poipu, kauai, hawaii · the poipu study area (transects 0 - 21) is located on the south coast of...

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  • 428014019

    428022026

    428022016

    428021001

    428022017428014999

    428017009

    428022004

    428021041

    428016004

    428015082

    428017024

    428016003

    428017011

    428020035

    428020008

    428027017

    428016007

    428017007

    428019022

    428014021

    428017001

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    428027018

    428027019

    428020003

    428014029

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    428014026

    428028093

    428017010

    428014018

    428022999

    4280

    1702

    7

    428027022428027999

    4280

    2399

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    4280

    1702

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    428019004

    428028999

    428019016

    428022010

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    428017016

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    4280

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    4280

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    428017023

    4280

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    428027001

    42801701

    4

    4280

    1803

    8

    4280

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    428020

    004

    4280

    2002

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    4280

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    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