Figure 1. SE Florida Inlets
SE Florida Inlets

Surface water from southeast Florida is conveyed to the coastal ocean through a sequence of coastal inlets (Figure 1). There is general agreement that these inlets are likely to be significant vectors of land-based pollution into the coastal ocean. However, determination of definitive mass loading (fluxes) from these inlets has not been possible due to the lack of water chemistry and hydrological data. To fill that gap, a series of experiments were conducted to measure the flux of chemical and biological materials through several of these inlets. These experiments are described below.

1. Boynton Inlet

Figure 2. The Boynton Inlet.
Boynton Inlet

To calculate the mass flux through the Boynton inlet (Figure 2), both the volume of water and the concentrations of potential pollutants exiting this inlet on outgoing tides must be measured. We conducted two 48-hour sampling intensive studies at the Boynton Inlet. Each involved multiple samples taken over a 2-day period, with four outgoing (ebb tide) and four incoming (flood tide) pulses of flow.

The intensives were conduced on June 3-4 and September 26-28, 2007. These samples were investigated for chemical and biological properties. In addition, high-quality water flow measurements were conducted. In addition to the sampling intensives, the flow through the Inlet was measured from February 2007 through October 2008 using a calibrated horizontally-directed acoustic Doppler current profiler (ADCP). The results from this study are available in this paper, and in two NOAA technical reports, Boynton Inlet 48-hour Sampling Intensives, June and September 2007, OAR-AOML-40, 2011 (pdf), and Boynton Inlet flow measurement study, OAR-AOML-43, 2013, 13 pp.(pdf).

2. Pt. Everglades Inlet

Figure 3. Port Everglades.
Port Everglades

Port Everglades is a major seaport as well as a connection of the Intracoastal Waterway into the Atlantic Ocean (Figure 3). To calculate the mass flux through the inlet, NOAA initiated the Port Everglades Shipping Channel (PESC) Study. To measure the flow through the inlet, we installed a 300-kHz HADCP (Teledyne RD Instruments) in February, 2009, on the south side of the Port Everglades inlet (Figure 2). The instrument was in place until 2011. In addition, a number of meteorological instruments were installed on the south side of the inlet (26°5.549' N, 80°5.532' W). The instrumentation included: wind speed and direction, relative humidity, dew point, barometric pressure, and rain parameters. The instrumentation had the designation as Buoy PVGF1 of NOAAs National Data Buoy Center, and of station PVGF1 of NOAA's CREWS/ICON coral reef monitoring program. The report, Port Everglades Flow Measurement System, NOAA Technical Report OAR-AOML-42, is available here (pdf).

3. Boca Raton and Hillsboro Inlets

Figure 4. Hillsboro Inlet.
Hillsboro Inlet.
Figure 5. Boca Raton.
Boca Raton Inlet.

While not significant shipping ports, the Boca Raton and Hillsboro Inlets are significant drains of surface runoff from high population districts and of canal water through the Intracoastal Waterway. NOAA conducted a series of experiments at both inlets consisting of 1) four sampling intensives using a small boat with down-looking ADCP instrumentation, and 2) biweekly grab sample analysis of water from the inlet over the course of a year. These data were used to provide estimates of the fluxes of materials through these inlets into the coastal ocean (paper, report).


Figure 6. Upper panels: monthly averaged rainfall from rain stations associated with the Hillsboro Inlet (left) and Boca Raton Inlet (right). Middle panels: monthly averaged canal flow through canals associated with the Hillsboro Inlet (Ieft) and Boca Raton Inlet (right). Bottom panels: estimated loadings (Kg/ebb tide) of five nutrients through the Hillsboro Inlet (left) and the Boca Raton Inlet (right), averaged over months. Silicate (Si) concentrations in the have been divided by 20 for ease of presentation. Vertical bars in all panels denote one standard deviation of the results for that month (±½σ). Some months include data from multiple years..
Boca Raton Inlet.