DELINEATION OF INLET HAZARD AREAS IN NORTH CAROLINA

The establishment of Areas of Environmental Concern (AECs) forms the foundation of the North Carolina Coastal Resources Commission's (CRC) permitting program for regulating coastal development. The Inlet Hazard AEC boundaries were originally approved by the CRC in 1979. Aerial photography diapositives were used to create a time series of historical shoreline positions. Best-fit curves of linear and quadratic regressions of shoreline trends were established along shore-perpendicular transects spaced at 300-foot intervals. The landward most 99% confidence interval projected to occur between 1978 and 1988 along a given transect represented the limit of the inlet hazard area at that transect (i.e., a 1% chance that shoreline position would exceed the designated hazard area at any time within the 10 years following the analysis). Presently, the inlet hazard AEC boundaries are more than fifteen years out of date. To address this situation, a new methodology considers a much larger digital shoreline database. Both the rates of change (linearly regressed) and standard deviations of shoreline positions, established at 50-m transect intervals, are used as proxies to identify the point along the oceanfront shoreline where inlet-related hydrodynamics no longer dominate coastal processes. From this point, the boundaries of the hazard area polygon are established using a combination of average and maximum beach width measured from the landward-most position of all shoreline data unique to each transect. Lateral migration or oscillation trends and rates, elevation, geomorphology, nearshore geology, and anthropogenic factors (e.g., dredging, channel relocation, beach fill projects, engineered structures) are also considered.