451004008

451003006

451005051

451005041

451005004

451005045451005046

451005048

451005049

451005047

451005044451005050

451005043

451005008

4510

0500

6

451003011

451003013451004025

451004013

4510

0401

5

4510

0401

1451004035

451004023

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

Kuli

haili

Stre

am

51

52

KakiuPoint