The permeability of the Floridan varies greatly because of differences in the character of its water-bearing materials. These materials include: (1) detrital units of foraminiferal remains and coarse sand-sized particles that hydraulically act as sand or gravel; (2) micritic limestone in the Florida panhandle that acts hydraulically as silt or clay; (3) networks of many small solution openings along joints or bedding planes that on a gross scale provide a uniform distribution of permeability; and (4) large cavernous openings developed in karst or paleokarst areas.

In areas where the Floridan is characterized by the first three types, diffuse flow predominates; however, in areas with large cavernous openings, conduit flow predominates.

For the areas where diffuse flow predominates, the methods of aquifer-test analysis developed for porous media are applicable. The response curves of aquifer tests outside the karst terrains generally match the classic nonleaky, leaky, or delayed-yield type curves. Many tests in the confined areas are characterized by a Theis (nonleaky) response throughout nearly the entire test duration. In contrast, porous-media flow theory cannot be applied, at least on a local scale, in the karst areas where conduit flow predominates. However, on a regional scale, analyses of the ground-water flow system using flow nets and "coarse-mesh" digital models have been done successfully in the karst areas, as discussed in Professional Papers 1403-C through H.