Date of Award

Fall 2004

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Environmental Engineering - (Ph.D.)

Department

Civil and Environmental Engineering

First Advisor

Yuan Ding

Second Advisor

Paul C. Chan

Third Advisor

Robert Dresnack

Fourth Advisor

Robert Hazen

Fifth Advisor

John R. Schuring

Abstract

Coastal aquifers are distinguished from other aquifers because of tidal effects which cause complicated groundwater flow and contaminant transport phenomena in regions immediately adjacent to the coast. This study is designed to address the significance of tidal influence on contaminant transport by focusing on one-dimensional homogeneous coastal aquifers.

This study formulates a conceptual model and corresponding flow and transport equations, analyzes coastal boundary conditions, solves numerically the transport equation, and uses experiments to verify the numerical results.

Results of numerical and experimental studies conclude that tides can have a significant impact on contaminant transport, especially when under unconfined conditions, subject to moderate to high tidal amplitude, with low flow velocity, and within areas adjacent to the coastal boundary. Quantitatively, under these favorable conditions, contaminant discharge can be enhanced by tides by a factor of two or three during early stages of discharge, and the enhanced discharge can still be substantial during later stages by an order of 30 to 50 percent. When the groundwater flow is close to stagnant, as demonstrated in the case study, the tidal impact is most apparent, resulting in significant discharge tens of years ahead of the case without tides.

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