TWO YEARS OF CONTINUOUS DATA FROM THE OMEGA CAVE SYSTEM: WHAT HAVE WE LEARNED SO FAR? (Invited Presentation)

A network of instruments was installed at a dozen remote sites in the ~48km long Omega Cave System between 2014 and 2015 to measure water temperature, discharge, and specific conductance at 7 weirs, and air temperature and humidity at these plus an additional 5 sites. June 2016 marks the second year of continuous data collection at many of the sites. As with any long-term installation of instrumentation in a field setting, unforeseen problems always present themselves, and this year was no exception. However, the data collected so far are of high quality and the problems are relatively minor; mostly related to battery life and in-cave computer-instrument communication problems.

One of the more surprising findings so far is how different hydrogeochemical (P/T/SC) signals and responses are in each of the 4 tributary streams, and how those responses change substantially over the course of a hydrologic year. For example, not all tributaries respond to precipitation in the early fall season when stored vadose water content is presumably low and ET demand still high, but these same tributaries respond rapidly in the early spring season when ET demand is low and stored vadose water content is presumably high. Responses occur in unexpected directions (with respect to T/SC, in particular), and with a variable magnitude changes when compared across sites. This suggests that the contributing zone for each tributary has substantively different properties, despite the fact that the surface karst appears to be relatively homogeneous in this system.

Because of issues related to downloading data in 2015, analysis after that field season was limited and much of the work so far has been descriptive in nature. However, we are beginning to quantitatively analyze data in an attempt to test a number of hypotheses and in order to explain the variability in the data across time and between sites.

Similar to the first year, our second year of data and work has resulted in both successes and technical problems. The project was designed to be a long-term instrumentation network requiring little maintenance and only annual visits and we hope that by 2017 we will have resolved all technical issues and have the network fully functional and collecting the best data possible.