Investigation of shoreline change and migration along Wai-San-Ding-Zou barrier island, Central Western Taiwan

Wai-San-Ding-Zou is the largest barrier island in Taiwan area. Due to natural driving forces and active coastal development, this barrier island has been suffering tremendous changes over the years. By using SPOT data taken on September 28, 1986 and July 13, 1993, with 1 cm difference in tidal height, the maximum beach erosion rates across the central section are 193 m/yr and 89 m/yr on the eastern and western sides, respectively. Meanwhile beach accretion has appeared in northern, central and southern parts of the sand-bar. The maximum beach accretion rate in southern part amounts to 257 m/yr. By comparing SPOT data taken on July 13, 1993 and February 6, 1994 with 73 cm difference in tidal height, the slopes of the beach profile across the central part are found to be 0.19° and 0.079° on the western and eastern sides, respectively. The slope at the northern tip is even smaller, about 0.042°.