A low-frequency (6–8 per minute) spilling wave, with a long wavelength and a low crest, running gently up the beach. Swash greatly exceeds backwash (which is reduced by percolation), leading to deposition. Spilling waves usually occur on gently sloping beaches, and may form beach ridges and berms (Hughes (2004) Coastal Eng. 51, 11–12; Coelho and Veloso-Gomes (2004) J. Coast. Res. SI-39). See Cooper et al. (2000) Water & Env. J. 14, 2 on beach profiling.