VERTICAL SHAFT HYDROLOGY AND EVOLUTION WITHIN THE MAMMOTH CAVE SYSTEM, KENTUCKY
The third phase is currently in the early stages at the Ednas Dome shaft complex. Flow and water chemistry parameters from both free falling and wall film water are being measured with two-minute resolution, either directly (spC, pH, and temperature) or indirectly (relating spC to directly analyzed key ions). Within a single bed around the shaft's perimeter, eight evenly spaced stations have paired electronic wetness indicators and micro-erosion pins. With limestone dissolution kinetics rate expressions these data allow calculation of the predicted wall retreat rate for each of the shaft's eight sections, which will then be compared with the direct and independent measurements using the erosion pins.
Preliminary results indicate a good linear fit between spC and bicarbonate (r2=0.81 for the shaft waters) but much lower for the calcium (r2=0.27)sulfate concentrations (x=10.8 mg/L) may indicate the presence of gypsym contributing an additional source of calcium adding complexity to the relationship. From directly measured samples, fluctuations in parameters (as measured by coefficients of variation(CV)) range from about 9% for spC to 19% for calcium. Water temperatures are also equilibrated to the aquifer temperature by the time they reach the shaft, with a CV of only 3% through the winter of 2001-02.