Theoretical Boundary Condition of Groundwater Flow at Drawdown End
Publication: Journal of Hydrologic Engineering
Volume 14, Issue 10
Abstract
This study has experimentally and theoretically derived the boundary condition of the unconfined groundwater flow at the drawdown end. It has been shown that the hydraulic gradient is theoretically 1 at the drawdown end, including the physical conditions of the pressure and bottom slope. The theoretical boundary condition at the drawdown end has been proved to be in good agreement with the experimental data for different slope and hydraulic conductivity. The downstream boundary condition is expressed by a linear relationship (equation) between discharge and thickness of fluid layer at the drawdown end. In the linear relationship, the effect of the bottom slope has not been found, as the experimental result indicates. This shows that the consequent fluid surface slope or hydraulic gradient at the drawdown end are constant. The resultant downstream boundary condition for measured discharges and water depths at the drawdown end predicts the hydraulic conductivity of the unconfined groundwater flow in the field. The effect of the capillary force on the linear relationship for the experimental data are found to be not negligible for the thin thickness of fluid layer.
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Acknowledgments
The writer wishes to thank M. Mizushima who was a graduate student in the Department of Civil Engineering, Kanazawa Institute of Technology, Ishikawa Prefecture, Japan, for conducting the experimental part of this study for his MS thesis.
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© 2009 ASCE.
History
Received: May 18, 2007
Accepted: Feb 19, 2009
Published online: Feb 21, 2009
Published in print: Oct 2009
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