MAPPING COASTAL TERRAIN DYNAMICS AND STRUCTURAL CHANGE USING A GIS-BASED ANALYSIS OF LIDAR DATA TIME SERIES

High-resolution, multi-year lidar surveys conducted over multiple years are now available for North Atlantic coastal regions, offering unprecedented insight into topographic change and land surface evolution. Two methods for quantification of land surface evolution and assessment of changes in structures have been developed for time-series of raster DEMs derived from lidar point clouds: (a) A feature-based method that extracts specific morphologic features (peaks, dune crests, or shorelines) from raster DEMs for each time snapshot using gradients, curvatures, and slope lines and then measures their vertical change and horizontal migration; (b) A raster-based method that applies a per-cell statistical analysis to high-resolution raster DEM time series, generating new type of maps that characterize the temporal evolution of land surface while preserving the original spatial resolution of the DEM. Extraction and quantification of both discrete and continuous changes is incorporated, including new methods for identification of changes in built structures (i.e. new construction, destruction, or redevelopment of buildings).

These methods were applied to selected sections of barrier islands of the North Carolina Outer Banks to quantify the spatial and temporal evolution of (i) large active dune system in a state park, (ii) the beach-foredune system in developed areas, and (iii) development and loss of buildings. The dynamics of the barrier island system during times of hurricane impact is compared with its evolution during periods of relative calm.