estuarine creek responses to extreme hydrologic events in northeastern Florida Bay
Estuarine Creek Responses to Extreme Hydrologic Events in Northeastern Florida Bay
Poster presented April 2003, at the Greater Everglades Ecosystem Restoration Conference
Data on water velocity, water level, salinity, and temperature are currently being collected continuously at 14 U.S. Geological Survey (USGS) monitoring stations in northeastern Florida Bay (fig. 1). Data from the monitoring stations are available from 1996 to present.
These data allow a detailed examination of estuarine creek response to extreme hydrologic events. Two creeks (McCormick and Trout) are presented here for comparison. Daily mean values of stage for Trout Creek (fig. 2) identify most of the major storms that affected northeastern Florida Bay since 1996, including five hurricanes, two tropical storms, and an El Nino related winter storm.
A comparison of storm surges between McCormick Creek and Trout Creek for Tropical Storm Harvey and Hurricane Irene indicates how storm strength and path can affect water levels and salinities across central and eastern Florida Bay. Tropical Storm Harvey made landfall near Everglades City on September 21, 1999 and moved east-northeast across Florida. Water levels between the two creeks were similar in magnitude during Harvey (fig. 3).
Hurricane Irene made landfall near Cape Sable on October 15, 1999 and moved to the northeast across Florida. Storm surge from Irene increased water levels at McCormick Creek about one foot more than at Trout Creek.
Increases in salinity at McCormick Creek and Trout Creek were observed during storm surges for both Harvey and Irene. During Harvey, McCormick Creek experienced an increase in salinity from about 20 to 30 parts per thousand (ppt) in 20 hours, with a subsequent decrease back to 20 ppt in only four hours (fig. 4).
At Trout Creek, salinity increased from about 7 ppt to 24 ppt in 24 hours, but took another 24 hours to drop back to 7 ppt (pre-surge conditions). During Hurricane Irene, McCormick Creek salinity increased from about 5 ppt to 17 ppt in 6 hours with a subsequent decrease to 5 ppt in 13 hours. Trout Creek salinity during Irene's passage increased from about 1 ppt to 20 ppt in 10 hours, decreasing back to 5 ppt over the next 24 hours. After an additional 42 hours, salinity returned to the pre-storm level of about 1 ppt. Both creeks experienced a greater salinity increase from Irene than Harvey. Residence time was also greater because more saline water associated with the surge was pushed upstream.
A detailed evaluation of estuarine creek responses to extreme hydrologic conditions and subsequent comparison to hydrodynamic model output will help verify model capabilities in simulating natural systems. The evaluation also will support a science-based approach for CERP activities.
SOFIA Project: Freshwater Flows into Northeastern Florida Bay
U.S. Department of the Interior, U.S. Geological Survey
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Last updated: 15 January, 2013 @ 12:43 PM (KP)