The mangrove-dominated coastline of the southwestern Everglades is a complex maze of small and large islands which are highly dissected by small streams and large tidal river channels (Wanless and others, 1994). The surface sheetflow, typical of the central and southern Everglades, slowly becomes channelized, first in small streams and then in larger, tidally dominated rivers as one nears the coast. Tidal influence can be detected for considerable distances from the river mouths. On the Shark River for instance, a tidal signature is present at Everglades National Park gauge P35, some 35 km upstream from the mouth of the river. Ground-water dynamics in this land-margin ecosystem are very poorly understood.

Beginning in 1993, a series of ground- and surface-water monitoring wells was established in a series of five transects across the freshwater marsh mangrove forest interface of Everglades National Park (ENP) as part of the South Florida Global Climate Change Program. Three transects are in the mangroves of the southwest coast of ENP. These run along the Shark, Lostmans, and Chatham Rivers. On each transect there is an upstream well located in a freshwater marsh setting; a midstream well located in a brackish marsh/mangrove forest ecotonal setting; and a downstream well located in a pure mangrove forest near the riverís mouth. On the Shark and Lostmans Rivers, lateral transects were also established to permit sampling near the riverís edge and in the interior of the large coastal islands. These island interior environments are usually dominated by brackish marsh vegetation. Two transects were located downstream of the C-111 canal in the "panhandle" region of ENP. These transects are on Highway Creek and Joe Creek.

At present, the sites are instrumented with surface, soil and ground-water wells to record water-elevation data. Conductivity measurements are made at a number of well locations. The sites are radio-telemetered to allow daily access and checking of operational status of the site. Data are quality analysis/quality checked on a regular basis and are currently archived at ENP. Vegetation plots have been established at most sites (see Smith & Whelan, this volume) so that ecological processes (for example, primary productivity) can be related to the hydrological information be gathered. A report detailing the first year of data acquisition (water year 1997) is in final stages of production (Anderson and others, 1999).

Data from the project are currently being used for two analyses of direct interest to resource managers in south Florida: (1) to examine the hydrological impacts of the passages of Hurricane Georges and Tropical Storm Mitch on the rivers of the southwestern coast of ENP; and, (2) to look at the hydrological impact of the removal of the levee along the south side of the C-111 canal and ask the simple but important question: Did removal of the C-111 levee improve the hydrology south of the canal? These analyses will be completed within the next several months.

Finally, this network of hydrological monitoring stations is uniquely suited for measuring the impacts of the south Florida ecosystem restoration on the downstream mangrove forested wetlands of the Everglades.

A significant part of the funding for this research was provided from the U.S. Department of the Interior, South Florida Ecosystem Restoration Program "Critical Ecosystems Studies Initiative" (administered through the National Park Service); and, in part, from the U.S. Geological Survey, Florida Caribbean Science Center for the project "Vegetation and Hydrology of Land-Margin Ecosystems in South Florida."

REFERENCES

Anderson, G.H., and others, 1999, Data Summary for the 1997 Water Year: Mangrove Hydrology Project: U.S. Geological Survey, Everglades Field Station.

Wanless, H.R., and others, 1994, Sea level control on stability of Everglades wetlands, in Davis, S.M., and Ogden, J.C., eds., Everglades--The ecosystem and its restoration: Delray Beach, Florida, St. Lucie Press, p. 199-224.

(This abstract was taken from the Proceedings of the South Florida Restoration Science Forum Open File Report)