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Purpose
To collect, compile, and assimilate historic and modern shoreline
data into a common form, and then use that data to determine
how shorelines behave in response to various forcings including
storms, sea level rise, and coastal engineering projects. Research
Team
Stephen P. Leatherman - Principal Investigator
Bruce Douglas - Senior Scientist
Keqi Zhang - Assistant Research Professor
Frank Galgano - Affiliated Research Professor Major
Study Areas Along The U. S. East Coast
- South Shore of Long Island, New York, principally the barrier
beaches from Jones Beach Island to East Hampton.
- Delmarva--Delaware, Maryland and the Virginia barrier islands.
- Northern Outer Banks of North Carolina, focusing on the area
from Duck to Cape Hatteras.
- Florida's southeast coast, especially the "Gold Coast" from
Palm Beach to Miami.
Current Findings
The scientific research completed during the first phase of Coastal
Processes Research project, funded by the Andrew W. Mellon Foundation,
yielded important new results in coastal geomorphology, including
the following:
- The largest and most accurate database of shoreline positions
ever assembled for the U.S. East Coast was quality controlled
and put into a computerized Geographical Information System (GIS).
This historical shoreline change data set spans the last 150
years and provides the best means of determining long-term erosion
rates.
- About 86% of the U.S. East Coast (NY-SC) beaches were shown
to be experiencing erosion, whose rate varies on a kilometer-by-kilometer
basis.
- Tidal inlets cause downdrift barrier beaches to develop an "arc
of erosion" that was shown to be a dynamic feature which
evolves in a predictable way dependent upon the longshore sediment
transport. Also, 70% of beach erosion was shown to be caused
by inlet activity.
- There is an underlying long-term rate of beach erosion equal
to about 150 times the rate of sea level rise, confirming for
the first time the so-called Bruun rule that relates beach erosion
to sea level rise.
- Very large storms cause losses of beach width in a few days
that may require a decade or more for recovery back to a position
consistent with the long-term trend; this implies that coastal
storms, while causing severe episodic erosion and damage to buildings
and infrastructure, play little to no role in long-term erosion.
- Analysis of storm surges derived from 20th century hourly water
levels for the U. S. East Coast shows that the erosion potential
of severe nor'easters depends critically on the storm tide and
storm surge; a storm erosion potential index (SEPI) was derived
to quantitatively express the relative role of storm surge and
time during the tidal cycle of storm occurrence.
- Analysis of hourly water levels during the 20th century demonstrates
that there is considerable interdecadal variation of storminess
along the U. S. East Coast, but no evidence of a trend in the
last century. The increase of loss due to coastal storms in recent
decades is due to coastal development, and not an increase in
the number of severe storms.
On-Going Research
Airborne laser (LIDAR) mapping instrumentation has been acquired,
enabling the project to efficiently monitor long stretches of
shoreline. Techniques to identify the high water line in LIDAR
observations
are being developed so that new LIDAR data sets can be compatibly
combined with our 150-year historical record. With the advent
of the LIDAR technology, we are able to continue (with greatly
increased
resolution in a temporal sense) our investigation of modes of
shoreline behavior, particularly focusing on storm-induced erosion
and post-storm
recovery, which are major unresolved issues in coastal process
science and engineering models.
For Information Contact
Dr. Stephen P. Leatherman, Director
PHONE: (305) 348-1607
FAX: (305) 348-1605
EMAIL: leatherm@fiu.edu
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