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WATER RESOURCES RESEARCH, VOL. 44, W03501, doi:10.1029/2007WR006601, 2008

Effects of turbulence on hydraulic heads and parameter sensitivities in preferential groundwater flow layers

W. Barclay Shoemaker

U.S. Geological Survey, Fort Lauderdale, Florida, USA


Kevin J. Cunningham

U.S. Geological Survey, Fort Lauderdale, Florida, USA


Eve L. Kuniansky

U.S. Geological Survey, Norcross, Georgia, USA


Joann Dixon

U.S. Geological Survey, Fort Lauderdale, Florida, USA


Abstract

A conduit flow process (CFP) for the Modular Finite Difference Ground-Water Flow model, MODFLOW-2005, has been created by the U.S. Geological Survey. An application of the CFP on a carbonate aquifer in southern Florida is described; this application examines (1) the potential for turbulent groundwater flow and (2) the effects of turbulent flow on hydraulic heads and parameter sensitivities. Turbulent flow components were spatially extensive in preferential groundwater flow layers, with horizontal hydraulic conductivities of about 5,000,000 m d−1, mean void diameters equal to about 3.5 cm, groundwater temperature equal to about 25°C, and critical Reynolds numbers less than or equal to 400. Turbulence either increased or decreased simulated heads from their laminar elevations. Specifically, head differences from laminar elevations ranged from about −18 to +27 cm and were explained by the magnitude of net flow to the finite difference model cell. Turbulence also affected the sensitivities of model parameters. Specifically, the composite-scaled sensitivities of horizontal hydraulic conductivities decreased by as much as 70% when turbulence was essentially removed. These hydraulic head and sensitivity differences due to turbulent groundwater flow highlight potential errors in models based on the equivalent porous media assumption, which assumes laminar flow in uniformly distributed void spaces.

Received 18 October 2007; accepted 18 December 2007; published 29 March 2008.

Keywords: conduit flow; turbulent flow; karst hydrology.

Index Terms: 1805 Hydrology: Computational hydrology; 1829 Hydrology: Groundwater hydrology; 1847 Hydrology: Modeling; 1849 Hydrology: Numerical approximations and analysis.

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Citation: Shoemaker, W. B., K. J. Cunningham, E. L. Kuniansky, and J. Dixon (2008), Effects of turbulence on hydraulic heads and parameter sensitivities in preferential groundwater flow layers, Water Resour. Res., 44, W03501, doi:10.1029/2007WR006601.