Rob A. Walker, David R. Basco


A new coastal storm-strength parameter, the Coastal Storm Impulse (COSI) parameter, was introduced at the ICCE 2006 (San Diego) and further discussed at the ICCE 2008 (Hamburg). COSI is based on the conservation of linear, horizontal momentum to combine storm surge, wave dynamics, and currents over the storm duration. Both tropical storms (hurricanes) and extra-tropical storms (northeasters) can produce similar COSI parameters that range from 0.69*10^6 N-m/hr to 49.72*10^6 n-m/hr with lognormal distribution. Potential implications of such a storm classification system include the evaluation of coastal structures and coastal infrastructure, as well as providing a universal storm strength indicator that is directly tied to coastal physical parameters and not limited to wind speed. This paper explores the application of COSI to predict coastal erosion along the sub-aerial ocean beach in Duck, North Carolina on the east coast of the United States. Data for the 10-year study period (1994 to 2003) has been analyzed to produce 249 storms for study of coastal erosion. When profile response to coastal storms was assessed through a pre- and post-storm volumetric determination, mixed results showing both erosion and accretion were observed. The paper also explores the possible explanations and implications of these findings.


coastal storm; beach erosion; storm surge; momentum; impulse

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