APPLICATION OF THE STORM EROSION INDEX (SEI) TO THREE UNIQUE STORMS

Jennifer Wehof,Jon K Miller,Jason Engle

doi:10.9753/icce.v34.management.39

Jennifer Wehof, Jon K Miller + Show 1 more

Open Access

https://doi.org/10.9753/icce.v34.management.39

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Abstract

During 2012 and 2013, the State of Florida was impacted by three tropical weather systems (Debby, Isaac, and Sandy) that caused significantly more beach erosion than similar, traditionally classified storms. Here, the storms are reclassified using the more recently developed Storm Erosion Index (SEI) which takes into consideration both the storm tide and storm waves, as well as the storm duration. The SEI has been shown previously to accurately represent the impact of coastal storms at a number of other sites (Miller and Livermont, 2008). When reanalyzed with the SEI, Tropical Storm Debby was found to be more significant in terms of beach erosion potential than any other storm in the record (since 1996), ranking as a “Category 5” storm with a return period of 23.4 years. Hurricane Isaac, which followed closely on the heels of Debby, ranked as a “Category 2” storm with an associated return period of 3 years. A sensitivity analysis performed on the results indicated that the wave steepness threshold used to separate erosion and accretion was particularly important during Isaac, as the conditions throughout the storm remained close to the threshold. While Hurricane Sandy is more known for the devastation it caused in the northeast, it also caused significant beach erosion in the State of Florida. The SEI more accurately reflects the significance of the beach erosion experienced during Sandy, and ranks the storm ahead of all of the other storms in the record (since 1994), including Hurricanes Frances, Gordon, and Jeanne which all made landfall near the area considered. Overall, Sandy registered as a “Category 5” storm in terms of beach erosion potential, with a return period of 40.5 years.

Highlights

Storms are one of the major threats to beaches and coastal infrastructure due to their often sudden impact and extreme power
The severe beach erosion caused by Debby resulted from the fact that the storm stalled in the Gulf of Mexico and generated an extended period of elevated waves and water levels
A return period calculated by fitting the Storm Erosion Index (SEI) data to a generalized pareto distribution (GPD), using a peaks over threshold (POT) approach suggests that a storm like Debby has a return period of 23.4 years

Summary

INTRODUCTION

Storms are one of the major threats to beaches and coastal infrastructure due to their often sudden impact and extreme power. Traditional measures of storm intensity consider stage frequency analyses of individual parameters such as water level, storm surge, or wave height alone. Northeasters are a specific type of non-tropical storm common along the US East Coast For these storms, there is no direct relationship between wind speed and the amount of damage potential (Herrington and Miller 2010); they cannot be classified in the same manner as hurricanes. The maximum value of the IEI during a storm can be used define a Peak Erosion Intensity (PEI), which represents the erosion potential of the storm at its apex. The storm duration is defined as the period of time during which the wave height or water level exceeds the mean plus two standard deviations. Combining the datasets gives a record that extends back to 1996 for the west coast and to 1994 for the east coast

RESULTS

Cum SEI ASWE

CONCLUSIONS