SUNSET BEACH AREA DESCRIPTION
The shoreline fronting the community of Paumalū
(transects 119 - 269) on the north shore of Oʻahu is the site of
world-famous big wave surf breaks including Sunset and Velzyland. The area is
exposed to swells from the north Pacific in winter months and easterly
tradewind waves year-round. Sunset Beach is the central portion of a continuous
(4 mi long) beach composed of carbonate sand and characterized by occasional
outcrops of limestone that may be intermittently buried or exposed by shifting
sand.
Shoreline change rates at Paumalū (1928- 2015) are
mostly low (< 1 ft/yr). Large winter swell causes dramatic changes in
shoreline position that largely recover the following season. Because of this,
shoreline change rates at Paumalū have high uncertainty due to short term
variations in shoreline position. Despite wide variations in beach width, the
vegetation line has remained approximately stable since 1928. The high rate
uncertainty and stable vegetation line suggest that the shoreline has remained
approximately stable over the long-term or that seasonal variations are masking
the true long-term change. These characteristics may also reflect shoreline
stabilization by armoring that holds the vegetation line in place. Short-term erosion
is a significant hazard to beach-front homes,
especially in winter with run-up from large waves. A number of beach-front homes were destroyed during a massive winter
1969 swell. Recent episodic erosion
at Sunset Beach Park resulted in damage to the existing bike path.
Previous studies by Hwang (1981) and Sea Engineering (1988)
found little net change or small seaward growth of the vegetation line at
Paumalū 1949 - 1988, except at Sunset Beach Park and at the west end of
Kaunala Beach where the vegetation line eroded. The vegetation line has since
recovered at Kaunala Beach (1988 - 2015).
For more information see: http://www.soest.hawaii.edu/asp/coasts/oahu/index.asp
1 Hwang, D. (1981) "Beach changes on Oʻahu as
revealed by aerial photographs", State of Hawaii, Department of Planning
and Economic Development.
2 Sea Engineering, Inc. (1988) ÒOʻahu shoreline studyÓ,
City and County of Honolulu, Department of Land Utilization.
Keywords:
Oʻahu; Sunset Beach; Velzyland