MĀLAEKAHANA AND LĀÔIE AREA DESCRIPTION
The beach at Mālaekahana and LāÔie Bays (transects
0 - 189) are located on the northeast coast of Oʻahu between Makahoa and
LāÔie Points of Oʻahu. Mokuʻauia (Goat Island, transects 190 -
196) is located 700 ft offshore of Kalanai Point. The beaches are composed of
calcareous sand. Headlands and offshore islets are composed of lime stone. The
area is exposed to refracted north swells during winter months and easterly
tradewind waves throughout the year.
The beach from Makahoa Point through Kalanai Point
(transects 0 - 19) has experienced little long-term change since 1928, with
most rates under 0.1 ft/yr. Historical shorelines and biannual beach profile
surveys (near transect 77) indicate this beach is prone to shorter-term change
(interannual - seasonal) with varying portions of the beach eroding or
accreting. Though long-term rates are low, short-term erosion can still pose a
serious hazard to beach-front property. The beach at
Kalanai Point is particularly unstable related to wave refraction around
Mokuʻauia.
The remainder of the beach at LāÔie Bay (transects 120
- 189) has experienced moderate to high rates of accretion since 1928
(>1ft/yr at some transects). LāÔie Point is a barrier to southerly
sediment transport causing sand to accumulate on its northern side.
A small beach on the leeward side of Mokuʻauia (Goat
Island, transects 190 -196) has experienced low rates of erosion (< -0.5
ft/yr) since 1928. Much of the erosion occurred between 1995 and 2011.
Hwang (1981) found the shoreline at Malaekahana and
LāÔie was approximately stable or accreting from 1949 - 1975, except at
Kalanai Point which experienced erosion. A follow-up
study by Sea Engineering (1988) found accretion throughout the study area and
recovery of the shoreline at Kalanai Point Both studies note instability of the
beach at Kalanai Point due to complicated wave refraction around
Mokuʻauia.
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; Mālaekahana Bay; LāÔie Bay; Makahoa Point;
LāÔie Point