anahola, kauai, hawaii · the anahola study area (transects 45 - 174) is located on the east coast...

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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 Apr 10 Apr 12 1988 1975 1975 Jul 1987 Sep Nov Oct 1992 1996 2007 1927 T-sheet Sep 1999 Contract C25514 Contract 7249 Charles Fletcher, Matthew Barbee, Siang-Chyn Lim, 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 22 o 09'50" W 467400mE 400 300 200 1200 900 600 100 300 0 0 100 300 Scale 1:3000 Meters Feet N 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. AREA DESCRIPTION The Anahola study area (transects 45 - 174) is located on the east coast of Kauai. The area is bounded by Aliomanu Beach to the north and Kahala Point to the south. 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 -0.4 ft/yr. The area lends itself to division into three portions. Aliomanu Beach (transects 45 – 88) is located to the north of Kuaehu Point. This section of the study area is experiencing erosion at an average rate of -1.1 ft/yr. Anahola Beach (transects 89 – 128) to the north of Anahola River has experienced erosion at an average rate of -0.6 ft/yr. Anahola Beach Park (transects 129 – 174) to the south of Anahola River has experienced accretion at an average rate of 0.3 ft/yr. Previous studies 1 found similar trends in shoreline change for the Anahola 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 3 -2 -1 0 1 2 3 45 50 55 60 65 70 75 80 85 90 88 89 95 100 105 110 115 120 155 160 165 170 174 Shoreline Change Rate (ft/yr) 125 130 135 140 145 150 128 129 Anahola Bay Anahola R iver Kahala Point Kuaehu Point Anahola Beach Park 45 50 55 60 65 70 75 80 85 88 90 89 95 125 100 105 110 115 120 130 135 140 145 150 155 160 165 170 174 47 128 129 Aliomanu Beach Anahola Beach

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Page 1: Anahola, Kauai, Hawaii · The Anahola study area (transects 45 - 174) is located on the east coast of Kauai. The area is bounded by Aliomanu Beach to the north and Kahala Point to

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Anahola, Kauai, Hawaii

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ava

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.

Mar

Apr 10Apr 12

1988

19751975

Jul 1987

SepNov

Oct

19921996

2007

1927 T-sheet

Sep 1999

Contract C25514 Contract 7249

Charles Fletcher, Matthew Barbee, Siang-Chyn Lim,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

22o09'50" W467400mE

400 300200

1200 900600

100

3000

0100

300

Scale 1:3000Meters

Feet

N 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 Anahola study area (transects 45 - 174) is located on the east coast of Kauai. The area is bounded by Aliomanu Beach to the north and Kahala Point to the south. 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 -0.4 ft/yr. The area lends itself to division into three portions. Aliomanu Beach (transects 45 – 88) is located to the north of Kuaehu Point. This section of the study area is experiencing erosion at an average rate of -1.1 ft/yr. Anahola Beach (transects 89 – 128) to the north of Anahola River has experienced erosion at an average rate of -0.6 ft/yr. Anahola Beach Park (transects 129 – 174) to the south of Anahola River has experienced accretion at an average rate of 0.3 ft/yr. Previous studies1 found similar trends in shoreline change for the Anahola 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.

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