HR: 0800h
AN: H41B-0508    [Abstracts]
TI: Results from the Southeast Oahu, Hawaii, Shoreline Erosion Study Utilizing the PX and PXT Shoreline Erosion Rate Methods
AU: * Romine, B M
EM: romine@hawaii.edu
AF: University of Hawaii Coastal Geology, School of Ocean and Earth Science and Technology 1680 East West Road, POST 721, Honolulu, HI 96822, United States
AU: Genz, A
EM: agenz@hawaii.edu
AF: University of Hawaii Coastal Geology, School of Ocean and Earth Science and Technology 1680 East West Road, POST 721, Honolulu, HI 96822, United States
AU: Fletcher, C H
EM: fletcher@soest.hawaii.edu
AF: University of Hawaii Coastal Geology, School of Ocean and Earth Science and Technology 1680 East West Road, POST 721, Honolulu, HI 96822, United States
AU: Frazer, L N
EM: neil@soes.hawaii.edu
AF: University of Hawaii Coastal Geology, School of Ocean and Earth Science and Technology 1680 East West Road, POST 721, Honolulu, HI 96822, United States
AU: Barbee, M M
EM: mbarbee@hawaii.edu
AF: University of Hawaii Coastal Geology, School of Ocean and Earth Science and Technology 1680 East West Road, POST 721, Honolulu, HI 96822, United States
AU: Lim, S
EM: siangl@hawaii.edu
AF: University of Hawaii Coastal Geology, School of Ocean and Earth Science and Technology 1680 East West Road, POST 721, Honolulu, HI 96822, United States
AU: Dyer, M
EM: mdyer@hawaii.edu
AF: University of Hawaii Coastal Geology, School of Ocean and Earth Science and Technology 1680 East West Road, POST 721, Honolulu, HI 96822, United States
AB: It is imperative that coastal erosion studies produce valid erosion rates and erosion hazard predictions to aid in the development of public policy and protect coastal resources. Currently, the Single-Transect method is the most common shoreline change model, which calculates a rate at each shore-normal transect without regard to influences of data from adjacent transects along a beach. Improving on Single-Transect, the University of Hawaii Coastal Geology Group has developed the PX (Polynomial in distance X) and PXT (Polynomial in distance X and Time) shoreline change rate calculation methods, which model all the shoreline positions within a beach simultaneously using polynomial techniques. PX is a special case of PXT that models shoreline change rates spatially along a beach. PXT not only models the shoreline change spatially, but it lets the rate change with time (acceleration). This is an important advance, as beaches may not erode or accrete at a constant (linear) rate. A linear sum of basis functions characterizes the shoreline change rate for both PX and PXT. These methods are an improvement on previous methods as they produce more meaningful, i.e., statistically significant rates and erosion hazard predictions. We use an information criterion (gMDL) to (1) identify the number of coefficients of the basis functions that are needed to describe shoreline change in PX and PXT, and (2) compare different methods to determine which method best describes shoreline change. The southeast coastline of Oahu, Hawaii, features a range of beach morphologies and littoral dynamics well suited for further testing of the PX and PXT shoreline change rate calculation methods. The PX and PXT methods find significant rates for 70% of the study area versus 28% significant rates with the Single-Transect method. In companion with the work presented by Ayesha Genz on the PX and PXT rate methods, we present results from the Southeast Oahu Shoreline Study as a demonstration of the utility of the new rate calculation methods and for comparison with the previously used rate methods.
UR: http://www.soest.hawaii.edu/coasts/
DE: 1819 Geographic Information Systems (GIS)
DE: 3020 Littoral processes
DE: 3270 Time series analysis (1872, 4277, 4475)
DE: 4217 Coastal processes
SC: Hydrology [H]
MN: 2007 Fall Meeting