Transient Electromagnetic Surveys Collected for Delineation of Saline Groundwater in the Genesee Valley, New York, October-November 2016

Publication Date

2017-08-01

Start Date

2016-10-26

End Date

2016-11-15

Johnson, C.D., White, E.A., Williams, J.H., and Kappel, W.M., 2017, Transient Electromagnetic Surveys Collected for Delineation of Saline Groundwater in the Genesee Valley, New York, October-November 2016: U.S. Geological Survey data release, https://doi.org/10.5066/F79C6VXX.

Surface geophysical methods can provide information for the characterization of the subsurface structure of the earth for aquifer investigations. Transient electromagnetic induction (TEM) surveys (also called time domain electromagnetic (TDEM) surveys) provide resistivity soundings of the subsurface, which can be related to lithology and hydrogeology. In the TEM method, electrical current is cycled through a wire in a transmitter loop (Tx), which in turn produces a static magnetic field. When the current is abruptly terminated, an instantaneous current is induced in the earth, and it moves downward and outward as the induced current decays with time. The decay is controlled by the resistivity of the earth. A receiver (Rx) at the center of the Tx loop measures the secondary magnetic field as a function of time (dB/dt). Decaying voltage measurements at the receiver are converted to apparent resistivity, which can be inverted to recover the depth-dependent resistivity structure of the earth.

• USGS New York Water Science Center