Northeastern Brazil Groundwater Project

Airborne Geophysical Survey Results
Serrinha, Rio Grande do Norte

The map below shows the apparent conductivity at the 4,443 Hz frequency in coaxial configuration for the Serrinha pilot area (approx. 7.5 km x 13.4 km) in the state of Rio Grande do Norte.  

Unlike in the Samambaia/PE and Juá/CE pilot areas, where conductivity highs form distinct linear patterns that are tentatively interpreted as water-bearing fractures and contact zones, the conductivity in much on the northwestern half of the Serrinha pilot area is high throughout indicating the presence of near-surface flat lying conductive material, possibly thick soil or alluvium, or a conductive weathering product from a particular rock type. 

In the southeastern half of the Serrinha area, the background conductivity is considerably lower allowing specific conductive features to stand out. One of these is a very prominent ribbon of high conductivity which follow a river valley. This valley is very distinct on the digital elevation map, and is probably filled with conductive alluvial material. A few north trending linears of higher conductivity are also visible in this southeastern region, which may represent good targets for groundwater. The total field magnetic map suggest that these linears may be fault structures. A large power line transects the eastern part of the survey area and is rendering the data immediately below the power line unusable. 

In spite of the conductive cover in the northwestern half of the area, several fissure type anomalies can be interpreted from the data by working with different frequencies and using the profile information. This allows us to “see” below the relatively shallow conductive material.