Comment:

The relative exposure of a reach of coastline to storm waves is a qualitative indicator of the potential for shoreline erosion. A given stretch of shoreline is generally exposed to either oceanic waves or locally-generated, wind-driven waves. Also, for a given wave height, waves that have a longer period have more power than shorter waves. Coasts that are exposed to the open ocean generally experience a higher exposure to waves than sheltered regions because winds blowing over a very large distance, or fetch, generate larger waves. Additionally, exposed regions experience the effects of long period waves, or swells, that were generated by distant storms. The model estimates the relative exposure of a shoreline point to waves Ew by assigning it the maximum of the weighted average power of oceanic waves, Eow and locally wind-generated waves, Elw. The model computes the wave exposure index at each shoreline point ranking from very low exposure (rank=1 for the 0-20 percentile) to very high exposure (rank=5 for the 81-100 percentile).