crest, no appreciable damage occurs on or behind the dune. Breaching can 

 occur due to erosion even though the peak surge level is below that of the 

 dune crest. This category of storm-related damage can not be directly 

 correlated with the local stage -frequency relationship since it requires a 

 means of evaluating dune erosion as a function of storm intensity. Erosion of 

 a dune of known cross -section and composition can be computed as a function of 

 a specific storm event hydrograph. The erosion volume computed from this 

 storm event can be assigned a frequency of occurrence corresponding to the 

 peak surge level of the storm; however, this volume is not uniquely a function 

 of the stage and return period of the storm. For example, erosion is depen- 

 dent on variables such as tide elevation, storm duration, surge elevation and 

 hydrograph shape, offshore wave conditions, wind velocity and direction, etc. 

 (Kriebel 1982, 1984 a, b, Kraus and Larson 1988, Larson and Kraus 1989). 

 Since events of equal surge elevation and frequency do not necessarily produce 

 identical erosion rates, the development of a dune recession-frequency of 

 occurrence relationship requires the simulation of an ensemble of storms with 

 known peak surge elevations and corresponding frequencies of occurrence. 



A project was initiated at the U.S. Army Engineer Waterways Experiment 

 Station's (WES) Coastal Engineering Research Center (CERC) to develop a means 

 of addressing the above problem in order to evaluate the effec-tiveness of 

 existing and proposed dune configurations along the New Jersey coastline from 

 Sea Bright to Manasquan (Figure 1) . The approach adopted was to combine a 

 numerical dune erosion model with an existing storm event data base. Both 

 components described below, have been used at CERC in previous coastal 

 studies . 



DUNE EROSION MODEL 



The dune erosion model used in this study is a modified version of the 

 model developed by Kriebel (1982, 1984a, 1984b) and Kriebel and Dean (1985). 

 It is a one -dimensional model based on the equilibrium offshore profile 

 concept first postulated by Bruun (1954) and further verified by Dean (1977). 

 This concept assumes that the offshore profile can be described by the 



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