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Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Geosciences

Year Degree Awarded

2015

Month Degree Awarded

May

First Advisor

Jonathan D Woodruff

Second Advisor

William D McCoy

Third Advisor

Don J DeGroot

Subject Categories

Atmospheric Sciences | Geomorphology | Oceanography | Other Earth Sciences | Other Oceanography and Atmospheric Sciences and Meteorology | Sedimentology

Abstract

Hurricanes are powerful storms that can cause billions of dollars in damage and kill many people when they strike populated coastal areas. Understanding how frequently coastal cities can expect storms of a certain magnitude would help inform more effective mitigation and adaptation strategies. Unfortunately, current estimates of hurricane frequency rely on numerical models based on weather observations that, on the east coast of the United States, only extend ~150 years into the past. While this is sufficient for estimating the characteristics (i.e. wind speed and storm surge height) of annual or decadal storms, the properties of larger, rarer, and more destructive storms have much uncertainty associated with them. Therefore, longer records of storm activity are needed to more accurately estimate the characteristics of these storms.

Such records can be found in coastal ponds. Nearshore sediments entrained in storm surges can form overwash deposits in these ponds. These deposits are easily distinguishable from lacustrine sediments due to their different grain size, organic content, and mineralogy. The grain size distribution and thickness of each deposit are related to the height and duration of the storm surge which created it and in turn this storm surge is related to the magnitude of the storm, itself. Additionally, lacustrine sediments can record regional changes in sediment supply and deposition rate.

Here, I present a 2500 year long reconstruction of hurricane intensity and activity from St. Marks, Florida and a 3000 year long reconstruction from Staten Island, New York. The St. Marks record reveals millennial-scale changes in hurricane intensity that may be related to the past position of the Loop Current (an oceanic surface current). The Staten Island reconstruction contains deposits of every recorded storm which produced a >2 m surge in New York City, including an 1821 hurricane which was more powerful than Hurricane Sandy. Finally, the Staten Island record shows a sudden decrease in hurricane deposits before 1600 CE, coincident with European colonization of the area. This is due to the removal of the oyster beds from the harbor which protected the coast from storm induced erosion.

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