451004008
451003006
451005051
451005041
451005004
451005045451005046
451005048
451005049
451005047
451005044451005050
451005043
451005008
4510
0500
6
451003011
451003013451
004025
451004
013
4510
0401
5
4510
0401
1451004035
4510
0402
3
451004014
4510
0401
0
451004016
4510
0404
0
30"20" 10" 50"159o22' W 40" 10"20"159o23'30" W
30"20" 10" 50"159o22' W 40" 10"20"159o23'30" W
40"
22o 1
2'30
" N
50"
22o 1
3' N
10"
22o 1
3'20
" N
40"50"
22o12'30" N
22o13' N
10"22
o13'20" N3814 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
32 3433 35 36 37461300mE 463900mE
3814 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 3433
35 36 37461300mE 463900mE
6061
6263
6465
6667
6869
7024559
00mN
7172
7374
7524576
00mN
2455
900m
N24
5760
0mN
6061
6263
6465
6667
6869
7071
7273
7475
HISTORICAL SHORELINES
Erosion rate measurement locations(shore-normal transects)
Historical beach positions, color coded by year, are determined
using orthorectified and georefer-enced aerial photographs and
National Ocean Survey (NOS) topographic survey charts. The low
water mark is used as the historical shore-line, or shoreline
change reference feature (SCRF).
Movement of the SCRF along shore-normal transects (spaced every
66 ft) is used to calcu-late erosion rates.
1927 T-sheetFebJulMay
Sept
MaySept
196219711975
1999
19871988
1984Sept
JanNov
2008 1999
Pilaa, Kauai, Hawaii
400 300200
1200 900600
100
3000
0100
300
Scale 1:3000Meters
Feet
N
Contract C25514 Contract 7249
Charles Fletcher, Matthew Barbee, Siang-Chyn Lim,Julia Ehses,
Matt Dyer and Ayesha GenzUniversity of Hawaii Coastal Geology
GroupSchool of Ocean and Earth Sciences and Technology1680 East
West Road, Honolulu, HI 96822, U.S.A.
The preparation of this poster was financed in part by the
Coastal Zone Management Act of 1972, as amended, administered by
the Office of Ocean and Coastal Resource Man-agement, National
Ocean Service, National Oceanic and Atmospheric Administration,
United States Department of Commerce, through the Office of
Planning, State of Hawaii.
Latitude/Longitude coordinatesUTM coordinates
159o19'20" W2440700mN
0
0 10km
10mi
KauaiPilaa
ava
Erosion RateAccretion Rate
SHORELINE CHANGE RATES
Historical shoreline positions are measured every 66 ft along
the shoreline. These sites are denoted by yellow
shore-perpendicular transects. Changes in the position of the
shorelines through time are used to calculate shoreline change
rates (ft/yr) at each transect location.
Annual shoreline change rates are shown on the shore-parallel
graph. Red bars on the graph indicate a trend of beach erosion,
while blue bars indicate a trend of accretion. Approximately every
fifth transect and bar of the graph is numbered. Where necessary,
transects have been purposely deleted to maintain consistent
alongshore spacing. As a result transect numbering is not
consecutive everywhere. The rates are smoothed alongshore using a
1-3-5-3-1 technique to normalize rate differences on adjacent
transects.
AREA DESCRIPTIONThe Pilaa study area (transects 44 - 97) is
located on the northeast coastline of Kauai. The shoreline is
composed of calcareous sand beach interrupted by basalt headlands
with a fringing reef offshore.
Overall, the area is eroding at an average rate of -0.6 ft/yr.
The area lends itself to division into four portions. The Waiakalua
Nui Beach (transects 44 51) is a large pocket sand beach located to
the north of Kakiu Point. This section of the study area is
experiencing erosion at an average rate of -0.8 ft/yr. Waiakalua
Iki Beach (transects 52 69) has experienced erosion at an average
rate of -0.7 ft/yr. Pilaa Beach (transects 71 97) is separated by a
low, rocky point. The western portion (transects 71 85) is eroding
at an average rate of -0.6 ft/yr. The eastern portion (transects 86
97) has expSerienced erosion at an average rate of -0.3 ft/yr.
Previous studies1 did not analyze the Pilaa study area
shoreline.
1 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.
-2
-1
0
1
-2
-1
0
1
Shoreline Change Rate (ft/yr)
44
50
55
60
65
69
45
5152
-2
-1
0
1
-2
-1
0
1Shoreline Change Rate (ft/yr)
71 75 80 85 90 95 9786
44
50
55
60
65
69
71 75
80
85
90
95 97
45
86
WaiakaluaIki Beach
PilaaBeach
KepuhiPoint
WaiakaluaNui Beach
Kulih
aili S
tream
51
52
KakiuPoint
