Site Characterization of a Restored Coastal Dune and Beach

                                
==Abstract==

Coastal beach and dune ecosystems are critically important for shoreline protection and significant resources have been allocated to their conservation. Dune vegetation is known to modify site response to wind, waves, and storms, but little focus has been given to understanding how belowground sediment structures enhance dune stability. A first step in addressing this knowledge gap is to determine optimal methods to measure subsurface sediment properties in onshore sandy environments. Our team performed a comparison of geotechnical and geophysical methods on a restored beach and dune system on Florida’s Atlantic coast. Methods included two types of dynamic cone penetrometer (DCP) systems, a multi-channel analysis of surface wave (MASW) system, a ground penetrating radar (GPR), soil vibracores, and grain size analyses. Two transects were investigated, a 50-meter cross-shore transect and an intersecting 20-meter along-shore transect. The transects were selected to study the gradient of sediment properties from the swash zone to the high dune. Key findings from this study were that the PANDA DCP provided a higher resolution of measurements compared to the standard DCP, which is extremely advantageous in the shallower, less consolidated soils. MASW shear wave velocity results showed similar trends to the DCP cone tip resistance and allowed for measurement of stiffer soils where the DCP reached refusal.  In addition, the results from the DCP, GPR and vibracores compared well. Thus, the use of the DCP and GPR systems as minimally intrusive testing options in fragile dune systems was verified.