Outfall Dilution: The Role of a Far‐Field Model
Publication: Journal of Environmental Engineering
Volume 111, Issue 4
Abstract
Effluent dilutions predicted by near‐field models do not realistically reflect near‐field conditions in tidally influenced coastal waters since they neglect the advection of the pollutant cloud over the source. A theoretical solution has been developed for the case in which a conservative pollutant is released from a line source into a uniform unsteady flowing ambient where diffusion is only significant in the cross‐stream direction. Considering the case of a sinusoidal variation of velocity along the streamwise principal axis, it has been shown that the expected concentration at a source located in a typical flow field may increase by as much as 15% per cycle over that predicted by the near‐field model. A hypothetical outfall was analyzed using real data and a dispersion model which accounts for the near‐, as well as far‐field mixing. The near‐field model was found to underestimate the average dilution at the source by about 21%. Extreme values were also underestimated. The results of this study indicate that a complete dispersion model should be used in predicting dilutions in outfall mixing zones of coastal regions.
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References
1.
Carter, H. H., and Okubo, A., “A Study of the Physical Processes of Movement and Dispersion in the Cape Kennedy Area,” Final Report, U.S. Atomic Energy Commission, Report No. NYD‐2973‐1, Chesapeake Bay Institute, The Johns Hopkins University, Baltimore, Md., 1969.
2.
Chin, D. A., and Roberts, P. J. W., “A Model of Dispersion in Coastal Waters,” Journal of Hydraulic Engineering, ASCE, Vol. 111, No. 1, Jan., 1985.
3.
Fischer, H. B., List, J., Koh, R. C. Y., Imberger, J., and Brooks, N. H., “Mixing in Inland and Coastal Waters,” Academic Press, New York, N.Y., 1979.
4.
Koh, R. C. Y., “Wastewater Field Thickness and Initial Dilution,” Journal of Hydraulic Engineering, ASCE, Vol. 109, No. 9, Sept., 1983.
5.
Roberts, P. J. W., “A Mathematical Model of Initial Dilution for Deepwater Ocean Outfalls,” Conservation and Utilization of Water and Energy Resources, ASCE, 1979, pp. 218–225.
6.
Winant, C. D., and Bratkovich, A. W., “Temperature and Currents on the Southern California Shelf: A Description of the Variability,” Journal of Physical Oceanography, Vol. 11, 1981, pp. 71–86.
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Copyright © 1985 ASCE.
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Published online: Aug 1, 1985
Published in print: Aug 1985
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