Integrating millennial and interdecadal shoreline changes: Morpho-sedimentary investigation of two prograded barriers in southeastern Australia

摘要: Abstract Prograded barriers are distinctive coastal landforms preserving the position of past shorelines as low relief, shore-parallel ridges composed beach sediments and commonly adorned with variable amounts dune sand. have been valued archives which contain palaeoenvironmental information, however integrating millennial timescale geological history observed inter-decadal modern processes has proved difficult. Technologies such airborne LiDAR, ground penetrating radar (GPR) optically stimulated luminescence dating (OSL) were utilised at Boydtown Wonboyn, in southeastern Australia, combined previously reported radiocarbon dates offshore seismic sedimentological data to reconstruct morpho-sedimentary prograded barrier systems. These technologies enabled reconstruction integrated an model ridge formation explaining GPR-imaged subsurface character barriers. Both Wonboyn began prograding ~ 7500–8000 years ago when sea level attained or near present height along this coastline continued until present-day initially slower rate shoreline advancement. Sources sediment for progradation appear be inner shelf shoreface a large sand body likely contributing Wonboyn. The Towamba River seems delivered Twofold Bay during flood events after transitioning mature estuarine system sometime ~ 4000 cal. yr BP. Some material appears reworked onto barrier, increasing seaward 50% deposited over ~ 1500 years. GPR imaged beachfaces shown similar geometry profiles following recent storm involving cut fill beachface, building backshore, explains preserved beachface record morphology ridges. This is applicable future management individual beaches where subject ongoing fill, inherited budget conditions.