Hydrology Update, January 11, 1997
Analysis of All Reported GLOBE Electrical Conductivity Data

Dear GLOBE colleagues,

During the months of October through December, 1996, the protocols of the measurement of electrical conductivity came "on-line" and now we are starting to get information back! As of the end of December, nine schools had reported at least 2 entries for electrical conductivity, and another 12 schools had reported 1 entry. Take a look at what has been recorded in the GLOBE data archive and see what you think!

Here is a quick assessment of what has been reported so far, by school:

• Belton Junior High School, Belton, Texas reports two entries of E.C. measurements from their water site. Both are at very normal levels for a stream system (700 microS, and 745 microS) It will be interesting to see how what data shows up in the future!
• Tabor Academy, Marion, Massachusetts has discovered that their water site consists of relatively pure water with a fairly low E.C. range of 60 microS - 22 microS thusfar. Compare these results to what Okemos High School reports and you'll see what a range of impurity levels natural water systems can have!
• Okemos High School, Okemos, MI measured E.C. with a range of 790 microS - 980 microS! This means that their water is fairly consistently full of dissolved chemicals.
• Mastricola Middle School, Merrimack, NH has reported 2 E.C. entries, 590 and 630 microS. Look at the other graphs and see where this school falls relatively. What would this indicate about the water? Keep in mind that electrical conductivity is an indicator of what ions are dissolved in the water, and may thus describe the rocks through which the water has flown.
• Happy Valley High School, Elizabethton, TN measures their electrical conductivities in a water source with relatively consistent and low values of E.C. (range: 300 microS - 360 microS) We encourage this school to continue reporting data so we know more about what the water is like in Tennessee and how it changes over the course of the year!
• Goethe-Schule, Wetzlar, Germany shows the biggest range of E.C. measurements of any of the schools we looked at. (Range: 339 microS - 993 microS ) They are regularly reporting data every two weeks or so and have found an exciting trend at their site! Over the course of about a month, their E.C. measurements began to climb. What could have caused this change in water chemistry?
• Mittelschule Elsterberg, Elsterberg, Germany shows that their hydrology water system is fairly consistent in terms of the levels of impurities measured. Their E.C. measurements range from 322 microS to 472 microS. Over the course of their measurements, we see that there has been a slow decline in measured conductivities. Why might be causing this?
• Crescent Elk School, Crescent City, CA has been reporting data consistently over the 3 month period. In addition their E.C. measurements appear fairly low and similar. This indicates that there have probably been no substantial changes during this time period and that their water source is fairly pure. We think we see a gently downsloping trend to the data. Do you?
• Chemisches Institut Dr. Flad, Stuttgart, Germany has developed a real reputation among the hydrology team for reporting many data points. Their E.C. measurements are no exception, and show that their water system changes not only over the course of the three month period of time, but also on a daily basis. Their data range all the way from 552 microS to 920 microS. We think we see evidence for individual storm events in the data here, and possibly a seasonal trend in the levels of impurities. Do you agree?

  Other schools reporting only one electrical conductivity entry include:

  • Enka High School, Enka, North Carolina, USA
  • Vinalhaven High School, Vinalhaven Island, USA
  • Jarrow Montessori, Boulder, Colorado, USA
  • Simsbury High School, Simsbury, Connecticut, USA
  • Jarrow Montessori, Boulder, Colorado, USA
  • Talley Middle School, Wilmington, Delaware, USA
  • Pascal College, Zaandam DA, Netherlands
  • Colony Middle School, Palmer, Alaska, USA
  • East Prairie High School, East Prairie, Missouri, USA
  • Kinkaid School, Houston, Texas, USA
  • Canandaigua Elementary School, Canandaigua, New York, USA
  • Carine Senior High School, Carine, Australia

IMPORTANT NOTE:

I hope that this brief report has stimulated some questions. Feel free to send email to me (roger@hwr.arizona.edu) or to my assistant, Chris Gutmann (cgutmann@hwr.arizona.edu).

Sincerely,

Roger Bales
Professor of Hydrology & Water Resources
University of Arizona