To appear: Proceedings Dredging '02, ASCE, 2002
THE U.S. ARMY CORPS OF ENGINEERS'
COASTAL INLETS RESEARCH PROGRAM
Barry W. Holliday1, E. Clark McNair2, M. ASCE, and Nicholas C. Kraus3, M.ASCE
ABSTRACT: Federal agencies are being required to do more with less. The U.S.
Army Corps of Engineers must maintain existing federal inlet and entrance channels
and respond to authorizations for channel deepening and new channels with a budget
that does not increase commensurately. The answer to serving the Nation's needs in an
era of declining resources is to advance understanding of inlet processes and
incorporate this knowledge in operation and maintenance practices of navigation
projects. The Coastal Inlets Research Program was established 5 years ago with the
mission of advancing knowledge and developing predictive technology to reduce the
cost of dredging, promote navigation channel reliability, and understand the sediment-
sharing interactions between inlets and adjacent beaches. This paper describes this
productive research program and introduces selected results.
Navigation projects located at coastal inlets are designed, operated, and maintained through
complex morphologic features. These features evolve with time scales and rates ranging from
short as in the response to storms to the gradual change exceeding a century as caused by
normally occurring waves and currents (Fig. 1). Because the hydrodynamics, inlet morphology,
navigation channel, and longshore sediment transport are connected, consequences of navigation
project maintenance and natural processes must be estimated to minimize channel dredging and
to promote sediment bypassing, either by natural processes or through dredging-related
activities. In addition to gradual long-term trends, near-discontinuous and periodic changes can
occur as a result of storms, changing weather patterns, dredging, and modifications to jetties.
Both conceptual and quantitative models of stabilized inlets that operate at geomorphic time
scales are lacking, and engineering practice at inlets is based on limited tools available for
evaluating project alternatives. Quantitative predictive models must be developed that can
calculate navigation channel and morphology change, such as at ebb shoals and flood shoals, and
connect the processes to the channels and adjacent beaches. Predictive capability is expected to
occur based on recognition of the space and time scales associated with the target process, as
shown in Fig. 1, and discussion below is put in context of the scales in this figure. Improved
predictive capability will aid in estimating the performance of channels to be deepened,
evaluating advance maintenance dredging, controlling channel migration, reducing channel
shoaling, and preserving and promoting sediment pathways to adjacent beaches.
1) Dredging and Navigation Branch, Construction and Operations Division, Headquarters U.S. Army
Corps of Engineers, 441 G Street, NW, Washington, DC 20314.
2) Clark McNair Consulting, 303 Pinehurst Street, Vicksburg, MS 39180. ClarkMc@canufly.net.
3) U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, 3909
Halls Ferry Road, Vicksburg, MS 39180; .