Spatial characterization, resolution, and volumetric change of coastal dunes using airborne LIDAR: Cape Hatteras, North Carolina

The technological advancement in topographic mapping known as airborne Light Detection and Ranging (LIDAR) allows researchers to gather highly accurate and densely sampled coastal elevation data at a rapid rate. The problem is to determine the optimal resolutions at which to represent coastal dunes for volumetric change analysis. This study uses digital elevation models (DEM) generated from LIDAR data and spatial statistics to better understand dune characterization at a series of spatial resolutions. The LIDAR data were collected jointly by the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the U.S. Geological Survey (USGS). DEMs of two study sites (100 x 200 m) located in Cape Hatteras National Seashore, North Carolina were generated using a raster-based geographic information system (GIs). Changes in the dune volume were calculated for a I-year period of time (Fall 1996-1997) at grid cell resolutions ranging from I x I to 20 x 20 m. Directional statistics algorithms were used to calculate local variance and characterize topographic complexity. Data processing was described in detail in order to provide an introduction to working with LIDAR data in a GIs. Results from these study sites indicated that a 1-2 m resolution provided the most reliable representation of coastal dunes on Cape Hatteras and most accurate volumetric change measurements. Results may vary at other sites and at different spatial extents, but the methods developed here can be applied to other locations to determine the optimum resolutions at which to represent and characterize topography using common GIs and database software. (C) 2002 Elsevier Science B.V. All rights reserved.