(b) The specific functions and protective values of different types of natural protective features may vary. Certain types of natural protective features are intrinsically better suited for certain types of uses, activities, or development than others. The standards and development restrictions of this Part that apply to regulated activities within specific types of natural protective features are based on:

1. (1) the protective functions that specific types of natural protective features provide; and
2. (2) the interaction between specific types of natural protective features and physical coastal processes.

(c) Described below are the erosion protection functions of various types of natural protective features and their relationship to physical coastal processes. These descriptions are to be used to guide the review of coastal erosion management permit applications as required in sections 505.5-505.9 of this Part, and in the review of variance requests as required in section 505.13 of this Part.

1. (1) Beaches buffer shorelands from erosion by absorbing wave energy that otherwise would be expended on the toes of bluffs or dunes. Beaches that are high and wide protect shorelands from erosion more effectively than beaches that are low or narrow. Beaches also act as a reservoir of sand or other unconsolidated material for longshore littoral transport and offshore sandbar and shoal formation.
2. (2) Bluffs protect shorelands and coastal development by absorbing the often destructive energy of open water. Bluffs are of greatest protective value during times of storm-induced high water. Bluffs are a source of depositional material for beaches and other unconsolidated natural protective features.
3. (3) Dunes, along with bluffs and beaches, buffer shorelands from the energy of open water. Like bluffs, dunes are of greatest protective value during conditions of storm-induced high water. Because dunes often protect some of the most biologically productive as well as developed coastal areas, their value as protective features is especially great. The two primary functions of dunes are prevention of wave overtopping and storage of sand for coastal processes. High, vegetated dunes provide a greater degree of protection than low, unvegetated ones. The keys to maintaining a stable dune system are the establishment and maintenance of beachgrass or other vegetation on the dunes and assurance of a supply of nourishment sand to the dunes.
4. (4) Nearshore areas dissipate a substantial amount of wave energy before it is expended on beaches, bluffs or dunes by causing waves to collapse or break. Nearshore areas also function as reservoirs of sand, gravel and other unconsolidated material that is returned to beaches. Sandbars, which are located in nearshore areas, control the orientation of incoming waves and promote the development of ice-cap formations which help to protect shorelines during winter storms. The roots of aquatic vegetation in nearshore areas bind fine-grained silts, clays and organic matter to form a fairly cohesive bottom that resists erosion. Such vegetation also assists in trapping sediments.