geofísica aplicada, prospecção de água subterrânea, recursos hídricos em rochas cristalinas
Abstract
Groundwater prospection in crystalline rocks concentrates mostly on identifying the presence and location in the field of fractures as being the most suitable sites for drilling deep wells. Among the several available geophysical methods used for this kind of investigation, this paper describes the use of the VLF (Very Low Frequency) method in the states of Bahia and Ceará, northeast Brazil. In Bahia the geophysical work was carried out on existing dry, salt water and potable deep-wells in order to correlate both geophysical and hydrogeological data. In Ceará the VLF survey was used to locate the most favorable points to be drilled. Deep wells were constructed to supply drinking water to farms, industries and urban communities. The results obtained so far in Bahia barely show any direct correlation between the geophysical and hydrogeological data of the drilled deep-wells. In Ceará the results of the drilled deep-wells at the located structures may conclude for a high rate of certitude.
