Ground‐penetrating radar and sedimentological analysis of Holocene floodplains: Insight from the Tuross valley,New South Wales

Ground‐penetrating radar (GPR) has been used on an array of floodplain types on the lower Tuross River, in southeastern New South Wales, as part of an investigation into controls on channel‐floodplain relationships. Ground‐penetrating radar transects from two floodplains are presented, along with sedimentological detail from trenches dug along the profiles at key locations. Sedimentological investigations showed that 100 MHz antenna gave an approximation of overall bedding trends in the upper 3 m when automatic gain control processing was used. Spreading and exponential compensation processing provided insight into textural changes associated with increased silt content distal of the levee crest. One trench showed that thinning beds were responsible for onlapping reflectors. Signal attenuation at ～4 m depth below the raised floodplain surface resulted from a >50 cm‐thick bed of sandy clay. The close integration of GPR and sedimentological data produced an excellent dataset, that enabled form‐process associations and floodplain evolution to be established for these sandy floodplains. However, accurate subsurface assessment and interpretation must stem from carefully combined GPR and sedimentological datasets.