Tem-fast: a useful tool for hydro-geologists and environmental engineers

Abstract

Time Domain Electromagnetic (TDEM) methods have proven to be efficacious in many studies involving environmental and engineering problems, producing better results than the traditional galvanic techniques. In fact, the major advantage of this method is that the soundings can be performed in a relatively short time and in a small place. TDEM sounding appears to be particularly useful for discriminating between layers having low resistivity, but interpretative limitations arise when intermediate and deep resistive layers occur. So the method appears complementary to the traditional electrical soundings. This method has been experimentally tested in well characterised test sites where geophysical investigations (reflection seismic, SEV, IP, gravimetry) and drillings, as well as chemical and isotopic analyses had already been conducted. The results confirm that the method is practical, economic and perfectly reliable, not only at large depths, but also in shallow research, using fast acquisition devices working in the range from 4 ms to some ms.