@rkraft,
wed need to see what th regional water table rises and falls over some time. Is the cycle due to tides? ground-water pumping? or some other cause.
Hs anyone monitored the water table?
At Yadra Pozza in Yugoslavia , there are several karst ponds that fluctuate in water level due to regional water supply pumping ans it can be calculated in m3 (inflow v outflow /m3)