Seagrass is a key stone component for the Indian River Lagoon (IRL) ecosystem,
and therefore it is an important topic for many studies in the lagoon. This study focuses
on the effects of seagrass beds on the hydrodynamics in the IRL. A hydrodynamic model
based on the Delft3D modeling system has been developed for the southern IRL
including the St. Lucie estuary, Ft. Pierce and St. Lucie Inlets, and adjacent coastal
waters. The model is driven by freshwater inputs from the watershed, tides,
meteorological forcing, and oceanic boundary forcing. The model has been systematically calibrated through a series of numerical
experiments for key parameters, particularly the bottom roughness, and configuration
including heat flux formulation and bottom bathymetry. The model skills were evaluated
with quantitative metrics (point-to-point correlation, root-mean-square difference, and
mean bias) to gauge the agreements between model and data for key variables including temperature, salinity, and currents. A three-year (2013-2015) simulation has been
performed, and the results have been validated with available data including observations
at HBOI Land-Ocean Biogeochemistry Observatory (LOBO) stations and in situ
measurements from various sources. The validated model is then used to investigate the
effects of 1) model vertical resolution (total number of model vertical layers), 2) spatial
variability of surface winds, and 3) seagrass beds on the simulated hydrodynamics. The
study focuses on the vicinity of Ft. Pierce Inlet, where significant seagrass coverage can
be found. A series of numerical experiments were performed with a combination of
different configurations. Overall, the experiment with 2-dimensional (2-D) winds, ten
vertical layers and incorporating seagrass provided the most satisfactory outcomes.
Overall, both vertical resolution and spatial variability of surface winds affect
significantly the model results. In particular, increasing vertical resolution improves
model prediction of temperature, salinity and currents. Similarly, the model with 2-D
winds yields more realistic results than the model forced by 0-D winds.
The seagrass beds have significant effects on the model results, particularly the
tidal and sub-tidal currents. In general, model results show that both tidal and sub-tidal
currents are much weaker due to increase bottom friction from seagrass. For tidal
currents, the strongest impacts lie in the main channel (inter-coastal waterway) and
western part of the lagoon, where strong tidal currents can be found. Inclusion of seagrass
in the model also improves the simulation of sub-tidal currents. Seagrass beds also affect
model temperature and salinity including strengthening vertical stratification. In general,
seagrass effects vary over time, particularly tidal cycle with stronger effects seen in flood
and ebb tides, and seasonal cycle with stronger effects in the summer than in winter. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection
| Identifer | oai:union.ndltd.org:fau.edu/oai:fau.digital.flvc.org:fau_33921 |
| Contributors | Habib, MD Ahsan (author), Jiang, Mingshun (Thesis advisor), Florida Atlantic University (Degree grantor), College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering |
| Publisher | Florida Atlantic University |
| Source Sets | Florida Atlantic University |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
| Format | 114 p., application/pdf |
| Rights | Copyright © is held by the author with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder., http://rightsstatements.org/vocab/InC/1.0/ |
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