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4280

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9

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1701

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1701

8

428027001

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4280

1803

8

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1903

1

4280

1800

1

428020004

4280

2002

5

4280

2702

6

4280

1700

5

428019003 4280

2001

0 428020014428018030

428019017

4280

1702

1

4280

1600

2

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1800

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6428018020

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4280

1900

9

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0

40"30" 20" 159o27' W10" 50" 159o26'30" W159o27'40" W

40"30" 20" 159o27' W10" 50" 159o26'30" W159o27'40" W

22o 5

2' N

10"

20"

30"

21o 5

2'40

" N

22o52' N

10"20"

30"21

o52'40" N

23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 4342 454400mE452200mE

23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 4342 454400mE452200mE

2418

000m

N81

8283

8485

8687

8889

9091

9293

9424

1950

0mN

2418000m

N81

8283

8485

8687

8889

9091

9293

9424195

00mN

HISTORICAL SHORELINES

JanNov

19281950

Mar 1972

1926 T-sheet

AprJul

Oct

SeptNov

19751987

2007

19921999

1988Mar

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.

Mar 1960

Apr 1975

Poipu, Kauai, Hawaii

400 300200

1200 900600

100

3000

0100

300

Scale 1:3000Meters

Feet

Contract C25514 Contract 7249

Charles Fletcher, Matthew Barbee, Siang-Chyn Lim,Julia Ehses, Matt Dyer, and Ayesha Genz University 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

159o27'40" W2418000mN

0

0 10km

10mi

Kauai

Poipu

ava

N

105

65

70

75

80

90

95

100

110

115

120

123

-2

-1

0

1

-2

-1

0

1

85

Shoreline Change Rate (ft/yr)

97 98

118

119

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 Poipu study area (transects 0 - 21) is located on the south coast of Kauai. The area is bounded by Lae o Kamilo to the west and Makahuena Point to the east. The shoreline is characterized by small pocket beaches interspersed among basaltic headlands.

Overall, the area is undergoing erosion at an average rate of -0.7 ft/yr. The area lends itself to division into three portions. The western portion (transects 65 – 97) is located between Lae o Kamilo and Kiahuna. This section is experiencing erosion at an average rate of -0.7 ft/yr. Poipu Beach Park (transects 98 – 118) to the east of Kiahuna has experienced erosion at an average rate of -0.5 ft/yr. Brennecke Beach (transects 119 – 123) has experienced chronic erosion at an average rate of -0.9 ft/yr. Previous studies1 did not analyze the Poipu 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.

Poipu

65

70

75 80

85

90

95

100

105

107

108

110

115

120

123

117

9798

119

Poipu Road

Poipu Road

Nu KumoiPoint

PoipuBeach Park

BrenneckeBeach

Lae o Kamilo

Kiahuna

MakahuenaPoint