412002013

412002001

412002026

417900mE 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 419700mE80 81

417900mE 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 419700mE80 8124

3490

0mN

5051

5253

5455

5657

5859

6061

6263

6465

6667

6869

7071

7273

7475

7677

7824

3790

0mN

2434900m

N50

5152

5354

5556

5758

5960

6162

6364

6566

6768

6970

7172

7374

7576

7778

2437900m

N

159o47’40” W 20” 10” 159o47” W 50” 159o46’40” W30”

159o47’40” W 20” 10” 159o47” W 50” 159o46’40” W30”22

o 01’

00”

N10

”20

”30

”40

”50

”22

o 02’

N10

”20

”22

o 02’

30”

N22

o01’00” N10”

20”30”

40”50”

22o02’ N

10”20”

22o02’30” N

0

0 10km

10mi

KauaiMana

400 300200

1200 900600

100

3000

0100

300

Scale 1:3000Meters

FeetLatitude/Longitude coordinatesUTM coordinates

159o47’20” W2434800mN

N

Mana, Kauai, Hawaii

Contract C25514 Contract 7249

Charles Fletcher, Matthew Barbee, Siang-Chyn Lim,Matt Dyer, Michael Borger, 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.

0

5

10

15

20

25

30

17

33

19

34

HISTORICAL SHORELINES

1962MayMay

1966Apr 1975

Jul 1987Mar 1988Oct 1991

Erosion rate measurement locations(shore-normal transects)

1950NovMay 1927

Historical beach positions, color coded by year, are determined using orthorectified and georeferenced aerial photographs and National Ocean Survey (NOS) topographic survey charts. The low water mark is used as the historical shoreline, or shoreline change reference feature (SCRF).

Movement of the SCRF along shore-normal transects (spaced every 66 ft) is used to calculate erosion rates.

Sept 1992Nov 2006

Sept 1984

AREA DESCRIPTION

The Mana study area is located on the west coast of Kauai on the Mana Plain. The area includes the air strips of the Pacific Missile Range with Mana Point at the center of the area. The shoreline is characterized by ex-tensive beach rock backed by vegetated sand dunes and broken by carbon-ate sand beach. The study area is exposed to swell from the northwest and west during winter and spring months, swell from the west and southwest in the summer as well as persistent tradewinds.

The area is divided into three discrete sections for analysis and description purposes. The southernmost section (transects 0 – 15) is experiencing ero-sion at an average rate of -0.5 ft/yr. The next section to the north (transect 17) is eroding at a rate of -0.1 ft/yr. The northernmost section (transects 20 – 33) is eroding at an average rate of -2.4 ft/yr. Previous studies1 did not analyze the Mana 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.

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.

-101-101

0

5

10

15

Shoreline Change

Rate (ft/yr)

-101

-101 17

Shoreline Change

Rate (ft/yr)

Shoreline Change

Rate (ft/yr)

2025

3033

19

34

-4-3-2-101

-4-3-2-101

Mana

Mana Point

Kinikini

Kau

mua

lii H

wy.

Pacific Missile Rangeair strip

Pacific Missile Rangeair strip