A SEDIMENT RESUSPENSION AND WATER QUALITY MODEL OF LAKE OKEECHOBEE1

Authors

  • R. Thomas. James,

    1. Respectively, Staff Environmental Scientist, Okeechobee Systems Research Division, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, Florida 33406; Vice President, Engineering Services, and Environmental Scientist, AScI Corporation, 987 Gaines School Road, Athens, Georgia 30605; and San Diego State University Foundation, U.S. Geological Survey, 345 Middlefield Road, MS 496, Meno Park, California 94205.
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  • James Martin,

    1. Respectively, Staff Environmental Scientist, Okeechobee Systems Research Division, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, Florida 33406; Vice President, Engineering Services, and Environmental Scientist, AScI Corporation, 987 Gaines School Road, Athens, Georgia 30605; and San Diego State University Foundation, U.S. Geological Survey, 345 Middlefield Road, MS 496, Meno Park, California 94205.
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  • Tim Wool,

    1. Respectively, Staff Environmental Scientist, Okeechobee Systems Research Division, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, Florida 33406; Vice President, Engineering Services, and Environmental Scientist, AScI Corporation, 987 Gaines School Road, Athens, Georgia 30605; and San Diego State University Foundation, U.S. Geological Survey, 345 Middlefield Road, MS 496, Meno Park, California 94205.
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  • P F Wang

    1. Respectively, Staff Environmental Scientist, Okeechobee Systems Research Division, South Florida Water Management District, 3301 Gun Club Road, West Palm Beach, Florida 33406; Vice President, Engineering Services, and Environmental Scientist, AScI Corporation, 987 Gaines School Road, Athens, Georgia 30605; and San Diego State University Foundation, U.S. Geological Survey, 345 Middlefield Road, MS 496, Meno Park, California 94205.
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  • 1

    Paper No. 95164 of the Journal of the American Water Resources Association (formerly Water Resources Bulletin). Discussions are open until December 1, 1997.

Abstract

ABSTRACT: The influence of sediment resuspension on the water quality of shallow lakes is well documented. However, a search of the literature reveals no deterministic mass-balance eutrophication models that explicitly include resuspension. We modified the Lake Okeechobee water quality model - which uses the Water Analysis Simulation Package (WASP) to simulate algal dynamics and phosphorus, nitrogen, and oxygen cycles - to include inorganic suspend. ed solids and algorithms that: (1) define changes in depth with changes in volume; (2) compute sediment resuspension based on bottom shear stress; (3) compute partition coefficients for ammonia and ortho-phosphorus to solids; and (4) relate light attenuation to solids concentrations. The model calibration and validation were successful with the exception of dissolved inorganic nitrogen species which did not correspond well to observed data in the validation phase. This could be attributed to an inaccurate formulation of algal nitrogen preference and/or the absence of nitrogen fixation in the model. The model correctly predicted that the lake is light-limited from resuspended solids, and algae are primarily nitrogen limited. The model simulation suggested that biological fluxes greatly exceed external loads of dissolved nutrients; and sediment-water interactions of organic nitrogen and phosphorus far exceed external loads. A sensitivity analysis demonstrated that parameters affecting resuspension, settling, sediment nutrient and solids concentrations, mineralization, algal productivity, and algal stoichiometry are factors requiring further study to improve our understanding of the Lake Okeechobee ecosystem.

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