Document Type

Thesis

Abstract

The erodibility of muddy estuarine beds, although a substantial control on the resuspension and transport of sediment in estuarine environments, is a poorly understood area of study. An improved understanding of erodibility is crucial to determining conditions of sediment mobility and its effects on channel evolution, ecological health, and the management of coastal navigation and development. Through the use of a prototypical configuration of Gust and LISST instrumentation, this study aims to evaluate erodibility and its relation with suspended particulate matter in real time and in greater depth than made possible by field measurements alone. Four sampling cruises were conducted on the York River between January 2013 and January 2014 to retrieve sediment cores for use in the Gust and LISST experiments as well as cores to be processed for sediment and moisture composition. Erodibility results from the Gust microcosm demonstrated that with increased shear stress the mass of sediment eroded from the cores tended to increase; however, the volume of eroded mass was not consistent among the four cores and varied at any given applied shear stress. Low moisture content, low fecal pellet concentrations, a recently bioturbated surface, and high river discharge during and preceding the time of collection all seemed to promote the erodibility of the cores. The LISST illustrated that at low stresses flocculi sized around 20 microns were the predominant material eroded from the cores and at higher stresses eroded particle sizes became more variable and included more resilient fecal pellets. Further study involves the collection of more core samples in order to complete a full two-year cycle of data collection to determine if the relationships we have found between stress, erodibility, and eroded particle sizes are maintained.

Date Awarded

2014

Department

Geology

Advisor 1

Grace M. Cartwright

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