Date of Award

8-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Civil Engineering

Major Professor

John S. Schwartz

Committee Members

Christopher D. Clark, Jon M. Hathaway, Athanasios N. Papanicolaou

Abstract

In-stream channel degradation as a result of alterations to flow and/or sediment caused by urbanization can have detrimental ecological and socio-economic impacts. Although steps have been taken to minimize these impacts through stormwater regulatory efforts, there has been variance in effectiveness. As efforts have evolved to meet regulatory requirements and improve effectiveness, an awareness of the need for integrated watershed planning has developed. However, understanding of the linkage between in-channel sediment contributions, hydrogeomorphic setting, level of anthropogenic disturbance, and time dependent response remains limited. The rate channel forming work is performed, as result of increased surface runoff, is complex; therefore, incremental increases in flow do not necessarily lead to incremental changes in channel morphology. Rather specific geomorphic attributes and their spatial organizations dictate imbalances in hydraulic and mechanical disturbing/resisting forces over temporal patterns of flow.In an attempt to address inefficiencies, a framework is proposed integrating stormwater related mitigation efforts (“channel protection”), related engineering practices, fluvial geomorphology, and economics in order to evaluate the outcomes of mitigating efforts and associated cost-effectiveness. This framework is supported by hydrological modeling and field surveys used to explore surrogate measures of eroding and resisting force with the intent to capture potential imbalances and define attributes that determine stability within the Ridge and Valley Province of Tennessee. In combination with these efforts, detailed in-situ flow monitoring was completed at three small stream systems to calibrate and validate coupled continuous simulation models of hillslope and in-channel processes. Models are utilized to explore response trajectory and efficacy of various mitigating suites.This research contributes to a growing body of literature that suggests channel protection efforts and TMDL implementation plans (for purposes of sediment loading reduction) should incorporate stream system specific prevalent erosive processes, the mechanisms of those processes, and the geomorphic attributes that influence them to improve efficacy of efforts.

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