Beach profiles at GLO06 and GAL01(see plot at bottom for locations) measured with electronic total station July 19, 2001, are compared with lidar last return and last return intensity collected July 17, 2001. The lidar data are compared with the ground data (total station survey) to determine how well beach features correspond. The wet/dry line (wet sand to dry sand) from the ground total station surveys matches well with the break in last return intensity values from more reflective (light, dry sand) to less reflective (dark, wet sand).

Lidar last return intensity image with hillshading of northeast end of Galveston Island State Park and southwest end of Pirates Beach subdivision. Dark sargassum at water's edge, as seen in photos above, is portrayed as a bright ridge seaward of the wet/dry line. The upper berm crest and wet/dry line are approximately 0.6 m above sea level. Therefore, the +0.6 m contour line was chosen to represent the shoreline for the 2001 survey. The wet/dry line and berm crest are the beach features that are typically mapped from aerial photography to represent the shoreline.