A long term calibration and verification of a submerged aquatic vegetation model for Lake Okeechobee

Abstract

Introduction: Submerged aquatic vegetation (SAV) has multiple functions in Lake Okeechobee. It provides critical habitat for fish and wildlife, stabilizes sediments, reduces phosphorus (P) concentration in the water column by preventing re-suspension of P-rich sediments, and provides a substrate for attached algae, which also helps to remove P from the water column. Ten year water quality and SAV growth simulations are presented and compared with observed SAV and water quality data collected in the nearshore zone in Lake Okeechobee. Methods: The SAV theory and approach used in the LOEM are modified from the Chesapeake Bay model and incorporate three state variables: shoots (above the bed sediment), roots (in the bed sediment), and epiphytes (attached to the shoots). The SAV model has direct linkages with the water quality model, including (1) a link between the growth and decay of SAV and the nutrient pool of the water quality model; (2) a link between the photosynthesis and respiration of SAV and dissolved oxygen dynamics, and (3) the ways in which settling of particulate organic matter and nutrient uptake affect nutrient levels in the water column and in the sediment bed. Results: Total suspended solids affect light attenuation and are another major driving factor for SAV growth in the nearshore and littoral zone area. The model performs reasonably well in reproducing the spatial distribution of SAV.

Application and validation of a 3-D calcium, chloride, and sulfate model in Lake Okeechobee

“…Modeled and lake averaged submerged aquatic vegetation (SAV) biomass (Jin and Ji 2013) indicate good correspondence (Figure 10b) On an aerial basis, the model and observed lake SAV distribution are very similar (Figure 10c).…”

“…The ASR wells provide water to the lake when the lake stage is low relative to the desired lake management and help maintain higher lake stage (more than 1 foot during dry season). The elevated water depth during the dry season is beneficial to SAV growth in the lake (Jin and Ji 2013 The possible interactions between Ca, Cl, and SO 4 with water quality variables are not included in the LOEM. Additional studies are needed to better understand the linkages among these variables.…”

An integrated environmental model for a surface flow constructed wetland: Water quality processes

“…The SAV model has direct linkages with the water quality model, including (1) a link between the growth and decay of SAV and the nutrient pool of the water quality model; (2) a link between the photosynthesis and respiration of SAV and dissolved oxygen (DO) dynamics, and (3) the ways in which particulate organic matter setting and nutrient uptake affect nutrient levels in the water column and in the sediment bed. Details of the SAV module of the LOEM are described in Jin and Ji (2013) and Ji (2008).…”

“…The SAV theory and approach of the LOEM (Jin and Ji, 2013) are modified from the Chesapeake Bay model and incorporate three state variables: shoots (above the bed sediment), roots (in the bed sediment), and epiphytes (attached to the shoots). The SAV model is coupled with the hydrodynamic, sediment, and water quality model, since SAV growth is dependent on nutrient uptake (generated from water quality model), available sunlight (calculated from hydrodynamic and sediment transport model), and water depth (provided from hydrodynamic model) (Cerco et al, 2002;Hamrick, 2004;Jin and Ji, 2013). The light intensity (or solar radiation) in a water column is calculated using Beer's Law.…”

“…They are also known to reduce P concentration in the water column by preventing resuspension of P rich sediments and absorbing P from the water column. The spatial extent of EAV and SAV varies in response to changing water levels in wetlands (Murphy and Yesaki, 1983;Dennison et al, 1993;Scheffer, 1989;Vermaat et al, 2000;Havens et al, 1999Jin and Ji, 2013).…”