Waves and currents interacting with bottom sediments produce changes in the beach and
nearshore bathymetry. These changes can occur very rapidly in response to storms, or slowly as
a result of persistent but less forceful seasonal variations in waves and current.
Since 1981 the FRF has been conducting
detailed surveys of the nearshore bathymetry.
These data now cover fifteen years and
include hundreds of surveys. This data set is
unmatched worldwide in terms of accuracy,
and temporal coverage. They provide
quantitative measures of the dynamic nature
of the nearshore zone, including during
storms when changes are most rapid. In
addition, the natural long-term cycle of beach
erosion and rebuilding, which may take many
years, is well documented. These data are
being used to refine theories of nearshore
morphologic change and to develop and test
numerical simulations of nearshore response
to changing conditions.
Nearshore bathymetry at the FRF is characterized by regular shore-parallel contours, a moderate
slope, and a barred surf zone (usually an outer storm bar in water depths of about 4.5 m and an
inner bar in water depths between 1.0 and 2.0 m.) This pattern is interrupted in the immediate
vicinity of the pier where a trough runs under much of the pier's length, ending in a scour hole at
the pier's seaward end where depths are up to 3.0 m greater than the adjacent bottom. Profile
configuration is typically single-barred with the most active zone extending from the base of the
dune to about the 6-m (20-ft) water depth. Maximum vertical change occurs just seaward of the
The surveys are conducted over a series of 26
shore perpendicular "profile lines" which
extend from the dune to approximately 950 m
offshore. These lines which are surveyed
monthly during the "Bathymetry Survey" are
shown in the figure above. In addition, 4 of
the 26 lines (58,62,188, 190) are surveyed
biweekly as part of a "4-line Survey."
Suggested reading for anyone planning to use FRF survey data. Easily printable.
PROGRAMS FOR PROCESSING SURVEY DATA: ISRP & VOLUME