USING GEOGRAPHIC/MARINE INFORMATION SYSTEM (GIS/MIS)FRAMEWORKS TO DETERMINE SPATIAL VARIABILITY OF BEACHSEDIMENTS AND NEARSHORE GEOMORPHOLOGY IN SUBTROPICALSOUTHEAST FLORIDA

摘要

Along the subtropical barrier reef coast of southeast Florida, relativelyrnlow-energy surf zone dynamics and extreme clarity of seawater permits acquisition ofrndigital, color, aerial photographs that discriminate seabed features to at least 10 m depth.rnThe morphologic features identified from large-scale aerial photography (e.g. 1:3600)rninclude coral-algal and rock reef tracts, a wide range of sedimentary features andrnengineering works. In spite of the complexity of the coastal geomorphic system, it isrnpossible to analyze the interrelationships and feedback mechanisms betweenrnmorphological features using a remote sensing-GIS/MIS (Geographic and MarinernInformation Systems) framework and applying interpretive approaches in the analysis ofrnbeach types and nearshore morphodynamics. In an effort to ascertain the best approach tornmorphodynamic interpretation, this research compares the Wright and Short (1984)rnmodel of beach and nearshore morphological change with observed morphologies ofrncoastal segments along the lithologically controlled SE Florida coast. Calculatedrndimensionless fall velocity (?) values are combined with beach and nearshorernmorphology mapped from aerial photographs to define beach types. Omega (?) resultsrnindicate a predominance of intermediate type beaches, several process-response formsrnand unique beach-hardground-bar configurations were mapped on the aerial photographsrnand used to divide the study area into six distinct morphozones that display therncomplexity of this geomorphologic setting. Although Palm Beach County beaches arernsimilar in range to the intermediate beach types described by Wright and Short (1984),rnsome adjustments are necessary to include morphologic feedbacks that result fromrnsediment starvation and exposure of hardgrounds in southeast Florida.