Date of Award:

5-2009

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Advisor/Chair:

Bethany T Neilson

Abstract

When approximating heat transfer through a streambed, an understanding of the thermal properties of the sediments is essential (e.g., thermal conductivity, specific heat capacity, and density). Even though considerable research has been completed in this field, little has been done to establish appropriate standard data collection approaches or to compare modeling methods for approximating these properties. Three mixture models were selected for comparison against each other and against a bed conduction model (SEDMOD). Typical data collection approaches were implemented for use in the mixture models while numerous data collection approaches were employed for use within SEDMOD. Sediment samples were taken from the streambed to estimate the necessary parameters for the mixture models (e.g., sediment volume, density, porosity, etc.) and to identify the minerals present. To yield more accurate estimates of the thermal properties from SEDMOD, methods of obtaining sediment temperature profiles representing the influences of conduction only were developed through the use of a steel cylinder and different capping materials (e.g., using geo-fabric or aluminum). In comparison to laboratory measurements of the thermal properties, it was found that the mixture model that provided the best estimates of the thermal properties was a volume weighted average. The method that best isolated conductive heating from advective heating was the steel cylinder with an aluminum cap. Using this data to calibrate SEDMOD yielded thermal diffusivity values most similar to the laboratory measurements. Due to its ability to estimate both thermal diffusivity and reproduce sediment temperature profiles, SEDMOD is recommended in combination with the aluminum isolation technique.

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