PART II: PHYSICAL ASPECTS OF BEACH PROFILE CHANGE 



9. This section discusses the general physical aspects of beach 

 profile change and dune erosion. The nomenclature associated with beaches 

 will be introduced together with the major variables believed to control 

 profile change and dune erosion. The natural variability found in measured 

 profile changes is quantified, and the equilibrium beach profile, a funda- 

 mental concept in present dune erosion models, is introduced. Finally, 

 overwash, a major process associated with storms, is discussed. Supple- 

 mentary discussions on the topics of beach profile change and littoral 

 processes can be found in Volume I of the Shore Protection Manual (SPM) 

 (1984) . 



Nomenclature 



10. Standard nomenclature for describing beach profiles is shown in 

 Figure 2. The locations and boundaries of various regions are somewhat 

 ambiguous because of the dynamic nature of the beach. Definitions and names 

 of certain features and regions may also vary from author to author. 



BtACM OR SHORE 



OFFSHORE BAR 0)EST 



Figure 2. Profile features and terminology (SPM 1984) 



11. The profile is usually measured at intervals from some point 

 landward of the dunes, across the profile, until a depth is reached where 

 little net sand movement is expected. This seaward limit, or "closure 

 depth," is on the order of 6 to 8 m (Hallermeier 1979, Birkemeier 1985b). 

 For convenience, the beach profile is conceptually divided into a subaqueous 



