Department of Coastal and Oceanographic Engineering, University of Florida
Abstract
This report responds to the 1986 Beaches Bill which, in recognition of the
potential deleterious impact on Florida's beaches of inlets modified for navigation,
mandated a study of those inlets with identification of recommended action to reduce
the impacts. This report addresses west Coast inlets; East Coast inlets are the
subject of a companion report.
There are 37 inlets along that portion of Florida's West Coast commencing from
Pensacola Bay Entrance to Caxambas Pass at the south end of Marco Island. Compared to
those on the East Coast, most West Coast inlets have not had the deleterious effects
on the adjacent beaches, yet all modified inlets without proper management have the
potential of impacting unfavorably on the adjacent shorelines. Moreover, at present
there is interest in opening three West Coast entrances which either have been open
in the past (Midnight Pass) or which have opened occasionally (Navarre Pass and
Entrance to Phillips Lake).
A review of inlets in their natural condition demonstrates the presence of a
shallow broad outer bar across which the longshore transport Occurs. These shallow
and shifting bar features were unsuitable for navigation which in many cases has led
to the deepening of the channels and fixing with one or two jetty structures. Inlets in this modified state along with inappropriate maintenance practices have the
potential of placing great ero$ional stress along the adjacent beaches. Moreover.
channel dredging can reduce wave sheltering of the shoreline by ebb tidal shoals and
alter the equilibrium of the affected shoreline segments. The ultimate in poor sand
management practice is the placement of good quality beach sand in water depths too
great for the sand to reenter the longshore system under natural forces; depths of 12
ft. or less are considered appropriate for Florida in order to maintain the sand in
the system.
With the interference of the nearshore sediment transport processes by inlets
modified for navigation, if the adjacent beaches are to be stabilized there must be
an active monitoring program with commitment to placement of dredged material of
beach quality on shoreline segments of documented need. Several East Coast inlets
have such transfer facilities; however. the quantities of sand transferred should be
increased. Although an evolution and improvement in the technical capability to
manage sand resources in the vicinity of inlets is expected, an adequate capability
exists today and a concerted program should be made to commence a scheduled
implementation of this capability at those entrances causing greatest erosional
stress on the adjacent shorelines.
A brief summary review for each of the 37 West Coast inlets is presented
including: a scaled aerial photograph, brief historical information, several items
related to sediment losses at each inlet and special characteristics relevant to
State responsibilities. For each inlet, where appropriate, the above infor~tion is
utilized to develop a recommenced action. (PDF has 101 pages.
