APPLICATION OF TOPOGRAPHIC ANISOTROPY FOR ASSESSING BARRIER ISLAND MORPHOLOGY

The resiliency of a barrier island, its ability to return to form and ecological function after storms, is of key scientific importance with further climate change and sea level rise. Response depends on relative height of the storm surge and the dunes, both heavily influenced by anthropogenic activities. The primary step in quantifying response to and recovery from environmental impacts threatening the longevity of barrier islands is differentiation of the dune(s) from back-barrier and beach structures with efficient delineation of the dune toe, crest, heel, washovers and blowouts. Barrier island morphology and the anisotropic nature of barrier islands highlights the complexities of topographic evolution. The purpose of this research is to identify the anisotropic properties of barrier island topography that reflect process regimes (i.e. wind dominated, wave dominated, current dominated) and morphological characteristics related to resiliency. The method presented is a multi-scale, directional-dependent assessment of topographic relief. A LiDAR-derived DEM portion of North Padre Island, Texas, USA was used to examine topographic anisotropy at a scale out to 250m. By computationally assuming topographic symmetry, it is possible to examine terrain anisotropy through geo-visualized ellipses and graphed anisotropy parameters. Results demonstrate that this new methodology is feasible and useful for assessing the anisotropic fabric of barrier islands. Furthermore, results demonstrate that beaches, washover channels, foredunes, and back-barrier regions exhibit unique anisotropic parameters. Consequently, anisotropic parameters have the potential to be used for assessing barrier island geomorphology and island resiliency in context of future climatic uncertainty.