Beach Profile Changes

beach and low bluff, storm waves breaking
Storm at Cape Lookout National Seashore, North Carolina.

NPS photo.

The profiles of beaches change in response to changing wave conditions, which can occur on a seasonal timeframe or during an individual storm. For many areas, low-energy waves dominate in the summer and storm waves dominate in the winter; thereby, coastal geomorphologists use seasonal descriptors to distinguish between low- and high-energy wave conditions. They describe the beach profile’s response to storm conditions through comparison of the “bar profile” and “berm profile.” Berms are landward-sloping shelves of sand on the backshore of a beach; bars are offshore ridges, banks, or mounds. When low-energy waves are present, the beach profile is generally characterized by a wide berm and smooth offshore profile; this low-energy profile is referred to as a “berm profile” as well as a “summer,” “normal,” or “swell” profile (Komar 1998). During periods of calm wave action, waves run up on the beach face and deposit sand, building the berm seaward and causing a steeper beach-face slope to form (Sorenson 1997). High-energy waves have intensified wave swash and remove sediment from the berm, which is stored offshore in bars parallel to the shoreline in a configuration described as the “bar,” “storm,” or “winter” profile (Komar 1998). Higher and steeper waves common during storm conditions cut back the berm, forming a scarp and flattening the slope of the beach profile (Sorensen 1997).

Last updated: June 5, 2019