Investigating coastal geomorphological response to the passage of Hurricane Dean 2007 in the Southern Caribbean: Cocos Bay, Trinidad

Abstract

Hurricanes form part of the annual weather phenomenon for many Caribbean territories during the months of June to November. Trinidad and Tobago lies south of the main hurricane belt and direct hits from these events are seldom, although, their associated effects from swell waves and spiral bands are experienced. This paper investigates the passage of Hurricane Dean on 17 th August 2007, and its associated effects on the beach profiles and sediment of Cocos Bay. While this hurricane did not make landfall, the effects on the coastal system are due to the storm generated swells which travelled outwards from the storm centre toward the east coast of Trinidad. Data was collected from 2005 to 2007 and included littoral processes, beach profiles and sediment data using standard geomorphological techniques. The beach's response to the event varied spatially along the bay. While beach erosion is typical at other Caribbean beaches during the passage of these extreme weather systems, at Cocos Bay, some areas accreted while others eroded. Results indicate that the beach's response to this high energy event is dependent on the state of the beach prior to the event. Morphological change seem to be fuelled by bar formation and migration which is enhanced by the passage of a high energy event. A proper understanding of the effects of high energy events on low-latitude tropical beach systems exposed to the Atlantic is invaluable towards informing proper management in a region forecasted to have increased and enhanced Tropical Cyclonic activity due to global warming.Keywords: beach system, beach erosion, beach accretion, extreme event, swells, beach sediment IntroductionTrinidad and Tobago's geographical location places its east coast against the high energy environment of the Atlantic Ocean and its tropical cyclone generating potential. Each year, tropical storms and hurricanes ravage the Caribbean region. Though Trinidad is the most southerly, and not usually directly hit by such tropical storms, the swell waves they generate impact the east coast (Darsan, et al., 2013). There have also been occurrences where hurricanes have made landfall producing storm surges along the east coast. The passage of these cyclonic weather systems add energy to the existing coastal processes and can therefore have significant impact on the beach and coastal system's equilibrium.The beach morphology of a coastal area is not static, but is dynamic, and changes in response to coastal processes and the movement of sediments. As such, morphology changes are influenced by wave energy, sediment characteristics, and their interaction. The beach profile area can be defined as extending from the low water of spring tides to the upper limit of wave action (King, 1972). Nearshore processes shape beach morphology (Hardisty, 1990), but there is feedback where morphology influences the processes at work in the nearshore (Komar, 1976). Beaches and their adjacent nearshore zones act as buffers to wave energy. As a result, they are sensitive to change over ...