Florida Bay West Basin Transport Study
Principal Investigators: Dr. Thomas N. Lee, Dr. Libby Johns, Dr. Peter Ortner
Participating Institutions: University of Miami / RSMAS, NOAA / AOML
Funding: NOAA / CIMAS / COP SFP (Contract: NA17RI226)
Project Dates: 2004 to 2005
In response to the Announcement of Funding Opportunity by the CSCOR/COP South Florida Ecosystem Restoration Prediction and Modeling Program (SFP) we conducted a two year study of the circulation and exchange processes that regulate the residence times and flushing rates within the NE basin of Florida Bay (Fig. 1). This project was conducted through CIMAS, Task 3, Theme 3: Coastal Ocean Ecosystem Processes. The overall goal was to improve understanding of the effects of modifying fresh water supply to the Everglades as part of Everglades restoration plans. It was uncertain how proposed changes in water delivery, with increased fresh water flows to Shark River and Taylor Slough would affect salinity variability within Florida Bay. The primary objectives were to quantify the circulation and exchange rates influencing salinity variability in the eastern regions of the Bay that directly receive fresh water discharge from a series of small rivers along the northern border (Fig. 1) and to determine their interactions with connecting regions, as well as to identify the controlling physical processes. This information is needed to aid evolution and evaluation of hydrodynamic models for prediction of future water deliveries.
Fig. 1. Satellite photograph of the Western Basins subregion of Florida Bay including Rabbitt Basin and Twin Key Basin and surrounding shallow mud banks (light brown). Mooring locations are shown with red triangles for UM/AOML sites and green dots for HBOI sites. Vessel track for bi-monthly surveys is also shown.
This study consisted of a joint effort between the University of Miami (UM), NOAA/Atlantic Oceanographic and Meteorological Laboratory (AOML) and Harbor Branch Oceanographic Institution (HBOI) to use observational techniques to determine the net exchanges of water volume and salt between the interior of Florida Bay and the connecting waters of the Gulf and Atlantic (Fig. 1 above). The project was conducted through CIMAS, Task 3, Theme 3: Coastal Ocean Ecosystem Processes.
A focused study of transport and salinity variability of the western sub-region of Rabbitt and Twin Key basins was recently undertaken in a joint effort by T. Lee, E. Johns and N. Smith for the SFP 2004 funding period. Rabbit Key and Twin Key basins consist of a pair of shallow water bodies adjacent to the western boundary of Florida Bay and enclosed by expansive mud banks that can be partially exposed at times of low water (Fig. 1). The basins are separated from the southwest Florida shelf waters by 9-Mile Bank to the west and from the southeast subregion of Florida Bay by Twin Key Bank. To the north lies a broad bank region separating the basins from the north-central sub-region of the Bay where hypersalinity is commonly observed during dry seasons. These western basins serve as a transition zone for water exchange between the southwest shelf and more restricted, poorly flushed inner basins of Florida Bay. Exchange of western basin waters takes place through a series of flow channels through the shallow banks, as well as directly over the banks when water levels are sufficiently deep. As part of our collaborative effort to better understand circulation and exchange processes throughout Florida Bay we deployed current meters, conductivity and temperature sensors to make direct measurement of volume and salt transports through nine of the larger flow channels connecting the western basins to surrounding regions (Fig. 2). Measurements took place over the June to November wet season of 2004 and the following December to June dry season of 2005. High resolution spatial salinity surveys were made at approximately 2 week intervals over the study period and sea level measurements were made continuously throughout both seasons. Interior basin circulation was observed with shallow drifters.
Data (Florida Bay Western Basin Project)
Deployment Period #1 Western Basins Study Wet Season June 9 – Oct. 29, 2004
Deployment Period #2 Western Basins Study Dry Season Dec. 1, 2004 – May 26, 2005
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