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Few studies have been published on three-dimensional (3D) hydrodynamic and water quality modeling of a wetland with extensive data sets for model calibration and verification. Wetland plants include submerged aquatic vegetation (SAV) and emergent aquatic vegetation (EAV). A major difference between SAV and EAV is that SAV resides primarily in the bottom layer of the water column, whereas EAV extends through the entire water column. In a SAV area, the surface velocity can be very different from the bottom velocity. In this study, the Lake Okeechobee Environmental Model for Constructed Wetland (LOEM-CW) is enhanced to simulate hydrodynamic and water quality processes in the Everglades Stormwater Treatment Area 2 (STA-2) in Florida. The 3D LOEM-CW is applied to 2 years (January 1, 2015–December 31, 2016) of extensive data sets for model calibration and verification. The 3D LOEM-CW was capable of resolving the vertical profiles of vegetation in wetland so that stratifications of key parameters were simulated realistically. The model is also applied to support STA operation and management. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge of estuarine hydrodynamics and water quality comes mostly from studies of large estuarine systems. The processes affecting algae, nutrients, and dissolved oxygen (DO) in small and shallow subtropical estuaries are relatively less studied. This paper documents the development, calibration, and verification of a three dimensional (3D) water quality model for the St. Lucie Estuary (SLE), a small and shallow estuary located on the east coast of south Florida. The water quality model is calibrated and verified using two years of measured data. Statistical analyses indicate that the model is capable of reproducing key water quality characteristics of the estuary within an acceptable range of accuracy. The calibrated model is further applied to study hydrodynamic and eutrophication processes in the estuary. Modeling results reveal that high algae concentrations in the estuary are likely caused by excessive nutrient and algae supplies in freshwater inflows. While algal blooms may lead to reduced DO concentrations near the bottom of the waterbody, this study indicates that stratification and circulation induced by freshwater inflows may also contribute significantly to bottom water hypoxia in the estuary. It is also found that high freshwater inflows from one of the tributaries can change the circulation pattern and nutrient loading, thereby impacting water quality conditions of the entire estuary. Restoration plans for the SLE ecosystem need to consider both a reduction of nutrient loading and regulation of the freshwater discharge pattern. [Copyright &y& Elsevier]

Three hurricanes (Frances and Jeanne in 2004 and Wilma in 2005) passed over Lake Okeechobee causing a number of changes in its sediment and environment. The unconsolidated sediment atop the mud sediments in the central region of the lake became thicker due to the settling and deposition of resuspended sediments after the hurricanes passed. The increased unconsolidated sediment layer was more easily resuspended, and resulted in sustained higher solids and nutrient concentrations and lower light transparency in the water column for more than 4 years after the hurricanes passed. Hurricanes Frances and Jeanne disturbed consolidated sediments to a depth of 7-15 cm from the surface while Hurricane Wilma extended the disturbance to a depth of 25 cm. Concentrations of total suspended solids (TSS) in the water column increased four to sixfold after the hurricanes. The high concentration of TSS was continuous and maintained 2-4 times higher than a normal situation in the lake until present. Hurricanes contributed to a decrease of submerged aquatic vegetation (SAV) density from 4-34 g dw/m2 to 0.1-4 g dw/m2 primarily through scouring. SAV recovery was very slow due to the increasing turbidity and reduced light transparency. [ABSTRACT FROM AUTHOR]

There are increasing demands for reliable engineering tools for sediment modeling and water resources management. The Lake Okeechobee environmental model (LOEM), which was calibrated and verified to simulate sediment resuspension and transport in Lake Okeechobee, Florida, is a dependable tool to meet those demands. The LOEM contains 2,126 horizontal grid cells and 5 vertical layers. The primary hydrodynamic and sediment transport driving forces are wind waves, surface wind stresses, and inflows/outflows. The LOEM was calibrated and verified, using two sets of observed data from May 16 to June 13, 1989 and January 17 to March 3, 2000, respectively. The model results indicate that sediment solids are resuspended primarily by wind–wave action and transported by lake circulation. The strong relationship between significant wave height and suspended sediment concentration in the lake indicates that sediment resuspension is primarily driven by wind-induced waves. To simulate this sediment resuspension, the processes of wind–wave- and current-induced bottom shear stresses on the lake bed were added to the LOEM. Once resuspended, the suspended sediment is transported to different areas of the lake by wind-induced currents. The importance of wind-wave, currents, and their interactions to sediment transport is included and discussed. By using the comprehensive data set for model calibration and verification, the LOEM model is proven to be a useful tool to water sources management in the lake. [ABSTRACT FROM AUTHOR]

A time-dependent three-dimensional hydrodynamic model of Lake Okeechobee was validated and used to understand the physical processes associated with vertical mixing in the lake. The lake has relatively uniform water depths in the open water areas, and the localized bathymetry irregularities are small, which enables the Lake Okeechobee Hydrodynamic Model with a grid resolution of 912 x 923 m to represent the hydrodynamic processes reasonably well. This work presents the results of a 7-week simulation that uses measured bathymetry, relative humidity, total solar radiation, wind velocity, inflow, and outflow. Surface elevation, velocity field, and temperature are computed and compared with observed data. Conservation equations for mass, momentum, and temperature transport are solved to provide values for water depth, current velocities, and water temperatures. The statistical comparisons between the simulated and observed results indicate that the model represents the circulation and temperature distribution of the lake very well. The model was run for a 7-week verification period, during which water levels receded because of dry conditions. The model also indicates that well mixed circulation patterns for the top and bottom layers result from high wind events. Diurnal thermal stratification impacts may result in a two-layer flow and affect the horizontal dispersion in Lake Okeechobee. The model results indicate that wind is the major driving force of horizontal and vertical water movement; however, during calm periods, geostrophic currents would be significant. DOI: 10.1061/(ASCE)0733-950X(2002)128:3(114) [ABSTRACT FROM AUTHOR]