Cooperative Ecosystem Studies Unit, South Florida/Caribbean CESU

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The main objective of this agreement can be summarized as a single undertaking that is designed to integrate several scientific disciplines to map porosity/permeability types and develop a dual-porosity karst framework between the Everglades wetlands and Biscayne Bay, which will be used in developing new procedures for numerical simulation of ground-water flow within the Biscayne aquifer dual-porosity system. The major research objective proposed in a new cooperative program include: Cooperate in testing and applying several scientific disciplines, including magnetostratigraphy, sequence stratigraphy, core-analysis, and near-surface geophysics, to map porosity/permeability and develop a conceptual dual-porosity karst hydrogeologic framework between the Everglades wetlands and Biscayne Bay. The new framework will be used in groundwater modeling during restoration of the Greater Everglades and in developing lattice Boltzmann groundwater modeling techniques that are being developed for the dual-porosity Biscayne aquifer through current USGS directed research. The objective requires laboratory analysis of samples, data analysis, report writing, and results presentation. Specific objectives for each task are as follows: Objective 1 – The USGS is currently implementing sequence stratigraphy, core analyses, and near-surface geophysics as major tools in providing an accurate means of mapping karstic preferential karstic flow zones within the carbonate Biscayne aquifer. This research is in support of USGS Priority Ecosystems Science and NPS Critical Ecosystems Science Initiative funding of the major project objective mentioned above. Results are providing useful data that is being used by groundwater modelers in developing new procedures (lattice Boltzmann modeling) for simulating groundwater flow in a dual-porosity aquifer system; however, a critical need exists for testing the continuity of mapped preferential groundwater flow zones with magnetostratigraphy. Many karst aquifers occur in cyclic platform carbonates (the fundamental framework of the Biscayne aquifer), so the magnetostratigraphic approach combined with sequence stratigraphy, core analyses, and near-surface geophysics is applicable to the rocks of the Biscayne aquifer. A rock-magnetic and paleomagnetic study of the weakly magnetic platform carbonates of the Biscayne aquifer will require use of a highly sensitive cryogenic magnetometer—specifically a small-bore cryogenic magnetometer outfitted with direct current, superconducting quantum interference devices (DC SQUIDs) with sensitivity to 2 x 10-11 Am2. Results from the magnetostratigraphy will be used to develop relationships between coreholes among facies, cyclicity, and porosity/permeability—key features of the aquifer architecture—and will form the basis for correlation and development of a sequence- and cycle-based conceptual karst hydrogeologic aquifer framework that is linked to groundwater flow properties. The current conceptual hydrogeologic model, which needs to be areally expanded and refined, is being used by CERP decision makers involved in Everglades restoration issues and policy. Results of this proposed more advanced study will be used in current USGS directed lattice Boltzmann modeling experiments that is developing procedures for modeling the dual-porosity system of the Biscayne aquifer. Final results will be made available to CERP researchers and decision makers.

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