A coastal storm hazard assessment involves two different activities. The first is classification of ground conditions and the second is translation of that information into a storm hazard vulnerability index. Present ground morphology and any man-made alterations of the land were first interpreted in the laboratory using three independent visual sources:
The video tapes and slides are oblique low-altitude photographs of the beach obtained during helicopter surveys with horizontal positions determined by a Global Positioning System (GPS).
- airborne color video surveys,
- 35 mm aerial color slides, and
- Digital Orthophoto Quarter Quadrangles (DOQQs) obtained from the U.S. Geological Survey EROS Data Center in Sioux Falls, South Dakota (http://edc.usgs.gov/index.html).
The video surveys, slides, and DOQQs were used to prepare the coastal classification units (Fig. 2) and to interpret the geomorphological and cultural attributes of each coastal segment. Elevations of the land surface adjacent to the barren backbeach were obtained by processing lidar data. The highest elevations of the foredunes or beach crest (where dunes are absent) are shown as a series of dots. Each dot is color coded to represent a narrow range of elevations. The units of elevation are decimeters, or tenths of meters.