PART VII: SUMMARY AND CONCLUSIONS 



124. This report has examined the merits of both theoretically based 

 and parameterized models for possible use in estimating the impact of dune 

 erosion in mapping high hazard V-zones. Among these, only the empirically 

 based models were shown to produce reasonable results with a minimum of 

 effort and required input data. Of the models evaluated in this feasibility 

 study, the Kriebel model was judged superior to the Vellinga model, not 

 because it produced more accurate results but because it (a) is applicable to 

 a wider range of beach configurations; (b) is less demanding in terms of the 

 accuracy requirements of the input data; and (c) accounts for storms of 

 varying duration. This last capability is particularly important because 

 Atlantic coast beaches are affected by both short duration hurricanes and 

 long duration northeasters. 



125. Currently, the Kriebel model does not fulfill all the 

 requirements of an ideal erosion model. Its limitations include an inability 

 to model offshore bars, a dependence on an overly simplistic profile shape, 

 and an insensitivity to varying wave conditions. Nevertheless, if properly 

 implemented, the Kriebel model is expected to produce reasonably accurate 

 dune erosion estimates, and it is believed that the capability of the model 

 may be improved in the future. 



126. The foregoing conclusion is based on examination of available 

 models, including the comparison given in Part IV. This comparison augmented 

 the limited verification of both the Kriebel and Vellinga models which had 

 been done to date. The Kriebel model was originally developed as a Master's 

 thesis and was evaluated with a single Florida profile surveyed after the 

 1975 Hurricane Eloise. Kriebel (1986) provided additional verification using 

 20 Florida profiles from Hurricane Eloise. Considerable data now exist which 

 would permit a more extensive evaluation. For example, the State of Florida 

 has hundreds of profiles surveyed after storms (Balsillie 1985c, d; Chiu 

 1977). 



127. Time constraints of this study permitted only a limited amount of 

 testing to be conducted. Consequently, if the recommended Kriebel model is 

 adopted, the experience that FEMA gains through use of the model on a wider 

 variety of coastal areas should be applied to improving the model and its 

 implementation. 



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