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We thank Corbett and Cable (2003) for questioning our results and for pointing out the great number of studies that have employed various forms of seepage meters. It was the ever-increasing use of seepage meters and the spurious results we obtained that led us to warn the seepage meter community of possible defects in the method. Apparently our choice of an eye-catching title served its purpose. It was never our intent to perform the kind of engineering style quantitative tests that we hope this exchange will stimulate. We purposely used larger collection bags, because preliminary experiments with smaller bags showed they filled to capacity in less than 24 hr. For reasons of efficiency and the large spatial nature of our meter distribution, it was not practical to sample on hourly or multi-hour schedules. Our purpose therefore was to obtain 24-hr measurements that would average about four tidal intervals. Because our monitoring wells vividly showed tidal pumping and water transport are limited to the porous and permeable Pleistocene limestone, we chose to permanently seal our meters directly to the rock. Lee-type meters, on the other hand, must be placed in the sedimentary veneer that caps about 25% of the limestone in eastern Florida Bay (Prager and Halley 1999). Unlike most other areas where meters have been used, ground water entering the Lee-type meters in the Florida Keys ultimately comes from and is driven by tidal pumping and leakage from the underlying limestone. We are nevertheless surprised and pleased that the Lee-type meters of Corbett and Cable produced seepage rates paralleling those we obtained directly from the rock. Clearly, their meters were placed either in permeable shelly or marine grass-covered shell and lime mud sediments where permeabilities are greater than on bare lime mud substrates. Such areas are riddled with |
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