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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 45 (1995), Pages 31-37

Episodic Atmospheric Forcing and Bayside Foreshore Erosion: Santa Rosa Island, Florida

Charles K. Armbruster, Gregory W. Stone, J. P. Xu

ABSTRACT

Preliminary findings indicate that atmospheric forcing associated with intense winter storms plays a significant role in the evolution of bayside shorelines along the Northeast Gulf of Mexico. Retrogradation of the north-facing bayside foreshore profile can exceed 1.5 m due to a single frontal passage, where the fetch is "non-limiting." Although masked within long-term effects of a rise in relative sea-level in the Gulf, chronic erosion is evident at sites where the fetch is large by outcropping of peat deposits on the foreshore, exposure of in situ tree roots, and erosion of dune/beach-ridge deposits. Data suggest that during cold front passages augmented wind forcing can produce dramatic changes in water levels in Pensacola Bay and significantly increase or decrease the depth of water in which storm waves propagate.

During the winter of 1995, a series of beach profiles was surveyed along the north shore of Santa Rosa Island, Florida to quantify morphosedimentary changes on the foreshore during several frontal passages. For one of these events an array of instruments was deployed including a two-dimensional current meter, an ultrasound sensor, an anemometer, and a wind vane to monitor wind and hydrodynamic conditions. Data indicate that strong post- frontal winds can exceed 9 m/s and produce along-shore currents capable of transporting sediment to the east.


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