GROUND-PENETRATING RADAR AS A TOOL FOR MAPPING THE PHREATIC-SURFACE, BEDROCK PROFILE, AND ALLUVIAL STRATIGRAPHY IN THE SABIE-RIVER, KRUGER-NATIONAL-PARK

This study evaluates the effectiveness of ground-penetrating radar (GP R) as a non-destructive, sedimentological tool for mapping the phreati c surface bedrock profile, and alluvial stratification within a homoge neous, sand-gravel fluvial deposit in the Sable River, Kruger National Park, South Africa. The bedrock topography was mapped using a 90 MHz center frequency antennae pair and a 500 MHz center frequency antennae was wed to achieve higher resolution for mapping the phreatic surface and alluvial sediments. The phreatic surface and bedrock profiles det ermined using GPR correlate well with ground-truthing data (R(2)=0.97 and R(2)=0.85, respectively). A groundwater monitoring system and phys ical probing provided the independent estimates of the phreatic surfac e and bedrock depths, respectively. Dynamic cone penetration (DCP) tes ts were used to infer interfaces between sediments of different Size a nd composition characteristics. The DCP interfaces assisted with the i nterpretation of the high-frequency radar imagery, enabling a detailed description of the alluvial stratigraphy.