Model for Wind-Driven Vertical Mixing in a Shallow Lake with Submersed Macrophytes
Publication: Journal of Hydraulic Engineering
Volume 131, Issue 6
Abstract
An energy flux model to simulate vertical mixing in a temperature stratified shallow lake with submersed macrophytes has been formulated. The model is based on a one-dimensional equation for transport and dissipation of kinetic energy produced by wind, coupled to heating at the water surface. Analytic solutions of the energy flux equation characterize the steady-state mixed layer depth for constant wind shear and constant heat input at the water surface. It is found that in water columns with sparse macrophytes, the mixed layer depth is controlled by the buoyancy length scale, which is proportional to the heat flux. In dense macrophyte beds, the mixed layer depth is controlled primarily by the macrophyte length scale, which is a function of the plant surface area. The analytic steady-state solutions give a lower bound for daytime mixed layer depth, which is controlled by simultaneous heating and wind mixing from the water surface.
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Acknowledgments
The senior writer gratefully acknowledges the Minnesota Supercomputer Institute for support of this work through a research scholarship grant. The authors also thank Professor Miki Hondzo for supplying the measurement raft used in this study, Ben Erickson for his help in deploying and retrieving the raft, and Dr. Chris Ellis for his help in obtaining weather data.
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Published In
Journal of Hydraulic Engineering
Volume 131 • Issue 6 • June 2005
Pages: 488 - 496
Copyright
© 2005 ASCE.
History
Received: Aug 5, 2003
Accepted: Nov 12, 2004
Published online: Jun 1, 2005
Published in print: Jun 2005
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