An Integration of Remote Sensing and GIS to Examine the Responses of Shrub Thicket Distributions to Shoreline Changes on Virginia Barrier Islands

Abstract

The high-water-shoreline positions in 1852, 1871, 1910, 1919, 1943, 1955, 1967, 1980, and 1990 for Hog Island, a barrier island located at the eastern shore of Virginia, were determined with the NOS T-sheets and aerial photographs. Shrub thicket distributions for northern Hog Island were extracted from black/white and infrared color aerial photographs for the years of 1949, 1962, 1974, and 1989. The overlay operations between shrub age and land age data layers indicated that shrub coverage on Hog Island was closely related with shoreline changes. By examining 138-year shoreline changes on 50-m-interval transects of Hog Island, it was found that the sine function could describe shoreline change patterns better than earlier used simple models. The overlay between old NOS T-sheets and 1993 TM  satellite image suggested that there would be at least three types of shoreline changes for different barrier islands. All these three types of shoreline change patterns could be interpreted with the sine function model. The potential distribution of shrub thickets on Hog Island was simulated based on the shoreline change model. The shrub line and shoreline positions were closely related with each other, but there were time lags between shrub thicket expansion and shoreline accretion.