NGWA Event and Education Recordings Archive

Groundwater studies are always limited by the availability of subsurface data points and the uncertainty of interpolating conditions between the points.  Shallow geophysical methods can help but most high resolution methods are limited to a few hundred feet and most deeper methods lose resolution below 500 to 1,000 feet.  The problem is most acute when exploring for deeper aquifer where the cost of drilling is high and the amount of available data is low.  Fortunately large parts of the country have been covered with high-resolution seismic reflection surveys for oil and gas exploration that can typically be purchased for a fraction of the original acquisition costs.  This data was collected to explore for resources much deeper than for most groundwater studies but advances in processing and interpretation software have made it easy to reprocess and reinterpret the data to explore for aquifers from depths of about 500 feet to many thousands of feet. 

Seismic reflection surveys are able to map fine scale stratigraphic details to depths of several thousand feet.  Modern processing and interpretation techniques can identify permeable sand zones, faults, and other stratigraphic and structural features that control well yield.  Seismic data can be combined with shallower geophysical methods, such as electrical resistivity to fill in the shallow zone and obtain a nearly complete image of the subsurface in higher resolution than ever before.  This is providing new opportunities to explore for new sources of water and identify the structure of the aquifers to develop more accurate groundwater models.

Several case histories will be presented to demonstrate how modern interpretation methods can be used on older 2-dimensional or more modern 3-dimensional seismic reflection data to map features such as sand channels, faults, and shale pinch outs of aquifer units.