Airborne and ground geophysics applied to groundwater prospection in hard rocks in Irauçuba, Ceara State, Brazil.

Abstract

This work involved geophysical prospecting techniques, remote sensing and litho-structural recognition, applied to groundwater research in a region formed by hard rocks located in Irauc¸uba, Cear´a State, Brazil. Geophysical magnetic and electromagnetic airborne data compiled from PROASNE project (Projeto Agua Subterraânea do Nordeste do Brasil ), Landsat ETM7 satellite images and electromagnetic land data, acquired in this research, were studied and allowed mapping lineaments related to geological structures, properly characterized by structural recognition on the field. The integrated analysis of geophysical and geological data, including hydrogeological information from deep wells, allowed understanding the pattern of fractures in the area, correlating the structures with the geological event responsible for their genesis and determining their hydrogeological potential. The results culminated in a structural-hydrogeological local model to be applied in areas with similar geological features. According to this model, geological brittle structures with approximate N-S direction are little penetrative and contribute to the recharge structures of WNW-ESE direction, which are the most promising for groundwater exploitation through deep wells.