‘Ō‘ōmanō study area is characterized by a narrow sand beach and hardened shoreline. The area is bounded by Kekaha Beach to the west and Kīkīaola Small Boat Harbor to the east. The beach is composed of black volcanic sand, mud, and calcareous sand. Terrestrial material is primarily delivered by the Waimea River which is located to the east.
The shoreline is exposed to south wave swell during the summer and occasional wrapping of northwest waves during the winter as well as persistent tradewinds. ‘Ō‘ōmanō Point (aka Davidson’s Point, transects 59 – 61) lies central to the area and effectively divides the area into two sections for description purposes. Previous studies* discuss the impact of Kīkīaola Small Boat Harbor, built in 1959, which interrupts alongshore sediment transport from the east. The resulting erosion at and near ‘Ō‘ōmanō Point has threatened Kaumualiʻi Hwy. and led to the construction of an extensive revetment by the U.S. Army Corps of Engineers to mitigate further erosion.
Overall, the ‘Ō‘ōmanō study area (transects 0 – 106) is experiencing erosion with an average shoreline change rate of -1.9 ft/yr. The eastern section of the area (transects 0 – 59) is experiencing erosion with an average shoreline change rate of -2.5 ft/yr while the western section (transects 61 – 106) is eroding with an average shoreline change rate of – 1.2 ft/yr.
*Makai Ocean Engineering and Sea Engineering, 1991 Aerial Photograph Analysis of Coastal Erosion on the Islands of Kauai, Molokai, Lanai, Maui, and Hawaii. State of Hawaii Office of Coastal Zone Management Program.
Last updated: July 2021
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