EXPERIMENTAL DESIGN OF DYE TRACE TO OBSERVE WATER FLOW FROM CONDUIT TO MATRIX

Recent modeling and in-situ aqueous geochemistry measurements have shown movement of water from phreatic conduit to matrix due to hyporheic flow or flood pulses. However, for some karst scientists, only a dye trace gives unambiguous proof of water flow. To our knowledge there has not been a successful dye trace from conduit to matrix, despite careful attempts.

We will attempt several dye traces to detect flow from conduit to matrix in Wakulla Spring Cave, near Tallahassee, Florida. Rather than attempting to detect the dye in wells near the conduit, we will place dye receptors in narrow boreholes drilled (< 1m) into the matrix from conduit wall. This will require underwater coring and instrumentation of the core holes with a multilevel sampler. We have developed both sets of hardware for this application.

A reviewer of our tracer test called it “some of the most delicate work I've seen proposed”. We would like to improve the test design and are actively soliciting comments and suggestions. There will be prototypes of the underwater pneumatic drilling system and multilevel sampler at the poster. The poster will describe our evolving experimental plan, and show our preliminary computational fluid dynamics modeling of dye injection and sampling extraction. Engineering plans for the pneumatic drilling system and multilevel sampler will be available at the poster.