HR: 0800h
AN: H41C-0322    [Abstracts]
TI: A Method of Discriminating Littoral Cells Using Stacked Erosion Transect Data
AU: * Genz, A S
EM: agenz@hawaii.edu
AF: University of Hawaii SOEST, Department of Geology and Geophysics 1680 East-West Road, Honolulu, HI 96822 United States
AU: Fletcher, C H
EM: fletcher@soest.hawaii.edu
AF: University of Hawaii SOEST, Department of Geology and Geophysics 1680 East-West Road, Honolulu, HI 96822 United States
AU: Dunn, R A
EM: dunnr@hawaii.edu
AF: University of Hawaii SOEST, Department of Geology and Geophysics 1680 East-West Road, Honolulu, HI 96822 United States
AB: Historical aerial photogrammetry and erosion-based statistics offer a new approach to identify littoral cells within alongshore contiguous beach systems, which are usually determined by visual assessment that becomes difficult to analyze when sediment input occurs from multiple sources. Historical aerial photogrammetry, making use of topographic surveys (NOAA T-Sheets) and vertical aerial photographs, has been successfully utilized in calculating shoreline change rates on beaches. We employ the Maui historical shoreline database to identify littoral cells on a decadal time scale. Shoreline change rates are calculated at shore normal transects spaced 20 m alongshore. These datasets are typically limited and characterized by low signal-to-noise ratio. To reduce noise and non-random errors, we stack data from transects belonging to the entire length of a beach onto one plot and calculate change rates using the Weighted Least Squares (WLS) method. We compare stacked rates with the individual transect rates to determine disagreements between them by using the F-test statistic at a 95% confidence interval. We divide the beach into littoral cells where disagreements occur until a majority of the individual transects agree with the stacked rate. This procedure shows that various types of beaches on Maui breakdown into different numbers of littoral cells.
DE: 4546 Nearshore processes
DE: 3210 Modeling
DE: 1815 Erosion and sedimentation
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting