New Spreadsheet Methodology to Filter Transducer Data

The use of pressure transducers to measure groundwater response to pumping or injection produces large sets of data that contain the desired response information but also instrument noise, drift, and the influence of rhythmic and non-rhythmic phenomena.   

The most common rhythmic influence affecting groundwater levels during a short-term (hours) pumping test is tidal fluctuations. Non-rhythmic influences on groundwater head in wells include diurnal variation in atmospheric (barometric) pressure, evapotranspiration, and recharge from precipitation.  The latter two are usually not influences that manifest in head level over the course of a short-term test of a confined aquifer.   Barometric fluctuation, however, can cause head level variation of up to six inches per day.  Vented transducers assume 100 percent barometric efficiency and are prone to complications with the venting system from suspension and/or moisture issues.

A methodology and spreadsheet formula are presented that can separate the response to pumping from unwanted barometric influence.  This methodology was used to obtain and filter barometric influence from several sets of pumping test data with good results.