Changes in Tidal Tilt Associated With Surfactant Infiltration Into the Vadose Zone
Abstract
Data gathered during a three year deployment of 3 Pinnacle Tiltmeters at the University of Arizona Maricopa Research Center have been analyzed. The instruments were installed near an irrigation field site in August and September of 2002. The first irrigation was with water only during a six week period in the fall of 2003. This was followed one year later by six weeks of irrigation with a solution containing 150 ppm of a bio- surfactant. The tiltmeters have a resolution of a fraction of a nanoradian (a tilt of 1 micron over 1 kilometer). The solid Earth tides are on the order of 100 nanoradians and emerge clearly from the data when environmental tilt events and long term drift, resulting e.g. from the installation, are removed. We are reporting on subtle changes in tidal tilt caused by changes in surface tension within the vadose zone resulting from infiltration of the surfactant. We utilize site specific theoretical tilts as a reference against which we search for these subtle tilt changes. The analysis of the data is ongoing. Both, using exponential functions to remove large background tilts interactively, and using fully automated polynomial fitting result in anomalies associated with the surfactant infiltration. The search for anomalies has been extended from the periods surrounding the irrigation times to the entire data set.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.H51G0943Q
- Keywords:
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- 1831 Groundwater quality;
- 1835 Hydrogeophysics;
- 1838 Infiltration;
- 1875 Vadose zone;
- 1895 Instruments and techniques: monitoring