Wave swash and backwash, berm building, longshore bar formation
Beach profiles respond dynamically to waves through onshore (swash) and offshore (backwash + undertow) sediment transport. During calm conditions, constructive swash builds a berm above the waterline. During storms, high-energy waves erode the berm and deposit an offshore bar. The Iribarren number (ξ = tan β / √(H/L)) distinguishes spilling (ξ < 0.5), plunging (0.5–3.3), and surging (ξ > 3.3) breaker types, each with distinct transport signatures. Dean's parameter (Ω = H / w_s T) separates erosive (Ω > 6) from accretionary (Ω < 1) conditions.