Observing systems and their importance for determining the significance of coastal storms

The major coastal storms experienced this past winter in the Northeast have brought up the recurring question: “Just how bad was it?” Recent work by Herrington & Miler (2010) and Munger & Kraus (2010), among other suggests that without observing systems consisting of at a minimum wave observation platforms and tide gauge records this question cannot be addressed in a satisfactory manner. Traditional means of assessing storm impact and severity on the basis of water level alone, failed to accurately reflect the severity of the Winter 2010 coastal storms. This has important implications as a variety of coastal management decisions rely solely on water level based analyses.

The November 2009, “Friday the 13th” storm was a glaring example of the importance of considering multiple inputs from an ocean observing system. The storm which resulted in a Federal Disaster Declaration in 12 NJ counties and caused over $50 million in damage statewide, produced a relatively modest storm water level of 7.32 ft MLLW, making it only a 5-10 year storm based on water level. The vast gap between the damage resulting from the storm and its classification as relatively minor storm highlighted the importance of considering factors such as storm duration and wave height. The March 2010 storm provided another example. Water levels during the storm only reached 6.61 ft MLLW, equivalent to that associated with a 2 year storm. Once again, the damage to New Jersey's beaches far exceeded what would be expected during a modest 2-yr storm. A more complete analysis however, including wave energy and storm duration more accurately suggests the storm had a return period closer to 6 years.

Integrated forecast models such as New York Harbor Observation and Prediction System which rely heavily on data assimilated from regional ocean observation systems represent the next link in providing valuable information to coastal stakeholders. As predictions of parameters such as storm surge and wave height, direction, and period, become more accurate, they can be looked at prior to or even during an event to help coastal decision makers make sound, science based, judgments.

References Herrington, T.O., and Miller, J.K., 2010. A Comparison of Methods Used to Calculate Northeaster Damage Potential. Shore and Beach, Vol. 78, No. 2, 20-26. Munger, S., and Kraus, N.C., 2010. Frequency of Extreme Storms based on Beach Erosion at Northern Assateague Island, Maryland. Shore and Beach, Vol. 78, No. 2, 3-12.