CETN II-33
(9/94)
types of beach fill design alternatives: (1) typical U.S. design, consisting of a flat berm extending
from the base of a dune line or existing structure seaward, then tapering to the existing sea bed with a
slope ranging from 1:10 to 1:30; (2) storm berm design, which is a berm with two levels, one of
which is intended to be sacrificial for building an offshore bar during a storm; (3) profile nourish-
ment, in which the fill is placed along the active profile from the berm crest to a depth offshore, as
proposed by Bruun (1988); and (4) protective dune design, consisting of a large protective dune with-
out a berm. They concluded that all designs withstood the impact of one northeaster or hurricane, but
the subaerial volume change varied. Their results suggested that the best design for protection of the
backshore area against storm impacts is a protective dune.
Kraus and Larson (1988) and Larson and Kraus (1989b) applied SBEACH Version 1.0 to two types
of beach fills with equal volumes, a Bmun-type fill and an artificial berm. The profiles were sub-
jected to a synthetic northeaster and hurricane of moderate intensity. The hurricane had a duration of
12 hr, with a peak surge of 2 m, and a duration above half the peak surge (1 m) of 6 hr. The north-
easter surge had a duration of 36 hr, with a peak surge of 1 m, and a duration above half the peak
surge (0.5 m) of 18 hr. The authors also varied grain size from 0.2 mm to 1.0 mm. Simulation
results indicated that the hurricane and northeaster produced about the same amount of erosion, with a
magnitude comparable to that observed on the mid-Atlantic coast for 2-5 year storms. Therefore, al-
though the northeaster had a lower peak surge, its longer surge duration was approximately equal in
erosion capacity to the higher surge of the shorter duration hurricane. They concluded that storm-
induced beach and dune erosion cannot be uniquely specified through a single storm-related parameter
Initial)
-----
Profile
Final)
Profile
300
400
500
600
700
800
900
1000
Distance Offshore (ft)
Figure 1. Measured and predicted profile response using calibrated SBEACH at POP with 199
HalIoween storm (from Smith et al. 1993)
5
CETN 9/94
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