Lack of Impact of Hurricane Michelle on Tidal Flats, Andros Island, Bahamas: Integrated Remote Sensing and Field Observations

Abstract

ABSTRACT Major storms commonly are cited as important geomorphic and sedimentologic agents, and their significance is perhaps most emphatically noted in interpretations of modern and ancient tidal flats. The purpose of this study was to assess the impact of Hurricane Michelle on the carbonate tidal flats of Andros Island, Bahamas, by coupling remote-sensing data and field observations. Although regional MODIS remote-sensing data reveal that the passage of Hurricane Michelle suspended sediments across the shallow bank, integrating ultra-high-resolution remote-sensing data with field observations demonstrates that the hurricane had almost no impact on the Andros Island tidal flats. This lack of impact is surprising because the storm still had hurricane-force winds as it passed immediately over some of the focal areas. With this hurricane, storm strength and intra-storm interval were probably not limiting factors. Instead, several influences combined to minimize the storm's impact on both sedimentation and erosion, including the low level of water on the bank resulting from ebb tides and, in the northwestern area, from offshore storm winds, and the short duration of the storm resulting from its high forward velocity. Given the apparent prevalence of widespread storm effects on ancient tidal flats, but the spatially limited major geomorphic impacts of storms on many modern systems, we suggest that the geologic evolution and preservation of ancient tidal-flat successions may have been shaped by mega-storms that simply cannot form in the present global climate. Nonetheless, understanding tidal-flat dynamics and changes on human timescales will require continued monitoring and assessment of low-impact storms such as Michelle, as well the more sensational hurricanes that produce widespread death, destruction, and deposition.