resulting in wide V-zones. The latter approach would be easy to apply and in 

 some areas may be the only rational approach. In actuality, dunes can 

 provide an important level of protection if they are of sufficient height and 

 width. In those areas with effective dunes, a method for estimating 

 potential storm erosion is desirable. 



7. To be of use to FEMA, a dune erosion prediction method must fulfill 

 a number of criteria. It must 



a. Be compatible with existing FEMA methodologies for computing 

 the nearshore hydrodynamics. 



b. Incorporate FEMA predictions of water level and wave height. 



c. Be easy to use and allow consistent application. 



d. Be relatively insensitive to uncertainty in input variables 

 such as the prestorm beach configuration, the duration of the 

 storm, and the sediment size. 



e_. Be deterministic and incorporate relationships which link the 

 erosion process to the physical characteristics of the storm 

 event . 



f. Have undergone calibration and verification with field data. 



Considerable research is currently under way which will improve both our 

 understanding of erosion/overwash processes and our ability to predict them. 

 This study is based on the capabilities of existing methodologies. The three 

 candidate methodologies finally selected for detailed consideration have only 

 recently become available, dating from 1982 or later, and work on them 

 continues. New reports on each were published subsequent to the completion 

 of the first draft of this report and are briefly noted here. 



Scope 



8. The report herein is organized into seven parts and one Appendix. 

 Part II introduces basic nomenclature, discusses the process of beach 

 erosion, and introduces the concept of an equilibrium profile. Part III 

 examines in detail the requirements and suitability of theoretical sediment 

 transport models. Part IV discusses three models which are currently used 

 for estimating dune erosion. Two of the methods are compared in Part V. 



