WATER CIRCULATION and CURRENTS

Modeling the Currents of Hawk Channel and Beyond

Florida Bay Project Profile - 106

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Question: Water entering Hawk Channel eventually reaches the reef tract and offshore waters. Can a computer model be used to separate the influences of nature and man to make predictions on how the water will flow and ultimately how the environment will respond?

Project: Currents in Hawk Channel and along the reef tract are measured directly and by remote sensing radar. The variations in salinity and temperature (which cause important changes in water density) are also observed. This allows the scientists to determine current flow speed and direction in response to combinations of driving forces such as wind, tide, nearshore run-off, and the Florida Current.

Findings to Date: The data from the field is used to calibrate a computer model developed to simulate the currents and salinity levels as they change while in the channel and over the reef tract. Fresh water runoff significantly reduces the nearshore salinity levels, but quickly dissipates in open waters. In Hawk Channel and across the reef tract the currents are mostly driven by tide and wind. The directions of these currents are very complicated. Depending on how the water is deflected off the curved shoreline of the Florida Keys, the flow of water can be to the north or to the south. The Florida Current is strong to the north outside of the fringing coral reef.

Status: The computer model is running and field work is continuing to improve the predictive accuracy.

Restoration Impacts: This model is very useful in explaining the water linkages between Florida Bay, Biscayne Bay, nearshore runoff and the Florida Keys reef tract. It is also valuable in predicting the effects of persistent winds, hurricanes, and man-made hazards, such as marine spills, on the ecosystem.

Funding Source: NOAA - Coastal Ocean Program

Related Profiles:

• FBPP-100 • FBPP-102

• FBPP-103 • FBPP-104

• FBPP-107