January 13, 2004
14:37
WSPC/101-CEJ
00097
513
Analytical Model of Incipient Breaching of Coastal Barriers
-- Greenwood and Keay, 1979). In a storm report documenting the damage of the
September 1967 Hurricane Beulah, the US Army Engineer District, Galveston (1968)
states that an inspection team found 31 breaches along 48 km of North Padre Island,
Texas, barrier beach. A book edited by Leatherman (1981) collects classic, primarily
descriptive papers on the processes, sedimentation, and morphology of overwash and
breaching. Other papers are discussed below to supplement and update information
in Leatherman (1981).
Dent (1935) documents the breaching of a 90-km long barrier beach at Ocean
City, Maryland, during an August 1933 hurricane. This breach was quickly stabi-
lized with jetties to form Ocean City Inlet and protect its federal navigation entrance
channel. Terich and Komar (1974) document the breaching of Tillamook Spit, Ore-
gon, that experienced a reduction in longshore sediment source by the construction
of a jetty. At high tide, the water-filled breach at Tillamook was nearly 1.2 km
wide. It was closed four years later by the construction of a setback rubble stone
revetment, with a sandy beach filling the indentation.
Rice (1974) describes closure conditions for the mouth of the Russian River, Cal-
ifornia. He noted an apparent causal relation between opening of the river mouth
during strong stream flow, and closure of the mouth to the season of largest waves
and greatest longshore transport. Nishimura and Lau (1979) discuss possible means
of minimizing closure of the mouths of small streams and propose innovative struc-
tures to promote hydraulic breaching by early-arriving storm flows as the eroding
agent. Kraus, Militello, and Todoroff (2002) document breaching of a barrier spit
by elevated water level in Stone Lagoon, California, and discuss the common occur-
rence of breaching of the Humboldt State Park, California, lagoons at the end of
spring, the season of maximum precipitation. The barrier spits fully enclosing the
Humboldt lagoons breach from the lagoon side when the water level rises to about 4
m above mean sea level. The lagoon breaches open to maximum dimensions within
several hours, similar to dike failure, remain open at low tide for days to weeks but
may be passable at high tide, then close through infilling by longshore sediment
transport.
Smith and Zarillo (1988) document the growth of an artificially induced breach at
Mecox Pond, Long Island, New York, that remained open during September 1018,
1985. Mecox Pond and neighboring coastal ponds are breached by digging a channel
to the Atlantic Ocean when precipitation raises the level of the ponds to threaten
flooding of neighboring property. Figure 1 shows (a) the west bank of the channel,
and (b) the length of a breach at Mecox Pond that was cut from a narrow pilot
channel in February 1998. Steepness of the walls of the highly rectilinear breach is
evident.
Terchunian and Merkert (1995) document two barrier island breaches formed
at Westhampton, Long Island, New York, for which the first and initially larger
breach (Fig. 2) closed by longshore transport and moderate engineering actions. A
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