Using GPR and EM to characterize barrier island transgression along the Texas Coast

A series of geophysical surveys using ground-penetrating radar (GPR) and electromagnetic induction (EM) were conducted at Padre Island National Seashore (PAIS), Texas to characterize barrier island transgression at a range of spatial and temporal scales. The first study (June, 2010-January, 2011) used GPR and vibracores to investigate variations within the internal structure of various-sized foredunes along a 2.5 km length of the non-driving (restricted vehicular access) section of PAIS. Three representative foredunes with different heights were selected within the storm impact regime proposed by Sallenger (2000). A small (1.79 m), intermediate (2.69 m) and large dune (3.77 m) represent inundation, overwash and collision regimes, respectively. The second preliminary study (May, 2013) used the EM induction method to measure spatial variations in apparent conductivity across the intermediate dune site surveyed by GPR in 2010-2011. A 100 m long EM transect was conducted in close proximity to the 2010-2011 GPR survey area. Additionally, a new GPR survey was conducted along the same EM profile for comparison with the EM data as well as the GPR profile taken in 2010-2011. Currently, we plan to conduct several extensive GPR and EM surveys at regularly-spaced intervals (~15 km apart) within the driving (vehicular accessible) section of PAIS and across the Laguna Madre wind-tidal flat system. © 2013 SEG