EROSION WITHOUT SEAWALL PROTECTION 
EROSION WITH 
SEAWALL PROTECTION 
INITIAL PROFILE 
Figure 23. Conceptual seawall effects 
the measured and computed volumes of erosion above MSL. 
144, The report by Birkemeier et al. (1987) concluded that the Kriebel 
model is capable of predicting order of magnitude estimates of erosion rates 
for storm events of known intensity and duration. Limited sensitivity testing 
was also performed in which the change in computed volumes of erosion result- 
ing from the alteration of certain key model parameters was investigated. 
Results showed the model to be stable with respect to these parameters if they 
were specified within reasonable limits. None of the 14 profiles referred to 
in Table 7 contained a seawall. In order to verify the seawall simulation 
modification of the model in the present study, additional sets of data were 
sought which were appropriate for that purpose. 
145. The scarcity of pre- and post-storm survey data for locations 
seaward of a seawall-backed beach is primarily due to the fact that post-storm 
surveys rarely concentrate on areas where no structural damage took place. 
Unless a seawall is undermined or experiences failure, quantitative measure- 
ments documenting the erosion of the beach directly in front of the seawall 
are often not made. However, one data set was obtained that was acceptable 
Te 
