such as the maximum surge elevation. Comparison of the two types of beach tills indicated that the
Bruun fill experienced greater initial erosion during the early stages of wave action, but also greater
recovery in the post-storm period. As mentioned in a previous section, the authors also found that
eroded volume tended to decrease as grain size increased from 0.2 mm to 0.4 mm, with only slight
decreases in the volume eroded for grain sixes from 0.4 mm to 1.0 mm. They concluded that it may
not be cost-effective to use beach fill with a median grain size much greater than 0.4 mm, due to the
typically greatly increased cost of larger sized material and declining benefit in decreased eroded
volume.
Recent mode3 improvements. Storm response data from the Ocean City, Maryland beach fill project
were used to develop and test the over-wash algorithm presently included in Version 2.0 of SBEACH.
During January 2-5, 1992, a strong northeaster struck Ocean City, Maryland. As part of an emer-
gency assessment of the beach fill project performance, numerical simulations of profile response to
the storm were conducted using SBEACH. Post-storm profile measurements were not yet available at
the time. Preliminary simulation results showed little erosion of the dune, whereas site inspections
indicated that significant erosion had occurred, with the dune being totally removed at some locations.
It was reasoned that the high waves and water levels associated with the storm caused significant dune
overwash which was not being simulated by the model. Therefore SBEACH was modified to include
an overwash algorithm, which produced results in qualitative agreement with site inspections. Figure
2 shows a comparison between the measured (pre- and post-storm) and predicted profiles at Ocean
City, using SBEACH Version 1.0 (calculated without overwash algorithm) and Version 2.0 (calculat-
ed with over-wash algorithm) with the January 2-5 northeaster storm data set.
Measured 2 Nov 9l
Measured 11 Jan 92
Calculated without
Overw.as.h. .A.lgorithm
. .. . .
Calculated with
Overwash Algorithm
-w-e-
74th Street
50
100
150
250
300
Distance from Baseline, m
Figure 2. Comparison of SBEACH Versions 1.0 and 2.0 using the Ocean City, Maryland data set
CETN 9/94
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