Hydrologic models that simulate flow of ground and surface water will be used to predict consequences of many of the South Florida ecosystem restoration plans, as well as guide future land and water-management decisions. The U.S. Geological Survey is providing essential hydrogeologic data to extend existing and next generation water management, natural system, and other models across southern Florida to the natural boundary of the southwestern coast.

New data from several recently drilled core holes, which investigate the shallow surficial aquifer system in Collier and Monroe Counties, indicate that the aquifer is confined to sediments above a structural boundary formed by the top of the relatively untransmissive "unnamed formation." The "unnamed formation" is a siliciclastic unit of Miocene and earliest Pliocene age that is roughly equivalent to the Long Key Formation below the Florida Keys. The formation consists largely of muddy sand with beds of mud and clay and thin isolated "clean" sands. The "clean" sands may be transmissive, but the unit as a whole can be considered to be untransmissive.

The top of the "unnamed formation" forms an irregular structural horizon that can be used to predict the depth of the transmissive beds and flow direction. The irregular surface forms a ridge of shallow depths paralleling the southwestern coast, deepening away from this ridge both to the northeast and southwest. Northeast of this ridge, toward the central part of South Florida, water flow is confined to sediments lying immediately above the "unnamed formation," and because this surface slopes, water flow direction can be predicted. The flow would be away from the structurally high ridge and then toward the southeast along the structural trough near the central part of South Florida. These new data will greatly aid current modeling of ground-water flow for restoration and development decisions.

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