Paper No. 9-0
RANKEY, Eugene C., Dept. of Geol. & Atmos. Sci./Virtual Reality Applications Center, Iowa State University, 253 Science I, Ames, IA 50011,

Coastal regions are very dynamic and vulnerable environments that are impacted a mix of biological and physical controls. The purpose of this study was to assess the spatial patterns of sediment accumulation and temporal changes on parts of the modern tidal flat system of Andros Island in the Bahamas. The primary data for this analysis include historical aerial photos and Landsat and ultra-high resolution (1 m) remote sensing data. These data sets were analyzed through a quantitative, statistical analysis of the spatial patterns using a GIS and by comparing the historical and satellite data.

The results of the spatial analysis suggest that subfacies area-frequency and lacunarity (gap size distribution) data exhibit power-law relationships over several orders of magnitude, indicating fractal characteristics and self-organization on the tidal flat. Spatial self-organization suggests that the system is characterized by non-linear process-response dynamics and chaotic behavior.

Comparison of historical aerial photos and recent remote sensing images illustrate that the entire coastal system, from the shoreline to the inland algal marsh, is changing. The shoreline is presently locally eroding, low algal marshes are contracting, several channels are extending headward, and shallow mangrove ponds are expanding. In this system, geomorphic evidence suggests that the in the Holocene, the shoreline and other geomorphic elements may not have migrated gradually, but instead moved in ‘jumps,’ perhaps reflecting extreme events.

These results illustrate two major points: 1) the entire coastal system is changing, not just the shoreline; and 2) this tidal flat appears to be significantly influenced by chaotic processes. Both results highlight the importance of holistic, multi-scale spatial and temporal study for deciphering the dynamics of coastal systems.

North-Central Section (36th) and Southeastern Section (51st), GSA Joint Annual Meeting (April 3–5, 2002)
Session No. 9
Shoreline Processes: Ocean Coastal and Great Lakes Issues
Heritage Hall: West
1:20 PM-4:40 PM, Wednesday, April 3, 2002

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