The mapping of shallow aquifers using ground EM surveys has become a standard approach. Fitterman et al. [1991] compare two ground EM methods, terrain conductivity meter (TCM) measurements and transient electromagnetic (TEM) soundings, in a study of a paleochannel aquifer in the Emirate of Abu Dhabi. This study showed the value of integrating surface and well log information to refine geophysical models. Taylor et al. [1991] used a TEM survey in an area of alluvium-covered volcanic flows near Reno, Nevada, to construct resistivity pseudo-sections and soundings. The pseudo-sections identified high conductivity areas associated with brecciated fault zones and clays. The soundings identified depths of potential aquifers. Hoekstra et al. [1992] used TEM measurements to map the approximate boundary between drinking water and brackish water in the Floridan aquifer. TEM measurements have also been used to locate the fresh-water/salt-water interface in coastal aquifers on Cape Cod [ Fitterman and Dennehy, 1991]. Traditional direct current resistivity work continues to play an important role in ground water [ Zohdy and Bisdorf, 1991; Zohdy et al., 1992] and salt-water intrusion studies [ Zohdy et al., 1993].
Reprocessing of seismic reflection and velocity data from a petroleum exploration project has been used to investigate a shallow aquifer system in an area of Abu Dhabi. Woodward and Menges [1991] used near-surface seismic velocity and layer thickness measurements (uphole data) to map the water table and the dune sand-alluvium contact. Woodward [1994] used reprocessed seismic reflection profiles to extract information about shallow (<550m) structural features that impact the aquifer system.
Ground penetrating radar has been used to map aquifer thickness and stratigraphy in glacial and fluvial deposits [ Beres and Haeni, 1991]. Lucius and Olhoeft [1993] examine statistical properties of GPR reflections in an attempt to estimate heterogeneity and scale of a shallow alluvial aquifer. Haeni [1994] shows examples of GPR and seismic reflection profiles collected on ponds, lakes, and rivers to obtain subsurface geologic and hydrologic information.