Knoxville, 2005. / Title from title page screen (viewed on Feb. 2, 2006). Thesis advisor: John Schwartz. Vita. Includes bibliographical references.

Thesis (M.S.)--Dept. of Geosciences. University of Missouri--Kansas City, 2004. / "A thesis in urban environmental geology." Typescript. Advisor: Raymond M. Coveney. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 27, 2006. Includes bibliographical references (leaves 77-80). Online version of the print edition.

Thesis (M.S.)--Texas State University-San Marcos, 2007. / Vita. Appendix: leaves 65-67. Includes bibliographical references (leaves 68-75).

In South Africa the need to protect and manage the national water resource has led to the development of the Reserve as a basic right under the National Water Act (1998). The Ecological Reserve relates to the quality and quantity of water necessary to protect the sustainable functioning of aquatic ecosystems. The geomorphological contribution to setting the Reserve has focussed on three groups of information requirements: the spatial and temporal availability of habitat, the maintenance of substratum characteristics, and the maintenance of channel form. This thesis focusses on the second and third information requirements. The thesis has attempted to achieve this by adding value to the theoretical and applied understanding of the magnitude and frequency of channel forming discharge for selected southern African rivers. Many of the eastern sea-board rivers are strongly influenced by bed rock in the channel perimeter, and by a highly variable hydrological regime. This has resulted in characteristic channel forms, with an active channel incised into a larger macro-channel being a common feature of eastern seaboard rivers. Within the active channel inset channel benches commonly occur. This alluvial architecture is used to provide clues as to the types of flows necessary to meet the Reserve. Three river basins are considered : the Mkomazi, Mhlathuze and Olifants. The Mkomazi is a relatively un-impacted perennial eastern-sea board river and forms the research component of the study. The Mhlathuze and Olifants rivers are highly regulated systems and form the application component of the study. Utilising synthesised daily hydrological data, bed material data, cross-sectional surveys, hydraulic data and relevant bed material transport equations, channel form was related to dominant discharge and effective discharge in an attempt to identify the magnitude and frequency offlows that can be considered to be ' effective'. Results from the Mkomazi River indicate that no single effective discharge exists, but rather that there is a range of effective discharges in the 5-0.1% range on the 1-day daily flow duration curves that are responsible for the bulk (>80%) of the bed material transport. Only large floods (termed 'reset'discharges) with average return periods of around 20 years generate sufficient stream power and shear stress to mobilise the entire bed. The macro-channel is thus maintained by the large ' reset' flood events, and the active channel is maintained both by the range of effective discharges and the ' reset 'discharges. These are the geomorphologically 'effective' flows. Results from the Mhlathuze River have indicated that the Goedertrouw Dam has had a considerable impact on the downstream channel morphology and bed material transport capacity and consequently the effective and dominant discharges. It has been suggested that the Mhlathuze River is now adjusting its channel geometry in sympathy with the regulated flow environment. Under present-day conditions it has been demonstrated that the total bed material load has been reduced by up to three times, but there has also been a clear change in the way in which the load has been distributed around the duration curve. Under present-day conditions, over 90% of the total bed material load is transported by the top 5% of the flows, whereas under virgin flow conditions 90% of the total bed material load was transported by the top 20% of the flows. For the Olifants River there appears to be no relationship between the estimated bankfull discharge and any hydrological statistic. The effective discharge flow class is in the 5-0.01% range on the 1-day daily flow duration curve. It has also been pointed out that even the highest flows simulated for the Olifants River do not generate sufficient energy to mobilise the entire bed. It is useful to consider the Olifants River as being adapted to a highly variable flow regime. It is erroneous to think of one ' effective' discharge, but rather a range of effective discharges are of significance. It has been argued that strong bed rock control and a highly variable flow regime in many southern African rivers accounts for the channel architecture, and that there is a need to develop an ' indigenous knowledge' in the management of southern African fluvial systems

This study investigates channel bed scour and fill as a result of individual flood events in a gravel-bed channel. Given the complexity of interactions between hydraulic force, the texture and arrangement of bed material, and input of sediment to a particular point of the channel bed, study objectives were pursued with the view that bed material movement is a stochastic phenomenon. A two-year field program was conducted in Carnation Creek, a small gravel-bed stream draining 11 km2 on the west coast of Vancouver Island, British Columbia. In the 900 m study reach, an array of measurement techniques, including scour indicators, magnetically-tagged stones, and conventional survey, yielded information about the fluctuations of the channel bed elevation and movement of scoured material for individual flooding periods. Frequency distributions of scour and fill depths associated with individual flooding periods are adequately modeled by negative exponential functions over the range of flood peak magnitudes observed in Carnation Creek. Analysis of scour depths measured in streams on the Queen Charlotte Islands demonstrates the applicability of the exponential model to flooding periods and flood seasons. Further, exploratory analysis suggests that a regional scour depth model is possible. Power functions relating mean depths of scour and fill to flood peak discharge show that depth increases with an increase in peak magnitude. Observed maximum scour depths in flooding periods are linked, in general, to streambed conditions influenced by antecedent flow conditions. These patterns in scour and fill exist within an overall pattern of increasing variability in depths of scour and fill as peak discharge increases. Evaluation of a heuristic model for mean travel distance as a function of particle size proposed by Church and Hassan (1992) provides convincing evidence for its general merit. Mean travel distance decreases inversely with particle size as size increases beyond the median diameter of subsurface sediment. This trend is consistent in both individual flooding periods as well as flood seasons. The majority of material finer than the median diameter of surface sediment is supplied from subsurface material, which influences the travel distances of these finer fractions because of burial. Computation of volumetric transport rates of bed material, based on the active scour depth and width of the channel bed, the virtual velocity of particle movement, and sediment porosity, suggests the potential for building scale correlations with streamflow, which have usually been defined by bedload sampling during floods. Error analysis indicates that determination of active width contributes most significantly to the imprecision of transport rate estimates. Results underscore the stochastic nature of sediment transport in gravel-bed channels. / Arts, Faculty of / Geography, Department of / Graduate

No description available.

Natural resource data are typically non-linear and complex, yet modeling methods often utilize statistical analysis techniques, such as regression, that are insufficient for use on such data. This research proposes an innovative modeling method based on pattern recognition techniques borrowed from the field of machine learning. These techniques make no data distribution assumptions, can fit non-linear data, can be effective on a small data set, and can be weighted to include relative costs of different predictive errors. Rapid Assessment Protocols (RAPs) are commonly used to collect, analyze, and interpret stream data to assist diverse management decisions. A modeling method was developed to predict the outcome of a RAP in an effort to improve accurate prediction, weighted for cost-effectiveness and safety, while prioritizing investigations and improving monitoring. This method was developed using channel stability data collected from 58 high-elevation streams in the Upper Colorado River Basin. The purpose of the research was to understand the relationships of channel stability to several hydrobiogeomorphic features, easily derived from paper or electronic maps, in an effort to predict channel stability. Given that the RAP used was developed to evaluate channel stability, the research determined: 1) relationships between channel stability and major land-use and hydrobiogeomorphic features, and 2) if a predictive model could be developed to aid in identifying unstable channel reaches while minimizing costs, for the purpose of land management. This research used Pearson's and chi-squared correlations to determine associative relationships between channel stability and major land-use and hydrobiogeomorphic features. The results of the Pearson's correlations were used to build and test classification models using randomly selected training and test sets. The modeling techniques assessed were regression, single decision trees, and bagged (bootstrap aggregated) decision trees. A cost analysis / prediction (CAP) model was developed to incorporate cost-effectiveness and safety into the models. The models were compared based on their 1) performance and 2) operational advantages and disadvantages. A reliable predictive model was developed by integrating a CAP model, receiving operator characteristic curves, and bagged decision trees. This system can be used in conjunction with a GIS to produce maps to guide field investigations. / Graduation date: 2001

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 634-646). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (M.S.)--Oregon State University, 2004. / Printout. Includes bibliographical references (leaves 86-91). Also available on the World Wide Web.

This thesis examines landscape diversity within alluvial valley floors using the case study of a Scottish wandering gravel-bed river. The thesis aims are two-fold; firstly to investigate the spatial and temporal patterns of valley floor landscape diversity within semi-natural environments, and secondly to develop a methodology for quantifying alluvial valley floor landscape diversity in space and time. The diversity analysis involves quantifying the spatial patterns of geo-, pedo- and biodiversity (flora) within floodplain zones which have been exposed to approximately 100 years of recovery since flood embankment abandonment along the most active reaches of the river. In addition historical records including aerial photographs, maps and narrative accounts were used to assess the temporal patterns of the diversity of landscape patches and how they have changed through time using a series of landscape indices. The analysis thus accounts for the role of river channel change in producing a complex mosaic of land cover types within alluvial valley floors. The spatial analysis revealed that landscape diversity tends to be greater in the perpendicular orientation to the main channel, i.e. along an aquatic-to-terrestrial environmental gradient. The temporal analysis results revealed that the landscape over the last 50 years has changed from being dominated by few relatively large isodiametric patches to a landscape dominated by small irregular shaped patches. Thus although landscape patch richness has increased along with an increase in land cover types through time, the landscape patches have also become more fragmented. The major outcomes of the research are the deriving of quantitative results of the spatial and temporal patterns of floodplain landscape diversity, an evaluation of the role of channel dynamics in creating the diverse mosaic of land cover types, the identification of the environmental controls and supporting floodplain habitats of a number of rare species and a proposed methodology for assessing landscape diversity to be validated on other river systems.