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Geophysical Monitoring and Evaluation of Coastal Plain Aquifers
Author(s) -
Land Lewis A.,
Lautier Jeff C.,
Wilson Nathaniel C.,
Chianese Gabrielle,
Webb Steven
Publication year - 2004
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.2004.tb02450.x
Subject(s) - aquifer , geology , depth sounding , coastal plain , borehole , groundwater , water well , inversion (geology) , basement , hydrology (agriculture) , geophysics , geomorphology , oceanography , geotechnical engineering , paleontology , structural basin , engineering , civil engineering
We use time domain electromagnetic (TDEM) soundings to monitor ground water conditions beneath the coastal plain in eastern North Carolina. The TDEM method measures the earth's response to an induced electromagnetic field. The resulting signal is converted, through a complex inversion process, to apparent resistivity values, which can be directly correlated to borehole resistivity logs. TDEM soundings are used to map the interface between fresh and salt water within coastal aquifers, and estimate depth to basement when siting new monitoring wells. Focused TDEM surveys have identified areas of salt water encroachment caused by high volumes of discharge from local supply wells. Electromagnetic sounding, when used in tandem with the state's network of monitoring wells, is an accurate and inexpensive tool for evaluating fresh water/salt water relationships on both local and regional scales within coastal plain aquifers.