o shipwreck beach, kauai, the shipwreck beach study area (transects 0– 20) is located on the...

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30"20" 10" 50"159o26' W 40" 159o25'10" W20"159o26'30" W

30"20" 10" 50"159o26' W 40" 159o25'10" W20"159o26'30" W

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AREA DESCRIPTION The Shipwreck Beach study area (transects 0– 20) is located on the southeast coast of Kauai. The shoreline is composed of carbonate sand beach interrupted by basalt headlands. Overall, the area is experiencing erosion at an average rate of -1.2 ft/yr. Previous studies1 found similar trends in shoreline change for the Shipwreck Beach study area. 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.

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.

T-sheet 1927

May 2000

Apr 1975 Jan

Mar

1982

1988 1987Jul

Oct 2007

Erosion Rate Accretion 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.

-3

-2

-1

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Shore line C

hang e Rat

e (ft/y r)

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Shipwreck Beach, Kauai, Hawaii

400 300200

1200 900600

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Scale 1:3000 Meters

Feet Contract C25514 Contract 7249

Charles Fletcher, Matthew Barbee, Siang-Chyn Lim, Julia Ehses, Matt Dyer, and Ayesha Genz University of Hawaii Coastal Geology Group School of Ocean and Earth Sciences and Technology 1680 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 coordinates UTM coordinates

159o26'30" W 2418400mN

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Kauai

Shipwreck Beach

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Shipwreck Beach

Keoniloa Bay

Makawehi