Characterization of the Capibaribe River Dry Bed with Ground Penetrating Radar (GPR)

ABSTRACT For an adequate hydrogeological study of alluvial layers in the semi-arid zone, it is important to know well its geometry and its hydraulics characteristics. Alluvial formations are generally constituted by erosion, transport and sedimentation processes, causing considerable heterogeneity in soil hydraulic parameters and water flow. The present research had as objective to perform a geophysical characterization using the Ground Penetrating Radar – GPR in the dry bed of the Capibaribe river. To the extent that depositional layers exhibit changes in water content, granularity, sediment type and layer orientation, the water table as well as sedimentary structures and lithological contacts tend to be identified, making the method effective for hydrogeology research. The study area comprises alluvial dry river bed of upper Capibaribe river in the municipality of Santa Cruz do Capibaribe. The results showed that GPR was efficient in the imaging of the subsurface contributing to the knowledge of the geometry and the stratigraphy of the aquifer of the dry bed of the river. In the dry bed of the river, with 400 MHz antenna the signal reached a depth of 2.65 m, and with the antenna of 200 MHz, the signal reached a depth of 6.00 m. The capillary fringe was identified at a depth of 3.0m with the use of 200MHz and 400MHz antennas.