Northeastern Section - 51st Annual Meeting - 2016

Paper No. 60-1
Presentation Time: 8:00 AM-12:00 PM

RELATIVE FLOW INTENSITY ANALYSIS OF MODERN AND HISTORICAL TROPICAL ATLANTIC HURRICANES


CASHMAN, Miranda1, WOODRUFF, Jonathan D.1 and DONNELLY, Jeffrey P.2, (1)Department of Geosciences, University of Massachusetts Amherst, 611 North Pleasant St, 233 Morrill Science Center, Amherst, MA 01003, (2)Geology & Geophysics Department, Woods Hole Oceanographic Institution, MS #22, 266 Woods Hole Rd, Woods Hole, MA 02543, mirandacashm@umass.edu

Hurricanes and tropical storms can cause devastating fatalities and expensive structural damage within coastal communities. In our warming climate, we do not yet understand how climate change will affect hurricane frequency or intensity, making accurate climate and storm proxies necessary to protect against hazardous storms. This study aims to better understand tropical Atlantic hurricane frequency and relative intensity by studying historic storm event sedimentation in a blue hole basin off the southern coast of South Andros, Bahamas. We determined coarse fraction every centimeter of our core, which preserves a 600 year record of tropical cyclone activity, and indicates a period of frequent storm events. To further assess relative hurricane flood intensity, we ran coarse fraction samples >15 percent coarse on the Camsizer for grain size analysis. We ran settling tube velocity tests for different grain size increments to produce a relationship between grain size and settling velocity. This relationship allowed our team to approximate the settling velocity of our storm-deposited grain sizes. Our grain size data provides a relationship between grain size and settling velocity for South Andros storm deposits. By setting shear velocity equal to settling velocity, we calculated the minimum bottom shear stress needed to transport the coarse storm deposits found in the core. Our minimum bottom shear stress analysis creates a basis for assessing relative flow intensities during historical hurricanes.