451004008 451003006 451005051 451005041 451005004 451005045 451005046 451005048 451005049 451005047 451005044 451005050 451005043 451005006 451003011 451003013 451004025 451004013 451004015 451004011 451004035 451004023 451004014 451004010 451004016 451004040 30" 20" 10" 50" 159 o 22' W 40" 10" 20" 159 o 23'30" W 30" 20" 10" 50" 159 o 22' W 40" 10" 20" 159 o 23'30" W 40" 22 o 12'30" N 50" 22 o 13' N 10" 22 o 13'20" N 40" 50" 22 o 12'30" N 22 o 13' N 10" 22 o 13'20" N 38 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 34 33 35 36 37 461300mE 463900mE 38 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 34 33 35 36 37 461300mE 463900mE 60 61 62 63 64 65 66 67 68 69 70 2455900mN 71 72 73 74 75 2457600mN 2455900mN 2457600mN 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 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-sheet Feb Jul May Sept May Sept 1962 1971 1975 1999 1987 1988 1984 Sept Jan Nov 2008 1999 Pilaa, Kauai, Hawaii 400 300 200 1200 900 600 100 300 0 0 100 300 Scale 1:3000 Meters Feet N 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 159 o 19'20" W 2440700mN 0 0 10km 10mi Kauai Pilaa ava 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 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 studies 1 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 51 52 -2 -1 0 1 -2 -1 0 1 Shoreline Change Rate (ft/yr) 71 75 80 85 90 95 97 86 44 50 55 60 65 69 71 75 80 85 90 95 97 45 86 Waiakalua Iki Beach Pilaa Beach Kepuhi Point Waiakalua Nui Beach Kuli haili Stream 51 52 Kakiu Point