Beach Profile Variation on Hawaiian Carbonate Beaches

Beach profiles from selected Oahu and Maui beaches quantitatively document beach volume variation and change between 1994 and 1999. Along exposed, high-energy beaches, large fluctuations in beach volume, characterized primarily by the formation and erosion of extensive berms, dominate the seasonal changes. Beaches along more protected stretches of coastline show much less variation in profile morphology. Beaches on the west (leeward) coast of Oahu experienced the most seasonal variation in profile volume, followed by the north shore, east (windward) shore, and south shore. Similar to Oahu, beaches along the west coast of Maui showed the greatest overall profile variation. However, the mean variation for profiles along a single coastal reach showed little difference compared to other coastal segments. Although some beaches showed net gain or loss during the study period, most beaches remained relatively stable with change limited to a finite envelope. No island-wide trends in beach erosion or accretion were observed during the study period. However, no extreme events, such as tropical storms or hurricanes, directly influenced the Hawaiian Islands during the study period. This data set should therefore be considered as representative of typical annual beach activity. Greater variation and possible long-term change would be expected during extreme events.