Shoreline changes in west-central Florida between 1987 and 2008 from Landsat observations

Shoreline changes caused by sediment erosion and accretion have important consequences for coastal ecosystems and coastal communities. Assessing such changes over long stretches of coastline, such as along the west-central Florida coast, represents a challenge to coastal zone managers. In this study, we used nine Landsat Thematic Mapper (TM) images from the west-central Florida coast (adjacent to Tampa Bay, FL) to study historical shoreline changes from 1987 to 2008. Specifically, we sought to evaluate the change of shorelines during the cold (1987-1998) and warm (1998-2008) phases of the Atlantic Multidecadal Oscillation (AMO). The cloud-free images selected for this study were collected during the periods when maximum tidal excursions were less than 9 cm from mean sea level, assuring minimal interference from tidal influence. The images revealed that the southern section of the Tampa Bay inlet showed a mean shoreline accretion rate of 1.30 m year(-1) and a cumulative mean shoreline change of 27.29 m over the past 21 years. The northern section of the Tampa Bay inlet showed a mean accretion rate of 0.34 m year(-1), with a cumulative mean shoreline change of 7.06 m during the past 21 years. Both sections experienced beach nourishment conducted by local communities which, while irregular, were effective in reducing beach erosion. The dynamics of opposing shores in the various inlets in the barrier islands of the study region varied substantially, with many showing accretion in the channel on one side but erosion on the other side.