Water-borne towed-transient electromagnetic survey data, along the Ouachita River near Blankston, Louisiana, October 2018

Publication Date

2022

Time Period

2018-10-21

Eric A. White, Carole D. Johnson, Ryan F. Adams, Shane J. Stocks, Wade H. Kress, James R. Rigby, and John W. Lane, Jr., 2022, Water-borne towed-transient electromagnetic survey data, along the Ouachita River near Blankston, Louisiana, October 2018: U.S. Geological Survey.

Type: Online Link Type: catalogItemUrl

Surface geophysical methods can provide information for the characterization of the subsurface structure of the earth for aquifer investigations. Floating transient electromagnetic (FloaTEM) surveys provide resistivity soundings of the subsurface, which can be related to lithology and hydrogeology. In the floating 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) towed behind 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 Lower Mississippi-Gulf Water Science Center

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