REMOTE SENSING COASTAL BATHYMETRY USING MULTIBEAM SONAR

摘要

Aerial photography, like this 1:24,000 NOAA NAPP mosaic, can be scanned,georeferenced, and mosaicked together to give detailed, high-resolution digital images oflarge areas; however, these images are limited to shallow, clear water (approximately20m depth) for determination of coral habitats. Multibeam sonar bathymetric surveyingtechniques can provide a more clear view of both shallow and deeper reefs. A multibeam4-meter resolution bathymetric survey of an area of Southeast Florida from 5 m to 250 mdepth was conducted January 5-29, 2001 under contract for by NAVOCEANO for theSouth Florida Ocean Measurement Center. This survey extended from 1 km offshore toapproximately 8 km and stretched from 13 km north and 16 km south of Port Evergladesinlet, Broward County, Florida. Depth contours, sunshading, and displays in 3dimensional perspective enhanced analysis interpretations of sea floor features. The wellknown First, Second, and Third Reef terraces (5, 10, and 20 m depth) are well depicted.Two deeper, previously unknown terraces were revealed in 45m and 90m depth. Themorphology of the 45m features is consistent with a Holocene coral reef possibly formed11,000 years before present during the Holocene sea level rise. The 90 m feature may beof reefal origin as well. Its age may be approximately 16,000 ybp. Future coring andradiocarbon dating will test these initial hypotheses.